MEDICAL MATTERS: Are you in good form after the Easter weekend? If so, it could be related to the number of Easter eggs you ate. And if these eggs were primarily of the dark chocolate variety, you may have benefited your cardiac health as well as your mood.
Researchers have identified almost 400 chemicals in chocolate. These include phenylethylamine and tryptophan, which are converted in the body to the neurotransmitters dopamine and serotonin. Dopamine has been linked to the experience of pleasure. Serotonin is a key chemical in maintaining normal mood. And chocolate is also thought to increase levels of mood-enhancing endorphins.
Chocolate comes from the tree Theobroma Cacao. Theo means God in Greek and broma means food, hence, it is sometimes referred to as the "food of the gods". Cacao is the key ingredient of chocolate from a health point of view. Over 100 medicinal uses for cacao have been described from as far back as the 16th century. It has been claimed to improve anaemia; to stimulate appetite; to "strengthen" the brain; and to increase breast milk production. Other claims for chocolate and cacao include improved longevity, increased libido, and use as a treatment for kidney stones and tuberculosis.
The cacao tree grows mainly in the West Indies and South America. It produces cocoa pods filled with beans. These are dried out before being lightly roasted, which enhances their colour and flavour. They are then ground into cocoa solids. It is the amount of these solids and the amount of milk combined with them that determines whether the chocolate will be dark, milk or white. As the important chemicals are contained in the cocoa, the higher the cocoa content - and the darker the chocolate - the greater the potential health benefits.
The key to the cardiovascular benefits of chocolate is the amount of flavanoids in different types. Flavanoids are potent anti-oxidant substances that protect cells and tissues from the damage induced by "free radicals", which have been implicated in the development of coronary heart disease and cancers.
Flavanoids are thought to protect against cardiac disease in a number of ways; they act as conventional antioxidants (in particular suppressing the oxidation of LDL - the "bad" cholesterol); they prevent the aggregation or "clumping" of platelets and so reduce clot formation; and they cut the inflammatory response to disease.
The evidence that chocolate could prevent coronary heart disease is mounting. One study from the Department of Nutrition at the University of California showed that dark chocolate reduced the clotting of platelets. Researchers fed volunteers either pieces of bread or 25g pieces of dark chocolate and then took blood samples two and six hours later. Those who had eaten chocolate had a significant decrease in platelet activity. Summarising this, and other research in an article last year in the American Journal of Clinical Nutrition, Dr Carl Keen and his colleagues noted: "several in vivo studies have provided strong support for the hypothesis that the consumption of flavanoid-rich foods such as certain cocoas and chocolates, may be associated with a reduced risk of vascular disease".
In 2003, research reported in Nature found plain, dark chocolate consumption resulted in a rise in the total anti-oxidant capacity of blood and in the blood content of a dietary flavanoid known to protect cardiac health. Significantly, however, the authors reported both beneficial effects were reduced when the chocolate was eaten with milk or if milk chocolate was used.
Prof Catherine Rice Evans of the department of biochemistry at Kings College, London, has analysed flavanoid-rich foods for their anti-oxidant power. She found that a typical 50g bar of dark chocolate has a similar anti-oxidant activity as 15 glasses of orange juice, six apples, two glasses of red wine or 4.5 cups of black tea.
But perhaps the most significant sign chocolate is being taken seriously as a therapeutic agent for heart disease is last week's announcement that a UK professor of therapeutics wants to test dark chocolate on patients with existing cardiovascular problems.
Of course, it is not all good news on the chocolate front. Milk chocolate bars contain 50 per cent sugar, have a high calorie content and little anti-oxidant action and so cannot be recommended. But just a few squares of quality dark chocolate (higher than 80 per cent cocoa) is sufficient to produce beneficial health effects without causing weight problems. So, if you have any eggs left over after the weekend, it's probably best for your heart to finish off the dark chocolate ones over a period of time!
Dr Muiris Houston is pleased to hear from readers but regrets he cannot answer individual queries.
