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Just in case you needed another reason to eat chocolate, research shows it has positive effects on heart and brain health, writes nutritionist Diana Robinson.

Cocoa has been shown in numerous clinical studies to act upon nitric oxide synthase, a substance which causes dilation of the blood vessels. The effect of this is that more oxygen can be distributed throughout the vessels, allowing for greater cardiac output. It is for this reason that nitric oxide precursors are often used in sports supplements. In relation to cardiovascular health, vasodilation also means that less blood pressure is exerted on vessel walls, which in turn means blood pressure may be reduced. When there is constant high pressure on blood vessel walls, as occurs with hypertension, this can damage the endothelial cells that line the arteries, increasing the risk of atherosclerosis (hardening and thickening of the vessel walls) and cardiovascular disease. Not only does cocoa provide nitric oxide production, the flavanols have also been shown to actually improve vascular tone of arteries and capillaries, thereby reducing the risk of atherosclerosis.

In the mood

Studies on chocolate's role in mood disorders have shown positive results, especially with regards to the link between the polyphenol content of chocolate and depression and anxiety. Studies show that people who regularly eat chocolate with a high polyphenol count demonstrate measurable improvement in mental calmness, and decreases in anxiety and depression. Along with the brain-altering chemicals found in cocoa, its antioxidant polyphenols also encourage the growth of beneficial bacteria in the gut; and, as there is a well-known link between the health of the gut and the brain, dark, low-sugar chocolate may improve mental health through numerous pathways.

The flavonoids found in the cacao bean belong to a group of polyphenols which are found in many different foods, the most well-known being those from grapes/wine and green and black tea. Phenethylamine (PEA), a chemical found in raw cacao beans, is also produced in the body when we fall in love. About 10 percent of the weight in the cacao bean comes from flavonoids, with dark chocolate being one of the richest sources of flavonoids. The more cocoa content the chocolate has, the higher its polyphenol level will be: for it to have the desired beneficial effects, the chocolate should contain a minimum of 70 percent cocoa. Milk chocolate will not have the same beneficial effects, sorry guys! And white chocolate? Forget it! White chocolate does not contain cocoa at all.

Cacao vs. cocoa

Cacao is the purest form of chocolate you can eat. The cacao tree (also known as the theobroma tree) contains pods which are cracked open to reveal the cacao beans. Cacao and cocoa powders are both produced by grinding cacao nibs to a paste or liquor, and then removing the cacao butter, which is the fat component of the cacao. Raw cacao powder is made using a cold-pressed extraction method, which preserves the highest level of antioxidants and nutrients. Raw cacao powder also retains the fibre content found in the cacao beans.

Cocoa powder, which is the one we all grew up with and is found in supermarkets, uses heat during the extraction process. There are two kinds, natural and Dutch-processed. Natural cocoa powder is reddish-brown in colour, very bitter to taste and has an acidic pH of around 5.3-5.8. The second type, Dutch-processed cocoa powder, undergoes an extra step at the beginning of production where the beans are soaked in potassium carbonate to alkalise the pH to a more neutral 6.5-7.6. Dutch-processed cocoa powder is darker in colour and less bitter. The good news is that essentially all studies which show positive health benefits of chocolate tested regular dark chocolate with a minimum 70 percent cocoa (imagine if they’d used raw!). Some compounds are very sensitive to heat, and so are destroyed during the heating process. This is why raw cacao products are generally considered superior, as they yield the highest antioxidant and mineral content. However, if raw is a little out of your budget, rest assured you can still achieve positive effects with minimum 70 percent cocoa.

Certain compounds are lost during heating. For example, vitamin C is found in raw chocolate only; once cacao is heated, all vitamin C is destroyed. Magnesium, manganese and iron are also found in raw cacao, yet are diminished during the heating process. Phenethylamine (PEA), a chemical found in the raw cacao bean, is also produced in the body when we fall in love. PEA is also what gives chocolate its ability to assist with mental clarity and alertness. Anandamide, often referred to as 'the bliss chemical', is a neurotransmitter that is produced by the brain when we feel good; it's also found in raw cocoa, as is tryptophan, the amino acid precursor to serotonin (the happy hormone). No wonder many of us turn to chocolate when we're down in the dumps! Chocolate can literally affect your brain chemistry and create feelings of love and happiness.

Diana Robinson is a qualified nutritionist. www.dianarobinson.com.au