Are PUFAs Healthy? The health industry notoriously shames foods and habits. It appears one day something is good for you, and the next it’s terrible. Unfortunately, this confusion has led to many misunderstandings when it comes to nutrition, especially around fats. Today we explore why all fats aren’t bad or good and highlight PUFAs (or polyunsaturated fats) as a generally problematic fat.
This article has been medically reviewed by Dr. Charles Penick, MD
What is a PUFA?
PUFA stands for polyunsaturated fat. Fats are differentiated based on how many couple bonds they are made up with, and PUFAs contain more than one double bond in their backbone. Saturated fats have no double bonds, while monounsaturated fats contain one double bond 1.
These bonds can be understood as a kink in the chain—the more kinks, the weaker the chain, and the more sensitive the fat. Sensitivity refers to how delicate the fat is to elements like oxygen and heat. Once the fat has been denatured (through exposure to oxygen), it is rancid and becomes toxic.
Are PUFAs Healthy? Dietary PUFAs
Although many labels have “heart healthy” labels to note that the food is low in saturated fat, this connection couldn’t be less true 2-3. Thus, there is a direct connection between polyunsaturated fats and heart disease, but unfortunately, you won’t find them marked anywhere on your packaged foods.
PUFAs have become so common in packaged foods that when in doubt, you can almost assume they will contain some. Dietary PUFAs are Omega 3, 6, and 9 fatty acids. And you may have to pick your jaw up off the floor after reading that because “aren’t these the healthy kinds of fats?”
The truth when it comes to fats, and especially PUFAs, is in the detail. Although we do need these essential fats in our diet, the key is which kinds, in what amounts, and most importantly, how they were processed before consuming them.
The big problem with PUFAs is that they are sensitive to oxidation 4. Therefore, processing them (especially using heat) will likely destroy their integrity (making them toxic).
The most common source of dietary PUFAs in packaged foods is cooking oils. Most cooking oils used in foods and restaurants are made from polyunsaturated fats, making them instantly rancid. These fats are so common is twofold: first of all, these processed oils are extremely heat resistant. Secondly, they are cheap.
Some of the most common sources of dietary PUFAs include: 5
- Canola oil
- Cottonseed oil
- Corn oil
- Soybean oil
- Sunflower oil
- Safflower oil
- Grapeseed oil
-
Ricebran oil
- Peanut oil
- Flaxseed oil
- Vegetable oil (which is a blanket name for many of these oils)
- Fish oil
Are PUFAs Healthy?
You will find these fats in almost every processed food in the supermarket, notably in margarine, chips, crackers, cakes, cookies, bread, other baked goods, condiments, and salad dressings. These fats are basically everywhere, so unless you make a conscious effort to avoid them, odds are you are consuming them daily.
You may have noticed fish oil made the list of common PUFAs, which is a controversial topic. Many health professionals advise consuming fish oil for its Omega 3 content. Although Omega 3 fatty acids are healthy, the key is consuming them not oxidized. Again, these fats are susceptible to light, heat, and oxygen. Extracting oil from a whole food makes it highly likely that the finished product is rancid before opening the bottle, and many studies highlight the rancidity of fish oil products 6.
Should You Avoid All PUFAs?
Although some PUFAs are downright toxic, they aren’t all bad. In fact, consuming specific kinds of PUFAs is incredibly important. Omega 3, 6, and 9’s are only available through dietary sources; we do not make them endogenously. The keys when it comes to getting the right kind of PUFAs in your diet are as simple as following these two rules–
1. Consume Only Wholefood PUFAs, As Raw as Possible
As soon as PUFA rich food is processed, you can bet it’s gone rancid. Therefore you want to outright avoid any processed PUFA. This means you can eat nuts and seeds but avoid nut and seed oils. These oils (especially vegetable oils like canola, corn, soy, sunflower, and safflower) are ubiquitous in packaged foods. So reading the labels is a must.
Fish oil is another example of a processed PUFA to avoid. Properly sourced small fatty fish are some of the most nutrient-dense foods on the planet, but avoid consuming these fats in the form of processed fish oil.
When consuming PUFA containing whole foods, try and keep them as unheated and as fresh as possible. Raw nuts instead of roasted, for example, whenever possible.
2. Are PUFAs Heart Healthy? Omega 3 to 6 Ratios
The next PUFA problem is the imbalance of Omega 3 to Omega 6 fatty acids in the body. Ideally, these ratios would be about 1:1 or 1:2, but because of how prevalent PUFAs are in packaged foods and used so commonly as cooking oils, the 3 to 6 ratio is off. In the modern American diet, most people have an Omega 3 to 6 ratio of 1:15 or more 7!
Omega 3’s essentially come from fish. Although some plant foods, like chia seeds, contain Omega 3’s as ALA, they have extremely low bioavailability in humans 8. On the other hand, Fish is loaded with DHA and EPA, the fat-soluble Omega 3’s that are very bioavailable in humans. So when it comes to Omega 3 intake, we’re essentially talking about fatty fish consumption.
Omega 6’s, on the other hand, are everywhere. They are found in nuts, legumes, margarine, all those packaged foods and condiments mentioned earlier that contain nut, seed, or vegetable oils 5. Fast food chains cook in them, as do restaurants. You would be hard-pressed to find a restaurant that does not use vegetable oils in their cooking.
As a result of the high prevalence of Omega 6’s in the food industry, a typical diet is highly imbalanced in favor of Omega 6 fatty acids. Unfortunately, too many Omega 6 fats lead to chronic inflammation in the body, associated with nearly every disease model 9.
