Effects of selenium fertilization on the selenium content of cereal grains, flour, and bread produced in Finland.

Abstract

Cereal Chem. 67(4):334-337 In order to raise the selenium (Se) content of agricultural products oats 0.19. Before 1985 the level of Se in all domestic cereal grains was in Finland, the main multinutrient fertilizers have been supplemented 0.01 mg or less per kilogram. The Se content of flours is also affected with sodium selenate since the fall of 1984. This intervention has affected by the proportion of imported to domestic grain in milling. In the 1980s, most locally produced agricultural products. The Se contents of grain the amount of imported grain has varied from 0 to 65%. Much of the (spring and winter wheat and rye), flour, and bread have been monitored grain has been imported from North America, where grain usually has regularly using electrothermal atomic absorption spectrophotometry every a high Se content; the range in the present study was 0.03-1.50 mg/ other month since 1983. The supplemented fertilization has distinctly kg dry matter. At present, American grain raises the Se content of Finnish raised the Se contents of cereals and cereal products, spring wheat showing cereal products, whereas other imported grain reduces it. The average the greatest increase (20-30-fold). The mean Se values (mg/ kg dry matter) Se intake in Finland is now about 0.11 mg/ day per capita at the energy in 1986-1988 were: spring wheat 0.25, winter wheat 0.05, rye 0.04, wheat level of 10 MJ (2,400 kcal), with cereals contributing about 18% of the flour 0.17, rye flour 0.07, wheat bread 0.18, rye bread 0.04, and rolled total intake. For geochemical and climatic reasons, selenium (Se) available from the soil in Finland has been exceptionally low (Koljonen 1975, Sippola 1979). Consequently, the Se contents of domestic agricultural products have also been low (Koivistoinen 1980). In the 1970s, the estimated average Se intake in Finland was about 0.02-0.03 mg/day (Varo and Koivistoinen 1980, Mutanen 1984), which was well below the safe, adequate intake level for adults (0.05-0.2 mg/day) defined by the U.S. National Academy of Sciences' National Research Council (1980). The low intake level was considered to be a potential nutritional risk for the Finnish population (Huttunen and Koivistoinen 1985). Cereals are normally an important source of dietary Se, but the Se content of cereal grains grown in Finland has been only about 0.01 mg/kg dry matter or less (Oksanen and Sandholm 1970, Varo et al 1980). In normal years, 5-10% imported grain is mixed with domestic grain in milling. In poor harvest years, the proportion of imported grain may be greater, even more than 50%. The Se content of grain imported from North America is usually high. Consequently, the Se content of cereal products and the average Se intake has been highly dependent on the ratio of domestic to imported cereal grains in milling. For example, the Se intake was doubled by the abundant grain imports in 19791980 (Varo and Koivistoinen 1981). In order to raise the Se content of domestic agricultural products, and also to increase and stabilize the Se intake, an official decision was made to supplement the main agricultural multinutrient fertilizers with sodium selenate starting in the fall of 1984 (Ministry of Agriculture and Forestry 1984). Because selenate is transported more efficiently to the vegetative parts of the plant than to the grain (Yldranta 1985), two supplementation doses are used: 16 mg Se/kg in fertilizers mainly used in grain production, and 6 mg/kg in fertilizers used in hay and fodder production. The amount of Se introduced by fertilization is about 8 g/hectare (ha) for cereal crops and 3 g/ha for grass crops (Ylaranta 1985). The primary objective of this intervention was to raise the Se level of domestic cereal grains to an approximate level of 0.1 mg/kg of dry matter. However, it was expected that other agricultural products would also be affected. An expert group was appointed by the Ministry of Agriculture and Forestry to evaluate and report annually the effects of the Se fertilization. The Se concentration of fertilizers, soils, animal feeds, human 'Department of Food Chemistry and Technology. 2 Address reprint requests to P. Varo, Department of General Chemistry, University of Helsinki, Viikki, SF-00710 Helsinki, Finland. © 1990 American Association of Cereal Chemists, Inc. 334 CEREAL CHEMISTRY sera, and 13 basic foods are monitored regularly. Occasionally other selected foodstuffs also have been analyzed. The present paper describes the effects of Se fertilization on the Se content of cereal grains and its consequences on Se intake in Finland. The effects of cereal grain imports in the present situation are also discussed. MATERIALS AND METHODS