Dr Karine Nohr looks at whether you should recommend a dose of chocolate to your patients with high blood pressure
Having lived with serial chocoholics (i.e. they eat one, then they eat another, and another, but they never eat more than one at once) who proclaim the alleged health benefits of their vice, I have had a go at looking at what these claims are about.
Chocolate contains polyphenols, such as procyanids, which are antioxidants. Like the antioxidants found in red wine, they are thought to not only inhibit the oxidation of LDL-cholesterol and but also to inhibit platelet aggregation. The flavanoids in cacao are also thought to upregulate nitric oxide synthase in endothelial cells and thus improve endothelial function, therefore having cardiovascular protective effects.
Additionally, there is an interesting relationship between cacao and hypertension. The first prospective trial (Dutch Zutphen Elderly Study), followed up 470 elderly men for 15 years and those with the highest cocoa consumption had had lower blood pressure and an adjusted 50% relative reduction in risk of cardiovascular and all-cause mortality. Other studies have confirmed these findings, including ones that compared the effect on BP of giving white chocolate vs black chocolate. The latter showed a significant reduction of blood pressure.
So telling your patients that it is good for their blood pressure to eat 10 to 30G of black chocolate every day is recommended by the author Nahal in his review of the subject, written up in the Canadian Family Physician Journal, 2008.
The caveat seems to be that the chocolate needs to be relatively unprocessed (and therefore not destroying the flavanoids) such as the ‘fine’ varieties, and at least 70% cocoa.
This is also because a large proportion of most commercial chocolate is full of sugar and fat. Most of the fat in cocoa butter is in the form of stearic acid, which is thought to act rather like monosaturated fat and thus not to raise cholesterol. However, milk chocolate contains a lot of added butterfat, which can raise cholesterol.
Does chocolate have any effect on mood? Why do women with PMT claim comfort from eating chocolate? Apparently there are a number of possible mechanisms for this.
Firstly, chocolate is claimed to boost serotonin levels.
Secondly, chocolate is thought to contain phenylalanine, which potentiates the action of dopamine and also triggers the release of endorphins. Phenylalanine is released when people fall in love.
Thirdly, chocolate is thought to contain a fatty substance called anandamide, which binds to the same receptors as cannabinoids.
Fourthly, chocolate contains theobromin, which is a xanthine alkaloid (like caffeine).
So there are possible explanations for why eating chocolate might make you feel good.
I must include an appeal in this article, to remind people of the link between the growing, harvesting and trade of cacoa and child slavery, and so encourage the choice of fair trade chocolate.
Dr Karine Nohr is a GP in Sheffield
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