Keep in mind that taking supplements at all is controversial, and some experts disdain even taking a vitamin.
1. Resveratrol: Metabolism Booster
Hailed as a potential anti-aging wonder since Harvard’s David Sinclair published research in 2003 and 2006 showing it extended the lifespan of mice, resveratrol has since shown extremely mixed results. The extract from the skins of grapes and red wine has demonstrated potential to reduce some problems, such as cardiovascular disease, and shown a disappointing ineffectiveness for others.
But in the past few years, a number of research teams around the country have begun studying resveratrol for its effects on metabolism and glucose tolerance and its resulting potential to trigger weight loss. In a very small but high-quality (randomized, double-blind, placebo-controlled) study published in the journal Cell Metabolism in November, 2011, Dutch researchers led by Sylvie Timmers found that obese men who took 150 mg of resveratrol daily had lower blood sugar, decreased liver fat, and lower blood pressure after just 30 days. While the men did not shed actual body mass in the short amount of time they were followed, these kinds of metabolic changes are associated with weight loss over time.
The year before, a French study published in BMC Physiology found that resveratrol had a significant effect on the body-mass of primates (mouse lemurs, to be specific). The researchers found that lemurs, which typically gain a great deal of weight as winter approaches, ate significantly less and gained less weight during a four-week period when their food was supplemented with resveratrol. The researchers noted that the lemurs’ body temperature and resting metabolic rate was affected by the resveratrol, suggesting that it functioned as a metabolism-booster.
Here’s the problem, though: most of the studies showing significant metabolism-boosting effects from resveratrol have been animal studies like the lemur study above, and resveratrol has a dismal track record when it comes to positive results from animal studies translating to humans, says Jill Crandall, MD, professor of clinical medicine at the Diabetes Research Center at Albert Einstein College of Medicine. “The animal data on resveratrol’s benefits are very convincing,” says Crandall. “But what actually happens when you give resveratrol to humans has turned out to be very different.”
Crandall herself is currently studying resveratrol for its effects on glucose metabolism and insulin sensitivity and is optimistic about its potential, but “we’re not there yet,” she says. “The field is really in controversy right now because there have been so many conflicting studies.” For example, when another group of researchers conducted a similar study to Timmers’ in normal weight people, resveratrol showed no effects on metabolism whatsoever. Crandall’s conclusion? “There’s no evidence from human studies to date that would lead me to advise people to take resveratrol,” she says. “It’s an exciting area of research but it would be premature to say it’s beneficial – the jury’s still out.”
That said, there was other important news about resveratrol three months ago, when resveratrol pioneer David Sinclair published a new study in Science that finally appeared to validate the mechanism behind resveratrol’s anti-aging effects. Sinclair’s team identified the molecular pathway by which resveratrol activates sirtuins, a type of cellular protein that enhances energy production and prolongs lifespan.
It might seem that Sirtris, the company founded by Sinclair to study, test, and market resveratrol, would be riding high on all this good news, but just days after Science released the new research, GlaxoSmithKline , which purchased Sirtris in 2008, shut the company down. The Boston Globe reported that GlaxoSmithKline plans to pursue Sirtris’ research on sirtuins, but will discontinue work on resveratrol. Future research or no, resveratrol is already being used in a number of weight loss supplements and I’m sure we’ll be hearing more about its potential to treat diabetes, insulin resistance, and obesity in the near future.
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| White kidney beans |
Having zoomed to popularity on the broad shoulders of Dr. Oz, white kidney bean extract, scientific name Phaseolus vulgaris, has been hailed as a “fat-blocker” that prevents or slows the absorption of starches.
Most of the excitement over white kidney bean extract has come from studies by anti-aging guru Nicholas Perricone. One small but randomized/double-blinded/placebo-controlled study, published in 2007 in the International Journal of Medical Science, found that 445 mg a day of the supplement caused weight loss in people who were just moderately overweight, even as they ate a high-carb diet.
Another randomized/double-blinded/placebo-controlled study, also involving Perricone and published in the Journal of Applied Research showed that 92 percent of subjects taking white kidney bean extract for two months lost weight in two months vs. 62 percent in a control group.
Extract of white kidney beans (or cannellini, for you cooks) appears to work by inhibiting the action of an enzyme called alpha-amylase, which breaks down carbohydrates. “What’s happening is that a carb present in beans occupies the enzymes that normally break down carbohydrates so they have to travel further down the intestine,” says noted obesity expert Louis Aronne, MD, Director of the Comprehensive Weight Control Program at Weill-Cornell Medical College. “They’re not really being blocked, but that their digestion is slowed.”
