Omega-3s and brain health: What the science really says with Dr. Bill Harris and Prof. Sarah Berry

Omega-3 fatty acids have long been lauded for heart health benefits. Yet, emerging research now points to an even more profound impact, directly on our most complex organ: the brain. 

Today, we delve into the critical, often misunderstood, role of omega-3s in cognitive function, mental well-being, and even the prevention of neurodegenerative conditions like dementia.

In this episode, Dr. Harris — along with ZOE's Chief Scientist Professor Sarah Berry — illuminate why most individuals may be operating with suboptimal omega-3 levels, and the tangible implications this has for mood regulation, anxiety, and long-term brain resilience.

We navigate nuances between omega-3 types like EPA and DHA, debunk common misconceptions surrounding plant-based sources and mercury content in fish, and explore the precise methods for assessing and improving your own "Omega-3 Index."

Try our new plant-based wholefood supplement* Daily30+

*Daily30 is naturally high in copper which contributes to normal energy-yielding metabolism and the normal function of the immune system.

We don't buy the hype — and neither should you

Our new app reveals what the food labels won't, using data from the world's largest nutrition study run by ZOE. (Only available in the US)

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Transcript

Jonathan Wolf: Bill, thanks for joining us today. 

Dr. Bill Harris: Glad to be here. Thank you. 

Jonathan Wolf: And Sarah, it's great to have you as my co-host today. 

Sarah Berry: Pleasure. 

Jonathan Wolf: So, Bill, we have this thing that we always do at the start of the show, which is a set of rapid-fire questions and answers that come in from our listeners. 

Now we have one very strict rule, which is very hard for professors: you're allowed to say yes or no, or if you have to, a one-sentence answer. Are you willing to give it a go? 

Dr. Bill Harris: Let's try it. 

Jonathan Wolf: Alright. Are the majority of people in the West deficient in omega-3? 

Dr. Bill Harris: Yes. 

Jonathan Wolf: Are plant-based sources of omega-3 as good as animal sources? 

Dr. Bill Harris: No. 

Sarah Berry: Is grass-fed beef high in omega-3? 

Dr. Bill Harris: No.

Jonathan Wolf: Are supplements the best way to get adequate amounts of omega-3?

Dr. Bill Harris: They're an adequate way, I prefer food. 

Sarah Berry: Bill, could consuming adequate omega-3s reduce your dementia risk. 

Dr. Bill Harris: Yes. 

Sarah Berry: And what's the biggest myth you've heard about omega-3s? 

Dr. Bill Harris: That plant-based omega-3s are the same as fish-based omega-3s. 

Sarah Berry: Love that one, I hear that all the time. 

Dr. Bill Harris: And it's not true. 

Jonathan Wolf: That's a myth.

Sarah Berry: Absolutely not true. 

Jonathan Wolf: I remember growing up that my parents always had fish oil supplements, and there was also a period that I was being told I should be eating lots of salmon. Then I feel I was told, well, that's not such a good idea. Now I'm just sort of confused about omega-3s.

I suspect there are a lot of listeners who are in the same situation that I'm in. I understand that you just have some fascinating new research about how omega-3s might affect not just our heart health, but also our brain health from mental health to dementia.

But before we jump into how this affects our health, could we just start with, what are these omega-3 fatty acids? Why are they essential? Why do we care? 

Dr. Bill Harris: Why do we care? So, omega-3 fatty acids are fatty acids typically found in fish oils. They're made primarily by these little single-cell organisms in the ocean that convert sunlight and sugar into omega-3 fatty acids.

Then the little fish eat the little cells, and then the big fish eat the little fish. And so like salmon, for example, doesn't really make omega-3 any better than we do, but they eat it. So their levels are high because they eat a lot. 

Why are they essential? Sitting here with Sarah, I can't really say essential because, EPA and DHA, which are the two omega threes that are most important, that are in fish oils are not actually essential in the diet because strictly speaking, in a nutritionist point of view, if you have an essential nutrient, if you don't eat it, you die. 

There are plenty of people on this planet who are vegans, who eat no preformed EPA or DHA, they eat the precursor. and that apparently gives them enough to survive, grow up, reproduce, and live a life.

So I think of EPA and DHA omega-3s as very bioactive, very important for health, but not essential for life. 

Jonathan Wolf: I've gone from omega-3s, and now you've already mentioned DHA and EPA. Could you just help me to understand that? 

Dr. Bill Harris: Right. So omega-3 is like a class, a family. If you look at the chemical structure of it, they all have a similar last name, so to speak, which is omega-3, and then there are four or five fatty acids in that family.

The three that we hear most about, one is called ALA, which is alpha linolenic acid, which is a plant-based omega-3, and then it's grown-up super cousins are the two that we get in fish, which are called EPA and DHA. 

EPA and DHA are the two that are in fish. ALA is the one that's in plants, and those are the three major ones in the family.

Jonathan Wolf: Why do they matter at all? You were saying they're not literally essential, so I can live without them. So they're not like vitamin C, I don't get scurvy. 

Dr. Bill Harris: Correct. You don't get scurvy. Right. 

Jonathan Wolf: But I get the sense that they are doing something of importance.  

Dr. Bill Harris: They are important for many biological factors.

They find their home, and when we eat them, they end up getting into cell membranes. All of our cells have some, or a little, or a lot of omega-3, depending on really, how much you eat. 

I think the way I like to explain why they're useful, it's a little difficult sometimes because it's not like you can say, for vitamin C, you know, if you don't have vitamin C, your teeth fall out. Okay, that's a problem. 

Omega-3 is more subtle. But as the omega-3s get into the cell membranes, they sort of act like grease on a hinge on a door. Because every cell has doors that let good things in, like nutrients. And the cell also has a door that opens up, out, to dump the trash. 

And if you've gotten enough omega-3 in your cell membranes, those doors swing smoothly. If you don't, they don't swing so smoothly, and some of the good stuff doesn't get in. Some of the bad stuff doesn't get out as well, and the cell just gets older and unhealthy. 

Jonathan Wolf: So they sound quite important. 

Dr. Bill Harris: They're important. 

Sarah Berry: And Bill, I'd love at this point to pick up on the myth that you said, which is about plant-based sources.

Because you've now talked about EPA, DHA, which are found in fish, and then ALA, the alpha-linolenic acid, which we know can come from plant sources. 

Lots of people say, Well, you can get all the EPA and DHA you need from plant sources. But we know that actually, how much you can convert is actually, quite small.

