If you haven’t read my blog post on why hypothyroidism increases risk for autoimmune diseases, check it out here. I highly recommend reading through that to get a thorough background on free radicals and oxidative stress.

 In summary, free radicals are created when we make energy in our body. These are small molecules that can create havoc, if they interact with other parts of our body, like mitochondria and cell walls. Luckily, the body has self-defense mechanisms to neutralize free radicals. It produces a very powerful antioxidant called glutathione. Other antioxidants include vitamin C and vitamin E. But when these mechanisms can’t keep up with the number of free radicals produced, our oxidative stress goes up. Oxidative stress is directly linked to autoimmune diseases, as well as diabetes, cancer, heart disease, and other chronic diseases.  

The biggest change you can make to reduce oxidative stress is to cut out Polyunsaturated Fatty Acids (PUFAs) from your diet.

What are PUFAs?

PUFAs are a type of fat, commonly found in vegetable oils, fatty fish, nuts, and seeds.

In the nutrition world, there are two types of PUFAs that are often talked about: (1) omega-3 and (2) omega-6. The 3 and 6 refer to how many double bonds each kind of fat contains. More on double bonds below and why it’s important to consider this when choosing the type of fat to eat.  

The evidence that omega-6 fats cause inflammation and increase free radicals is pretty unanimous. But omega-3s are more controversial because the evidence for their benefits or risk is not conclusive. Some studies show omega-3 fats reduce inflammation (often measured by how well the body is able to neutralize free radicals before and after taking the supplement). Other studies, like this 2018 Cochrane Review showed that omega-3 supplementation, consuming fatty fish, or omega-3 rich plant foods had very little or no impact on risk for heart disease or stroke. 

Another important note to keep in mind when thinking about polyunsaturated fats, like omega-6s and omega-3s, is that they both compete for the same pathways in the body. So when you put omega-3 into the same body that already consumes a large amount of omega-6, the omega-3 will help offset some of the harmful effects of omega-6s. Which might show up us reducing inflammation.

However, consuming a high amount of omega-3 is not necessary, if your diet is already low in omega-6. The benefits of omega-3 are likely only in the context of a high omega-6 diet. Unfortunately, this is exactly what the American diet looks like: very high in omega-6 fats. A diet, collectively, low in PUFAs (that means very little omega-6 and omega-3 in the diet), is the most beneficial in reducing free radicals and oxidative stress.

Many of the studies that show benefits of omega-3 fatty acids are also epidemiological, meaning these studies look at correlations and use statistics to derive connections between people’s diets and outcomes, like occurrence of disease. However, they can never determine if there is a relationship of causation. Meaning, an epidemiological study can never conclusively say that omega-3 fatty acids reduce risk for heart disease, or consuming red meat increases risk for cancer. Nutrition research is very difficult to do because there are so many confounding variables that have to be accounted for. It’s really hard to narrow down the relationship between one specific nutrient or food and an outcome. Well, not hard, but those types of studies are not ethical. So, making claims about a specific food, or food component, is hard to do. That’s why there is so much confusion in the nutrition world. There is always evidence for or against the same exact recommendation.

So, while the studies are inconclusive on omega-3 fats, here’s my take on why you should cut down as much PUFAs in your diet as possible:

PUFAs oxidize very easily. This means, they interact with free radicals and make even more free radicals. The more PUFAs in our diet, the more PUFAs in our cell and organelle walls. And the more free radicals we produce, the higher our oxidative stress.

Here’s a great article written by several individuals with doctorate degrees assessing the evidence on the recommendation to consume more polyunsaturated fats in place of saturated fat.

Why PUFAs Increase Oxidative Stress: It’s All in the Structure

PUFAs contain double bonds (pictured below). These bonds are what make PUFAs liquid at nearly any temperature and the lack of double bonds is what makes saturated fat solid at most temperatures.

Double bonds are places on the fat that provide opportunity for things like free radicals, oxygen, heat, or light to interact with the fat. When these things (free radicals, oxygen, heat, light) interact with a PUFA, the end result is more free radicals.

The pictures below show what a PUFA and saturated fat look like zoomed in. The arrows are pointing to the double bonds.

As you can see, saturated fats do not have any double bonds. So there is no opportunity for oxygen, light, or heat to interact with the saturated fat and create free radicals.

We literally become the fats we eat. These fats become a part of our cell membranes, organelles, and depending on which kind we’re eating, they can compromise the structural stability of our cells. One review showed how oxygen interacting with PUFAs creates free radicals at a much faster pace than would normally happen in the body (Spiteller & Afzal, 2014). This is because PUFAs have multiple points (the double bounds) where free radicals can interact with them. That’s exactly why they’re called polyunsaturated fats. The poly means multiple double bonds.  

Think about it this way: fish oil is recommended for its “benefits”, but you also have to keep it in the fridge so it doesn’t go rancid or bad. Because heat, light, and oxygen interacting with the oil makes it rancid. But then we put it in our bodies that run at a minimum temperature of 96 degrees F (if optimal, at 98.6 degrees F) and where there is plenty of oxygen and free radicals. Why would we expect fish oil to NOT go rancid in our bodies?

The more PUFAs we consume, the higher number of free radicals. If not neutralized, these free radicals can go on to destroy important enzymes, damage the thymus gland, and other organs.

The American Diet

The American diet is very rich in polyunsaturated fats because most of us have bought the lie that we should use canola oil or other vegetable oils instead of butter to cook. And because vegetable oil is so cheap, it will be very difficult to find a restaurant that cooks with butter or other animal-based fats.

A Brief Recap

The first step to reducing your risk for autoimmune disease is to reduce your oxidative stress by cutting out as much polyunsaturated fats in your diet as possible.

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