Chocolate and coronary artery disease

I have read with interest and acknowledge the recent article by Krittanawong et al.¹ published in this journal. The authors identified six prospective studies published between 2007 and 2018 in which chocolate consumption was related to the incidence of coronary artery disease (CAD). Reported risk ratio was 0.92 (95% CI 0.86–0.99).

Cacao beans, a main ingredient of chocolate, contain more than 600 plant chemicals. The authors claim that different constituents from cocoa products may provide cardio-protective effects such as flavanols, methylxanthines, polyphenols, and stearic acid. Thus, the question arises whether the beneficial effects are induced by these single ingredients of dark chocolate or, at best, whether the effects recognized are the result of multifactorial interactions of nutrients present in cocoa.

One of the nutrients often neglected in this and similar reviews is magnesium. Dark chocolate is known to be rich in magnesium, concentration being in the range 200–300 mg/100 g.² Actually, the NHS recommends 300 mg magnesium a day for men (19–64 years) and 270 mg a day for women (19–64 years)—then a bar of dark chocolate may well supply the recommended daily allowance of magnesium (US NIH RDA 420 and 320 mg/day, respectively). Milk chocolate contains only a fraction of this amount, white chocolate nothing at all. Due to magnesiums’ physiological role, there are many reports describing its beneficial health effects. Due to its blood pressure lowering effects, its anti-inflammatory potential, because epidemiologically inversely related to CAD, dark chocolate was suggested as a potential prophylactic agent to reduce the CAD risk.³ In the recently published ARIC study, the incidence of CAD, defined as mortality or myocardial infarction, was related to serum magnesium concentration.⁴

Thus, all the single ingredients of dark chocolate mentioned above as well as magnesium are known for their beneficial effects. Especially, lowering of blood pressure was reported in different studies comparing in trials dark with white chocolate. Studies are warranted to examine whether the beneficial effects on CAD are really the result of single nutrients in cacao or rather a biologically effective combination of all of them. Pharmacological actions of magnesium within such a combination should be taken into consideration.⁵ Similar deliberations may also apply to nuts, which are likewise rich in magnesium. Health-related biological effects of magnesium in its interaction with other food components from whole foods are important (see also A. Melse-Boonstra. doi: 10.3389/fnut.2020.00101) and may explain much of the variability in observed outcomes.