Dark Chocolate: Beneficial or Not?

It was likely the ancient Mayans who first cultivated the cocoa bean more than 1,500 years ago, and chocolate has been a part of the human diet ever since (Motamayor et al. 2002). However, the way in which people eat chocolate has changed over the years, transforming what was initially an unsweetened, medicinal beverage into the decadent chocolate bars and candies of today. Given its widespread popularity, it should come as no surprise that science has sought to define the possible health impacts of chocolate consumption. Dark chocolate in particular has been heralded as somewhat of an anomaly, an indulgent yet healthy treat. It sounds almost too good to be true—or does it?

Many of the purported benefits of dark chocolate are attributed to its polyphenol content. Polyphenols are a diverse group of phytonutrients, including flavonoids, phenolic acids, and tannins (Halib et al. 2020). They have received increasing attention over the past few decades due to their antioxidant and anti-inflammatory properties, and they have been studied for their potential roles in mitigating a variety of diseases, including cardiovascular disease and diabetes. Many foods and beverages contain polyphenols, including fruits, vegetables, coffee, and, of course, chocolate (Halib et al. 2020).

While polyphenols make up an estimated 10% of the weight of dry cocoa beans, this amount is greatly reduced during processing (Zugravu and Otelea 2019). That said, the chocolate and cocoa products that people know and love today still retain some of their original polyphenol content. The amount retained depends on the type of product. Cocoa powder has about five times more polyphenols than dark chocolate, and dark chocolate has about three times more polyphenols than milk chocolate (Katz et al. 2011).

Polyphenols are responsible for the bitterness of unsweetened cocoa and chocolate products and for their antioxidant properties. Those found in chocolate are thought to protect the lining of blood vessels from oxidative stress and to promote the production or availability of nitric oxide, a potent vasodilator (Katz et al. 2011). Such effects are the proposed mechanisms for many of dark chocolate’s supposed health benefits.

While numerous benefits have been attributed to dark chocolate, improvements in lipid profiles, blood pressure, and insulin sensitivity, all of which reduce risk of cardiovascular disease, are some of the ones most frequently cited in the literature. Unfortunately, studies looking at the impact of dark chocolate intake on these parameters have yielded mixed results (Halib et al. 2020, Zugravu and Otelea 2019, Tan et al. 2021, Ried et al. 2017, Garcia et al. 2018). While many clinical control trials have investigated the health impacts of dark chocolate, these trials typically had small sample sizes, provided different types and amounts of cocoa and chocolate to subjects, and ran for less than six months. For instance, among the 15 studies included in a 2021 review, only one had more than 100 participants, and interventions ranged from a 99% cocoa supplement to pure cocoa butter (Tan et al. 2021).

The aforementioned review concluded that dark chocolate consumption had no effect on blood pressure; total, LDL, or HDL cholesterol; or fasting blood glucose levels. There was a 4 mg/dL reduction in triglyceride levels associated with dark chocolate consumption, though whether this reduction would confer any clinical benefit is unclear (Tan et al. 2021). A 2017 meta-analysis reported a small reduction of about 1.8 mm Hg in both systolic and diastolic blood pressure with dark chocolate consumption. However, here too there were significant differences among the studies in both the baseline characteristics of participants and in the interventions provided (Ried et al. 2017).

Observational studies of dark chocolate consumption have elicited similarly conflicting results (Halib et al. 2020). Due to their prospective, long-term nature, a few of the studies also looked at chocolate’s impact on development of cardiovascular diseases. Again, the results were mixed (Garcia et al. 2018). Furthermore, most observational studies failed to differentiate between white, milk, and dark chocolates, so the results cannot be attributed to dark chocolate alone (Halib et al. 2020, Garcia et al. 2018).

So is dark chocolate healthy? Maybe, maybe not; the evidence is limited. Future research should investigate the long-term effects of dark chocolate consumption, ideally through clinical control trials with greater sample sizes. Until then, people should eat chocolate for the sake of enjoyment rather than for health.ft