Consuming polyphenol-rich dark chocolate or cocoa products may reduce total and LD cholesterol levels, but has no effect on HDL levels, according to a meta-analysis of 10 clinical trials.
Researchers from Brigham and Women’s Hospital and Harvard Medical School in Boston report that short-term consumption of dark chocolate was associated with a reduction of total cholesterol of 6.23 milligrams per dl, while LDL was reduced by, on average, 5.9 ml/dl.
“The degree to which LDL and [total cholesterol] levels were reduced in this analysis reflects some measure of potency of the cocoa regimen,” wrote the researchers in the European Journal of Clinical Nutrition.
Led by Luc Djoussé, MD, DSc, the researchers also noted that the effect appeared to be greater when cocoa polyphenols were consumed from dark chocolate, compared with a cocoa beverage.
The health benefits of polyphenols from cocoa have been gathering increasing column inches in the national media. To date studies have reported potential benefits for cardiovascular health, skin health, and even brain health.
The majority of science into the potential benefits of cocoa have revolved around cardiovascular benefits of the flavanols (also known as flavan-3-ols or catechins), and particularly the monomeric flavanol (-)epicatechin.
Recently, however, scientists from the University of Reading in England and Mars reported that cocoa may also affect gut microflora and possess prebiotic potential.
The new meta-analysis was designed to evaluate the effects of cocoa products and dark chocolate on blood lipid levels. The researchers suggested that, since dark chocolate is formulated with saturated fat and additional calories, that it may adversely affect blood lipid levels.
Dr Djoussé and his co-workers performed a detailed literature search and identified 10 clinical trials of flavanol-rich cocoa products or dark chocolate involving 320 participants. Five of the studies used daily flavanol doses of less than 500 mg, while the other five used doses exceeding 500 mg per day.
After crunching the numbers, the researchers report that dark chocolate/cocoa products consumption was associated with significant LDL and cholesterol reductions.
On the flip side, there were no changes observed in levels of HDL cholesterol or triglyceride.
“These current analyses are consistent with beneficial effects of dark chocolate/cocoa product consumption on LDL and neutral effects on triglyceride and HDL in a short-term intervention,” wrote the researchers.
Commenting on the potential mechanism and bioactives involved, the Boston-based researchers point to the flavonoids contained in cocoa and dark chocolate.
"Flavan-3-ols in cocoa are present as monomers, oligomers or polymers, better known as procyanidins, and generally are thought to inhibit cholesterol absorption as well as the expression of LDL cholesterol receptors," they noted.
The researchers called for additional studies to elucidate the best dose of cocoa consumption, as well as the long-term effects of dark chocolate consumption on cholesterol levels.
Source: European Journal of Clinical Nutrition
Published online head of print, doi:10.1038/ejcn.2011.64
“Effects of cocoa products/dark chocolate on serum lipids: a meta-analysis”
Authors: O.A. Tokede, J.M. Gaziano, L. Djoussé