Future challenges and present ethical considerations in the use of personalized nutrition based on genetic advice.

N UTRITIONAL RECOMMENDATIONS DIRECTED toward the general population are based mainly on estimated average nutrient requirements for a target group. These norms intend both to meet the needs of most individuals in a community and to prevent common diseases, such as obesity, diabetes, and cardiovascular problems. Personalized nutrition guidelines are currently focused on people with metabolic disorders. Infants with inborn errors of metabolism (eg, maple syrup urine disease, phenylketonuria) or adults carrying specific genetic monogenic disorders (eg, familial hypercholesterolemia, hypolactasia) benefit from genetic-based dietary advice. Current management of nutritional and metabolic diseases is based mainly on clinical examinations and dietary advice. However, as a result of the Human Genome Project, advances in molecular biology and “omics technologies” have emerged in the last few years. This progress in genetic technologies is contributing to the extension of this practice to other diseases with gene-related backgrounds in order to individualize the dietary prescription under genetic premises. Decreased costs and increased analytical speed have boosted the commercialization of robust genetic testing for clinician and consumer use. However, important concerns must be addressed, such as validity and correlation with specific nutritional diseases, target population, and the inter-relationships of single genetic variants with unknown, compensatory genetic mechanisms or nutrient gene interactions. Nutrigenetics envisages dietary personalization through a genetic “reading” of nucleotide sequence and polymorphisms (single-nucleotide polymorphisms [SNPs]) in order to offer an individualized dietary prescription. This approach is based on the detection of those genetic variants (alleles) that can influence the patient’s development of nutritionor metabolism-related diseases. Knowledge of genetic traits can complement the data collected by the registered dietitian (RD) and other health professionals concerning anthropometrics, biochemical analyses, and dietary assessment. Also, it would contribute to more deeply customized recommendations for dietary and lifestyle modifications. Genetic variations can predict susceptibility to health problems caused by poor diet or detrimental lifestyle habits. Therefore, nutrigenetics represents a promising preventive tool in primary care by providing early information to RDs about environmental and genetic interactions influencing obesity and other nutritionally related diseases. In fact, it is an instrument for delaying or preventing disease onset through personalized dietary advice. Diverse companies are considering the potential of this applied nutrition field and a number of genetic test panels have emerged in the last 10 years. Most of them are marketed using the internet through affordable direct to consumer testing because it is considered a good medium to reach people and showcase new technology. However, this system of publicity and sale involves ethical concerns because the web is open and the seller could offer services and information with insufficient scientific accuracy or exclusively with commercially driven interest. Direct to consumer testing could also provide biased information to clients with not enough knowledge. These new tools are worthless without adequate interpretation and subsequent translation into colloquial language by trained RDs. These professionals should have the ability to assess and recommend the best genetic test by evaluating the assayed genetic variants, price, available information, quality, and other values related to nutritional interactions. The aim of this commentary is not only to provide an overview of the genetic test panels currently available in the US and European markets, but also to provide information about the analyzed genetic variants and the scientific evidence relying on these variants in order to help RDs and other nutrition and health professionals choose suitable products and use the information provided critically. To develop this search, a systematic review of the websites of genetic diagnostic laboratories was performed during 2012. Apart from general Google pages, we used specialized search engines (such as the National Center for Biotechnology Information and SNPedia) and biomedical research partnerships (eg, ASEBIO, in Spain). To interpret raw data, the matches and mismatches between genes analyzed in Spain and the United States were specifically checked.