National Public Health Institute, Helsinki, Finland
Berry Consumption in Humans: Bioavailability of Polyphenols and Effects on Cardiovascular Risk Factors
Erlund Iris, Koli Raika, Alfthan Georg, Marniemi Jukka, Mattila Pirjo, Jula Antti.
Dept. of Chronic Disease Prevention, Disease Risk Unit, National Institute for Health and Welfare
Berries are a rich source of various polyphenols and other potentially bioactive compounds. However, few studies have investigated the bioavailability of the compounds from berries or the effects of berry consumption on cardiovascular risk factors.
The above-mentioned issues were investigated in a single-blind, randomized, placebo-controlled intervention trial. During the trial, middle-aged, unmedicated subjects (n=72) with cardiovascular risk factors consumed moderate amounts of berry or control products for eight weeks. The subjects in the berry group (n=36) consumed bilberries, lingonberries, blackcurrants and chokeberries (as well as small amounts of strawberry and raspberry) as whole berries, puree, nectar and juice. The mean amount consumed daily was 160 g/day (=5.6 ounces/day). The subjects in the control group (n=36) consumed sugar water, jelly sweets and porridges prepared from semolina and rice. Blood samples were collected at baseline and weeks 2, 5 and 8. Urine samples were collected at baseline and week 8. The intake of polyphenols from berries was 826 mg per day, as measured by HPLC.
The concentrations of various polyphenols increased in the plasma and urine samples collected from the berry group (compared to the control group). Plasma vitamin C concentrations increased also. Plasma folate and tocopherols, as well as urinary sodium and potassium, were unaffected by the intervention.
Favorable changes were observed in some cardiovascular risk factors after berry consumption. Serum HDL cholesterol concentrations increased, but other lipids were unaffected. Systolic blood pressure decreased and the decrease mostly occurred in subjects with high blood pressure at baseline. Furthermore, berry consumption inhibited platelet function as measured with a platelet function analyzer. Plasma biomarkers of platelet activation, coagulation and fibrinolysis did not change during the intervention.
In conclusion, moderate daily consumption of berries may be beneficial for cardiovascular health. Polyphenols (and vitamin C) are the most likely compounds to mediate the effects. More studies are now warranted to explore the effects of berry consumption on human health.