Flavonoids are good antioxidants because they are able to reduce free radicals by donating electrons. Berries are a particularly rich source of flavonoids mainly because of their high content of anthocyanins (figure 1), but also on account of their high vitamin C content. Anthocyanins have been researched extensively because of their beneficial health properties. One such study, published in the American Journal of Clinical Nutrition in 20081, fed a group of healthy middle aged men a mixture of berries that included bilberries, lingonberries, blackcurrants, strawberries, choke berries and raspberries (125 grams a day plus 0.35 litres in a drink). After 8 weeks the subjects consuming the berries showed statistically significant reduction in blood pressure as well as favourable changes in platelet function and blood lipids when compared to controls.
Figure 1. The molecular structure of cyanidin, a member of the anthocyanin family of flavonoids
Berries are one of the only good sources of anthocyanins, and so increasing intakes is a worthwhile step to optimum nutrition. The anthocyanin content tends to be highest in blackberries and blue berries, but a range of different coloured berries should be consumed in order to provide a variety of different flavonoids in the diet. Studies have confirmed that frozen berries maintain their flavonoid levels for long periods and so are also an excellent way of increasing intake. Supplements are available but they tend to cost prohibitive because of the low flavonoid contents. If you know where to look, a range of berries are also available for free in hedgerows, woods and forests. Collecting these in the autumn and freezing them can provide anthocyanins year round for little cost.
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