March 9, 2007 -- Drinking cocoa each day may boost levels of HDL ("good") cholesterol, Japanese researchers report.
Researchers, who included Kazuo Kondo, MD, PhD, of Tokyo's Ochanomizu University, studied 25 healthy Japanese men with normal or mildly high cholesterol levels.
None of the men were taking any prescription drugs, antioxidants, or vitamin supplements. They weren't overweight, judging by their average BMI (body mass index), and they didn't drink a lot of alcohol.
First, the researchers checked participants' blood and urine samples and divided them into two groups.
One group was assigned to drink cocoa containing sugar each day for 12 weeks.
For comparison, the men in the other group were told to drink a sugary beverage containing no cocoa for 12 weeks.
But it was no ordinary cocoa the first group drank. The researchers bought the cacao beans themselves and roasted, cracked, and ground them in their lab. They also analyzed the cocoa powder to make sure it hadn't lost major amounts of antioxidants during processing.
At the end of the 12-week experiment, participants provided more blood and urine samples.
HDL Cholesterol, LDL Cholesterol
The men in the cocoa group showed a 24% rise in their HDL, or "good," cholesterol levels. HDL levels also rose for the comparison group, but to a lesser extent (5% increase in HDL).
The researchers also tested the men's LDL ("bad") cholesterol.
Those tests included blasting samples of the men's LDL cholesterol with free radicals to trigger a process called oxidation. Oxidized LDL cholesterol may be particularly hazardous because oxidation may help LDL cholesterol build up in the arteries, the researchers explain.
The lab tests showed that the LDL cholesterol of the men who drank cocoa daily for 12 weeks was more resistant to oxidation than the LDL cholesterol of men who didn't drink the cocoa.
However, the study shows similar blood levels of LDL cholesterol for both groups -- including oxidized LDL -- regardless of cocoa consumption.
Cocoa contains antioxidants called polyphenols, which may be responsible for the study's results, note the researchers.
The study doesn't prove cocoa was the sole reason for the men's increase in HDL cholesterol.
The researchers stop short of recommending daily cocoa drinks for everyone. Tea, wine, fruit, and vegetables also contain polyphenols and may help heart health, note Kondo and colleagues.
"Moreover," they write, "it is irrefutable that a balanced daily diet is important for the promotion of human health." In other words, don't count on cocoa to make up for an unhealthy diet.
The researchers included six staffers from Meiji Seika Kaisha, a Japanese food and pharmaceutical company whose products include chocolate.
Don't know your cholesterol levels? A simple blood test can fix that. The results can help you and your doctor make a plan to improve your cholesterol profile.