The Health Benefits of Dark Chocolate

by Ericka Naegle MS, RDNNutrition
Pieces of chocolate bars

Many of us don’t need to be convinced to indulge in a cup of hot cocoa or a few bites of chocolate. And if there weren’t already tons of reasons to love chocolate, research shows that it can be good for our health, too!

Cocoa is the non-fat product of ground cocoa beans (1). It is used to make cocoa powder, which we use in baking or to make hot chocolate, and solid chocolate, which contains cocoa, cocoa butter, sugar and other ingredients (1).

Cocoa is a prebiotic food (2), which means it’s good for the gut microbiome, and a good source of iron, magnesium, copper and manganese. It is also rich in flavanols, a type of polyphenol that has anti-inflammatory and antioxidant properties. And it contains compounds called methylxanthines, including caffeine and theobromine, which have been shown to be good for our health (3).

Research has shown that cocoa and chocolate can be beneficial for blood pressure, insulin resistance, vascular function, oxidative stress, hyperlipidemia (4), blood flow and neural activity (3). These effects can be attributed to both cocoa’s flavanol and methylxanthine content.

Cocoa and heart health

To date, much of the research on cocoa is about its effects related to cardiovascular disease risk. Multiple observational studies have demonstrated these effects, as in a Dutch study that followed 470 older men for 15 years, tracking their cocoa intake, blood pressure and reasons for death (5). The researchers found that those who consumed the most cocoa had the lowest blood pressure and were half as likely to die from heart disease – or any cause, in fact – over the 15 years they were studied. These results held true independent of BMI, blood pressure, smoking status, physical activity, alcohol consumption or socioeconomic status.

In addition to population studies, experimental data is emerging showing that cocoa flavanols are good for cardiovascular health and may even be superior to green tea or red wine (4). A review of 42 randomized, controlled trials found that chocolate or cocoa have been shown to reduce insulin resistance, diastolic blood pressure and triglycerides, as well as to have beneficial effects on mean arterial pressure and flow-mediated dilation, two measures of arterial health (6). There is also some evidence that cocoa or chocolate can potentially lower LDL cholesterol and raise HDL cholesterol (6).

Cocoa and metabolic health

Insulin resistance and inflammation have been central subjects of cocoa studies. Both play a role in cardiovascular risk but are also risk factors for diabetes and metabolic syndrome. One study looked at the effects of eating 30 grams of dark chocolate daily, along with receiving advice on lifestyle changes, in 44 diabetic patients aged 52 years on average (7). After eight weeks, compared to a group that received only lifestyle advice, the group that ate dark chocolate experienced significant decreases in their fasting blood sugar, HbA1C (a measure of insulin resistance), LDL cholesterol and triglyceride levels. They also showed significantly reduced levels of TNF-⍺, IL-6 and CRP, all measures of inflammation.

Another study explored whether flavanol-rich chocolate could counteract the negative effects of two nights of total sleep deprivation in healthy young people (8). Compared to those who were sleep-deprived and did not eat flavanol-rich chocolate, those who did consume chocolate showed better results for both cardiovascular health – including endothelial function, blood pressure and arterial stiffness – and vigilance and cognitive skills, especially working memory.

Cocoa and brain health

Dark chocolate is not only good for your heart and your metabolism, however. A growing body of research also demonstrates that cocoa can impact mood and cognitive function (3). An epidemiological study looked at chocolate consumption by 968 American adults of all ages and found that those who ate chocolate once per week scored significantly better on a range of cognitive tests than those who ate chocolate less frequently (9). Those who ate chocolate more than once per week performed even better. The study’s authors proposed that regular intake of chocolate flavanols may protect against age-related cognitive decline.

In one experimental study, young adults who drank a beverage enriched with cocoa flavanols performed better on cognitive tests and experienced improved mood relative to those who didn’t consume the cocoa flavonols (3). In another intervention, 90 older adults who suffered from mild cognitive impairment took a range of cognitive tests and then drank a beverage containing low, intermediate or high levels of cocoa flavanols every day for 8 weeks (10). Those who consumed moderate and high amounts of flavanols showed significant improvements to their own scores and scored significantly better than the control and low-flavanol groups on tests of executive function, working memory, short-term memory, long-term episodic memory, processing speed and global cognition. They also showed improvements to insulin resistance, blood pressure and lipid peroxidation, a marker of oxidative stress and cardiovascular risk.

