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Dark Chocolate Reduces Insulin Resistance

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Dark chocolate has many health benefits, from blood sugar to blood pressure and cholesterol. Photo: Flickr/Jules Clancy

Finally, some research we can all get really excited about.  If you love chocolate as much as I do, then I have good news, but before you go out and by a 25kg carton in the interests of your health,  I must put a disclaimer at the beginning: the sugar content of chocolate bars does women with PCOS the world of no good and the fat content needs to be factored into your daily caloric limits. Even pure cocoa powder has some carbohydrate in it – about 3 g per tablespoon.

Studies have now shown that chocolate can be good for you, or more specifically the primary ingredient in chocolate: cocoa.  It has many health benefits across areas including blood pressure, blood sugar and cholesterol.  It lowers blood sugar and insulin resistance; improves cholesterol profiles by increasing HDL cholesterol and lowering LDL cholesterol oxidation and can normalise blood pressure by making blood vessels more flexible and reactive.

Cocoa is a nutritional powerhousewith a good macronutrient balance: 35% carbohydrates, 50% fats and 15 % protein by caloric contribution.  A tablespoon or 5 grams contains just 12 calories  and is high in fibre, rich in antioxidants including polyphenols, flavonoids, oligomeric proanthocyanidins (OPCs) and catechins; minerals and vitamins such as calcium, some B vitamins including folate, magnesium, iron, copper, sulphur, potassium, phosphorus, zinc and selenium.    It also contains substances which increase the production of some neurotransmitters which produce a sense of well-being such as serotonin (a natural anti-depressant), dopamine (the reward neurotransmitter), endorphins (responsible for the ‘runners’ high), phenylethylamine (a chemical produced in the brain when people are ‘in love’), and anandamide (the bliss chemical).

Cocoa comes from the pods of the theobroma cacao tree, an evergreen which is indigenous to the deep tropical parts of the Americas.  Although it is possible to buy whole cocoa in the form of raw or roasted cocoa nibs in some boutique and health food shops, it is more commonly processed into two main components: cocoa butter, the fatty component and cocoa powder, the remaining dry constituent after the cocoa butter has been removed.

60% of the fats in chocolate are saturated making it one of the most stable oils you can find.  It also contains 32% mono-unsaturated fats, the kind that make olive, avocado and macadamia so healthy.

The ORAC, or oxygen radical absorbance capacity, is the standard way to measure antioxidant capacity of foods, with the value is expressed in micromoles of Trolox Equivalents per 100 grams of sample.

Cocoa is one of the most potent antioxidant foods around with an ORAC score 55,653 µ mol TE/100g, putting it well above the majority of antioxidant foods, except for spices.  To put that into perspective, the popular antioxidant superfood Acai berries come in at 102,700 µ mol TE/100g, whilst fruits such as cherries, apples, raspberries and blueberries, also considered excellent antioxidants all come in at between 3,500 – 5,500 µ mol TE/100g.  Green tea comes in at only 1253 µ mol TE/100g, red wine 4523 102,700 µ mol TE/100g.

One factor to consider, however, is that combining cocoa with milk reduces, almost to the point of elimination, the benefits associated with all the flavonoids in it. The same goes for tea.

Dark chocolate has also been found to decrease fasting insulin levels by 25% and improve utilisation of glucose by cells. Insulin sensitivity is partly dependant upon insulin-mediated nitric oxide release.  Cocoa, being high in flavonols, improves the bio-availability of nitric oxide, which results in better insulin sensitivity.

Studies have shown that consuming dark chocolate without increasing your total caloric intake, decreases blood pressure. It is possible that this may be due to the action of cocoa as a renin-angiotension enzyme inhibitor, the same mechanism by which pharmaceutical antihypertensive medication works.

A study in the Journal of the American Medical Association (JAMA) in 2003 reported the results of a small (13 subjects) and brief (14 days) German study conducted at the University of Cologne, which found that dark chocolate consumption reduced blood pressure of hypertensive subjects in just 2 weeks.  The effect was only maintained whilst the participants continued to consume dark chocolate.  After the study, blood pressure returned to pre-study levels.  The study participants were aged between 55 and 64 and had a mean systolic blood pressure of 153 mm/Hg and a mean diastolic of 84 mm/Hg (153/84) and normal body mass index (BMI). The had all been recently diagnosed with mild hypertension and were yet to commence treatment for it.

The group was divided into two groups. One group ate a 100-gram bar of white chocolate daily containing no polyphenols and the other group ate a dark chocolate bar, rich in polyphenols. After only two weeks, the period of the study, those who received the dark chocolate reduced their systolic blood pressure by an average of 5.1 mm/Hg and their diastolic by 1.8 mm/Hg.  Those who received the polyphenol-free white chocolate bars had no change in their blood pressure.

The bottom line then is that chocolate, the darker the better, can be a healthy addition to a nutritious diet so long as it doesn’t result in an increase in the amount of calories consumed, nor sugar.

The best way to benefit from all that cocoa has to offer is to consume raw, organic cocoa nibs.  As they have not been processed, they have the highest antioxidant and polyphenol content.

If that’s not your thing however, there are some brands of chocolate now that use non-caloric, non-glycaemic sweeteners such as stevia, xylitol and erythritol rather than sugar.  These are a healthier option than traditional chocolate bars.  Fair trade and organic options also abound, so for a healthy treat that will make you feel good on all sorts of levels, look out for fair trade, organic and stevia/xylitol sweetened dark chocolate.


More Information:

Taubert, D. Chocolate and Blood Pressure in Elderly Individuals With Isolated Systolic Hypertension   The Journal of the American Medical Association, Aug. 27, 2003; vol 290: pp 1029-1030.

Serafini, M. Nutrition: Milk and absorption of dietary flavanols Nature, Aug. 28, 2003; vol 424: p 1013. U.S. Department of Agriculture Nutrient Data Laboratory.

Lee KW, Kim YJ, Lee HJ, Lee CY.  Cocoa has more phenolic phytochemicals and a higher antioxidant capacity than teas and red wine.  J Agric Food Chem. 2003 Dec 3;51(25):7292-5.

Grassi D, Necozione S, Lippi C, Croce G, Valeri L, Pasqualetti P, Desideri G, Blumberg J, Ferri C.  Cocoa Reduces Blood Pressure and Insulin Resistance and Improves Endothelium-Dependent Vasodilation in Hypertensives. Hypertension.  2005; 46: 398-405

Zeng G, Nystrom FH, Ravichandran LV, Cong LN, Kirby M, Quon MJ. Roles for insulin receptor, PI3-kinase, and Akt in insulin-signaling pathways related to production of nitric oxide in human vascular endothelial cells.Circulation. 2000; 101: 1539–1545.


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