What is nutrigenomics?
Nutrigenomics evaluates how nutrition influences gene activity; in other words, the food you eat provides information to your genes about how they should function. One person's food can be another's poison. For instance, your immune system may have an inflammatory response to gluten that causes your genetic uniqueness to see the protein as a foreigner that must be rejected. Same goes for lactose, sodium, and cholesterol. Not everybody needs to be on a salt-restricted diet; not everybody needs to be on a cholesterol-restricted diet.
Why test your DNA?
A phenotypic test measures how the body responds to its environment, as when it's exposed to a food or substance. For example, most people's blood cholesterol hardly goes up when they eat two eggs a day. But for a “hyperresponder,” two egg yolks a day would cause blood cholesterol to rise quite remarkably. In this case, a phenotypic test for blood cholesterol indicates how an egg will influence heart disease risk.
New genotypic tests assess genetic markers to predict your body's individual strengths and predispositions to specific problems or conditions.
What do the results mean?
Doctors in this emerging field are coupling genotypic and phenotypic testing so they can advise patients about lifestyle choices that will be best for them.
For example, a gene called methylene-tetrahydrofolate reductase (MTHFR) controls production of the enzyme that regulates folic-acid metabolism. If the enzyme is not working optimally, homocysteine can build up in the blood — a condition associated with Alzheimer's and vascular diseases. So a doctor could perform a genotypic test to measure for MTHFR, then a phenotypic test to measure homocysteine. If your test showed you were a poor folic-acid metabolizer and that your blood contained elevated homocysteine levels, you might increase folic-acid supplementation to reduce your disease risk.
From a conversation with Jeffrey Bland, PhD, CNS, leader in nutritional medicine and founder of the Institute for Functional Medicine, at the 2009 Natural Supplements Conference in San Diego.