Dr. Bill Harris: Quite small. 

Sarah Berry: And so I wonder if you could explain a little bit about that to listeners. 

Dr. Bill Harris: Sure. There is a mechanism in the body. There are processes that will take ALA, which is 18 carbons long. So fatty acids are simply a linear chain of carbon atoms. And this one's 18 carbons long, and it has three, what we call double bonds in chemistry. Many fatty acids have no double bonds. These have three double bonds. 

The EPA and DHA are 20 or 22 carbons long, and they have five and six double bonds. So, in order to go from the ALA, which is 18 carbons in three, you’ve got to add two or four more carbons to the molecule, and you’ve got to add more double bonds. There's a lot of processing there, and it's difficult to do.

Maybe 5% of the ALA you eat, might get converted to EPA, and less than that, it goes on to DHA. 

So if you really want to increase your EPA and DHA levels, the important omega-3s, eating them preformed. This is the best way to do it. You don't have to make them. 

Sarah Berry: Yeah, and I think that's a really important point because lots of people, Jonathan say, Well, you can get all of your really good omega-3s, which is what Bill's been talking about, the EPA and DHA from plant sources through this process in the body where it converts the ALA to these longer chains, more desaturated versions.

But actually, the conversion is really limited. So it's interesting, estimated only around 5%. And so that's why as nutrition scientists, we always say, if you can, get what we call preformed EPA and DHA, because our bodies are pretty rubbish at converting it. 

Jonathan Wolf: Can I just ask one clarification? Because you were describing the way that these omega-3s help my cells let things in and out better, and this is why it's like a more finely performing cell is how I was understanding.

Dr. Bill Harris: Sure. I think that's fair. 

Jonathan Wolf: It needs to be the EPA and DHA types of omega-3, not the ALA that was from plants, is that what you're saying?

Dr. Bill Harris: That's correct. 

Jonathan Wolf: So, if I eat all of this stuff from plants, it's got this ALA omega-3, but then my body, I'm thinking about some sort of like refinement process, right from crude oil to petrol.

It's a lot of hard work to turn this then into these special forms of omega-3, right. But if I were to eat them directly, then I don't need to do the refinement, and it goes straight to helping me out. 

Dr. Bill Harris: Exactly. Yeah. A fair amount of the ALA we eat just gets burned like other fats, so it doesn't even get a chance to be converted into EPA and DHA in the liver, which is pretty much where that happens.

So, right away, we're behind the eight ball because you're losing a lot of it just for energy. 

Sarah Berry: Omega-3. Like Bill said, it's a big family. Have different fatty acids, but each of them have different roles.

The ALA has a different role to the DHA, to the EPA, for example. And so that's why you can't just assume if you've got ALA in your nuts that, hey, that's you on omega-3 sorted. 

So Bill, lots of people are eating less fish now than before. Lots of people are vegan, lots of people are vegetarian. Can you estimate what the prevalence is in the U.S. in the U.K. of people who are deficient in omega-3 

Dr. Bill Harris: Oh, who are deficient in omega-3? Well, we need to define deficient. 

The healthiest level we think, from our research, is 8%. Meaning 8% of fats in the membrane are EPA and DHA. The level that's fairly common in the U.S. and western Europe is around 5%. 

We've seen vegans and U.S. military personnel, sorry to say, in the 3.5% level, which is quite low.

So under 4%, we think, is where you don't want to be. Over 8% is where you do want to be. About 90-95% of Americans are under that 8%. So to call that deficient, I'll say that they're not optimal. 

Sarah Berry: And I think that 8% that I often teach to our students, the omega index, I know you've published a lot on, I always explain to them, this is kind of what I would consider optimal, based on your research, that's optimal in terms of a lower risk of cardiovascular disease, a lower risk of all cause mortality, those kind of outcomes.

Dr. Bill Harris: That's true. Right. It's linked with many good outcomes. And so 8% is uncommon. It's achievable. 

Jonathan Wolf: If generally you get these best forms of omega-3 from these oily fish, lots of our ancestors grew up nowhere near a salmon or an oily fish, and I often hear this story: we come from hunter-gatherers in Africa.

Can you help me to understand, were there omega-3 sources there? Is this about saying that as human beings, we work fine without them, but we can be much better with them. 

Could you just help me to understand that? 

Dr. Bill Harris: First of all, let's examine some of those premises because human beings have always needed water. Wherever they live, they have water. 

Of course, there's sea coasts, and there's rivers. So people have always been able to get fish, because they have to be by the water, and the fish live in the water. 

It's interesting, if you look at all the major religions in the world, fish symbols are all over the place. So fish has always been there. 

You're right, the richest in omega-3 are the deep sea ocean-going fish. But fish in rivers too, do have some omega-3 fatty acids too. So I think people have always been getting preformed omega-3 from eating fish. It's not like at one time we didn't have any omega-3, and then we did. 

Jonathan Wolf: Because I hear this word oily fish. It's not just salmon… 

Dr. Bill Harris: Those are the best  sources, but not the only sources. 

Jonathan Wolf: But a lot of other fish had some, so we would've got this in our diet. 

Dr. Bill Harris: Yes, it's a full spectrum of omega-3 levels. 

So all I know, is in the current context, pretty much of the Western diet where we have plenty of calories, we have plenty of omega-6, we have plenty of other nutrients. We know now that this 8% is a healthy target. 

If you go back 200 years, people didn't live past 50 years old. So a lot of these diseases of aging that we see now weren't a problem then, because people didn't live to see them. So it's hard to really guess what's going on in human evolution.

Jonathan Wolf: That's actually a brilliant transition to my next question, really, which is understanding how these omega-3s are actually affecting our health. 

You were describing that with this omega index, you have an 8% level, it's much better than 5%. What is that affecting in somebody's health?

Dr. Bill Harris: Every cell gets these signals from the body, from outside the body saying, Hey, we've got an inflammation we've gotta deal with. And the cell has to respond and make certain chemicals. 

If it responds properly, the inflammation comes and then it goes away. and that's the way it's supposed to be.

Cell membranes become more flexible. Stiff cell membranes don't respond very well, flexible ones are able to be kind of fleet of foot. You can move quickly. 

The general idea is just being flexible is a good thing, and the omega-3s help make that membrane more flexible. 

Jonathan Wolf: So the first time I heard about omega-3s was related to heart health. I think that was the story there as just a regular member of the public. Picked up. Is that right? And how does that work? 

