Quite some time ago, I wrote about the substance resveratrol as an ingredient in a nutraceutical intended to treat canine cognitive dysfunction. Here was my conclusion at the time:
Resveratrol is a chemical extracted from grapes that has been touted as a general anti-aging panacea. There are numerous in vitro and lab animal studies that suggest the compound may act as an antioxidant and have a variety of effects promoting and inhibiting the expression of a number of genes. There is mixed evidence in lab animals that it may prolong life and inhibit, or in some cases promote, cancer. Human clinical trials for a number of possible uses are ongoing, but no data is available to suggest safety or efficacy for any particular use.
Likewise, there are apparently no veterinary clinical trials of resveratrol alone for cognitive and behavior dysfunction. As the newspaper article quoted above suggests, it is a promising but unproven compound which has been marketed well in advance of reliable evidence to its safety and efficacy. Resveratrol is an ingredient in Senilife, which has only weak supporting research evidence for clinical benefit in veterinary patients.
The latest reviews of the human literature suggest that the evidence hasn’t changed much; still promising but unproven.
Vang O, Ahmad N, Baile CA, Baur JA, Brown K, et al. (2011) What Is New for an Old Molecule? Systematic Review and Recommendations on the Use of Resveratrol. PLoS ONE 6(6): e19881. doi:10.1371/journal.pone.0019881
The overall conclusion is that the published evidence is not sufficiently strong to justify a recommendation for the administration of resveratrol to humans, beyond the dose which can be obtained from dietary sources. On the other hand, animal data are promising in prevention of various cancer types, coronary heart diseases and diabetes which strongly indicate the need for human clinical trials.
Epidemiologic studies can find associations between the consumption of foods or dietary supplements and various health outcomes. Animal experiments can demonstrate what can happen in the species tested. However, only human clinical trials can determine whether supplementation is useful for humans. Resveratrol has not been tested in clinical trials, and most clinical trials of other antioxidants have failed to demonstrate the benefits suggested by preliminary studies. Some substances—most notably beta-carotene—have even produced adverse effects. My advice is to ignore the hype surrounding resveratrol and eat a balanced diet that contains adequate amounts of fruits and vegetables.
There doesn’t appear to be any clinical trial literature on the subject in dogs or cats.
An interesting twist to this story involves one of the most visible researchers promoting resveratrol, Dipak Das from the University of Connecticut. In January, Dr. Das was charge by his university with multiple counts of fraud for falsifying and fabricating data. Since then, 12 of his published papers have been formally retracted. He has published 117 articles on the subject of resveratrol, many of which have been cited numerous times, so this could have some impact on the reliability of the evidence concerning resveratrol, though other researchers in the area contend Dr. Das’ work is not central to the field. In any case, it is a fine example of both the dangers of excessive and premature commitment to a hypothesis and promotion of products based on it as well as of the ultimately self-correcting nature of the scientific process.