Why dark chocolate is a superfood
Chocolate comes in all sorts of shapes, sizes, and cocoa content. But it is only dark chocolate containing a minimum of 60–70% cocoa which is beneficial, while white or milk chocolate, which has none or little cocoa, respectively, are high-sugar, high-fat and unhealthy alternatives. As a life-long chocoholic, who was unable to discern the good from the bad, for a good quarter of a century, I feel it now relevant to shed light on the remarkable heart health benefits of cocoa, from which real chocolate is made.
Cocoa is so powerfully nutritious that it ranks as one of the highest foods on the antioxidant scale.
The main antioxidants (1) are polyphenols, a subclass of which are flavanoids. Flavanols are a further subgroup of flavanoids, and thought to be the reason for cocoa’s benefits, particularly on cardiovascular health.
These cardiovascular benefits were only recently discovered in Kuna Indians, who lived on islands nearby Panama (1). This population had resisted any age-related increase in blood pressure, age-related kidney dysfunction and had much lower rates of death from cardiovascular diseases than their fellow countrymen who lived on the mainland in Panama City. Unlike the city dwellers, the Kuna Indians spent much of their days drinking large amounts of cocoa products-around 11 cups daily. When they moved away from the islands to Panama City and stopped this cocoa habit, their cardiovascular health detrimentally mimicked that of the city dwellers.
These protective effects of flavanols on cardiovascular disease were then observed in several other studies, such as; A 16-year study of post-menopausal women living in Iowa (2), found that women who consumed the most flavanols from different foods such as apples, pears and red wine, had the lowest risk of dying from cardiovascular diseases. This inverse association was also found, with the women who consumed the most cocoa; In a study of 470 elderly men, in Holland (3), the men who had the highest amounts of cocoa, reduced their risk of dying from cardiovascular events by an astonishing 50%.
Numerous research since then has suggested that chocolate consumption has protective effects against high blood pressure, cardiovascular disease, and diabetes. Some of this research is mentioned below, to show the specific amounts of cocoa consumed, and its remarkable effects:
Overweight adults who ate chocolate bars with 22g cocoa, daily, had lower blood pressure (sugar-free cocoa being more effective than sugared cocoa) (4); Flavanol-rich cocoa consumed daily by healthy and pre-hypertensive adults, reduced their blood pressure and improved the cells that line the blood vessels (endothelium) (5); Patients with high blood pressure and glucose intolerance who consumed 100g dark chocolate for 15 days experienced a reduction in blood pressure, an increase in insulin sensitivity, as well as enhanced beta cell function (the insulin releasing cells in the pancreas), and also improved endothelial function (6); Daily ingestion of 27g of dark chocolate plus isoflavones for one year by postmenopausal women who had diabetes type 2, led to a reduction in their low density lipoprotein (LDL or “bad cholesterol) and an increase in insulin sensitivity (7); Diabetes type 2 patients given 48g polyphenol rich chocolate for 8 weeks led to a rise in their High density lipoprotein (the “good” cholesterol) improving overall cholesterol levels (8).
These studies suggest that a good source of around 22g–100 g of dark chocolate daily, may play a pivotal role in prevention of cardiovascular disease and Type 2 diabetes. A systematic review and meta analyses (9) of published research, which looked at 11,4009 people, and their consumption of dark chocolate and associated risk of developing these diseases concluded similar results: Consumption of cocoa rich chocolate reduces cardiovascular disease by 37%, stroke by 29% and diabetes by 31%.
If consuming so many grams of chocolate daily seems daunting (for the non-chocoholics), alternatives include cocoa nibs, ground or whole, and/or drinking cocoa (see below).
Mechanisms on how flavanols exert these potentially life saving effects involve a key flavanol, epicatechin. This molecule increases the availability of nitric oxide (NO) to the vascular endothelium, which relaxes, and widens blood vessels (vasodilatation). This vascular endothelium is composed of a thin layer of epithelial cells lining the inside of blood vessels, and is present throughout our circulatory system, including the heart, veins, arteries and capillaries. Reduced NO is associated with endothelial dysfunction, and in turn cardiovascular disease and narrowing of blood vessels (as well as erectile dysfunction!). NO also increases insulin sensitivity and exerts its beneficial effects on cholesterol by preventing the oxidation of LDL.
