The dangers of grain and legume consumption and of excess fructose consumption has been discussed on this website, but another common toxin in Western diets needs more attention: PUFAs (Polyunsaturated fats). I see that a lot of people are confused about which fats are the good ones and which are the bad ones. This article will clear the confusion and will also show that limiting PUFA consumption is an extremely important step to achieve and maintain great health.
Dietary fats are divided in three main categories: saturated fats, monounsaturated fats and polyunsaturated fats. Vegetable oils and animal fats are most often composed of a mixture of those kinds of fat. For example, olive oil is composed mostly of monounsaturated fat with some polyunsaturated fat. Coconut oil is mostly saturated fat. Lard is usually about half saturated fat and half monounsaturated fat, but also contains a fair amount of polyunsaturated fat. Most vegetable oils except palm oil, olive oil and coconut oil are high in PUFA while most animal fats are mostly composed of saturated and monounsaturated fat.
The main dietary PUFAs, omega-3 fat and omega-6 fat, are considered essential because they can’t be metabolized by the body and they need to be obtained from food. This could also suggest that they aren’t all that important because the most important macro nutrients like glucose, monounsaturated fat and saturated fat can be metabolized by the body when there is a need. Moreover, PUFA deficiencies are extremely rare and could only be reproduced in humans at the time when complete parenteral nutrition didn’t contain any PUFAs. The quantities needed are really small and the food naturally found in nature contains more than enough to meet our needs.
Not surprisingly, PUFAs usually contribute only a minor part of our own fat tissues, while the major part is saturated and monounsaturated, like most other mammals. Most of the time, it’s a good idea to consume macro-nutrients in the same ratio that our own tissues contain.
One of the main problems with PUFAs is that they are chemically really unstable. They have 2 or more unsaturated double bonds in their carbon chain and are therefore at risk of being altered and denatured by what surrounds them. Outside of us, these fats easily become rancid or oxidized in the presence of heat, light or oxygen. Inside our bodies, PUFAs easily react and bond to proteins and sugars to create toxic by-products like AGEs (advanced glycation end-products), which can then cause numerous sorts of damage. It’s good to note that PUFAs react much more to the sugar fructose than to the sugar glucose. This brings yet another reason why fructose consumption should be kept low. Another good practice is to avoid eating PUFAs at the same time as sources of fructose like fruits.
Since they are unstable fats, when they are eaten in large quantities and become an increasing part of cell membranes, the cells themselves become more fragile and prone to oxidation. Oxidized PUFAs also contribute to the oxidation of low-density lipoproteins (LDL) to create a form of cholesterol transporter in the blood that’s very unstable and atherogenic. That’s the form of cholesterol that people should really worry about.
A reason why PUFAs are essential, but also a reason why they become problematic when consumed in excess, is that they are used to modulate and regulate inflammatory eicosanoids. Inflammation is critical in the body as a response to infections, viruses or traumas, but chronic inflammation can become very problematic. For example, normal inflammatory processes stimulate the immune system, but chronic inflammation suppresses it. We therefore need PUFAs in small amounts to modulate some essential inflammatory pathways, but in excess they backfire, make us chronically inflamed and lead to all sorts of problems in the long-term. Lets not forget that inflammation is at the source of just about every modern health problems to the fact alone that excess PUFA consumption promotes general and chronic inflammation shouldn’t be taken lightly at all.
The is a lot of talk in the Paleo diet community about consuming the main PUFAs, Omega-6 and Omega-3, in the proper ratio and there is definitely a lot of truth to that. Omega-3 and Omega-6 PUFAs are used and transformed on some of the same pathways and an excess of one can suppress the absorption or transformation of the other. Furthermore, Omega-3 fats are said to be anti-inflammatory because they mitigate the action of Omega-6 fats. Since vegetable seed oils, for which most are very high in Omega-6 PUFA, are a huge part of our food system right now, most people consume way to much omega-6 fat and way too little Omega-3 fat to be in a good balance. A good ratio of omega-6 to omega-3 would be at around 1 to 1 to 3 to 1 parts Omega-6 to Omega-3, while many Americans today get up to 20 parts to 1 Omega-6 to Omega-3. This excess total PUFA and excess Omega-6 consumption is a huge insult to the body and causes many problems in the long term.
Omega-3 PUFAs have got a very good reputation and have gotten really popular as a supplement in the last few years, especially in the form of fish oil capsules. The main sources of Omega-3 PUFAs are fatty fish and some seeds like flax seeds, but fatty fishes like salmon, sardines and herring really are the real desirable sources of Omega-3 PUFA because they contain the usable forms of the fat, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). The form of omega-3 often found in plants sources like flax seeds is ALA (alpha-linolenic acid) and needs to be elongated multiple times to be transformed to a usable form to the body. The process is not efficient at all and only a small fraction of Omega-3 in the ALA form ends up being transformed to a usable form.
Omega-3 fats are also only needed in small quantities and high levels can cause problems, especially since they are so chemically fragile, even more fragile than Omega-6 fats. In the Paleo diet community, there is often too much focus placed on getting to the proper ratio of Omega-6 to Omega-3 consumption that we forget that the total amount of PUFA consumed should be kept to a minimum. A way better strategy to obtain the two categories of PUFAs in the proper ratio is to keep Omega-6 consumption to a bare minimum and to get just enough Omega-3 from food sources to balance things out.
Fish oil capsules can also be a problem as a source of Omega-3 fat because they often sit on shelves for long periods of time or are exposed to sunlight, two things that can easily damage the fat and make it really toxic to our bodies. A good solution to this issue would be to only consume Omega-3 from fresh fish, where the fat is most likely to be in its unadulterated form. Of course, if you find it hard to eat wild fatty fish on a regular basis, you can seek out a fish oil that comes from a very reputable source and that’s kept refrigerated in the stores in which they are sold.
We learned that a high total PUFA consumption is one of the main reasons why we are so sick as a population today and that those fats are often already denatured and oxidized when consumed. Our total PUFA intake should be kept low and Omega-3 fat should be consumed in about the same amount as Omega-6 fats, but only from fresh sources like wild fatty fish. Care should also be taken not to overheat sources of polyunsaturated fat and that’s why I don’t recommend cooking with olive oil, even if olive oil has low enough quantities of PUFAs to be considered a healthy fat.
A good rule of thumb would be to consume no more than 4% of your calories as Omega-6 fat and around as much Omega-3 fat. Practically, this means cutting off all vegetable oils except coconut oil, olive oil and palm oil, cooking with low PUFA oils and fats like clarified butter, coconut oil and tallow and eating only limited amounts of the nuts that are high in Omega-6 fat. With this strategy, a pound of fresh fatty fish per week is enough to balance out the Omega-6 consumption.
P.S. Be sure to check out the Paleo Recipe Book. It’s a cookbook I’ve created to help you cook the best food for your health. It contains over 370 Paleo recipes and covers absolutely everything you’ll ever need.