Food and Drugs Affect Individuals Differently
Humans can metabolize a wide variety and range of amounts of food chemicals. The flexibility in metabolic response to changes in type and concentration of dietary chemicals demonstrates an important clue for understanding the effects of diet on health. It is the interactions of dietary chemicals with genetic machinery and information (diet X genotype interactions) that play a key role in maintaining health and preventing diet-influenced chronic diseases.
Pharmacogenomics is Similar to Nutrigenomics
The advances and concepts of pharmacogenomics underscore the importance of genotype X environment interactions by showing how individual genetic variation in human populations can affect a drug's efficacy and severity of undesirable side effects. Genotyping is now being incorporated into clinical trails to predict drug safety, toxicity, and efficacy. By relating phenotype to genotype, drug companies are designing and developing better drugs with fewer adverse side affects. By identifying the non-responding sub-populations, pharmacogenomics can also develop new drugs from compounds previously thought too toxic for human use.
Personalized Medicine includes Personalized Nutrition
The concept of "personalized" medicine is now being extended to the field of nutrition. It is now accepted that nutrients (i.e., macronutrients, micronutrients) alter molecular processes such as DNA structure, gene expression, and metabolism, and these in turn may alter disease initiation, development, or progression. Individual genetic variation can influence how nutrients are assimilated, metabolized, stored, and excreted by the body.
The Food Pyramid
Government efforts to inform Americans about good nutrition and healthy eating habits have had some degree of success although obesity and related diseases continue to rise. Furthermore, dietary guidelines are based on studies that do not reflect the genetic and cultural diversity of the U.S. population.
The USDA recently created a new Food Guide Pyramid called MyPyramid (http://www.mypyramid.gov/). This new pyramid recognizes that one set of food recommendations may not be optimum for every individual. MyPyramid recommendations now take into consideration factors such as age, gender, and physical activity levels. Although there is still a long way to go for individualized recommendations, the recognition that each person differs in the way the respond to their nutritional environment is a major step toward personalized nutrition. Research is also showing that physical activity can also alter molecular pathways involved in health and disease, and MyPyramid acknowledges the importance of exercise in choosing diets and foods.
Application of Nutrigenomics for Personal and Public Health
The application of nutritional genomics to personal and public health poses ethical issues similar to those of pharmacogenomics, particularly with respect to genetic privacy. In addition, some believe that the predictive power of a genetic test for diet advice is too low to be of concern. However, as we decipher the complex biology of gene-nutrient and gene-gene interactions, the probability of identifying disease susceptible increases: genetic testing may identify individuals with predisposition to diet induced disease. The biggest ethical and practical issue facing the application of the results of nutrigenomics research is timing: when is there a sufficient amount of results and knowledge available to interpret genetic tests. These issues require dialogue among all stakeholders.
Castle, D, Cline, C, Daar, AS, Tsamis, C, and Singer, PA. 2006. Nutrients andNorms: Ethical Issues in Nutritional Genomics. In Nutritional Genomics: Discovering the Path to Personalized Nutrition. Kaput, J and Rodriguz, R (eds). Wiley and Sons, Inc. NY. 2006.
Corella, D and Ordovas, JM 2004. The metabolic syndrome: A crossroad for genotype-phenotype associations in atherosclerosis. Curr Atheroscler Rep 6, 186-196 PMID: 15068743
Kaput, J., Swartz, DA, Paisley, EA, Mangian, HJ, Daniel, WL, and Visek, J. 1994. Diet-disease interactions at the molecular level: an experimental paradigm. J Nutr, 124, 1296S-1305S. PMID: 7914920
Kaput, J and Rodriguez, RL 2004. Nutritional Genomics: the next frontier in the postgenomic era. Physiological. Genomics. 16, 166-177. PMID: 14726599 (free access)
Source of "Inside the Pyramid" animation: United States Department of Agriculture - MyPyramid.gov