Flavanols also prevent platelets from aggregating together and from sticking to the blood vessels, which can cause blood clots and narrowing of blood vessels, respectively. The stearic acid fat (a saturated fat that is “good”) in chocolate further serves to reduce platelet volume. These effects on platelets are so profound that a nightcap of cocoa was found to have the same effects on platelet activity as aspirin (10). The antioxidant effects of flavanoids may also have a direct effect in preventing free radicals from damaging endothelium, while improving endothelium function.
Drinking cocoa, leads to a rapid increase of antioxidants in blood plasma. If you’ve had a bad day, you could try having a cup of flavanol-rich cocoa for a powerful antioxidant remedy. For those who are at high risk of cardiovascular disease, such as heavy smokers, at least one high flavanol cocoa drink daily, could help to increase their NO concentration.
Cocoa has numerous other health benefits, which include; its effects on boosting the immune system, protecting nerves from injury and inflammation, stimulating the pleasure centers in the brain, increasing brain acuity, as well as conferring anti-ageing properties. Cocoa can also increase the feeling of fullness, and contrary to popular belief, lead to weight loss.
A few years ago, I met a renowned nutritionist at Harvard, who told me that “dark chocolate is so good for you, that it can make up 25% of your daily diet”, and since then, I have been living that dream. I consume around 50g of cocoa a day in various forms, and recently prescribed it to my mother. She had been suffering from incessant severe migraines, and upon daily ingestion of 50–75g of cocoa, she was able to become migraine-free.
It is crucial to consume cocoa the right way, which is not always clear from the commercial labelling. Most of the above studies used flavanoid-enriched cocoa products, or dark chocolate with at least 60–70% cocoa. Unfortunately and all too commonly, manufacturers can be deceiving, using additives and processing methods that can diminish or deplete the flavanol content from the chocolate. The natural cocoa solids can darken and the bitter tasting flavanoids removed, but the chocolate will still be labeled as “dark”.
Unless you are eating cocoa nibs, a 100% cocoa chocolate bar, or drinking pure cocoa powder, dark chocolate will have added fat as well as sugar, both of which will add to your calorie count. But sugar is the demon in dark chocolate, for it hampers the blood pressure lowering effects of dark chocolate (4), is detrimental to general health and increases the risk of developing diabetes Type 2. If you do opt to have a sweeter dark chocolate, then it should have natural sweeteners and preferably be bought from a renowned organic shop. Cow’s milk also has a deleterious effect on the antioxidant and protective effects of cocoa, and must be replaced with water or alternative milk, such as almond or rice milk in cocoa drinks.
Ideally, flavanoid and antioxidant content would be clearly labeled and we could become better informed, about the true level of goodness in the darkness of our chocolates.
References
1. McCullough ML., et al. Hypertension, the Kuna and the epidemiology of flavanols. J Cardiovasc Pharmacol 2006; Suppl 2:S103–9.
2. Mink PJ et al., Flavonoid intake and cardiovascular disease mortality: a prospective study in postmenopausal women. Am J Clin Nutr March 2007 vol. 85 no. 3 895–909
3. Buisse B et al. cocoa intake, blood pressure, and cardiovascular mortality: the Zutphen Elderly study. Arch Intern Med. 2006 Feb; 166(4): 411–7
4.Faridi Z et al., Acute dark chocolate and cocoa ingestion and endothelial function: a randomized controlled crossover trial. A J Clin Nutr 2008 Jul; 88,1): 58–63.
5. Desch et al. Effect of cocoa products on blood pressure: systematic review and meta-analysis. Am J Hypertens. 2010 Jan(1):97–103. Epub 2009 Nov 12
6. Grassi D. et al., Blood pressure is reduced and insulin sensitivity increased in glucose-intolerant, hypertensive subjects after 15 days of consuming high-polyphenol dark chocolate. J. Nutr. September 2008 vol. 138 no.9 1671–1676
7. Curtis P J, et al, chronic ingestion of flavan-3-ols and isoflavones improves insulin sensitivity and lipoprotein status and attenuates estimated 10-year CVD risk in medicated postmenopausal women with type 2 diabetes. Diabetes Care 2012. Vol.35 no. 2 226–232
8. Mellor D.D. et al,. High –cocoa polyphenol-rich chocolate improves HDL cholesterol in Type 2 diabetes patients. Diabetic Medicine2010. DOI:10.1111/j.1464–5491.2010.03108.
9. Buirago-Lopez A et al., Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis BMJ 2011: 343 doi:10.1136/bmj.d4488
10. Rein D. et al. Cocoa inhibits platelet activation and function. American journal of clinical nutrition 2000; 72:30–5.