Back in 1930, research proved that high-fat diets cause higher rates of cancer.
But it wasn’t until the 70s that researchers started testing each and every fatty acid independently.
A clear trend emerged.
And in the search for what causes cancer, they found that unsaturated linoleic acid is a potent stimulator of cancer.
But other fatty acids had little to no effect.
By 1980, they found that corn oil is also a potent stimulator of cancer growth.
And a study by Chan & Ferguson in 1983 tested corn oil directly against the fully-saturated coconut oil.
They divided the rats into five groups of 30 mice each.
Then they injected each rat with a massive dose of a potent carcinogen and fed them 25% fat diets of different types.
The one exception was one group who received an extremely low-fat diet of just 4% corn oil.
The high-corn oil group had the highest incidence of tumors and the greater amount total.
The first palpable mammary tumor detected in the 5 dietary groups of rats was in the order of high-corn oil > high-lard > high-beef tallow > low-corn oil > high-coconut oil.
Coconut oil and beef fat were far less cancer-promoting at 25% intake than corn oil.
This finding was similar to a nearly fat-free diet.
He also plotted the linoleic acid concentration against the tumor incidence and found a clear trend.
Most fats do contain at least a small amount of linoleic acid.
Coconut oil has 2%, olive oil has 7%, but corn oil is a whopping 48% linoleic acid.
Beef is low but, the amount is highly variable, as it depends on the cow’s diet.
No other fatty acid seems to correlate very well with cancer growth and incidence.
Further analyses showed that the total oleic and linoleic acid intake in the five groups of rats correlated positively with mammary tumor incidence.
Linoleic acid even has an effect on spontaneous cancer incidence in people.
In another study, researchers fed a group of men in a veteran’s home a very high PUFA diet.
These men ate a diet that consisted of an incredible 39.5% polyunsaturated fatty acids.
The control group ate a more modest, but significant, 10% PUFA.
And the total calories were identical.
They were trying to lower cardiovascular disease, but instead, they found a significant increase in cancer.
As this finding spread through the medical and scientific communities in the 80s, researchers had new questions.
They started wondering why linoleic acid increases cancer incidence and growth so much more than other fatty acids.
The most convincing theory is through the synthesis of eicosanoids.
Eicosanoids are slightly-modified and elongated linoleic acid molecules.
The prostate contains some types in high concentrations.
Some of these are so unique to the prostate that their official classification is prostaglandins.
Prostaglandins are a subclass of eicosanoids.
These are such powerful signaling molecules that you could even say that they have a similar effect as hormones.
Research shows that dietary linoleic acid increases prostaglandins.
So, it should come as no surprise that linoleic acid is associated with prostate cancer.
He found 89 people with prostate cancer and 38 confirmed cancer-free controls.
The research team took fat biopsies to measure the fatty acid composition.
And they measured the blood cell fat composition as well.
They found massive correlations between prostate cancer and linoleic acid.
The other fatty acids measured didn’t have a positive effect.
Men in the highest quartile of linoleic acid consumption had as much as a 5-fold increased risk of prostate cancer compared to men with low levels of consumption.
So, the researcher David Rose decided to test the theory that prostaglandins were the culprits.
He decided to test linoleic acid on prostate cancer cells with a few inhibitors.
He first confirmed that linoleic acid stimulated the prostate cancer cells.✔
Then he added the drug indomethacin to the cells.
Indomethacin is a powerful inhibitor — it stops linoleic acid from converting to the hormonal prostaglandins.
He noticed roughly the same reduction in cancer cell growth with indomethacin as another researcher in 1983.
The identical findings proved that eicosanoids/prostaglandins are involved.
The results from our experiments with pharmacological inhibitors of eicosanoid synthesis imply that prostate cancer cell growth is dependent primarily on LT production.
Prostate cancer, like breast cancer, is often considered hormone-dependent cancer.
You commonly hear things like “estrogen-resistant,” or “androgen-resistant,” in the literature.
Besides the sex hormones, sometimes prolactin is involved as well.
David Rose also tested two more eicosanoid inhibitors.
He tested one that inhibits prostaglandin synthesis called piroxicam.
And he also tested another that inhibits leukotriene synthesis called esculetin.
He found that esculetin had the greatest effect, strongly implying that a leukotriene was involved.
Actually, esculetin is an all-natural molecule found in some plants.
But they a flavonoid called fisetin was an even more effective leukotriene inhibitor.
You can find this flavonoid strongly in strawberries (and apples, to a lesser extent).
Besides avoiding PUFA, aspirin and indomethacin are common prostaglandin inhibitors.
Linoleic acid, although found in vegetable seed oils such as safflower (75% of total fatty acids), walnut (60%), sunflower (54%), corn (53%), soybean (52%), cotton (49%), palm (8%), and coconut (2%), is not a major component of vegetables.
Corn is a major source of linoleic acid.
But soy, canola oil, and others are significant sources of large amounts.
Almonds have 21.52%, and then peanuts also have a large 44.6% portion.
But coconut has just 2% and macadamia 3% — negligible levels.
Other unsaturated fatty acids can cause issues, such as lipid peroxidation.
Lipid peroxidation occurs when oils react with oxygen, a phenomenon entirely impossible with saturated fats.
But only linoleic acid can stimulate prostate cancer through the production of prostaglandins and leukotrienes.
So, it makes linoleic acid the most dangerous polyunsaturated fatty acid.
Only fats containing large amounts of polyunsaturated fatty acids, such as corn oil and safflower oil, enhanced tumor growth.
I’d avoid it as much as you possibly can.
INCIDENCE OF CANCER IN MEN ON A DIET HIGH IN POLYUNSATURATED FAT
Biomarkers of Essential Fatty Acid Consumption and Risk of Prostatic Carcinoma
Effects of Fatty Acids and Eicosanoid Synthesis Inhibitors on the Growth of Two Human Prostate Cancer Cell Lines
Inhibitory activity of a series of coumarins on leukocyte eicosanoid generation
Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut