This year I was invited to speak at Chatham House, and my talk was titled “Germs, Genes and Geography.” I spoke about how diets evolved and with it how new genes were expressed.
In researching for my latest book, The Genetics of Health, I was especially concerned at falling omega-3: omega-6 ratios in modern humans. The ratio between omega-3 and omega-6 fatty acids is important for cell membrane function and, for regulating blood pressure and inflammatory processes. What’s the science behind omega-3 fatty acids? Let’s take a look.
The human body, both for prehistoric humans and today’s population, is capable of producing all the fatty acids it needs except for two: linoleic acid (LA), an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3 fatty acid. Although the levels of LA are usually much higher than those of ALA in many plant seed oils, rapeseed oil and walnut oil are still very good sources of ALA.
About 8 to 20 percent of ALA is converted to eicosapentaenoic acid (EPA), which has been shown to have cardio-protective abilities and is found in fish oils. Flaxseed oil, for example, is rich in omega-3 oil but not as efficient as fish oil in converting this to EPA or docosahexaenoic acid (DHA) that is helpful for brain development.
Analyses of ancient diets reveal that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1:1, whereas, in Western diets, the ratio can be up to 15:1. Many of the oils we think healthy are in fact omega-6 oils (such as sunflower oil, evening primrose oil and peanut oil).
Reports have suggested that a lower omega-6 to omega-3 ratio reduces the risk of breast cancer (in women), rheumatoid arthritis and Alzheimer’s disease. Therefore, I was interested to read some news reports recently that suggested that omega-3 supplements did not protect against heart disease. These reports were based on a Cochrane Report that studied over 100,000 people.
In my view, the key was that most studies looked at fish oil supplements and not eating fish as food. The report suggested fish oil supplements made no difference to the risk of death or heart attacks or strokes, the Cochrane researchers found, but eating more ALA from supplemented margarine or walnuts did convey a small benefit, even if small. The lead author, Dr. Lee Hooper was also quoted in The Guardian as saying that “Extra fish replaces something else in the diet, which may be less good for you …also iodine, selenium, calcium and vitamin D are at good high levels and much less common in other foods that the fish might replace.”
I was alarmed by a report on pollution and climate change by the WHO about air quality and that dementia, mental illness and reduced intelligence, diabetes, kidney disease and premature births were all on the rise due to worsening air pollution. A study on mice showed that omega-3 fatty acids (OFAs), found in flax, hemp and fish oils, can both prevent and treat the inflammation and oxidative stress caused by air pollution, with the OFAs delivering a 30-50% reduction in harm. While studies on mice must be interpreted with caution, the lead researcher of this study, Dr. Kang suggests that 2-4g of omega-3 fatty acids (O3FAs) would be the equivalent human dose – a fairly generous portion of fish, it must be said.
I’m not surprised about the differences between fish-oil supplements and eating real fish. I have noted the same effect in my skin research using vitamin C. As I mentioned in The Genetics of Health, I found the same when testing vitamin C serums, foods and supplements. I could see the benefit in eating vitamin C in fruit form. As many dermatologists prescribe high-dose vitamin C tablets, which is the synthetic version, I tested supplements and found no skin benefit.
In the beginning, I thought this was an error in my analyses or scanner. But now I know that this phenomenon is well-known as “xenobiotic metabolism”—wherein the body recognizes synthetic versions as alien to normal metabolism and absorption. Oral vitamin C tablets may work on other internal organs, but on the skin’s surface, there is no visible benefit. We can however see benefits of vitamin C on skin when it is used as a skin serum or consumed as food. Therefore, natural is best; as with any food source, the less processed the better.