In January 2018, the New York Times published an article titled: High-fat Diet May Fuel Spread of Prostate Cancer, citing an animal study that looked at the relationship of fats with this male disease. Is there an association between a high fat diet and prostate cancer? The question is not new. Back in the early 1940s, a researcher, Dr. Tannenbaum postulated that fats contribute to cancer. But back then until roughly the late 1990’s, dietary fats were considered the big evil monster – a primary culprit of all deadly health problems.
High Fat Diet and Prostate Cancer Study Details
- About ten mouse models were studied.
- Some mice were fed a high, 60% fat diet and others a low, 17% fat diet.
- Researchers observed two genes, PTEN and PML. (These genes normally protect us from cancer, and they are known as tumor suppressor genes.).
- When mice had little or no PTEN and PML genes, prostate cancer cells spread and produced fat molecules.
- When mice producing fats were given an obesity drug named “fatostatin” cancer regressed. This drug works by stopping the production of fat formation.
- A group of mice was then fed a high-fat diet compared to another group who at a low-fat diet and researchers noticed more tumor spread in the fat eating mice.
Does this Study Prove that Dietary Fats Fuel Prostate Cancer?
First, as you may guess, one cannot make strong conclusions from animal studies for human application. If we would, we’d have the cure for every disease by now. Second, what exactly was in the food in the group of mice eating a high-fat meal?
I was curious to know. Here’s what I found:
- Among other things, the high-fat meal fed to mice contained non-fat components that are linked to prostate cancer; 265g Casein and Choline 3.0g. All these ingredients have been linked to prostate cancer and lard (pork fat) is probably the least culprit.
- Casein, a protein found in dairy has been linked to the proliferation of prostate cancer.
- Choline is a water-soluble vitamin also associated with advanced prostate cancer in studies.
- To note, the low-fat feed contained no casein or choline.
Third, don’t be fooled, researchers in this study are interested in researching a drug interfering with fat metabolism and hopefully slowing down the spread of cancer, which is not the best diet for to avoid or manage prostate malignancies.
Is There a Connection Between Dietary Fats and the Spread of Prostate Cancer?
There is no conclusive association between eating fat, including saturated fat and prostate cancer. However, there are two possible exceptions, too much Omega 6-fatty acids and consumption of trans-fatty acids.
Omega 6 fats are good for the body but only when in the balance with Omega-3 fatty acids. The omega-6 to omega-3 ratio in the standard American (heart attack) diet is 20 or 30:1, omega 6 to omega 3. The healthier ratio is 2 or 1:1, respectively.
Trans-fats or partially hydrogenated oils, are an industrially created unsaturated fat that gets hydrogenated (synthetically adding hydrogen atoms) causing a trans molecular structure compared to the most natural cis form. Since trans structured fats are unnatural, eating them causes havoc in the body including hardening of blood vessels (atherosclerosis) and increases systemic inflammation.
In 2015, the FDA gave food manufacturers a deadline of June 2018 to remove all trans fats in foods. Since then manufacturers have begun introducing new oils and fats for frying, baked goods and food stuffs like powdered coffee creamers. Does that mean that our patients can eat more fried or processed foods with this new law? To be blunt, no.
Overall, fried and simple carbohydrates in processed foods are public enemy number one. There is no getting around the fact that contribute to cancer, obesity, and disease-related deaths.
What do Human Studies Say about the Connection between Fats and Prostate Cancer?
The correlation between fat consumption and the risk of prostate cancer seems to depend on the specific types of fat and their constituent fatty acids. Here are 6 examples that counter the notion that fat intake may lead to prostate cancer.
- One researcher studying close to 150 Jamaican men evaluated the relationship between the intake of dietary fatty acids and prostate cancer biopsy grade and volume and concluded that omega-6 fatty acids stimulated prostate cancer cell growth, whereas omega-3 fatty acids inhibited cancer cell growth.
- Another meta-analysis that studied close to 450,000 subjects showed a significant 63% reduction in prostate cancer–specific mortality, not prostate cancer diagnosis. Most fish is largely high in Omega 3-fats.
