June 21, 2010 -- How does drinking red wine manage to keep the cardiologist at bay? Two studies suggest different approaches as to how merlots and cabernet sauvignons and other types of red wine offer heart-healthy benefits.
In the first of two studies published in the July issue of American Journal of Clinical Nutrition, scientists at the University of Ulm, Germany, investigated the biological behaviors of resveratrol in human fat cell biology. Resveratrol is found in the skins of red grapes and has been shown to be a potent biological agent that may offer protection against cardiovascular disease, cancer, type 2 diabetes, and neurodegenerative disorders such as Alzheimer's disease.
Researchers hypothesized that resveratrol might decrease obesity by preventing immature fat cells from fully maturing, and also help activate sirtuin 1 (Sirt 1), a protein that protects the heart from inflammation.
Laboratory tests conducted in vitro on human cells, in which cells were managed in a control environment, such as a petri dish, showed that resveratrol influenced fat cells' form and function. Resveratrol blocked immature fat cells from developing and differentiating, which, in turn, affected the fat cells' abilities to function. Several studies have used animals to examine resveratrol's effects, but this is one of the first to use human fat cells.
They also found that resveratrol stimulated glucose uptake into human fat cells and blocked molecules from converting into fat. Moreover, resveratrol influenced Sirt1 in a beneficial way and it also affected the secretion of adipokines, fat cells that engage in cell-to-cell communication. The findings indicate that resveratrol might interfere with obesity and other metabolic effects that could increase the risk for cardiovascular disease.
Researchers suggest resveratrol could offer some therapeutic opportunities in the treatment of obesity, which is quite prevalent in the industrialized world. Reducing obesity, a major risk factor for cardiovascular disease, may also help improve heart health. According to the World Health Organization (WHO), there are 1.6 billion people age 15 and older who are overweight -- meaning they have a body mass index (BMI) of 25 or higher -- and at least 400 million people who are obese, meaning their BMI is 30 or higher. The WHO projects that in five years there will be 2.3 billion overweight adults and more than 700 million obese adults.
"Our findings open up the new perspective that resveratrol-induced intracellular pathways could be a target for prevention or treatment of obesity-associated endocrine and metabolic adverse effects," the authors write. "Resveratrol may act on different levels of cell signaling."
Red Wine and Blood Vessel Cells
In the second study, researchers from the Israel Institute of Technology, Haifa found that red wine enhanced the health of the cells in blood vessels. The research team studied 15 healthy adults with a mean age of 29 years who agreed to consume 250 mL (8.5 ounces or two servings) of red wine everyday for three consecutive weeks. The participants provided blood samples at the beginning and end of the three-week study period so that researchers could evaluate blood vessel function.
The researchers write that "daily red wine consumption for 21 consecutive days significantly enhanced vascular endothelial function," which means it improved the health of the cells lining the blood vessels, which then improves blood flow and heart health. Drinking red wine every day also helped reduce cell death or what is known as apoptosis.
"The prevalence of cardiovascular disease is low in populations that consume large amounts of red wine," they write. "Moderate consumption of red wine provides cardiovascular protection, but the mechanisms that underlie this protection are unclear."
The researchers suggest that red wine increases nitric oxide bioavailability and triggers a cellular communication process necessary for blood vessels to function. Endothelial cells lining the interior of the blood vessels rely on nitric oxide to signal to the vessel tissue to relax, which aids in blood flow. Red wine, the researchers report, facilitates cellular communication that then activates this process.
In an accompanying editorial to both studies, researchers from the National Institute on Aging in Bethesda, Md., suggest clinical trials are needed to measure the effect of red wine and to assess whether the compounds in red wine can reverse or attenuate established cardiovascular disease.
Resveratrol "acts both indirectly (through adipose tissue) and directly (through endothelial cells) to prevent cardiovascular disease," they write. The two studies provide "new insights into the mechanisms underlying the potential benefits of resveratrol in metabolic disease." However, they caution, questions remain about red wine's biological properties and mechanisms.