Impact of beverage intake on metabolic and cardiovascular health

This review is based on a presentation that was made at a meeting concerning hydration. It summarizes the epidemiological evidence for selected beverages in relation to cardiovascular and/or metabolic health. The review focuses on tea, cocoa, milk, orange juice, alcohol, and beverages sweetened with sugars. These beverage types were chosen because of their widespread consumption, with tea, cocoa, orange juice, and milk being of potential benefit while alcohol and sugars may be detrimental. There is reasonably consistent evidence of reduced risk of cardiovascular disease (CVD) in association with high consumption of tea, with the tea flavonoids appearing to be responsible for these benefits. There is also a growing evidence base for cocoa flavanols to have beneficial cardiovascular effects. The bulk of the evidence supporting these conclusions is epidemiological and needs to be confirmed with randomized controlled trials. Milk is associated with reduced risk of CVD, particularly in relation to blood pressure, with certain milk tripeptides being implicated in having effects to reduce angiotensin action. Further work is needed to confirm these potentially beneficial effects. There is some evidence of potentially beneficial effects of orange juice on aspects of cardiovascular function, but this is by no means convincing, and further evidence is needed from randomized controlled trials, together with the elucidation of whether any benefits are linked to the citrus flavanones or simply to the vitamin C content. While there is some evidence that red wine may convey some health benefits, there is also clear evidence that alcoholic beverages can have undesirable effects on blood pressure and increase the risk of CVD. It is possible that low to moderate intakes of alcoholic beverages may be beneficial. There is some evidence that beverages sweetened with sugars may contribute to increased energy intake and weight gain, and there is also an indication from longitudinal cohort studies that they are associated with an increased risk of developing type 2 diabetes. The mechanism of this latter association has not been explained. In conclusion, there is a substantial amount of epidemiological evidence for benefits of tea and cocoa in relation to cardiovascular health. There is a growing literature describing randomized controlled trials, but more evidence is needed. Potential cardiovascular and metabolic health benefits of milk and orange juice needs further investigation. The associations of higher alcohol intakes and consumption of beverages sweetened with sugars and their increased health risks are of concern, and more attention should be focused on this area.