Omega-3s are ‘essential,’ but why? Part 2

Welcome to the second part of our two-part feature on the wonders of omega-3 fatty acids. In it, we ask why omega-3s are “essential."

In other ZOE articles, we’ve covered the links between consuming enough omega-3s and health. In this feature, we’re asking how these health effects happen. 

In the first part, we covered the basics of omega-3s, a little bit about their discovery, and why they’re vital for the proper functioning of your cells' membranes.

In this part, we’ll start with the omega-3s in your brain. Then, we’ll move on to their role in inflammation. We'll finish by looking at how omega-3s affect heart health.

Before we get going, we should mention that a lot of the relevant research is based on animal models. So, the story might be different for humans.

Right, let’s begin in the brain.

Omega-3s in your brain

As we learned in part one of this deep dive, omega-3s are present in every type of tissue in your body.

Scientists are still getting to grips with the roles of omega-3s in the brain, but it seems that they’re important in a number of ways. 

Development and maintenance

We mentioned in part one that omega-3s are essential during the development of your nervous system in early life. But they remain important throughout your life.

The cells in your nervous system die and are refreshed continually — although more slowly than other tissues in your body.

So, we need a steady supply of DHA to ensure that everything can be built as needed.

Blood flow

Your brain is a hardworking organ, receiving around 20% of the blood that’s pumped from your heart.

One study found that people with higher levels of omega-3s in their blood had increased blood flow in parts of their brain that are involved in storing and retrieving memories.

The blood-brain barrier

This virtual barrier separates the central nervous system from the rest of your body. It helps keep infections and toxins from reaching your brain.

Some early animal studies found evidence that DHA might help support the blood-brain barrier.

Ion channels

As we saw in part one, DHA can influence how cell membrane proteins function, and this includes the membranes of nerve cells, or neurons. 

The membranes of your neurons have protein channels that let charged particles (ions) in and out.

There are many types of these ion channels, and DHA can influence how readily they open and close, affecting the function of your brain and nervous system.

Neurotransmitters

When a nerve fires, it releases chemicals called neurotransmitters. These chemicals move across a space between nerves called the synapse. Neurotransmitters pass on information from one nerve to the next.

DHA is essential for the formation of synapses during development, and it remains important throughout your life. 

Also, animal studies in the 1990s found that when rats were deficient in omega-3s, they had lower levels of the neurotransmitters serotonin and dopamine in some parts of their brains. 

Inflammation

Inflammation is a healthy response to threats like injuries or infections. However, if inflammation continues for long periods in the absence of a threat, it can damage cells and tissues.

Because inflammation is vital for protecting health but can be harmful if it persists, your body keeps a tight rein on it.

And omega-3s and omega-6s are part of this important balancing act. First, let’s return to your brain.

Neuroinflammation

Omega-3s' anti-inflammatory effect may be important for brain health. 

For instance, there’s some evidence that inflammation in your brain, also called neuroinflammation, might be linked to psychiatric conditions like depression.

Although there’s limited evidence in humans, some scientists hope that omega-3s might form part of future treatments for depression.

Arachidonic acid

As we’ve seen, omega-3s form part of cell membranes. Omega-6s, which are also essential fatty acids, do the same. 

One of the most well-studied and important omega-6s is arachidonic acid. Like DHA, it helps keep membranes fluid, affects how membrane proteins work, and supports brain health.

When a cell receives certain signals, its membranes release arachidonic acid, which is converted into hormones called eicosanoids.

Importantly, omega-3s and omega-6s compete for space in the membrane. So, having more omega-3s in your cell membranes means that fewer inflammatory compounds are released.

Now, we need to add a caveat here because seed oils, which are rich in omega-6s, have received a bad rap over the years. Some people suggest that their pro-inflammatory eicosanoids are responsible for a range of chronic diseases. And that’s not entirely fair.

Although arachidonic acid eicosanoids are slightly pro-inflammatory, consuming them doesn’t cause increased inflammation.

When we wrote about the drama surrounding seed oils, we spoke with ZOE’s Chief Scientist Dr. Sarah Berry. 

She explained that “As long as you’re consuming adequate omega-3, it’s perfectly fine to be consuming omega-6. Based on current evidence, it will not cause an unfavorable inflammatory response. Omega-6 has a protective effect against many chronic diseases.”

Also, animal studies show that when omega-3s are present in the membranes of some immune cells, those cells release less inflammatory proteins called cytokines.

So, by a number of mechanisms, omega-3s help keep inflammation in check, which helps protect you against diseases, including cardiovascular diseases, which we’ll look at next.

Omega-3s and heart health

Studies investigating whether omega-3 supplements protect heart health have produced conflicting results. 

However, consuming enough omega-3s in your diet is important for maintaining heart health.

Atherosclerosis and inflammation

Atherosclerosis is the buildup of a fatty compound on the lining of your arteries. As these so-called plaques grow, they increase the risk of a heart attack or stroke.

In fact, atherosclerosis is the most common cause of cardiovascular disease.

Experts believe that inflammation plays an important part in the development of atherosclerosis. So, by reducing inflammation, omega-3s may slow its progression.

Lowering triglycerides

Also, omega-3s help lower levels of triglycerides (fat) in your blood. Elevated levels of triglycerides are associated with an increased risk of cardiovascular diseases.

Experts are still figuring out how omega-3s lower levels of fat in your blood, but they do have some theories. 

There’s also some evidence from animal studies of another mechanism: Omega-3s help produce compounds that may reduce how much fat is broken down in your gut. 

And if it’s not broken down, it passes out in your poop rather than being absorbed into your blood.

More?

 Aside from reducing inflammation and blood triglycerides, omega-3s might also protect heart health in other ways. For instance, they may help reduce blood pressure and prevent blood clots. 

Omega-3s might also help prevent abnormal heart rhythms called arrhythmias. 

So, these fatty acids might help stabilize your heart rhythm.

As you’ve probably gathered, there are many links between omega-3s and heart health. And we have a lot left to discover.

What should you do?

While scientists continue to unearth the roles of these fatty acids in our bodies, there’s one thing we know for sure: They’re essential. So, you should consume them.

In general, ZOE recommends a “food first” approach. So, rather than reaching for a supplement, try to get your omega-3s from food. We have an article that explores good food sources of omega-3s.

If you're worried about getting adequate amounts, ask a doctor for advice.

Despite the length of this two-part feature, we’ve only scratched the surface of what omega-3s do in your body. 

If you only take one thing away from these articles, it should be that omega-3s are amazing.