Dr. Bill Harris: Yeah. In the 1970s, two investigators from Copenhagen, Dyerberg and Bang, heard these stories about these Inuits in Greenland who were apparently not having heart attacks, despite the fact they were eating by the standards of the day in 1970.

This terrible diet, virtually no fruits and vegetables, lots of saturated fat, lots of animal fat, lots of cholesterol. They should be falling over from heart attacks all the time by our current worldview. But they were not. It was a paradox. 

So they went over to check it out and they analyzed the food, they analyzed the blood of these people and what's going on. They found on their analysis of the blood and the food, these unusual fats, fatty acids, EPA, and DHA, and said, Well.

Then they started thinking, well, that's different than the Danes back home. They don't have those fatty acids in their blood. What do they do? And then these guys did some experiments to show that actually these fatty acids make the blood thinner, less likely to clot. 

And they said, Aha, that's why they don't have heart attacks, because these fatty acids are reducing the tendency of the blood to clot. And it was believed at the time, it's still somewhat true that a clot in the coronary arteries of the heart will cause a heart attack. 

So if you can prevent that, kind of like taking an aspirin, same idea, but this came from food. So it all began in heart disease. 

Jonathan Wolf: You said that's how we understood it then. Do we still believe it's important for our heart health, and if so… 

Dr. Bill Harris: Oh yes. There's no uncontroversial fatty acid at this point, except perhaps trans fats, I don't know. 

But they’re very complicated. All the fatty acids do different things. And there's again, omega-6 family, omega-3 family, a monounsaturated family, a saturated family, and there's subsets of all those.

We are much more understanding of what individual types of fatty acids do, which they didn't know at the time. Back in the seventies, it was animal fat was bad, plant fat was good. End of story. 

We had this thing called a P to S ratio. The polyunsaturated de-saturated ratio, and the Eskimo diet didn't fit well into that paradigm. 

So it just didn't make sense until these Danish investigators said, these two fatty acids are actually good. And so it kind of opened up the window into individual fatty acids are having different roles in biology and we need to understand them.

Sarah Berry: And I think in those experiments that they did with the Inuits many years ago, there's a really nice way to visualize it. If you were to cut your finger, so when the Inuits cut their finger, they bled for a lot longer than the Danes because their blood, they simply put, like Bill said, it is thinner.

So you're producing less of these kind of clotting factors, et cetera. So they just keep bleeding. I mean Okay, eventually…

Dr. Bill Harris: To a point, yeah. This is one of the controversies about omega-3s now, do they increase risk for bleeding? And the answer really is no in a meaningful way, but nobody's eating the amount of omega-3 that these Eskimos ate either.

Jonathan Wolf: And you said that there was a theory then about how it helped our heart health, but maybe this has changed. 

So today, how do we understand that these EPA and DHA are helping our hearts? 

Dr. Bill Harris: Yeah. It's that and more. Yes, they still thin the blood. And yes, that is still a mechanism by which they reduce risk for heart attacks.

But they also affect the heart muscle in different ways. One thing they do is, and it's not really clear how they do it, but they actually lower your heart rate, drops your heart rate from 2, 3, 4 beats a minute, which has long-term effects. 

Some people think you get a certain number of heartbeats per life and that's it. You know, once they're all used up, they're used up. 

We've looked at animals with slow heart rates, long lives. Animals with really fast heart rates, short lives. And so reducing heart rate, actually, is a good thing. 

It's help is your body's using oxygen better, the blood is flowing better, the cells are using the oxygen because it doesn't have to beat so fast. So that's one thing it does. 

It also reduces the chance that you will have what we'll call an arrhythmia, which is when the heart beats irregularly. And that can be fairly innocuous or lethal, depending on where it is and how it happens. So the omega-3s reduce the risk for that.

They reduce blood pressure to some extent. They reduce levels of one of the blood lipids called triglycerides, which is a somewhat of a risk factor for heart disease. They make the blood vessels more elastic so that they're not so stiff, so the blood can can get… and the red blood cells can probably move because they're more flexible. 

They have to kind of line up when they go through a capillary at the end of the arterial system, to get into the tissues, they have to line up and go one by one through these little capillaries and they have to compress, which is where they offload oxygen, pick up carbon dioxide and head back to the heart. 

The omega-3s make it easier. A rich omega-3 level in a cell makes it easier to do that. So all these things play together for heart health.

 Sarah Berry: Yeah, and I think it's fascinating when you hear Bill explain it, so many different mechanisms. Some people just talk about cholesterol or just talk about blood clotting. There's so many different ways that the EPA, the DHA omega-3s impact factors related to heart health. 

I think what I've seen recently, it's been a little bit frustrating, is some controversy because of some really big studies that came out saying, actually no, omega-3 supplementation doesn't help heart health.

I think it's a really important point of time to kind of clear that up, that there are lots of studies out there that consistently show improved effects on these intermediary risk factors. 

Yes, there has been the odd epidemiological study, that may be questions there. But actually, if you look at the totality of the evidence, and you look at, depending on dose, you look at, depending on who's actually receiving it, is it pre-heart attacks, post-heart attacks, et cetera.

I would love you to give a top line of whether you as an expert in this agree that taking it as a supplement improves heart health. 

Dr. Bill Harris: Yes, I think it does. And just a short little rabbit trail. You mentioned cholesterol. If I had another shot at a myth, is that fish oils lower cholesterol, but they do not. They lower triglycerides, which is another blood limit. 

So anyway, that's off the table now, and that's okay. They still reduce risk for heart disease. 

So the controversy that you're referring to is about atrial fibrillation. It's called AFib, and that's not a fatal kind of rhythm. There's a ventricular rhythm arrhythmia, which means the lower parts of your heart go wacky and they'd stop pumping blood and that’ll kill you right away. That's bad. 

But atrial fibrillation, which is the two upper chambers, when they don't quite beat in synchrony, it doesn't kill you by any means. It's annoying. It feels like a fast heartbeat and it does increase risk for strokes. Because if your blood is not moving properly through the heart, you can actually have some blood clots in your heart that go to your brain.

So that's a concern about afib. And there have been two or three big studies where they gave high doses of omega-3 and actually pharmaceutical forms of omega-3 to patients who are at very high risk for heart disease. It was the point of the study to see if they could help. And in both of those studies, they saw a small increase in risk for atrial fibrillation from the people that were getting the omega-3, the high dose, roughly three or four grams of EPA and DHA, which is way beyond what most people would ever supplement.

