Some fats can help prevent cancer and some cause it. It depends on the type of fat and the health of the individual. However, the long chain saturated fats in red meat and palm oil are unhealthy for everyone. The shorter saturated fats in coconut oil are healthy. The unsaturated fats in flaxseed oil, algae (Spirulina), fish oil, salmon, mackerel and sardines are also healthy for most people. The purpose of this article is to describe some of the past misconceptions about fat and the current thinking about whether or not two particular dietary fats, DHA and ALA (docosahexaenoic acid and α-linolenic acid), can help prevent prostate cancer or cause it. As described previously, systems thinking should be used to understand that the answer depends on the person (or living system) that is consuming ALA or DHA and the other foods that they consume 1.

As mentioned in another previous article in the WSI, there have been some serious misconceptions about fat and human health in the past 2. It was once assumed that because excess body fat can lead to many types of cancer, that one should not eat much fat. Also, we were taught that people became fat because they did not have enough self-discipline. Supposedly, they were fat because they ate too much and did not exercise enough. In fact, fat is a type of molecule and nutrient, not a description of a person. So, nobody is fat. Obese people are not fat, they are obese. This is seldom due to a personality flaw or a lack of self-discipline. Often it is due to bad advice. That is, a low-fat diet can be deadly. This was shown in the Prospective Urban Rural Epidemiology (PURE) of 125,287 participants from 18 countries in North America, South America, Europe, Africa, and Asia 3.

Participants who cut back on fats had shorter lives than those enjoying plenty of fats, even if they came from butter, cheese and meats. Even though the British National Health Service (NHS) warned people not to eat too much saturated fat, the group that ate the least amount of saturated fat had a 13% higher incidence of death. The group that consumed the highest amount of total fat had a 23% lower incidence of death. More importantly, the group that consumed the highest amount of carbohydrates had a 28% higher incidence of death. The authors of the study stated that consuming a proper balance of fats and carbohydrates was best for the health of the population. The conclusion was that 35% of all of one’s calories should come from fats 3. Still, this is an oversimplification. One should consume unsaturated fats – especially omega fats that are found in many types of seafood and plants – and avoid the saturated fats that are in meat.

There is a broad scientific consensus that long chain saturated fats are bad for almost everybody, when consumed in excess 4. In contrast, unsaturated fats and omega fats can help prevent neurodegenerative and cardiovascular diseases, as well as many types of cancer. Some of them are especially good at preventing colon cancer, Alzheimer’s disease, stroke and heart attacks 4. However, ALA is controversial. It may have caused prostate cancer or prevented it, depending on whether you read articles published in 2004 or 2018 5. Let us look at current government recommendations and show how they oversimplify some important issues.

The United States Department of Agriculture (USDA) recommends consuming “Oils, including those from plants” 6. Furthermore, “Americans should be encouraged to consume less than 10 percent of calories per day from saturated fats. Foods that are high in saturated fat include butter, whole milk, meats that are not labeled as lean, and tropical oils such as coconut and palm oil.” 6. Such recommendations are usually written after many reviews and heated discussions of previous drafts. It is always difficult to strike a balance between giving enough information to enable consumers to make intelligent decisions, while keeping it simple enough so most people can understand them. So, compromises are made. As a result, the quotes are oversimplifications. They do not mention that coconut oil contains shorter saturated fats (with fewer carbons) than palm oil, the production of which is devastating some tropical rain forests 7.

However, not all unsaturated fats and omega fats have the same health effects on everybody. Some, like DHA, have been linked to a lower incidence of neurodegenerative and cardiovascular diseases, as well as many types of cancer 8. It is an essential fatty acid that is a major component of cell membranes in the human brain (especially the cerebral cortex), skin and retina. However, some studies have shown that overconsumption of DHA may increase a man’s risk for prostate cancer 8. Still, it is great for babies. Mother’s milk is naturally enriched with DHA. It is also in fish oil and fatty fish. It can also be made in the body from ALA that is found in meat, plants, Spirulina (blue-green algae) and algae oil. However, only a small portion of dietary ALA is converted to DHA. Still, some people consume flaxseed oil, which is almost 50% ALA 9. Unlike fish oil, flaxseed oil does not contain any of the environmental toxins that are in salmon and fish oil. However, women might want to consume DHA since they do not have a prostate gland but do have brilliant brains that could use the protective effects of DHA. Older men who are physically and mentally active and are at low risk of cardiovascular and neurodegenerative diseases might want to avoid DHA supplements. However, if they are at risk of developing prostate cancer, they might want to consume ALA, which has many health effects 10-12.

To complicate things, there have been conflicting reports about the effects of ALA on cancer 13-15. One study showed that even though ALA might help prevent fatal heart attacks, it may increase the risk of prostate cancer 13. A later report looked at previous clinical trials and research 14. It concluded that omega-3 fats probably neither cause nor prevent prostate cancer. Expressed in scientific language, “We found no consistent evidence supporting a role of n-3s in either the causation or prevention of prostate cancer at any stage or grade” 14.

Note that there are no acids of any kind in fish oil, flaxseed oil or dietary supplements containing pure ALA or DHA 16, 17. The ALA and DHA are not present as individual molecules but are part of a larger molecule called a triglyceride. The triglyceride is not acidic, so people who have acid reflux can consume ALA, DHA, fish oil and flaxseed oil 16, 17. Instead, the triglycerides that we eat are broken down into fatty acids plus glycerol 16. The polyunsaturated omega-3 fats can be further converted to protectins and resolvins that protect against inflammation and resolve inflammation when it occurs 16. There is a wide scientific consensus that avoiding chronic, low grade inflammation (smoldering inflammation) can help prevent many diseases, instead of cancer. So, why did previous data suggest that this might not be true for prostate cancer?