Buying (and eating!) chocolate

There’s a lot of evidence for the benefits of cocoa products. But how do we know what products to choose? How much should we eat? The following tips should help you in your search for better health through chocolate:

1. Cocoa or cacao? Technically, the word “cocoa” is just another version of the Mayan and Aztec word “cacao” (11). Today, some manufacturers use the term “cacao” to indicate a healthier, less processed product. While use of the terms “cacao” and “cocoa” is not regulated, “cacao” generally indicates that beans are raw or roasted at low temperature, whereas “cocoa” may indicate higher roasting temperatures. Because heat can destroy some of the flavanol content, “cacao” may contain higher levels of flavanols than products labeled “cocoa.” When purchasing in powdered form, cacao powder has a more nutrient dense profile, though because of the lack of regulation regarding these terms, some packaging labels may be misleading.

2. Solid chocolate or powder? The highest amounts of flavanols are found in cocoa powder, followed by baking chocolate and then solid dark chocolate; semisweet and milk chocolate contain relatively small amounts of these polyphenols (12).

3. Check the cacao percentage! Dark chocolate products are labeled according to the percent cocoa (often referred to as cacao) content. Anything at least 70% cacao is considered dark, but the higher the percentage, the better for your health. Aim for at least 85% cacao.

4. Don’t go Dutched. Cocoa beans often undergo alkalization, or “Dutching,” in the process of making cocoa powder. This processing can destroy much of the flavanol content (13). Avoid cocoa powders that are labeled “Dutched,” “alkalized” or “processed with alkali.” Most solid chocolate products are not processed this way, but check the package for these terms to be sure.

5. Bake wisely. Feel free to heat cocoa powder to make a healthy hot cocoa, but be careful when using it for baking. A study that looked at cocoa products used to prepare other foods found that the polyphenol content of cocoa powder was preserved in hot cocoa and cookies but substantially reduced when baked in a cake (14). The authors believe that baking soda, an alkaline product, was responsible.

6. Hold off on milk. The evidence isn’t conclusive, but some studies have shown that milk may reduce the ability to absorb cocoa flavanols (13). Milk chocolate also tends to contain more sugar, which can negate the benefits to eating chocolate. Stick with dark chocolate.

7. Enjoy in moderation. Research has not established an ideal “dose” of cocoa products for health benefits, but they can lead to metabolic issues and weight gain when consumed in excess (or when consumed in low quality, high sugar, highly processed products). Additionally, chocolate may contain traces of lead, cadmium, and other heavy metals, which can add up when eaten excessively. Small amounts of chocolate can have both cognitive and cardiometabolic benefits (3, 7, 15), and performance on cognitive tests has even been shown to plateau at daily consumption of approximately 10 grams (0.35 oz, or about 1/3 the serving size on most nutrition facts labels) per day (16).

We still have a lot to learn about the potential benefits of cocoa and dark chocolate, but the research is promising. Until we know more, incorporating small amounts of organic, dark chocolate into a healthy diet may be a delicious way to invest in your health!