Luckily, if you stick to point number 1 (consume only wholefood PUFAs, as raw as possible), have whole fish regularly, and avoid overdoing it with nuts, your ratio should be optimal without having to test or worry.
The Dangers of PUFAs
Understanding that not all PUFAs are the problem, but rather the processed kinds, and in excess, let’s discuss what can happen in the body when you consume the wrong types regularly.
1. Obesity
The long-perpetuated myth that ‘fat makes you fat’ has been debunked (thankfully), but it’s important not to over-correct. Not all fats make you fat, but some kinds certainly do. Unsurprisingly, considering all that we have covered, oxidized PUFAs are bad fats that make you fat 4.
There are a few ways that PUFAs can lead to obesity. The first is simply because toxicity gets stored in body fat. As a measure to protect you from toxins (in this case, the toxic nature of oxidized fats), your body intelligently stores it away in your body fat. Getting rid of the PUFAs stored in body fat can occur either through exercise or by excreting it in breast milk.
The problem with trying to burn it off is that when triggered by exercise, these polyunsaturated fats shut down your body’s ability to produce energy 10. This failure to burn fat for fuel results in a craving for glucose (sugar), which in itself can lead to obesity by causing insulin resistance 11. This is why afternoon slumps (sugar or caffeine cravings, brain fog, or irritability) can often signify metabolic distress.
When your body cannot switch into ‘fat burning mode’ during times in between meals or on a longer fast, there is metabolic dysfunction. If you can’t burn body fat, it accumulates over time!
Studies have correlated the rise of PUFA consumption with the increase in obesity in America. The levels of PUFA fats stored in body fat levels have increased by 136% over the last half-century. This increase is highly correlated with an increase in dietary PUFA intake over the same period 12.
2. Cancer
There is a well-established link between PUFA consumption and cancer rates. Two studies highlight the consumption of PUFAS with the increase in breast cancer rate in rats 13-14. This link in animal studies was later confirmed in human studies, too. One study in particular highlights that the increase in breast cancer was prevalent only with polyunsaturated fats and not with mono or saturated fats 15.
Later studies explore the impact of these fats on men and cancer rates too. The consumption of PUFA-rich corn oil was linked to testicular cancer in rats 16. An eight-year study published the findings comparing men on a low-PUFA diet with those on a high PUFA-diet, and indeed, cancer rates were much higher in the high-PUFA cohort 17.
The lag in science-to-government recommendations is real. Many cancer organizations still demonize other fats despite all this research without mentioning the dangers of excess and oxidized PUFA consumption.
3. Heart Disease
Although many labels and organizations preach saturated fat as being the cardiovascular-causing fat, the reality is that there is very little connection (if any) between saturated fat and heart disease 3. On the other hand, polyunsaturated fats are connected with heart disease, particularly with the relatively high consumption of Omega 6 to Omega 3 fatty acids.
A typical example is the study of Israeli-Jews. They, as a culture, consume some of the highest Omega 6 PUFAs in the world, about 8% more than Americans and 10-12% higher than in most other Europeans. They also have a higher prevalence of cardiovascular diseases, hypertension, non-insulin-dependent diabetes mellitus, and obesity-all diseases that are associated with hyperinsulinemia and insulin resistance 18.
4. Impaired Immune Function
Finally, one reason to avoid over-consuming Omega 6 fatty acids or consuming oxidized, rancid PUFAs at all is that they impair the immune system. PUFAs act as an immunosuppressant on the body, making you more susceptible to various ailments, including bacteria, viruses, and cancer.
One of the most commonly found PUFA is sunflower oil. Sunflower oil was once used as an immunosuppressant for patients undergoing renal transplants to decrease the likelihood of the body rejecting a new kidney. Although it worked, the cancer rates in these patients also sored (up to 20% higher than expected) 19.
You may have noticed that the side effects of oxidized PUFA consumption are the number one killers in America. Indeed, the rise of PUFA consumption is directly correlated with the increase in the death toll of America’s major killers.
Are PUFAs Healthy? Summary
You must consume polyunsaturated fats with extreme caution. Eating rancid PUFAs or an imbalance of Omega 6 to 3 fatty acids can lead to many ailments, including obesity, cancer, heart disease, and generally suppressing the immune system. The key is avoiding processed PUFAs (especially oils), which can be difficult because they are found in most packaged foods and restaurant dishes. When it comes to PUFA consumption, it’s essential to consume the food in its whole-food form and keeping it as raw as possible.
Medical Disclaimer: This article is based upon the opinions of Dr. Daniel Pompa. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Pompa and his associates. This article has been medically reviewed by Dr. Charles Penick, MD for accuracy of the information provided, but Dr. Pompa encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional.
References
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10 Shanahan, Catherine. The Fatburn Fix: Boost Energy, End Hunger, and Lose Weight by Using Body Fat for Fuel. Flatiron Books, 2021.
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16 Lloyd, Jessica C et al. “Effect of isocaloric low fat diet on prostate cancer xenograft progression in a hormone deprivation model.” The Journal of urology vol. 183,4 (2010): 1619-24. doi:10.1016/j.juro.2009.12.003
17 Pearce, Morton Lee, and Seymour Dayton. “Incidence Of Cancer In Men On A Diet High In Polyunsaturated Fat.” The Lancet, vol. 297, no. 7697, 1971, pp. 464–467., doi:10.1016/s0140-6736(71)91086-5.
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19 Uldall, P.r., et al. “Unsaturated Fatty Acids And Renal Transplantation.” The Lancet, vol. 304, no. 7879, 1974, p. 514., doi:10.1016/s0140-6736(74)92032-7.
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