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The Case for Chocolate

Systematic review
Results
Stearic acid
Flavenoids in chocolate
Chocolate and mechanisms
Flavenoids and heart disease
Comment

Bandolier obviously has chocolate lovers among its readers, but chocolate lovers who want a healthy lifestyle. Can it really be true, they ask, that chocolate can be good for you? Henry's mother's hairdresser's friend was always of the opinion that a little of what you fancy does you good, but here a systematic review [1] promised some evidence to support any prejudices.

First a note on chocolate. It is made from cocoa beans that are fermented, roasted and cracked to leave a kernel, which is ground to a paste. If hardened, this is bitter chocolate. Adding sugar and cocoa butter produces dark chocolate, and the addition of this to milk concentrate produces milk chocolate. Cocoa butter and milk concentrate contain fats, a large proportion of which is (saturated) stearic acid. Chocolate also contains theobromine and caffeine, and particularly antioxidant flavanoids, procyanadins, and flavenols. These antioxidants are considered to have significant protective effects against heart disease.

Systematic review


The search was limited to English language studies found in MEDLINE to mid-2005, which examined at least one of several aspects of the relationship between chocolate and cardiovascular health.

Results


The review covered about 140 publications and looked at several different aspects.

Stearic acid


Observational studies of stearic acid (dietary, or serum levels) generally show that it is associated with higher levels of heart disease, either as incidence or mortality. Stearic acid comes predominantly from meat and dairy products, so there is little surprise there. Stearic acid from chocolate is a small contributor to stearic acid intake, of about 5% in the average western diet.

Flavenoids in chocolate


Chocolate, dark or milk, has higher levels of flavenoids or oxygen radical absorbance capacity than almost any other food, based on weight (Figures 1 and 2) or on energy. Only apples come close.


Figure 1: Flavenol and procyanadin content of chocolate compared with other foods high in antioxidants







Figure 2: Oxygen radical absorbance capacity of chocolate compared with other foods high in antioxidants






Chocolate and mechanisms


Over 20 small trials have studied effects of chocolate on physiological and biochemical parameters over the short term. The quality of the studies and the magnitude of the effects cannot be seen from the review. Several reported lower blood pressure, decreased low density cholesterol oxidation, decreased platelet aggregation, improved endothelial function, and greater antioxidant capacity.

Flavenoids and heart disease


The review reports 11 prospective observational studies of the association between flavenoid consumption and heart disease or stroke. Studies were conducted in populations of 500 to 40,000 (about 190,000 people in total), followed up for 5 to 28 years. Most reported some reduction in coronary heart disease mortality. A meta-analysis indicated a significant protective effect between flavenoid consumption and risk of coronary heart disease mortality, with a relative risk of 0.81 (95% confidence interval 0.71 to 0.92).

Comment


Many different polyphenols contribute to antioxidants in the diet. There is no absolute need to eat chocolate to get antioxidants. But chocolate has lots of them, and different ones, and is pretty nice on the whole for most of us. Eating too much chocolate is not a good idea, though, because of the sugar and stearic acid it contains. Like so many other things, a little chocolate taken regularly is likely to be a good thing; a little of what you fancy.

Reference:



  1. EL Ding et al. Chocolate and prevention of cardiovascular disease: a systematic review. Nutrition & Metabolism 2006 3:2 (online journal: www.nutritionandmetabolism.com)

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