To Your Health

Q. I'm seeing advertisements for services that will test your DNA and provide customized vitamins based on your genetic needs. Is this a valid method for determining the supplements you need? A. DNA (deoxyribonucleic acid) is the material that contains the instructions for many visible and invisible body features such as eye color, stature, disease resistance, and a host of other inherited traits. It is a long stringlike molecule present in almost every cell of our body. Each of our body's cells that possess a nucleus contains a complete copy of our DNA, so within an individual all the muscle cells, brain cells, liver cells, white (but not red) blood cells, sperm cells, and lots of other cells have identical copies of DNA. During reproduction, DNA is copied and passed on to the offspring.

All DNA testing is based on the observation that the genome (the complete set of chromosomes) of each person, except in the case of identical twins, is unique. DNA testing identifies the subtle differences in the DNA of individuals. It can determine your genetic susceptibility to a disease, confirm a diagnosis, or determine whether a disease you already have is genetically based. At this early stage of development, it cannot yet directly determine which nutrients you need in extra amounts. It is still a powerful tool to help you make some very important health, medical, and lifestyle decisions.

DNA test results must be combined with information about the effect of diseases on nutritional requirements in order to come up with recommendations for food supplements. At present, few genetic conditions are documented to be corrected through nutritional intervention, but there is immense potential. The May 6, 2005, "To Your Health" column mentioned using DNA testing to uncover the mutation in folic acid metabolism that makes 5-methyltetrahydrofolate more helpful than folic acid for some individuals.

There are several DNA test panels that focus on mutations associated with some common diseases that are manageable with improved nutrition. For example:

• A cardiac panel identifies the mutations associated with increased risk of developing atherosclerosis, hypertension, and coronary artery disease. The tests check for risk factors that include blood clotting syndromes, cholesterol regulation defects, and inflammation markers.

• An osteoporosis panel identifies mutations associated with increased risk of developing osteoporosis. The tests check for inherited defects in calcium metabolism, vitamin D3 activity, parathyroid hormone action, and collagen synthesis.

• A detoxification panel identifies mutations associated with our ability to remove toxins from our bodies. Detoxification defects have been associated with increased risk for certain cancers, chronic fatigue, and alcoholism.

• An immune panel identifies mutations associated with increased risk of developing defects in our immune system that lead to asthma, heart disease, and infectious diseases.

• A test for the hereditary iron overload disorders that affect as many as one in 10 men promises to prevent many serious problems, including diabetes, liver, and heart disease.

Once you are aware of an increased risk, you can make the lifestyle modifications, including nutritional intervention, which will better shield you from harm.