Monday, August 22, 2011

Resveratrol derivative helps obese lab mice live longer – so what?

Do the new findings about the resveratrol derivative SRT-1720 extending the normally shortened lifespan of obese mice tell us anything new? It’s been a long and ultimately disappointing road with the red wine derivative resveratrol, once touted as the basis for miracle anti-aging drugs and now a fading star. As I have described here before, resveratrol was purported to activate an enzyme system known as sirtuins, which in turn activate anti-aging genes that trigger a unique lifespan extension phenomenon normally associated with severe caloric restriction. Take a pill and skip the starvation diet was the promise, and live up to 40% longer. The idea was so compelling that the biotech company Sirtris was founded to exploit more potent (and patentable) resveratrol derivatives such as SRT-1720.

This latest report showed that giving mice resveratrol after rendering them morbidly obese through an unhealthy diet helped them live longer than they normally would have, by improving insulin sensitivity and otherwise normalizing metabolic parameters thrown out of whack by the diet. But there are problems with the study: firstly, the subject mice still didn’t live as long as mice on a healthy diet. Secondly, there isn’t really anything new here; this has all been reported before.

The real problem is that neither resveratrol nor any of its derivatives has been proven to directly activate sirtuins in the first place. In fact, several labs other than Sirtris have definitely concluded that it doesn’t, that the initial reports were an artifact of the testing method. SRT-1720 may prove to be a useful drug for type 2 diabetes, joining a crowded market. But – and here’s the interesting twist – another diabetes drug, metformin, does extend lifespan in mice on a normal diet.

I have always been a little bit uncomfortable with attributing wine’s well-established health benefits to resveratrol. There isn’t enough resveratrol in wine to explain all of the good things that a glass or two with dinner imparts. There are a lot of things in wine besides resveratrol, including alcohol, and a lot of healthy habits that moderate wine drinkers have. So while I wish the good people at Sirtris all the best of luck, let’s not forget the simple things we can do for a long and healthy life now.

Monday, August 15, 2011

Is organic wine a healthier choice?

Many people accept as gospel that organic food (and wine is a food) is healthier. No chemicals, harmful pesticides, or hormones must mean more nutritional value, right? Maybe, but there is a surprising lack of evidence in the form of dietary intervention studies –that is, actual measures of health parameters comparing organic and regular diets. That isn’t to say that there aren’t any, and recent studies are helping to shed some light on the subject.

Beyond the questions of environmental stewardship and moral/ethical reasons to eat organic, it is important to identify what sorts of nutrients that organic foods might contain in greater abundance and how this translates into better health. Vitamins aren’t the answer; simple enough to take a multivitamin pill and get what you need. A more promising possibility is antioxidants, nutrients such as the polyphenols that make red wine red and in general seem to be more prevalent in brightly colored foods. Antioxidants come in a variety of types, but in general they act as part of self-defense systems against spoilage and a number of environmental challenges. A well-know example is resveratrol from wine; this pluripotent polyphenol is an antiviral, antifungal, all-around good guy that seems to have a wide range of anti-aging properties. And because plants make these in response to environmental stress, they should make more of them when not pampered with sprays, fertilizers, and all manner of unnatural things, they should be more nutritious when left to fend for themselves. (A related concept is “biodynamic” farming.)

So a diet higher in antioxidants is a good thing. The science, however, is a bit trickier, since there are various ways of measuring antioxidant potency, and what works in the lab may not in the diet. Among the various ways to measure antioxidant potency is the ORAC test (Oxygen Radical Absoption Capacity), and it is possible to measure a sort of whole body ORAC with what is called “human plasma total antioxidant capacity.” The aforementioned study started by determining the ORAC levels of organic vs. traditionally farmed foods, including wine, and the scores were higher for the organic foods (with a few exceptions.) In test subjects converted to an organic Mediterranean diet, an increase of 21% in total body antioxidant capacity was seen after 14 days.

Does this mean your wines (and other foods) should be organic? You could make a case for it, but there are plenty of non-organically grown wines that pack a healthy punch. Winemakers already intentionally stress the vines in specific ways because more polyphenols also means more flavorful and distinctive wines. It is just fortunate that good wines tend to be good for you too.