Cocoa flavonols linked to low blood pressure
from cardiovascular disease (CVD) by half, reports a long-term
study of elderly men.
Previous studies have linked flavonols to improved cardiovascular health markers, but this is the first study to look at the effect of chocolate consumption on blood pressure.
"To our knowledge, this is the first observational study that found that habitual cocoa intake was inversely associated with blood pressure in cross-sectional analysis and with cardiovascular and all-cause mortality in prospective analysis," wrote lead author Brian Buijsse from the National Institute for Public Health and the Environment, Bilthoven, and Wageningen University, the Netherlands.
The study, published in the Archive of Internal Medicine (Vol. 166, pp. 411-417), measured cocoa consumption from cocoa-containing foods for 470 men with an average age of 72.
The cocoa-containing foods included chocolate confectionary, cocoa sandwich filling, cocoa desserts, cocoa drinks, and dietary supplements.
After 15 years of follow-up, the researchers observed that the men who consumed the most cocoa (more than 2.3 grams per day) had lower systolic diastolic blood pressures (3.7 mmHg and 2.1 mmHg, respectively) than those who consumed the least cocoa (less than 0.36 grams per day).
During the study, 314 of the volunteers died, and CVD was the cause of death for 152 men.
When analysed in terms of CVD risk, the men who consumed the most had a 50 per cent lower risk. When the results were adjusted to exclude the intake of other nutrients, like vitamins C and E, magnesium, beta carotene and folic acid, the results were similar.
High cocoa consumption was also linked to a 40 per cent lower risk from death of any kind (all-cause mortality).
This led the researchers to propose that the link between cocoa consumption and the lower risk of CVD, and lower blood pressure, was due to the presence of the flavonols.
Several studies have shown that flavonol consumption increased blood vessel opening (vasodilation), and improve endothelial function (the cells that line the blood vessels).
It is this latter effect that the scientists propose as the mechanism by which the flavonols reduce CVD risk and all-cause mortality.
However, because the scientists did not take blood samples and measure serum levels of different nutrients, it was not possible to identify the exact effect of the cocoa.
"Because cocoa is a rich source of antioxidants, it may also be due to other diseases that are linked to oxidative stress. This merits further investigation," wrote Buijsse.
Experts however want against consumers gorging themselves on chocolate.
Cathy Ross, medical spokesperson for the UK charity, the British Heart Foundation, said: "There is some evidence that when eaten in small quantities, dark chocolate might have some beneficial effects on blood vessels and lowering blood pressure, but as yet no study has investigated the long-terms clinical effects. This small study from Holland reinforces the fact that more still needs to be done to determine how eating cocoa affects coronary heart disease in the long term."
Ross stressed that large amounts of cocoa are not readily tolerated in its raw state, and if people wanted to eat the suggested 'therapeutic' amount that they would have to eat about 100 grams of dark chocolate a day.
"This would mean an average intake of 500 calories per 100g and an average 30% of fat. Eating less did not produce the same effect.
We are certainly not suggesting people never eat chocolate - everyone can enjoy a treat from time to time. But there are much better ways of improving your heart health," said Ross.
Products are already available on the market with increased flavonol content, and offer an alternative to the traditional bars of chocolate. For example, confectionary giant Mars offer the CocoaVia brand that contains over 100 mg of flavonols per 85 ml serving.
CVD causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy an estimated €169 billion ($202 billion) per year. According to the American Heart Association, 34.2 percent of Americans (70.1 million people) suffered from some form of cardiovascular disease (CVD) in 2002.
