April 7, 2021
Fat has had a bad reputation in the nutritional world since researchers first suggested that a high-fat diet was linked to unhealthy high cholesterol levels as far back as the 1940s.
For decades, the idea that a low-fat diet is the healthiest diet for everyone has embedded itself deep in the minds of the public and health professionals.
But this doesn’t make fat a nutritional bad guy.
“Fat is not only an essential nutrient, but fat in foods also provides texture and taste that makes eating a pleasurable experience,” says our scientific collaborator and nutrition expert Dr. Sarah Berry from King’s College London.
So how can we strike the right fat balance that fuels our body, keeps our taste buds happy, and supports our health?
It turns out it’s not just how much fat you eat that’s important, but the types of foods you get it from and its quality too.
“When we're talking about fat quality, we're talking about the healthiness of the fat and its food source, and there are many things that determine how healthy a fat is,” says Sarah.
“We need to consider the molecular composition of the fat, the structure of the food which contains the fat, and other bioactive compounds which accompany the fat in the food.”
On a molecular level, fats are made up of long chains of carbon and hydrogen atoms. The main difference between the types of fat we eat is variations in the length of these chains and how the carbon atoms are joined together, creating saturated, mono- or poly-unsaturated fatty acids.
The ‘healthiness’ of fat is often discussed in terms of which of these fatty acids it contains, with saturated fats being viewed as less healthy than unsaturated fats. But recent research has shown that we need to look beyond these simple categories.
“Not all saturated fatty acids have the same effects on health,” says Sarah. “For example, current evidence shows that stearic acid has a neutral effect on cardiovascular health while palmitic acid has an unfavorable effect. But both are saturated fatty acids, and both are found in a variety of plant and animal foods.”
Looking at the individual fatty acids in food can give a better insight into how healthy a fat is, but even this approach is too simplistic.
“We can’t reduce the composition of foods and fats down to individual components,” says Sarah.
Every fat you eat is contained within a food with its own structure and composition (the food matrix) that will influence how you respond to it and how healthy it is for you.
“A great example of this is dairy. Dairy foods are high in saturated fatty acids and contain individal fatty acids that have been linked to poor health, so if we were to classify dairy based on these facts alone, we would say it is bad for you. But we now know that most dairy, excluding butter, has a favorable effect on health thanks to its beneficial molecular makeup,” Sarah explains.
For example, in calcium-rich dairy foods like cheese, fat droplets are encased in membranes that reduce how much fat gets absorbed in the gut, compared with eating a portion of butter containing the same amount of fat.
When you eat a high-fat meal, the lipid (fat) levels in your blood rise then eventually fall, depending on how well your body metabolizes fat. If you break down and use fat more slowly, these lipids can build up in your bloodstream if you eat lots of fatty meals over the same day.
Having high blood lipid levels over a sustained period leads to a whole cascade of unfavorable effects such as oxidative stress and inflammation. So it’s best to stay below your unique fat threshold to avoid prolonged, unhealthy lipid responses after eating that can increase your long-term health risks.
There is also lipoprotein remodeling, where the fat particles in your blood change size, number, or composition, making them more likely to cause damage to your arteries. Over time, all these responses contribute to an increased risk of heart disease.
However, other nutrients in the foods we eat and their influence how our bodies process and respond to fats.
Recent research has shown that polyphenols and other antioxidants, such as those found in minimally processed extra virgin olive oil, can protect against these negative impacts of increased blood fat levels after eating. This makes it healthier than a more processed olive oil with the same fatty acid composition and food matrix.
Find out more about fat in our article about macronutrients.
We believe there are no ‘good’ or ‘bad’ fats, just foods that you can eat more often and other foods that you might want to eat less frequently. We think that food is there to be enjoyed, and no food should be off-limits.
However, it can be challenging to balance your desires and the potential health impacts of food before deciding exactly what to put on your plate at each meal.
That’s why the ZOE program is designed to help you understand your metabolism and how often you can include healthy – or even less healthy! – fats as part of your diet.
Using our machine learning technology, we can give you personalized ZOE scores for thousands of foods and meals, based on your test results.
These take into consideration how you as an individual respond to fat, as well as the quality of the fats in your foods, which takes into account the fatty acid profile, food matrix, and nutrient profile, and their impact on your microbiome. The higher the number, the healthier the food will be for your unique biology.
This means that the ZOE scores for different foods will be personalized to you, depending on how your body handles fats.
For example, avocados, almonds, and seeds all have a very high ZOE score for many people, which means that they can be eaten freely by most people (in varying quantities depending on their individual fat threshold).
But there is more variation for foods that contain less healthy fats. For example, people with less healthy fat responses have a typical ZOE score of around 49 (enjoy in moderation) for cheddar cheese, while the score for someone with a good fat response is around 73 (enjoy freely). Butter ranges from 41 to 69, and sausages from 0 to 18.
Finally, it’s important to remember that there’s more to what we eat than just fat. ZOE also takes into account how your body responds to sugar and how different foods affect the microbes in your gut (known as your gut microbiome) - both of which play a vital role in your health.
If you’re curious to discover how your body responds to food and to get personalized insights that will help you find the foods your body loves, start your journey with ZOE today.