These studies have a placebo group that's getting nothing essentially, and then you have your omega-3 group.

The placebo group say, had developed over this four or five years, 2% of the people developed AFib on the omega-3 side, 3% developed AFib.

Well, the way we express that in medicine is that's a 50% increase in risk because 3% is 50% higher than 2%, but it's only 1% what we call absolute risk increase. Very small. 

Actually, this is not published yet, but we've just finished a big meta-analysis with summary of lots of studies together that have looked at this. And we found that this only occurs in that particular setting. 

High risk cardiovascular patients getting three to four grams of EPA and DHA. That's a group where this increased happens. Again, it's a small absolute risk, but in people who are just taking dietary supplements or eating fish, there's no increased risk for AFib.

So it's not a concern for the dietary supplement world, or the fish-eating world, because you're not getting those three and four grams a day of EPA. 

Most people taking dietary supplements are getting probably between 500 and maybe 1500 milligrams a day of EPA and DHA. That would be a great dose, but it's not the three and four grams.

So it's the high dose, I think, that's causing this concern about atrial fibrillation. Fish oil supplement use is not associated with increased risk for any cardiovascular outcome. 

Sarah Berry: It's so conclusive that fish supplementation improves so many aspects related to heart health, except for a minority of people at very high dose.

Jonathan Wolf: Could you clarify then, I guess, when you look across all of this,  what are the benefits for heart health 

Dr. Bill Harris: Consistently, we see people who have the highest omega-3 levels live longest. And a good example of that is Japan.

The Japanese, just because of their diet, have an omega-3 index that's about 8% or 9% on average, so it's like twice as high as the West, and they live on average for four and a half years longer than we in the U.S. live. 

Despite the fact they smoke more, despite the fact they have more high, high blood pressure than we do, despite the fact they have more stress than we do, they live longer. And I hate to attribute all of that to an omega-3 effect and I can't. But I can say that's one brick in the wall.

And when we look at risk for death from heart disease, it's the same story. Higher omega-3, lower risk for death from heart disease, lower risk for death from cancer, lower risk for death from all other causes combined with high omega-3. 

So it's doing something across not just heart health. It's helping us stay alive and resilient longer.

Jonathan Wolf: And if you choose to take supplements, is there evidence that if you take supplements, that that will improve my heart health? 

Dr. Bill Harris: Yeah. That's again, back to the U.K. Biobank. There have been several studies that just looked at fish oil supplement use: yes/no. 

It's a very crude measure because we, we don't know how much they're taking, how frequently they're taking, you know, what product they're taking, any of that stuff. It's just a yes no. 

But the people who are taking omega-3 supplements in that UK Biobank are lower risk for multiple kinds of heart outcomes. 

We've looked at stroke and we looked at blood levels of omega-3, which is much better than asking people if they take fish oil, just look at their blood levels. And we find that the higher the blood level, the lower the risk for stroke.

Which contradicts that whole atrial fibrillation concern because the problem with AFib is increased risk of stroke. Well, even in the big studies with the pharmaceutical products where they reported this 1% or 2% increase in risk for AFib, they had  20% reduced risk for stroke.

So the omega-3s are still benefiting heart health and in a wide variety of ways. Even in these people, again, with high risk for heart disease who are taking high dose, pharmaceutical products, they're still getting a lot of good heart benefit, even if there's a small increased risk for AFib.

Sarah Berry: So I think, Jonathan, the evidence is really clear that omega-3s beneficially impact heart health. I think it's really important to say as well for any skeptics out there, one fantastic thing about omega-3 is because we can't make it. It means that any increase in the blood we know is coming from what you are eating.

Because people often say, Oh, well how do you know it's because of what they're eating. So this is one fat that we can say, actually, what's in the blood is coming from the food you're eating. 

So I think where there's some really exciting new research though, is around brain health. And I think this is something certainly when I was teaching, even up until a few years ago, a lot of what I was saying was, oh, we just don't know yet.

And I know this is something you focused on more recently in your research, so it'd be great to understand a little bit about what the latest evidence says around omega-3 and brain health. 

Dr. Bill Harris: Sure. I'm sure when you do your lectures, you start with babies in the womb and the formation of the brain in the first place.

Which is very important because the brain has a lot of one of the two omega-3's called DHA. It's part of the structure of the brain. It’s important from the very beginning in your eyes too, right? 

Actually the eye is an extension of the brain and the level of omega-3 in the retina, the back of the eye, is one of the highest in the whole body.

So it's there for a reason. It's always there for a reason. The omega-3 story in dementia has been growing over time. 

We know that, when they do autopsies on people who died of dementia compared to controls who died of something else, those who had dementia have lower omega-3 levels in the brain. That's one piece of the story. 

We've seen that higher levels of omega-3 in the blood, higher omega-3 index predicts a lower risk for developing Alzheimer's disease or all cause of dementia, over time. So that's another important piece of it. 

If you're B vitamin nutrition is good, then the omega-3s seem to increase, help increase cognition, improve brain health, reduce risk for developing dementia.

If your B vitamin levels are too low, actually, I'm talking about homocysteine, which is a particular molecule in the blood that's kind of a barometer of how well your B-vitamins are working. If that homocysteine level is high, the omega-3 effect goes away. 

So there's what we call an interaction here between those two nutrients. And so it's important to get good B vitamin nutrition, good omega-3 nutrition for brain health. 

But it's been difficult to show in the kind of randomized trial that we're all used to. Give somebody some omega-3 for three or four years and then another group not, and then see who develops dementia. We haven't got time. Either that, or you pick people who are already so far down the road you can't do anything about it.

So at this point, the omega-3 and brain health connection is mostly, I think, based on these observational data, what we call epidemiology, more so than randomized trials. Because we haven't got that much randomized trial data yet.

Sarah Berry: And what about in relation to mental health more generally? 

Dr. Bill Harris: We've just got a paper accepted a couple days ago on anxiety and depression as a function of omega-3 levels. And again, higher omega-3 levels are always linked with less current depression and anxiety and less risk for developing over time.

Jonathan Wolf: And Bill, I think a lot of people listening will be really surprised the shift from heart health and dementia, to anxiety and depression. 

Because most of us were brought up with this idea that our mind and our bodies are separate and the first is really physical. But anxiety and depression, how could that be affected by how much salmon I ate? 

Do you understand at all what's going on there? 

Dr. Bill Harris: No. Is the short answer. I can't tell you what's going on. 