The answer comes from systems thinking. It is not just the ALA but the entire food that is important. In a recent report, this fact became apparent 15. The reason why most older studies found that ALA could cause prostate cancer was because back then, eating meat was much more common than it is now. Many subjects obtained their ALA from meat. In more recent clinical trials, more of the subjects obtained ALA from plant sources, such as flaxseed oil 15. Moreover, flaxseed oil can help prevent cardiovascular diseases, including heart attacks. However, unlike coconut oil and olive oil, flaxseed oil should not be used to cook or fry foods. It has many carbon-carbon double bonds that can react with oxygen and light to produce cancer-causing byproducts 6. So, flaxseed oil should be stored in a dark container.

Still, science recognizes that the currently available evidence is incomplete and misleading. A recent article made a strong argument that this is the case for nutrition 18. The authors questioned the validity of tens of thousands of epidemiological studies that were based on the subjects’ self assessment and accurate reporting of the foods they ate. These self assessments were almost never accurate 18. This makes sense. One of the first things that any popular diet tells you to do is to write down what you eat and drink. We tend to forget the extra snacks that we might consume. Sometimes, it can be quite difficult to see yourself as you really are.

All we can say is that the best evidence that we have now supports the hypothesis that older men who have a low risk of cardiovascular and neurodegenerative disease should probably avoid taking dietary supplements containing DHA and should limit their consumption of red meat – especially if it is grilled 19. Instead, such men should consider consuming ALA from flaxseed oil and/or Spirulina. In contrast, some foods, like tomatoes (especially when cooked), broccoli (and other Cruciferous vegetables) 19 and pomegranate juice 20 can also help prevent prostate cancer. Finally, one’s health depends on much more than just one part of one’s diet. The entire diet and lifestyle, as well as genetics and epigenetics affect our health.


1 Smith, Robert E. Modern medicine. Systems thinking and total quality management, 24 September, 2018.
2 Smith, Robert E. Don’t eat meat! Save yourself and humanity, 24 October, 2018.
3 Mente, Andrew et al. Association of dietary nutrients with blood lipids and blood pressure in 18 countries: a cross-sectional analysis from the PURE study. Lancet Diabetes Endocrinology, 5: 774-787, 2017.
4 Wang, Dong D et al. Association of specific dietary fats with total and all-cause mortality. Journal of the American Medical Association, Internal Medicine, 176: 1134-1145, 2016.
5 Greupner, Theresa et al. Effects of a 12-week high-α-linolenic acid intervention on EPA and DHA concentrations in red blood cells and plasma oxylipin pattern in subjects with a low EPA and DHA status. Food & Function, 9: 1587-1600, 2018.
6 United States Department of Agriculture. HHS and USDA Release New Dietary Guidelines to Encourage Healthy Eating Patterns to Prevent Chronic Diseases. January 7, 2016.
7 White, Rob. The Global Context of Transnational Environmental Crime in Asia. In: The Palgrave Handbook of Criminology and the Global South Carrington Kerry et al. (eds). Palgrave Macmillan, London, 2018.
8 Calder, Philp C. Very long-chain n-3 fatty acids and human health: fact, fiction and the future. Proceedings of the Nutrition Society, 77: 52-72, 2018.
9 Rodriguez-Leyva, Delfin et al. The cardiovascular effects of flaxseed and its omega-3 fatty acid, alpha-linolenic acid. Canadian Journal of Cardiology, 26: 489-496, 2010.
10 Greupner, Theresa et al. Effects of a 12-week high-α-linolenic acid intervention on EPA and DHA concentrations in red blood cells and plasma oxylipin pattern in subjects with a low EPA and DHA status. Food & Function, 9: 1587-1600, 2018.
11 Rajaram, Sujatha. Health benefits of plant-derived α-linolenic acid. American Journal of Clinical Nutrition, 100: 443S-448S, 2014.
12 Barceló-Coblijn, Gwendolyn and Murphy, Eric J. Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: Benefits for human health and a role in maintaining tissue n-3 fatty acid levels. Progress in Lipid Research, 48: 355-374, 2009.
13 Brouwer, Ingeborg A. et al. Dietary α-linolenic acid is associated with reduced risk of fatal coronary disease, but increased prostate cancer risk: a meta-analysis. Journal of Nutrition, 134: 919-922, 2004.
14 Dinwiddle, Michael T et al. Omega-3 fatty acid consumption and prostate cancer: a review of exposure measures and results of epidemiological studies. Journal of the American College of Nutrition, 35: 452–468, 2016.
15 Wu, Juan et al. A 24-year prospective study of dietary α-linolenic acid and lethal prostate cancer. International Journal of Cancer, 142: 2207-2214, 2018.
16 Smith, Robert E. Systems Thinking in Medicine and New Drug Discovery, Volume Two. Cambridge Scholars Publishing, Newcastle upon Tyne, 2018.
17 Guillén, Maria D. and Ruiz, Ainhoa. Rapid simultaneous determination by proton NMR of unsaturation and composition of acyl groups in vegetable oils. European Journal of Lipid Science and Technology, 105: 688-696, 2003.
18 Archer, Edward et al. The failure to measure dietary intake engendered a fictional discourse on diet-related diseses. Frontiers in Nutrition, 5: 15, 2018.
19 Gann, Peter H. and Giovannucci, E.L. Nutrition and Prostate Cancer, Prostate Cancer Foundation, Santa Monica, CA, 2005.
20 Paller, Channing J. A review of pomegranate in prostate cancer. Prostate Cancer and Prostatic Diseases, 20: 265-270.