Polyphenols are a large group of compounds divided into several subgroups: phenolic acids, flavonoids, lignans, and stilbenes. Cocoa, chocolate, tea, and red wine are foods high in polyphenolic compounds. Polyphenols have been shown to have antioxidant properties (Galleano et al. 2010; Quideau et al. 2011). The Rotterdam Study found a significant inverse relationship between total flavonoid intake from the diet—in particular, black tea—and myocardial infarction incidence (Geleijnse et al. 2002). Supplementation with quercetin, which is one of the most frequent polyphenolic compounds in the human diet, was found to reduce systolic BP and plasma oxidized LDL concentrations in subjects with a high risk of CVD (Egert et al. 2009). To sum up, there is available evidence to support that polyphenolic compounds could have a beneficial effect in the prevention of CVD; however, further research and meta-analyses are required in order to establish this relationship (Rangel-Huerta et al. 2015).
Increased dietary intake of vitamin B (folate, vitamin B6, and vitamin B12) or folate supplementation can result in lower levels of homocysteine (an independent risk factor for CVD) and CHD risk. (Muskiet 2005). A meta-analysis of prospective studies showed that high folate intake was significantly associated with a 31% decreased risk of CAD, while increased folate intake of 200 ug/day was associated with a 12% decreased risk of CAD (Wang et al. 2012). At the same time, there are also several RCTs and meta-analyses that do not support the beneficial effects of vitamin B intake and supplementation in decreasing the risk of CHD (Bazzano et al. 2006). There is not sufficient evidence to allow the use of supplements as a means of secondary prevention and treatment of CHD, and further research needs to be conducted.