I mean, some of the cells in the brain are kind of there to reduce inflammation. A certain small part,  not the big chunks of it, but there's certain cells, their job is to control inflammation and the omega-3s can get into those cells and help reduce inflammatory signaling in the brain. And that's good. 

But at this point we're just seeing associations between a high omega-3 that doesn't, strictly speaking, and Sarah understands this very well: because you have an association, doesn't mean you have a cause. 

Sarah Berry: So this is what I'm fascinated by now, listening to you. Have there been any supplement trials where they give people omega-3 supplements and see whether it reduces levels of depression, levels of anxiety, improves mood, happiness, those kind of things. 

And should people who are not feeling happy, should people who are suffering from depression, in addition to whatever therapy they have, also be taking omega-3?

Dr. Bill Harris: So yes is the answer to that.

There have been studies, particularly in depression, for many years. What they've discovered was somewhat surprising to most people. 

Because when you pull together a bunch of studies that were done to try to affect depressive symptoms, some of these supplements that were used in those studies are rich in DHA. Some of them are richer in EPA. All the supplements have both, but some have heavier EPA, heavier DHA. 

The hypothesis has always been pretty simple. The brain's got a lot of DHA, so give it DHA, so that ought to be the one. Well, it turns out that when they look at these studies, they say, Well, the studies that provide a supplement that's richer in EPA are the ones that seem to find a reduction in depressive symptoms, not the ones that have DHA.

So again, a good hypothesis out the window. But based on observational research and the theoretical explanation is that the EPA is more of an anti-inflammatory omega-3 than DHA. 

That's something about the getting more EPA. EPA doesn't really get into the flesh of your brain, it doesn't get incorporated, but it is in the blood circulation throughout your whole brain, and it can be made into some molecules that are anti-inflammatory that may help reduce risk for depression.

Sarah Berry: So your recommendation to people who are suffering from an array of mental health issues would be, in addition to whatever therapy they have, to also try fish supplements, but focusing on EPA rich ones. 

Dr. Bill Harris: Yeah. People always ask, Is EPA better than DHA? And I always say they're both good. They're both in nature, they're always together in fish. We always eat them together. 

I think they should have all of them in a supplement, maybe for depression. We have evidence that richer in EPA may be better. 

Sarah Berry: And that's because the anti-inflammatory effect of EPA rather than the structural effect that DHA has in our brain. 

Dr. Bill Harris: Presumably. Yes, that's right. 

Sarah Berry: So when we're eating, let's say a portion of fish, we've got two things happening. We've got an increase in DHA in our brain because of the structural components. And then the EPA then helping with the inflammation. 

Dr. Bill Harris: Yeah. And this is complicated because we know that giving more EPA and DHA will raise blood cell omega-3 levels, the omega-3 index.

From other studies, we know that you can increase the level of omega-3 in your liver, in your kidneys, in your heart, in your lung. 

But brain is not so easily moved. Just take an adult like you and me and start giving us omega-3 and DHA. We could take a biopsy of the brain, we would probably see that the DHA level's not going up. 

There is this blood-brain barrier that's very specific. At this point, I don't think we can say that taking DHA is actually going to raise your brain tissue DHA levels. 

It's good for your brain health, but it doesn't have to be because it became part of the meat of your brain. It could be doing other things in the brain that could be even just the blood vessels that go through, improving the circulation of the blood through the brain would be helpful without changing the composition of the brain.

So I think that's still an area of active research, is trying to figure out why when you give omega-3s, you can see an increase in, in cerebral spinal fluid, which is the fluid that flows around the brain and spinal cord, and you can get more omega-3 in there. 

But actually as part of the brain tissue, it doesn't seem to go up like it does in the liver.

Sarah Berry: So is there a window of opportunity? Because I know we often talk about making sure during pregnancy you're getting enough because of how important it's for your baby, but also for young children. I think a lot of parents, Jonathan, don't think about this. 

Is there a window of opportunity to make sure that you as pregnant women, but also your children are getting it, to make sure there is enough DHA in the brain.

Very simplistic question. I'm afraid. It's quite confusing.

Dr. Bill Harris:  It's a great question, and it makes the most sense for pregnant women to be sure they're getting enough omega-3, particularly DHA during pregnancy because all the omega-3 that your baby's getting is coming from mom, whether it's in utero or from breast milk.

Optimizing the amount of omega-3 early in life, it makes the most sense to me. And really, brain development goes up til like 18 or 20 years of age actually. 

Most of it is in that first thousand days of life where your brain is really put together, and that's the most important time to get the omega-3, get a good standing for the rest of your life.

I'm not sure it'll stay if you, you know, eat cheeseburgers the rest of your life. 

Jonathan Wolf: So my daughter is six. So you're saying at this point already, it's sort of too late to change this DHA in her brain because there's this barrier that you were describing. 

Dr. Bill Harris: No, I wouldn't throw my hands up in despair.

My grandkids, and my kids, back then, we made sure they have omega-3 all the time they're growing up. 

It's safe. We don't know for sure what it's doing all the time. We have good indications that higher levels are good across the lifespan. So why not do it? The risk is zero. 

Jonathan Wolf: Can I ask a clarification question? Because you were talking about EPA and DHA, and saying that for depression that EPA seemed to be more critical.

Before you were talking about your research around dementia. 

Dr. Bill Harris: I think a mix is always best for overall health above and below the neck. 

Jonathan Wolf: So I'm definitely sitting here thinking, I need to make sure I get enough omega-3 in my diet. It feels like a very strong pitch from Bill with a lot of support here from you, Sarah.

And just before we talk about the advice, the first question I have now is, I'd like to measure my own omega-3 levels, because we've been talking about that. 

Can I ask my doctor to measure my omega-3 index and see whether I'm at this magic 8% level already? 

Dr. Bill Harris: Yeah, the doctor will be a deer in the headlights.

Sarah Berry: I was about to say, they'd be pretty cross in England if you asked them that. 

Dr. Bill Harris: What's the omega-3 index? They don't know.

But yes, it could be done. This is where personalized nutrition, people taking their health in their own hands I think is really important, in the U.K. particularly.

It's very easy to get the omega-3 index done, but you just go online and order the test. They'll send you a little kit in the mail, you pick your finger and you drop a blood on it, put it in the mail, and in about a week you get a report of your omega-3 index. 

Sarah Berry: We do actually measure this in our ZOE Predict studies.

