RFF#100 – Your ethnicity may be a clue to your ideal diet

Nutrigenomics—the science that combines nutrition and genetics—is revolutionizing the traditional “one size fits all” approach to nutrition recommendations. Scientists are now discovering the gene variants that cause people to respond differently to the same nutrient. A closer look at omega 3 and 6 fatty acids offers a unique view of how nutrition, in combination with genes, dictates health.

By now, everyone has heard that omega 3s are good for your brain. However, omega 3 is a generic name for a family of fats. Docosahexaenoic acid (DHA), a specific type of omega 3 found in fish, krill and algae, is what your brain is made from. While humans have the ability to convert the type of omega 3 in walnuts and seeds into DHA, new research has shown that the degree to which these omega 3s are converted is dictated by your genes.

The scientist behind this discovery is Dr. Floyd Chilton, a full professor of Physiology and Pharmacology at Wake Forest University in North Carolina. In his research, Dr. Chilton has shown that 83% of African Americans are high converters (meaning they can readily convert ALA to DHA), in contrast to only 42% of European Americans. This makes perfect sense when you consider the geography of these regions. In the landlocked countries of Africa, people don’t have access to seafood, hence, they rely on nuts and seeds for their omega 3s. Meanwhile, Europeans don’t require the ability to convert DHA from these other sources, because they tend to get a rich supply from seafood. Biologically speaking, all of this works well, until people migrate and abandon their ancestral diets.

Presently in North America, “we almost have an omega 3 deficiency syndrome,” according to Dr. Chilton. Therefore, you’d think that it’s advantageous to be a high converter. Unfortunately, it’s not that simple. The ability to convert more omega 3s means you also have the ability to convert more omega 6s. This is problematic as Dr. Chilton explained “we have 40 years of studies showing that (omega 6s are) converted to a set of highly proinflammatory mediators… (and) their biochemistry suggests that they can impact inflammation in a potentially negative way.” Therefore, these genetic differences may partially contribute to disparities in health among different ethnic groups.

When asked about what led to this discovery, Dr. Chilton explained “one of the things that really got my attention is the inconsistency of the clinical trials, (this) led me to think that there must be something that we’re missing.” While some studies showed that omega 3s had great benefits, others showed no effect. Part of the reason for this is heterogeneity in the study populations, “when you mix everyone together, it becomes very difficult to make sense of it all.”

In conclusion, this story illustrates one of the great challenges in nutrition. Everyone is genetically different and thus, everyone’s ideal diet is different. As long as we continue conducting trials on genetically heterogeneous populations, it’s likely that we’ll continue seeing anomalies that create confusion and uncertainty. It’s the dawn of a new era in nutrition. Your optimal diet is likely a product of your genes, and while you may have not yet had yourself genotyped, your ethnicity may be a clue to guide you in the right direction.

Special thank you to Dr. Chilton for sharing his expertise. For more information on omega 3s and inflammation, please check out Dr. Chilton’s website www.genesmart.com which offers a wealth of resources.

RFF#70 – Depending on an infant’s genes, breast milk may, or may not, influence their IQ

One of the most interesting studies I’ve come across while preparing for my comprehensive exam showed that the benefits of breastfeeding can depend on one’s genes. In the study, the authors compared the IQs of children who were breastfed in contrast to children who were formula fed. Normally, we expect that the children who were breastfed will have a higher IQ. In keeping with dogma, this is what the authors found in those with a certain variation of the FADS2 gene. However, in children with a different variant of the FADS2 gene, they found something surprising. In these children there was not difference in the IQ of those who were breastfed versus those who were formula fed.

So what does this mean? Well, perhaps there is a gene that either accentuates the ability of the breast milk to promote neural development, or conversely, there may be a gene that prevents the ability of breast milk to improve neural function. At this point, they’re really not sure.

I want to be crystal clear about something…these findings should not be interpreted as a rational for formula feeding. Breast milk is–and always will be–the gold standard when it comes to infant nutrition. Nevertheless, this study illustrates some of the interesting things going on inside the body, the things we (probably ) can’t control, and perhaps, the things that make us who we are.

I learned about this fact from: Caspi et al. Moderation of breastfeeding effet on the IQ by genetic variation in fatty acid metabolism. PNAS, 104(47): 18860-18865.