- In the North Carolina-Louisiana PC Project, 322 cases out of 1800 were considered an aggressive disease. High total fat-adjusted and saturated fat intake was associated with increased prostate cancer aggressiveness, with a suggestion of a stronger effect in men not using statins.
- Another study had the exact opposite results after prospectively following about 385 men for an average of five years. The saturated fat consumption was significantly associated with higher survival from prostate cancer (p = 0.008). Compared to men in the lower intake of saturated fat, those who ate more saturated fat had three times less risk of dying from prostate cancer.
- The long European multi-center prospective study of 142,520 men in the European Prospective Investigation into Cancer and Nutrition (EPIC) study suggest that there is no association between dietary any type of dietary fat and prostate cancer risk.
- Lastly, one study reported that consuming high amounts of fat from vegetable sources (e.g., olive oil, nuts) after diagnosis of non-metastatic prostate cancer was associated with lower risk of developing lethal disease.
- Interestingly, in this same study, replacing 10% of calories from carbohydrates with vegetable fat was associated with a 29% lower risk of lethal prostate cancer.
- Perhaps even more interesting, Men who consumed more vegetable fat after diagnosis had a lower risk of all-cause mortality. Replacing 10% of calories from carbohydrates with vegetable fat was associated with a 26% lower risk of death from any cause.
- Researchers also found a 5% increase in saturated fat was associated with a 30% higher risk of death and a 1% increase in trans fat was associated with a 25% higher risk of death.
What to make of the Studies on Dietary Fats and Prostate Cancer
Inconsistent and contradictory results from nutrition studies will continue to emerge in part because of the inherent variability of foods, as well as the uncontrolled variables in study populations and experimental designs.
In the North Carolina-Louisiana PC Project, for example, is the link between saturated fats and aggressive prostate cancer the result of eating too many cheeseburgers or pints of ice cream? In populations where obesity is rampant and fried chicken is a staple meal, one has to look at the types of fats consumed rather than throw all fats under the proverbial bus.
Though, I do like my gumbo now and then.
We know more today and our studies should reflect that knowledge. Why are we are not studying groups of people eating a tablespoon of butter (saturated fat) a day compared to another group eating a tablespoon of olive oil (monounsaturated fat) and the another taking an ounce of flaxseed oil (polyunsaturated) and then seeing what happens in ten years or so? This type of methodology would limit other variables found in fatty foods and provide clarity on what is truly causing what. Such a study, which would be difficult for obvious reasons, would show insight about the type of fat that may cause prostate cancer and overall deaths and which fats do not.
Just look at the animal study in question at the beginning of this post. The high-fat meal wasn’t only saturated fat, it consisted of other ingredients known to promote aggressive prostate cancer. So, what caused cancer spread on these fat eating mice? Was it the saturated fat? Was it the casein? What it the choline? This is why making oversimplified conclusion in nutrition science is so challenging.
How I provide solid guidelines for patients and my students at NYU:
- Tirelessly reading most of the research papers on this type of topic, not just the last published study. There is more value in the preponderance of data than the latest journal article.
- Have a good understanding of nutrition and biological science. In other words, I teach my students (and patients) to learn how the body functions normally so identifying dysfunction becomes easier.
- I am my own experiment. I simply try different diets, different supplements and different exercises to see how I feel and what the labs results reveal.
- Too much of any macronutrient has detrimental prostate cancer effects and interferes with longevity. That’s why I’ve become a fan of intermittent fasting as of late where you don’t eat any macronutrient for a longer period than usual, say twelve to sixteen hours a day or more. Yes, I am my number one guinea pig.
- In my busy practice, I get to see what works and what doesn’t with patients. And see for whom something works and doesn’t.
Above all, it’s important to understand the nuances of fats. We are no longer living in a fat-fearing world and studies like this one only serve to further the misunderstandings. Our patients don’t need any more confounding advice to add the already confusing world of nutrition and health.