5 September 2007
Genetic testing services, including paternity and some health-related tests, are becoming increasingly available to the general public via the internet and other direct-to-consumer routes. Providers claim this increases the privacy and convenience of testing but, as with other types of genetic tests, limited regulation applies to their use.
One group of tests offered over-the-counter are nutrigenomic tests, which combine testing for multiple common genetic variants (such as those linked in some way to heart disease or osteoporosis) with information on diet and lifestyle, and on the basis of these results suggest a diet supposedly tailored to promote health and reduce the risk of disease in the individual. A report by the US Government Accountability Office last year raised concerns that such tests might mislead consumers by, for example, making unsound or ambiguous predictions about health risks, and making unwarranted recommendations to purchase unnecessary dietary supplements (see previous news story).
It is also feared that people may be following the dietary regimes ‘prescribed’ by such tests without proper medical advice; although many manufacturers advise that consumers discuss test results with their doctors, it is uncertain how many people follow this advice. This issue is addressed in a new paper analyzing the results of two 2006 US surveys on direct-to-consumer nutrigenomic tests [Goddard KA et al. (2007) Genet Med. 9(8): 510-7].
In a survey of the general public, 14% of the 5250 respondents were aware of nutrigenomic tests and 0.6% had used them. These figures showed that awareness of nutrigenomic tests was on a par with that of pharmacogenetic tests (despite the fact that there is far more scientific evidence to support the use of selected forms of pharmacogenetic testing), and lower than awareness of other forms of genetic testing such as disease risk prediction, diagnosis or screening (30-50%). A significantly higher proportion of the 1225 clinicians interviewed in a second study reported awareness of nutrigenomic tests (44%), although almost half (41%) had never had a patient ask about such tests, and most (74%) had never discussed nutrigenomic test results with a patient.
The authors report that “the vast majority” of individuals who reported awareness of direct-to-consumer nutrigenomic tests had not used them, but note with some concern that the media was the primary source of information for both consumers and clinicians. They therefore call for more prominent educational initiatives from professional and government bodies in this area, if only to emphasise the current lack of evidence to support nutrigenomic testing. It is suggested that awareness of this form of testing is likely to rise in the future as advertising increases, and that appropriate policies and education should be developed.
Looking further ahead to a time when genuinely beneficial and validated forms of nutrigenomic testing might become available, the authors also express concern that direct-to-consumer testing might increase health disparities, because of their finding that younger, wealthier and better educated individuals had generally higher awareness of (and presumably capacity to pay for) nutrigenomic tests.
Comment: This study provides new data and raises a number of important issues, including the importance of making sure that health professionals are suitably informed about the health benefits (or otherwise) of forms of genomic testing that are becoming increasingly available (and marketed) to the general public.