So we have this big ZOE Predict cohort. In a subgroup of that 300,000 people, we have measurements of all of the different fatty acids.

So not just the saturated mono and polyunsaturated, but the individual saturated, the individual fatty acids, including the EPA, the DHA, the ALA. 

Dr. Bill Harris: You have 300,000 people?

Sarah Berry: We have 300,000 people in our Predict cohort. 

Dr. Bill Harris: All women? 

Sarah Berry: No, so they're about 65% women, 35% men, a huge proportion of peri and postmenopausal, and we just have this gold mine of data. It's mind-blowing as a scientist, what we have. 

Dr. Bill Harris: How many do you have blood on? 

Sarah Berry: We use a device called tasso. And so we have that on all of them. And then on a subgroup of individuals, which is probably about 10,000 now, we have the fatty acids and would be able to do the omega index. 

Dr. Bill Harris: Oh, 10,000. Great. 

Sarah Berry: But what's amazing with this cohort, we can start to really dig down into the kind of things that we've been talking about and the nuances that's so important in nutrition.

Dr. Bill Harris: Wow, that's fantastic. U.K. only? 

Sarah Berry: U.K. and U.S. 

Dr. Bill Harris: And U.S. Oh, that's fantastic. 

Jonathan Wolf: I would like to talk about what do you do if you want to hit this magic 8% number and you have a suspicion that you're in the 90 to 95% of people you described who don't have that.

So could you describe how someone could try and get there?

Dr. Bill Harris: Sure. So I think the most important thing is to start with knowing where you're at. So getting a blood test to know your omega-3 index to begin with, that's your baseline. 

We did a study several years ago, pooling data from 14 different other studies that we had done where we had measured omega-3 index before and after. We were able to figure out how much omega-3 in additional you need to get EPA, DHA, in order to go from where you are now to 8%. 

So we've reduced that down to a mathematical equation that's sort of buried in the website. And so if you come back as a 5% or a 4%, 4% would be not atypical. 

If you put that in the calculator, you're going to find that you need about 1500 milligrams more a day of EPA and DHA together. That's a place to start. 

There's a lot of variability in how each individual responds to omega-3 intake. But on average, that's a great place to start. 

You could eat salmon every day, or you could start taking an omega-3 supplement red blood cells, which is where we measure the omega-3 index.

You get a whole new crop of red blood cells every four months. And so now you can, if after three and four months you could do another test, see where you're at. 

We call it titration. You test, you intervene, and then you test again and see what the result was. And if you're where you want to be, keep doing it. If you're not, you need more. 

Sarah Berry: Bill, you've said quite a large amount as in one serving every day. 

Something that I hear anecdotally, a lot of people saying to me is, Oh, but I'm worried about mercury. I've heard that if you have too much oily fish, it's going to give you mercury poisoning. And I believe it's actually preventing a lot of people from increasing their oil efficiency.

I think it's really important to get some clarity on that. 

Dr. Bill Harris: Very important. Mercury has gotten a much bigger concern than it really is. It's primarily a concern, originally in pregnant women and young children. And, back in the early 2000s, the Food and Drug Administration put out this warning about mercury and fish, based on some, I think, very narrowly flawed research.

There's good evidence that that advice caused lots of pregnant women to say, I'm not going to eat any fish, even though there's only maybe four fish: swordfish, tilefish, king, mackerel, shark, things that nobody eats. 

Anyway, those are the ones that had high mercury, and that was the warning in the United States, and the FDA stay away from those fish.

Well, women stay away from those fish anyway. I mean, salmon has virtually no mercury in it. Sardines, mackerel, herring, virtually no mercury. Those high omega-3, just the amount of omega-3 and the amount of mercury not related to each other.  

Sarah Berry: So, unless it's those quite unusual fish you are saying, don't worry.

Dr. Bill Harris: Don't worry about it, absolutely. And for God's sake, don't avoid eating fish because you're worried about mercury.

Jonathan Wolf: Salmon every day is a lot of salmon. I don't want to eat salmon every day. 

Dr. Bill Harris: Okay. You can mix it up with sardines. 

Jonathan Wolf: Is that to get my very most optimal, do I really need to eat this every day?

Dr. Bill Harris: I wanted to make the point that you don't have to take supplements, to get to an 8%. you can do it with fish. I was just giving an example of salmon every day. 

You can eat salmon twice a week. You could eat maybe, mackerel once a week and you might get up to 8%. It just depends on you, and it's very possible.

But if you don't want to do that, supplements are a fine substitute for that. A serving a salmon once a week, may be 1200 milligrams of EPA and DHA, well, that's divided out by seven. That's about 200 milligrams a day. Well, that's twice the average American intake right there of omega-3, which is around 100, 150 milligrams is on average what Americans eat.

So you double it or triple it by just eating an oily fish once a week. So it's a good thing to do. It's just not going to get you by and large to 8%. You're going to need to eat more than that. 

Jonathan Wolf: And that pushes you towards supplements, it sounds like.  Realistically, if you're going to stay at that, unless you are an Inuit or maybe some of the Japanese that you're describing about the level of, true fish intake. 

Just before we go onto supplements, I know that one of the questions we get a lot is about farmed fish. So not about mercury, but I think concerns actually, about the overall health. 

And Sarah, you talk a lot about this, right? About the overall health of a food rather than just one element. And concerns that their farming might not be very healthy. 

Dr. Bill Harris: In 2010, 2012 there was a report. They got a ton of press about, not mercury in farm salmon, but PCBs, dioxins, other industrial organic chemicals that are not good for you.

And this is set off alarms all over the world. And most of these fish in this particular study were from the Baltic Sea and North Sea farming.

And it turns out that the reason that those salmon that they were feeding had those levels was because the food, the oil that they got, from other fish that they feed the salmon. Because the salmon needed to be fed fish oil order to get the omega-3s up. 

The fish oils that they were feeding them, were not clean. They had those pollutants in them. So it was true.

But the industry has cleaned it up tremendously. Our lab in Scotland is also an aquamarine lab, meaning they analyzed fish carcasses for the industry. And there are very strict levels on PCBs, dioxins, and they're not there anymore. 

Now salmon, which is kind of the classic farm fish, used to be back, say 10, 20 years ago, when fish oil wasn't so expensive, it was expensive. Now, because people want supplements, you know, there's a demand. So fish oil's become expensive.

Salmon producers have been reducing the amount of fish oil in the feed and increasing the amount of plant oils in the feed, trying to balance cost, and health, and longevity, and nutritional composition.