References

  1. Cooper, K. A., Donovan, J. L., Waterhouse, A. I., & Williamson, G. (2008). Cocoa and health: A decade of research.British Journal of Nutrition,99(1), 1–11. doi.org/10.1017/S0007114507795296
  2. Institute for Functional Medicine. (n.d.)Prebiotic foods for postbiotic abundance. https://www.ifm.org/news-insights/prebiotic-foods-postbiotic-abundance/
  3. Scholey, A. B., French, S. J., Morris, P. J., Kennedy, D. O., Milne, A. L., & Haskell, C. F. (2010). Consumption of cocoa flavanols results in acute improvements in mood and cognitive performance during sustained mental effort.Journal of Psychopharmacology,24(10), 1505–1514. doi.org/10.1177/0269881109106923
  4. Selmi, C., Cocchi, C. A., Lanfredini, M., Keen, C. L., & Gershwin, M. E. (2008). Chocolate at heart: The anti-inflammatory impact of cocoa flavanols.Molecular Nutrition and Food Research,52(11), 1340–1348. doi.org/10.1002/mnfr.200700435
  5. Bujisse, B., Feskens, E. J. M., Kok, F. J., & Kromhout, D. (2006). Cocoa intake, blood pressure, and cardiovascular mortality.Archives of Internal Medicine,166, 411–417. doi.org/10.4103/ijpvm.IJPVM33917
  6. Hooper, L., Kay, C., Abdelhamid, A., Kroon, P. A., Cohn, J. S., Rimm, E. B., & Cassidy, A. (2012). Effects of chocolate, cocoa, and flavan-3-ols on cardiovascular health: A systematic review and meta-analysis of randomized trials.American Journal of Clinical Nutrition,95(3), 740–751. doi.org/10.3945/ajcn.111.023457
  7. Jafarirad, S., Ayoobi, N., Karandish, M., Jalali, M., Haghighizadeh, M. H., & Jahanshahi, A. (2018). Dark chocolate effect on serum adiponectin, biochemical and inflammatory parameters in diabetic patients: A randomized clinical trial.International Journal of Preventive Medicine,9(86), 1–6. doi.org/10.4103/ijpvm.IJPVM33917
  8. Grassi, D., Socci, V., Tempesta, D., Ferri, C., De Gennaro, L., Desideri, G., & Ferrara, M. (2016). Flavanol-rich chocolate acutely improves arterial function and working memory performance counteracting the effects of sleep deprivation in healthy individuals.Journal of Hypertension,34(7), 1298–1308. doi.org/10.1097/HJH.0000000000000926
  9. Crichton, G. E., Elias, M. F., & Alkerwi, A. (2016). Chocolate intake is associated with better cognitive function: The Maine-Syracuse Longitudinal Study.Appetite,100, 126–132. doi.org/10.1016/j.appet.2016.02.010
  10. Desideri, G., Kwik-Uribe, C., Grassi, D., Necozione, S., Ghiadoni, L., Mastroiacovo, D., Raffaele, A., Ferri, L., Bocale, R., Lechiara, M. C., Marini, C., & Ferri, C. (2012). Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive impairment: The Cocoa, Cognition, and Aging (CoCoA) Study.Hypertension,60(3), 794–801. doi.org/10.1161/HYPERTENSIONAHA.112.193060
  11. Afoakwa, E. O. (2010).Chocolate science and technology.Wiley-Blackwell. 10.1002/9781444319880
  12. Miller, K. B., Stuart, D. A., Smith, N. L., Lee, C. Y., Mchale, N. L., Flanagan, J. A., Boxin, O. U., & Hurst, W. J. (2006). Antioxidant activity and polyphenol and procyanidin contents of selected commercially available cocoa-containing and chocolate products in the United States.Journal of Agricultural and Food Chemistry,54(11), 4062–4068. doi.org/10.1021/jf060290o
  13. Katz, D. L., Doughty, K., & Ali, A. (2011). Cocoa and chocolate in human health and disease.Antioxidants and Redox Signaling,15(10), 2779–2811. doi.org/10.1089/ars.2010.3697
  14. Stahl, L., Miller, K., Apgar, J., Sweigart, D., Stuart, D., McHale, N., Ou, B., Kondo, M., & Hurst, W. (2009). Preservation of cocoa antioxidant activity, total polyphenols, flavan‐3‐ols, and procyanidin content in foods prepared with cocoa powder.Journal of Food Science,74(6), C456–C461. doi.org/10.1111/j.1750-3841.2009.01226.x
  15. Taubert, D., Roesen, R., Lehmann, C., Jung, N., & Schömig, E. (2007). Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide.JAMA,298(1), 49–60. doi.org/10.1097/smj.0b013e31817a76e3
  16. Nurk, E., Refsum, H., Drevon, C. A., Tell, G. S., Nygaard, H. A., Engedal, K., & Smith, A. D. (2009). Intake of flavonoid-rich wine, tea, and chocolate by elderly men and women is associated with better cognitive test performance.Journal of Nutrition,139(1), 120–127. doi.org/10.3945/jn.108.095182