Ellagitannins - nature, occurrence and dietary burden

The occurrence of ellagitannins in common foodstuffs is limited to a few fruit and nut species. Dietary intake of ellagitannins is largely explained by the consumption of strawberries, raspberries and blackberries. No reliable figures are available for the ellagitannin burden, but it will probably not exceed 5 mg day−1. Their bioavailability is not well defined. A fraction of the ellagitannins ingested is hydrolysed in the gut and the resulting ellagic acid absorbed and metabolised, but whether intact ellagitannins are absorbed is not clear. There are apparently conflicting claims for beneficial and toxic effects caused by ellagitannins, ellagic acid or ellagitannin-containing extracts in various animal species including rodents and ruminants. It seems unlikely that normal consumption can cause toxic effects in man, but any attempt to increase the intake significantly in pursuit of the suggested benefits should be resisted until the metabolism and pharmacokinetics are better understood. © 2000 Society of Chemical Industry