It is nothing short of a miracle that those of us who lived through the fat-free and low-fat diet recommendations that were firmly in place by the 1990s made it to the age we are today with any measurable level of health.
Regarded by many modern nutritionists as the worst dietary experiment to ever befall the American people, the low-fat craze began around 1976 when the late South Dakota Senator George McGovern believed there to be a link between the American diet and heart disease after eight U.S. Senators died of heart-related issues in the 60s and early 70s.
It was at this time the cholesterol theory of heart disease was born and there was evidence at that time that saturated fat, the fat found in eggs and meat (but also in breast milk and coconuts), could raise low-density lipoprotein (LDL) cholesterol — also called the "bad cholesterol." With far too little data and much speculation, it wasn't long before all fat was villainized and getting it out of American diets sounded like the way to go.
Carbohydrates were what was going to keep us healthy, thin and disease-free.
But like all farmers know, the best way to fatten any animal is to feed it corn and grain — simple carbohydrates. But from the mid-70s through the mid-90s, based on erroneous health advice, we greatly increased the amount of sugar and carbs in our diets and managed to up our national levels of obesity, diabetes and heart disease in equal measure. Up until 1980, obesity rates in the US were around 12% to 14%, but by the early 2000s, one-third of Americans were overweight.
Unfortunately, the recommendation to move away from eating like our grandparents and great-parents and move to industry-created cooking oils and food-like substances didn't take long to fully take root.
For over 35 years, the US Dietary Guidelines said to limit dietary cholesterol, believing it to increase the risk of heart disease. It was never proven that dietary cholesterol affected blood cholesterol; it was just an assumption.
However, in 2015, cholesterol was finally deemed "no longer a nutrient of concern."
It is slowly becoming indisputable that eating a low-fat or fat-free diet is one of the worst things you can do for your overall health.
Study after study, trial after trial, more proof is gathered that a variety of dietary fats — polyunsaturated, monounsaturated and saturated — are essential for boosting our metabolism and absorbing certain vitamins, as well as for proper hormone production and brain health. Eating a variety of fats can also aid in combating age-related maladies, diabetes, cardiovascular disease, Parkinson's, dementia, Alzheimer's and many different types of cancer.
How do you do this? One of the most critical ways is by paying attention to the types of polyunsaturated fats you're consuming.
Polyunsaturated fats: It's complicated
The two critical fats in this category are omega-3 and omega-6 fatty acids. They are both "essential," meaning we must get them from our diets as our bodies require them and cannot make them.
Omega-3 is sort of the "good guy" of the two as it reduces inflammation and is credited with protecting both brain health and cardiovascular health and helps prevent metabolic disorders like diabetes. There is compelling evidence that getting enough omega-3 can improve mental disorders like depression and bipolar disorder, as well as lowering rates of obesity.
The body needs two specific types of omega-3 fatty acids: DHA and EPA, both found in oily fish like salmon, sardines, mackerel and black cod, and also found in pastured chickens and eggs, grass-fed and grass-finished meat, flaxseeds, hemp seeds, chia seeds, algae and walnuts.
Omega-6, although necessary and "essential" to our overall health, is inflammatory, meaning it can cause widespread inflammation in the body. Put another way, it will cause inflammation if you get too much of it — and in today's world, most people do.
To back up, omega-6 is found in seeds and vegetables and the oils extracted from them — oils like soybean, corn, canola, cottonseed, safflower and sunflower. You find omega-6 fatty acids in grains and beans as well, but for most, these whole foods are not necessarily causing the imbalance.
Nutritionists agree that we should get our omega-6's from whole foods rather than the highly-processed oils made from them. Unfortunately, an average American gets well over 10% of their calories from soybean oil, which is very high in omega-6 as well as being generally consumed most often in its hydrogenated form, which is simply a trans fat by a different name.
Found in virtually every packaged food on grocery store shelves — from dessert items to salad dressings to snack foods to grab-and-go meals — soybean oil is also the predominant oil used in restaurants, from fine dining to fast food. It is hard to avoid getting too much in today's world.
The technology used to extract these high omega-6 oils has only been around about 100 years, so our bodies have not had time to adapt to such a massive increase in consumption. Perhaps the human body never will since these "foods" are so very far removed from their seed and vegetable origins.
These oils are exposed to extremely high heat, sometimes bleached, sometimes deodorized because they smell so bad after such extraction measures; the heat alone can turn these oils into trans fats. What's more, these crops from which the oils are extracted are some of the most, if not the absolute most, glyphosate and pesticide ridden crops on the planet and have been genetically modified.
According to research from the National Institute of Health, in a matter of 50 years, between 1958 and 2008, the amount of omega-6 fatty acids found in body fat stores had increased 200%. I'm sure they are even higher now.
What ratio of polyunsaturated fats should I be consuming?
The ideal ratio between omega-3 and omega-6 fatty acids should be about 1:3 or 2:3. There was a time when that ratio was easily achievable. Yet in this present age of consuming predominantly factory-farmed meat and farm-raised seafood (which are corn, soy and grain-fed), as well as eating out more often than at home where you have control over your ingredients, the American population as a whole is consuming a ratio that's closer to 16:1, according to the 2006 study "Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases."
The animal sources where we get omega-3 fatty acids (and other nutrients) are being jeopardized in large part because of inhumane farming conditions: Over-crowding, widespread antibiotics use for disease management, hormone and steroid use for rapid growth, and wrongly feeding a mostly corn, soy and grain diet instead of the natural diet of the fish or animal being farmed
That said, some scientists don't necessarily believe the answer is trying to consume enough omega-3 fatty acids to match the incredibly distorted ratio, although, supplementing with cod liver oil or other sourced omega-3 supplement would be beneficial for most. New data points to limiting omega-6 fatty acids specifically from soybean oil.
A 2020 study in "Endocrinology" by researchers from UC Riverside — who also found in 2015 that soybean oil induces obesity, diabetes, insulin resistance and fatty liver in mice — details how the oil has pronounced effects on the hypothalamus of mice, where a number of critical biological processes take place.
In speaking with Science Daily, Poonamjot Deol, first author on the study, said, "If there's one message I want people to take away, it's this: reduce consumption of soybean oil."
Cooking more at home, eliminating ultra-processed food, choosing grass-fed beef, dairy products and pastured eggs from certified humane companies all go a long way in helping to shift away from eating a high omega-6 diet.
As far as making a shift in your own kitchen, the following oils in moderation are good for cooking due to their higher smoke-point: avocado oil, grass-fed butter or ghee, virgin coconut oil (though, the Mayo Clinic advised in 2019 that coconut oil's supposed benefits still haven't been proven in large-scale human research) and humanely-raised animal fats like tallow, lard, duck or chicken fat. Look to these oils for salad dressings: Extra-virgin olive oil; walnut, almond, macadamia and sesame seed oil; and flax and hemp oil.
UPDATE: This story has been updated to include additional information regarding UC Riverside's research into the effects of soybean oil on the biological function of mice, as well as clarification on the Mayo Clinic's stance on coconut oil.