So the omega-3 level has gone down in salmon. Now it's about the level of wild salmon. It used to be higher. It used to be that you get more omega-3 per serving of farmed salmon than wild. Now they're about the same. 

So I don't have a problem with farmed salmon. It's still a great source of me, but it's not as good a source as it was maybe 20 years ago. But that doesn't mean it's not a great source today it still is.

Sarah Berry:  But it really nicely leads us on to another myth that I think is really important to cover briefly while you are here. And this is around the omega-6 to omega-3 ratio. 

So one of the reasons people say, Oh, farm fish isn't as good is because by being fattier, it's also got a higher amount of omega-6.

I'd love to quickly get your perspective, if you can give me kind of top line views on the omega-6 to omega-3 ratio. Because it's everywhere at the moment in relation to seed oils and so many other things.  

Dr. Bill Harris: I think the omega-6, omega-3 ratio is a useless metric for so many reasons.

Number one, it assumes the omega-6 fatty acids are bad and that's not true. Linoleic acid is the one we're talking about. Linoleic is the primary omega-6 in seed oils and in our diet.

Higher levels of linoleic acid in the blood are associated with lower risk for heart disease, for diabetes, for all-cause mortality. Everything is better with higher levels of the major omega-6.

So the idea that it's bad is wrong, so there's no reason to have a ratio of something good to good. It doesn't make any sense. 

Secondly, you can have high levels of omega-6, high levels of omega-3 in a food, or you can have low levels of omega-6 and omega-3, and you have exactly the same ratio. 

If your ratio is wrong, the thing to do is not to reduce your omega-6, is to increase your omega-3. 

So if you increase the denominator, the ratio gets smaller, that's okay. That's a reasonable response. 

But I think this dependence on the omega-6, omega-3 ratio is way outdated. That's from the eighties. It should just be thrown in the trash can and ignored. 

We need to look at the amounts of fatty acids we're eating, not this ratio.

Sarah Berry: Thank you. This is exactly what I say and why I get a lot of hate mail. 

I wonder if we can go back to thinking about how we can increase our omega-3 levels. You've talked about having oily fish. You've talked about supplements. 

I think something really important to cover is at what point should we be supplementing through our life course? Is it safe to give young children supplements? Should we be having higher doses as we get older? 

Dr. Bill Harris: I think yes, it's safe to supplement children. Again in that 1000 milligram a day EPA, DHA. It’s no question about that being healthy

Sarah Berry: From what age? 

Dr. Bill Harris: It's hard to draw a line in sand. If I could dictate, I'd say from minus nine months through your life. I don't see any, any place where all of a sudden, now here is where you need it. 

Clearly, increasing your omega-3 levels is always going to help somewhat. And the earlier you do it, the better the more you hit. Because these are what we call fat-soluble nutrients. So they stay in the body a lot longer than the water-soluble things like vitamin C, which kind of come and go.

But the fat solid won't stay in longer. And the longer you feed omega threes into your cells, the levels just go up, up, up, up. 

Jonathan Wolf: And Bill, can you overdose on omega-3? 

Dr. Bill Harris: Not that we know of. It's kind of self-limiting in a sense that people just can't eat that much fish.

Again, the Japanese, who eat much more than we do, are healthier than we are. So we haven't seen it. 

The other issue that comes up is bleeding, and that was a concern, as you mentioned. Cut an Eskimo's finger back in the day, and it would bleed a lot or nosebleeds. You would have pictures of blood all over the place. And this scared people.

And we did find in early studies that we were doing that you give high doses of omega-3, you will in increase what's called the bleeding time. It increases, but it increases like aspirin increases it. Not outrageous, not hemorrhaging, not you're going to die from a nosebleed. None of that stuff. 

Then we've looked at other studies lately, or not lately, over the last several years of people who are taking blood thinners already or taking aspirin, and seeing that taking omega-3 on top of those does not increase the risk for anything that's clinically significant bleeding. 

Jonathan Wolf: And if I make this change and increase the amount that I'm taking, how long might it take for me to feel some of the effects of this optimal level of omega?

Dr. Bill Harris: Oh, good question. And I'm not sure you can feel an effective omega-3.

People are given omega-3s say, to lower their blood triglyceride levels, for example. That's a pharmaceutical reason to take it. And you don't feel a blood triglyceride level. You don't feel a high blood pressure. 

What you feel is achy joints. And this anecdotal experience that we get is that people say, My shoulder just doesn't hurt anymore. My knees feel better now. 

So that is probably, you know, 3, 4, 5 months into taking omega-3s after your tissue levels go up. 

Jonathan Wolf: So I would love to switch to really clear actionable advice. 

Now, I think we've had this brilliant description. I think lots of people listening and saying , Oh, I'd like to eat more food that has this omega-3 in.

Could you just very simply tell us what foods should be in that list? 

Dr. Bill Harris: There's an acronym. We talked about oily fish. SMASH is the acronym. S-M-A-S-H. So, salmon, mackerel, A stands for anchovies. I'm not sure anybody eats…

Sarah Berry: Oh, I love anchovies. 

Dr. Bill Harris: Except Sarah. Anchovies, S would be sardines, and H is herring.

So, those are the SMASH fish, and those are really the highest omega-3. 

Jonathan Wolf: And is there anything other than oily fish that has higher levels of omega-3 and therefore is worth adding for that reason? 

Dr. Bill Harris: Without being fortified with omega-3. You can feed chickens, EPA and DHA, and in their eggs, you'll have more DHA.

But they have to, that's not natural. It's because you're feeding it to them. 

Jonathan Wolf: Anything natural?

Dr. Bill Harris: Anything natural? No. We hear about microalgae. Vegetarians or vegans who want no animal products can take EPA and DHA as algal products because scientists realized that the original source of omega-3 is certain kinds of microalgae.

We're not talking about seaweed. These are single-cell organisms. So they find the exact species that makes EPA or DHA. They put them in a vat in the middle of Iowa, give them sugar and water and sunlight, and they will make EPA and DHA. And then they harvest lipids out of these and put them in capsules.

And that is a perfectly good source of EPA and DHA that does not come from an animal. 

Jonathan Wolf: If I understood rightly from what you're saying, that is actually sort of the original source of this EPA and DHA.

So when you're eating a fish, it's eaten these little algae. It's inside it. And these days, honestly, most of the time I'm eating a fish, it's probably farmed. So you're describing it's sort of being taken and fed sort of manually to these fish, and then I'm eating them. Am I understanding that right? 

