Dietary fats are a crucial component of a healthy diet, but the devil’s in the details, and the type of fats you choose can make a world of difference. Replacing dangerous oils with healthy fats is one simple way to boost your health and reduce your risk of chronic disease. 

Sadly, the fats that promote ill health are the very ones we’ve been told are the healthiest, and vice versa. Among the absolute worst types of fat you can eat are vegetable oils, such as corn oil, soybean oil, sunflower and canola oil, found in most processed foods and restaurant meals.

According to the 2017 U.S. Department of Agriculture report,¹ “U.S. Trends in Food Availability,” consumption of saturated animal fats such as butter, lard and beef tallow fell by 27% between 1970 and 2014, while consumption of vegetable oils rose by 87%. Intake of salad and cooking oils specifically rose by a remarkable 248%.

In my view, processed vegetable oils, rich in omega-6 polyunsaturated fatty acids (PUFAs), are the most dangerous dietary factor of them all, taking a greater toll on human health than high fructose corn syrup even. 

Not only have vegetable oils been linked to heart disease, gastrointestinal diseases such as irritable bowel disorder, and inflammatory conditions such as arthritis, they’ve also been linked to cancer, especially neuroblastoma, breast, prostate, colon and lung cancer. ²

Vegetable Oils — A Hidden Cause of Cancer 

In a November 8, 2019, Medium article,³ Maria Cross, a nutritionist with a master of science degree, discusses the science behind vegetable oils and what makes them carcinogenic. She explains:

“There are two classes of PUFA: omega-6 and omega-3. Although functionally distinct and non-interchangeable, these two classes are perpetually engaged in a metabolic balancing act, pushing and pulling as they compete for absorption in the body.

There is nothing intrinsically wrong with omega-6 PUFAs: we need them … If omega-6 fat is essential to health, it makes no sense that it can also cause cancer …

That’s why scientists believe that it is not omega-6 per se that is to blame; it’s the balance between the two groups of PUFA that is out of kilter and wreaking havoc on our bodies. We evolved on, and are genetically adapted to, a diet that provides more or less equal amounts of omega-3 and omega-6⁴ … 

With the industrialization of our diets, and the vast quantities of vegetable cooking oils that go into them, the ratio between omega-6 and omega-3 has shifted enormously and we consume up to 25 times⁵ more omega-6 than omega-3 …

There can only be consequences, and indeed there are: experimental data⁶ supports the theory that it is this skewed balance between the two PUFAs that influences the development of a tumor.”

How Lopsided PUFA Ratios Promote Cancer

The cancer connection is also reviewed in a 2016 paper,⁷ “Role of Diets Rich in Omega-3 and Omega-6 in the Development of Cancer,” which points out that “Omega-6 and omega-3 PUFAs often compete with one another for metabolism and act in an opposing manner.”

Your body metabolizes omega-3 and omega-6 PUFAs into eicosanoids, which are hormone-like substances, and as a general rule, omega-3 eicosanoids are anti-inflammatory while omega-6 eicosanoids have proinflammatory effects.⁸ Part of the benefits of omega-3 fats is that they block the proinflammatory effects of omega-6 eicosanoids. 

As noted in the 2016 paper⁹ cited above, “several studies have demonstrated that omega-6 PUFAs induce progression in certain types of cancer,” while “omega-3 PUFAs possess a therapeutic role against certain types of cancer.” 

Table 1 in that paper lists eight known mechanisms by which omega-3 lowers your risk of cancer. For example, omega-3 has been shown to inhibit insulin-like growth factor (IGF) and down-regulate growth factor receptors involved in cancer. 

Omega-3 fats also reduce angiogenesis and cell-to-cell adhesion, improve the structure and function of cells, combat inflammation (which is a hallmark of cancer¹⁰) and induce cancer cell apoptosis (cell death).¹¹ Table 2 in that same paper lists the pro-tumor mechanisms of omega-6 fats, which include:¹²

• Creation of reactive species that damage DNA
• 17-beta-estradiol epoxidation, which in turn generates a carcinogenic compound
• Enhancing the genotoxic effects of other compounds

 

As explained in my book, “Superfuel,” co-written with James DiNicolantonio, Pharm.D., omega-6 also inhibits cardiolipin, an important component of the inner membrane of your mitochondria that needs to be saturated in DHA in order for it to function properly.¹³ 

Cardiolipin can be likened to a cellular alarm system that triggers apoptosis (cell death) by signaling caspase-3 when something goes wrong with the cell. If the cardiolipin is not saturated with DHA, it cannot signal caspase-3, and hence apoptosis does not occur. As a result, dysfunctional cells are allowed to continue to grow, which can turn into a cancerous cell.