The dark side of chocolate: healthy and heart-friendly

January 6, 2009 by  

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Resource post for January

Have you ever looked at the chocolate section in the supermarket lately? I’m sure many of us do not, to avoid temptation. After all, chocolate is the number enemy of weight watchers, diabetics, heart patients, and health-conscious parents. Or is it? Lately, more and more studies indicate that chocolate can have a healthy side – and it is the dark side.

No wonder chocolate manufacturers are reinventing chocolate. We now have dark chocolates with up to 90% cacao content, chocolates which are sugar-free, with low-fat. And yes – even chocolate for diabetics.

Chocolate research

Now, before we go on, let’s take a look at the research studies on the health effects of chocolate.

Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide
This study by German researchers evaluated the effect of dark chocolate on the blood pressure of adults with prehypertension and stage 1 hypertension. The 44 study participants were randomly assigned into two groups. One group was given 6.3 g of dark chocolate per day (equivalent to 30 kcal, with 30 mg of polyphenols) for 18 weeks. The other group was given polyphenol-free chocolate of the same quantity for the same duration. The study results showed that from baseline to 18 weeks, dark-chocolate intake reduced mean systolic BP by 2.9 mm Hg (p<0.001) and diastolic BP by 1.9 mm Hg (p<0.001) without changes in body weight, lipids, glucose, or 8-isoprostane. Hypertension prevalence decreased from 86% to 68%.”

Dark chocolate improves coronary vasomotion and reduces platelet reactivity
This study by Swiss researchers at the Zurich University Hospital investigated the effect of polyphenol-rich dark chocolate in the health outcomes of 22 heart transplant patients. An intake of 40 g of dark chocolate with 70% cocoa “induces coronary vasodilation, improves coronary vascular function, and decreases platelet adhesion 2 hours after consumption. These immediate beneficial effects were paralleled by a significant reduction of serum oxidative stress and were positively correlated with changes in serum epicatechin concentration.”

Cocoa consumption for 2 wk enhances insulin-mediated vasodilatation without improving blood pressure or insulin resistance in essential hypertension
This study by American researchers investigated the effects of effects of dark chocolate on insulin sensitivity in people with high blood pressure. The study participants were given 150 mL flavanol-rich cocoa drink two times a day equivalent to approximately 900 mg of flavanols per day for two weeks. The results showed that cocoa treatment at the said dose “did not significantly reduce blood pressure or improve insulin resistance and had no significant effects on skeletal muscle capillary recruitment, circulating plasma concentrations of adipocytokines, or endothelial adhesion molecules… [and] … wasnot sufficient to reduce blood pressure or improve insulin resistance in human subjects with essential hypertension.” However, it was shown to enhance insulin-mediated vasodilation.

Dark chocolate fights heart woes
A study by Japanese researchers showed that eating dark chocolate improves blood flow to the heart muscles. The study participants were 39 male adults who were given either dark chocolate (with 550 mg polyphenols) or white chocolate (no polyphenols) every day for 2 weeks. It was observed that coronary blood circulation significantly improved after 2 weeks in the group given dark chocolate but not those who ate white chocolate.

Cocoa could be a healthy treat for diabetic patients
Yet another study by American researchers evaluated the effect of chocolate on the functioning of vessels among diabetic patients. The study reported that after diabetic patients drank specially formulated high-flavanol cocoa for one month, blood vessel function went from severely impaired to normal.” The vascular improvement observed was comparable to those brought about by exercise and common diabetic medications.

What makes dark chocolate healthy?

For chocolate, the darker, the better and the darkest secret of chocolate is in the cacao polyphenol. Cocoa, the raw powder from the cacao plant, is rich in polyphenols, compounds which have cardioprotective and antioxidation properties. Polyphenols are also found in many plant products such as tea, grapes, walnutsolive oil, and many other fruits and vegetables.

Cacao polyphenol is a flavonoid, which is a subgroup of polyphenols. It is estimated that cacao polyphenol contains four times as much flavonoids per serving than either tea or red wine.


Does this mean we can gobble as much chocolate as we want?

Not really. Remember: “Life is just like a box of chocolates. You never know what you get.”

The studies described here were performed under strict conditions where the quality of the chocolate, the sugar as well as the fat content, are controlled and standardized. This is not like that in the real-life chocolates as we know them – the ones that come in boxes. In other words, we really don’t know what we are getting in terms of flavonoid content. This is because chocolate flavonoid content depends on many things, including:

  • The type of cacao beans
  • The processing (e.g. roasting, temperature, fermentation)
  • The additives

Thus, the percentage of cacao in a bar of chocolate is not really a sure indication of flavonoid content.

And, we know that too much of a good thing can be bad and that also applies to chocolates. Chocolate may have flavonoids but it also contains fat and calories that can make you gain weight.

So, no, we cannot use chocolate as the next “wonder health food” and go on an “all-chocolate diet.” But we can indulge ourselves every now and then without feeling guilty or concerned for our health.

Photo credit: stock.xchng

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NOTE: The contents in this blog are for informational purposes only, and should not be construed as medical advice, diagnosis, treatment or a substitute for professional care. Always seek the advice of your physician or other qualified health professional before making changes to any existing treatment or program. Some of the information presented in this blog may already be out of date.

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