Men who are blessed with a sunny disposition and a predilection for a cup of cocoa before bedtime are also likely to live longer, scientists have discovered.
Two separate studies in the Netherlands have found that regular cocoa drinkers have lower blood pressure than non-drinkers and that an optimistic outlook helps you to avoid heart disease.
Both studies looked at large numbers of men between the ages of 64 and 85 who were interviewed about their lifestyles in order to tease out any associations with potentially lethal diseases.
Brian Buijsse of the National Institute for Public Health and the Environment in Bilthoven investigated the cocoa-drinking habits of 470 elderly men, whereas Erik Giltay of the Institute of Mental Health in Deft looked at levels of optimism among 545 men of a similar age.
Dr Giltay said that optimism was assessed in questionnaires given out in 1985, 1990, 1995 and 2000 which asked the men to rate their agreement with statements such as "I still expect much from life" or "I do not look forward to what lies ahead of me in the years to come".
During the 15 years of follow-up, Dr Giltay and his colleagues found that optimism was linked with about a 50 per cent lower risk of cardiovascular disease.
"Optimism can be estimated easily and is stable over long periods. It is yet to be established whether interventions aimed at improving an older individual's level of optimism may reduce the risk of cardiovascular mortality," Dr Giltay said.
Meanwhile, over the 15 years of the study looking at cocoa drinking, the scientists found that the men with the highest consumption levels had significantly lower blood pressure than those who hardly drank the beverage.
The study also found that regular cocoa drinkers were also at half the risk of developing serious heart disease compared to non-drinkers and were more likely to live longer, according to Dr Buijsse and his colleagues.
"The lower cardiovascular mortality risk associated with cocoa intake could not be attributed to the lower blood pressure observed with cocoa use," the scientists write in the Archives of Internal Medicine.
"Our findings therefore suggest that the lower cardiovascular mortality risk related with cocoa intake is mediated by mechanisms other than lowering blood pressure."
One theory is that cocoa powder is a rich source of antioxidants, such as plant flavanols, and that these natural substances help to prevent a range of diseases associated with damage due to aerobic metabolism.
"Because cocoa is a rich source of anti-oxidants," the scientists say, "it may also be related to other diseases that are linked with oxidative stress, for example pulmonary diseases, including chronic obstructive pulmonary disease, and certain types of cancer."
What's in a bean
* Cocoa beans contain a range of anti-oxidants including plant flavanols.
* Flavanols are thought to increase nitric oxide in the blood.
* That is thought to improve the function of blood vessels.
* Anti-oxidants help to prevent a range of diseases associated with damage due to aerobic metabolism.