M.T. Ravi Subbiah, PhD
Dr. Subbiah is from the Department of Internal Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio. Disclosure: Dr. Subbiah reports no relevant conflicts of interest.
Nutrigenomics is a growing field related to genetic testing based on the documentation of genetic mutations in an individual, giving us the ability to correct metabolic imbalances (personalized medicine) through specific dietary supplements or nutraceuticals. An off-shoot of nutrigenomics called dermagenetics (testing for selected genetic mutations related to skin health followed by advocating the use of either nutraceuticals or skin creams enriched by cosmeceuticals) is heading toward commercialization at a rapid rate by directly targeting the public. Although this growth represents an opportunity to explore the benefits of genetic advances in skin health, it is essential that the science, product claims, and ethical standards be critically evaluated and clear national guidelines be set in order to protect the consumer.
The field of nutrigenomics promises the ability to tailor diet based on individual genetic make up. Human Genome Project has provided a framework for the following: a) documentation of single nucleotide polymorphisms (SNPs) in candidate genes; b) exploration of their association with metabolic imbalances; and c) creation of a panel of nutrigenomic tests that can be evaluated in the clinical laboratory. Studies based on ethnopharmacology, phytotherapy, and dietary supplement use have provided strong evidence for the interaction of nutrients and botanicals with the genome causing marked changes in gene expression[3,4] and the ability of genetic variations to cause marked differences in individual response to dietary factors. This has led to the commercial development of nutraceuticals and functional foods that seek to modify negative health effects of individual genetic profile.[6,7] Large-scale nutrition intervention studies currently underway will further help validate nutrigenomic concepts in selected genes and continue to add new tests to the nutrigenomic panel. These nutrigenomic concepts are gaining popularity by giving the individuals at risk of developing metabolic problems some options to practice preventive health.
Dermagenetics and metabolomics
When evaluating the application of nutrigenomics to skin health, one has to be aware that the situation will present some unique options and concerns.[9,10] While it is perfectly reasonable to assume that the skin tissue will derive some benefits of the nutraceuticals given orally, skin is also unique in being amenable to assimilating phytonutrients (so called cosmeceuticals) after direct topical application. Research studies examining the benefits of oral nutraceuticals have clearly shown that the oral route can indeed improve certain aspects of skin health.[11,12] Recently, however, this approach has taken a twist by linking skin health with dermagenetics. Dermagenetics (an off shoot of nutrigenetics) examines selected genetic mutations to determine what nutraceuticals will offer to benefit the individual skin health. The common mutations examined are related to the enzymes involved in the following: a) collagen breakdown, b) photoaging and free oxygen radical elimination, c) degradation of environmental pollutants, and d) generation of pro-inflammatory molecules. Some companies have utilized dermagenetics to lure customers into getting expensive genetic testing, then recommend specific nutraceuticals or skin creams enriched by selected cosmeceuticals. There are strong disagreements as to the validity of dermagenetics and its benefits for the following reasons: First, there is no guarantee that a given mutation will indeed display significant abnormalities at the blood and tissue levels due to the contributions of post-translational modifications. Second, no evaluation of blood parameters are actually made in subjects before recommending a selected nutraceutical. For example, the normal levels of blood oxidative stress parameters in a given individual are still not firmly established to warrant antioxidant or other dietary supplementation. It is suggested that dermagenetics could considerably benefit patients by incorporating metabolomics, a rapidly growing science that actually examines metabolite profiles in blood and tissues under defined conditions, providing meaningful basis for intervention.
The use of topical skin creams containing cosmeceuticals has developed into a multibillion dollar industry. How much benefit these cosmeceuticals actually provide when applied topically is currently a matter of debate. As discussed by Choi and Berson, the degree of benefits achieved might depend on formulation methods, the degree to which the active compounds can maintain integrity and the duration of their effects, and factors affecting their release from the carrier vehicles. How are these benefits evaluated? In most cases, the benefits of skin creams are evaluated not by their ability to change a given cell function, but rather by the appearance of the skin. The proliferation of skin care lotions claiming the ability to remove wrinkles and change skin coloration and texture warrants that well-controlled efficacy studies be a prerequisite to actually claimed benefits of specific cosmeceuticals.[16,17] Recent advancements in the application of nanotechnology[18,19] to the development of cosmeceuticals will certainly enhance the penetration of the active ingredients into the skin and may offer maximum benefits.
Finally, as the field(s) related to nutritional genomics expand their scope into cosmetic and beauty products, it is essential that state/federal regulatory agencies set clear guidelines for diagnostic laboratories, especially for those offering genetic tests (that link with skin health) directly to consumers (without physician referrals); more strictly monitor health claims of ingredients in skin creams; and work with the universities to train physicians, nutritionists, and dietary professionals in nutrigenomics to meet the health challenges of this postgenomic era.
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