Cocoa and health: turn to the dark side

In another recent article, we looked at some new research on the link between gut health and athletic performance. Essentially, this research suggests that improving gut health by supplementing with friendly bacteria can result in significant performance gains for athletes in training – the take home message being that optimizing gut health through good diet and probiotic supplementation is something that all athletes should consider when planning a nutrition strategy. Well, just as we put the finishing touches to that article, a new research paper dropped on cocoa products for athletes – specifically how they can impact gut health, and cardiovascular health. That being the case, we felt it was only right to also report on what this paper has discovered and what it means for athletes!

Cocoa and health

It was around the turn of the century when scientists began to take an earnest interest in the potential health benefits of cocoa products such as dark chocolate and cocoa beverages. At that time, there was a growing understanding of the role of naturally occurring plant antioxidants (phytochemicals – see this article) in human health, and it was soon identified that the humble cocoa bean was a very rich source of source of polyphenol and flavanol antioxidants, which are known to help reduce the incidence of various degenerative diseases, especially cardiovascular disease⁽¹⁾.

In particular, it soon became apparent the there was an inverse association between the intake of flavanol-rich cocoa products and blood pressure⁽²⁾. In short, consuming higher levels of flavanols in cocoa products seemed to result in lower (and healthier) blood pressure levels. These findings were also supported by real world observations; the Kuna Indians in the Caribbean consume large quantities of flavanol-rich cocoa powder and have very low levels of blood pressure compared to Western societies. They are also known to have very high levels of longevity - presumably through improved cardiovascular health thanks to the high flavanol intakes⁽³⁾.

Benefits for all

As research has progressed, the benefits of cocoa products have now been observed more widely across different populations. In a 2022 study on cocoa consumption and health/mortality, researchers found a highly protective effect from cocoa⁽⁴⁾. Regardless of other health factors such as body mass index and blood cholesterol levels, scientists found that there was significantly lower risk of mortality from cardiovascular disease, heart disease and cancer of 13%, 16% and 12% respectively when cocoa consumption was high compared to when it was low or nil. A reduction in blood pressure accounted for only around 4.3% of this reduced risk, indicating that while there is a protective effect associated with reduced blood pressure and cocoa consumption, this protection extends into other aspects of health too!

Many of the cardiovascular benefits (and potential performance benefits) arising from cocoa product consumption are believed to occur via improved blood flow - particularly through the micro-capillaries of muscle tissue - thanks to the flavanols present^(5-8). Cocoa flavanols achieve this by stimulating an enzyme call ‘NO synthase’, which leads to high levels of nitric oxide (NO) synthesis. NO is a powerful blood vessel relaxant, enabling blood vessels to dilate (vasodilation), resulting in improved blood flow and reduced blood pressure. Of note is that NO-mediated vasodilation is the same mechanism of action that produces sub-maximal exercise benefits in athletes who consume nitrate-rich beetroot juice.

In a previous SPB article, we looked at a thorough review of the data about this effect, which found that the increase in NO-mediated improved blood flow effects from cocoa product consumption resulted in health benefits across the board, including already fit athletes. However, in the latest research we’re about to discuss, the researchers looked specifically at athletes, to see if consuming cocoa products benefited not only cardiovascular health, but also gut health (which as mentioned, researchers now believe plays a significant role on muscle function and athletic performance).

New research

In this brand new study, which was published in the ‘International Journal of Sport Nutrition and Exercise Metabolism’ a team of Italian and British researchers investigated the impact of consuming dark chocolate in professional and highly trained soccer players⁽⁹⁾. (NB: dark chocolate is typically defined as chocolate with no added milk and containing a high proportion of cocoa solids – usually 70% or more) As mentioned above, the researchers not only wanted to investigate the effect of dark chocolate consumption on markers of cardiovascular health, but they also wanted to see if it had an impact on gut health.

In addition, they looked at whether dark chocolate consumption was able to positively impact the omega-3 status of the soccer players by improving their omega-3 index (O3I). The omega-3 index (see this article) measures the proportion of essential omega-3 fats in the body compared to other lipids; in most people consuming Western diets, omega-3 status is insufficient, which is not only bad for cardiovascular health, but can also increase inflammation and oxidative stress following exercise – a bad thing for athletes!

What they did

In this 30-day intervention study, 38 professional male soccer players were recruited then randomly assigned to one of two experimental groups:

·        Dark chocolate – in this group, the soccer players consumed 30 grams of dark chocolate per day for 30 days.

·        Control group - in the control group, the players consumed 30 grams of white chocolate for 30 days. This chocolate was similar in composition to the dark chocolate except that being white, it contained no cocoa solids (and therefore no antioxidant flavanols).

During the intervention, the soccer players were instructed to maintain their normal dietary patterns (as supervised by a dietician), and avoid consuming other foods that are rich in flavanols. They were also instructed to maintain their normal training habits – ie to ensure the only significant variable was the dark vs. white chocolate consumption. At the start of the intervention and again at the end, measurements of the players anthropometric data (weight, body fat %, lean muscle mass etc) were taken along with samples of blood. These blood samples measured antioxidant levels, total cholesterol (both high and low-density cholesterol) and blood lipids. In addition, before/after faecal samples were taken to determine if and how the gut microbiota of the players had changed over time with dark chocolate consumption.