New research from the UK has revealed that selenium (Se) levels in British bread-making wheats are 10 to 50 times lower than in their American or Canadian counterparts.
The study, published in the Journal of the Science of Food and Agriculture , concludes that bread made from such wheat will fail to help consumers meet the Se intake levels recommended for human health.
The UK scientists suggest that, ironically, reduced pollution may be partly to blame. "A general deficiency of Se in UK soils, and reduced atmospheric deposition from fossil fuel burning are probably the most important contributory factors," said Professor Steve McGrath of Rothamsted agricultural research institute and author of the study.
In 1998, dried grain collected as part of the HGCA (Home-Grown Cereals Authority) cereals quality survey had an average of 0.025ppm Se. Consumption of bread made from such wheat would result in a daily dietary intake of 6.4µg, only one-tenth of recommended levels, whereas consumption of bread made with Canadian wheat translates to a daily intake of 51.2µg, enough to meet the target once average daily consumption of other SE-containing foods is taken into account.
Consumption of food made from low Se, home-grown wheat is likely to be one reason, the researchers suggest, for the 50 per cent reduction in dietary intake of Se by the British population over the last 30 years. Most Se-containing enzymes in animals exert antioxidant activities, and a number of studies have linked low Se intake to cancer.
The scientists write that one obvious way to alleviate the problem would be to use Se-enriched fertilisers, an approach that has been adopted successfully in other low Se countries such as Finland. However, more research is required first. "We need to test Se additives under UK conditions, with UK cereal varieties to determine what should be added and when," said Professor McGrath.