Sarah Berry: I think it's really important, Jonathan, to clarify, again, thinking back to where we started at the beginning, that when Bill's talking about omega-3, he's specifically talking about the EPA and DHA sources.

Because I don't want people listening saying, Oh, well hold on. You can get these from flaxseeds, from walnuts, et cetera. Specifically, the EPA and DHA. 

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Dr. Bill Harris: Yeah. And there's nothing wrong at all with these products that are rich in ALA, flaxseed oil, chia seeds that it's fine. They're good for a variety of other things. It's just not the substitute for fish oils. I think that's really the point. 

Don't expect that to meet all your omega-3 needs if you're going to do a plant-based diet.

Jonathan Wolf: So could we maybe wrap up with supplementation, because I think one of my takeaways from this is that for this optimal level that you're talking about, it's actually quite hard to get there. 

So it feels like that does push you towards supplementation. So I guess my first question is, do you supplement yourself, Bill?

Dr. Bill Harris: Yes. 

Jonathan Wolf: Imagine that someone can't do the testing, so they don't know their own baseline. What would you advise? 

Dr. Bill Harris: Not the pregnancy world, but the regular world, you would say, I would aim for about 1000 milligrams a day of EPA and DHA combined roughly 50/50. 

It could be 40/60, 70/30, whatever, but both of them, a thousand milligrams a day, would be a fairly typical of the average Japanese intake. At least historical. I mean, the Japanese are now becoming more westernized. The younger people are not following the traditional diets. 

But historically, the Japanese intake has been around a gram a day. That's a healthy target intake. You can do that with two or three pills a day, some supplements, one a day. 

You'd just have to look on the back of the label of the product to see how much EPA and DHA is in there per capsule. And then take enough to get a thousand a day then I think that's a great start 

Jonathan Wolf: And final question on this, supplements are not as well regulated as medicine in almost all countries. Might be a little worse here in the states, I think, than in some others. 

Is there any concern you might have as you think about the supplements? Is there any way to judge that you're going to get what you are looking for?

Dr. Bill Harris: Yeah. Commonly, the more you spend, the higher the concentration per capsule and the cleaner it is.

Not to imply that the ones that are are fairly cheap are dirty, they're not. You might get more of a fishy burp from some of the cheaper products. 

The fishy taste doesn't come from the omega-3. It comes from other oil products, other breakdown products in there. But it doesn't mean that the omega-3s are gone, the omega-3s are still there. 

I use a product that's got 700 milligrams of EPA and DHA per capsule. That's in a triglyceride form. I think that's important to get a triglyceride form and not an ethyl-ester form, which is the drug form, an ethyl-ester form which is not as well absorbed as triglyceride, which is more of a natural form. 

Sarah Berry: I think the really big takeaway, Jonathan, from me listening to Bill on this, is that any type of supplement is better than no supplement.

Because you do see such big disparities in cost, and I would hate to think that someone thought, Oh, I can only get this ridiculously expensive one. 

Yes. It might not be quite as pure, but it's still going to be beneficial in terms of your health. So I think that's really important.

Dr. Bill Harris: Yes, well said.

Jonathan Wolf: Bill and Sarah, thank you so much for taking us through. It's quite a tricky and complicated topic. I'm going to try and do a summary, and I'm counting on you to correct me where I've got it wrong. 

So I start with the fact that fish oil is not a myth, which is surprising because almost everything I was taught about nutrition when I was growing up seems to have been reversed.

But here we're saying there really is something magical in omega-3, but specifically this EPA and DHA. I think what I've understood, which I hadn't got before, is that omega-3 is like a family, you described it, and within that, there are these different types. ALA is this one from plants, but the one that you are really excited about is EPA and DHA.

It does some quite magical things. So although you said it does not lower cholesterol, that is a myth. It can improve your risk for heart disease. And now we have this new science suggesting it can lower your risk for dementia.

But also, really amazingly, it is linked to less anxiety and depression. And you were saying that you think that might be linked to reducing inflammation in the brain.

Which is interesting because often on this podcast, we talk about research, which is looking at sort of the microbiome and gut health and the links to inflammation and other things. So it's just interesting to me to hear you say that.

You have developed this thing called the omega-3 index, which actually basically tells me how much of this EPA and DHA is actually my individual cells.

The healthiest is 8%. You said on average in America, someone has 5% and for people who are vegans in the military, which I suspect does not have the best diet, you can get as low as 3.5%. Right? And you can function in all of this. So it's not like you're going to die by not having this, but you definitely see improvement as you go from average to optimal.

You can't visit your doctor and get this measured, which is disappointing. But we will put a link in the show notes for how you can go and get yourself tested. 

Basically, if you want to get this through food, then you have to go to these oily fish. And you said SMASH, so I think I wrote down salmon, mackerel, anchovies, sardines, herring.

Everything else is much, much lower. So it's not that there's none, but it's not going to really change this percentage in a big way. 

Dr. Bill Harris: Lower. Much is a little strong, just lower. 

Jonathan Wolf: You're allowed to add any foods here that you think are critical, and what I heard is there are plants that are high in ALA.

That's definitely better than not having it, but it's really hard to turn that into this EPA and DHA and hence these algae products, which sound very exciting to me because that's like the original source of this, right?

 So you're just eating the fish in order to get at the plant, basically, or the algae. So that sounds very exciting. 

We'll see whether we can find any links for that as well, where you can get the direct EPA and DHA, and therefore Bill, you are supplementing yourself rather than just trying to solve it with food. Because you want to be at this optimal level. 

The key thing I took away was, aim for a thousand milligrams. It's going to be EPA and DHA combined, roughly 50/50. But you weren't too worried about it being 60/40 or 70/30. 

Critically, though, you can't just buy something that on the front says a thousand milligrams of fish oil. You need to turn it around and look on the back. And it sounds like you might find that those amounts of EPA and DHA might be quite a bit lower.

So you need to do a little bit of calculation to make sure that you're not buying something that seems good on the front, but it's low on the back. 

That would be your advice for someone who wants to get to the optimal basis. 

Dr. Bill Harris: Right. Well done.

Jonathan Wolf: If you've enjoyed this deep dive into omega-3s and brain health with Bill and Sarah, I think you'll really enjoy this conversation with Sarah about omega-3 supplements and whether we really need them. 

As always, thanks for watching, and we'll see you next time.