Effect of a dietary rapeseed protein concentrate on the contents of alpha-tocopherol and zinc in serum, liver and tibia of rats.

In order to study the effects of a dietary rapeseed protein concentrate (RPC) on tocopherol and zinc levels in serum, liver and tibia, female rats were fed a tocopherol-reduced diet for a 3-week period and were then transferred to either of a RPC diet or a control diet containing casein at 20% levels of protein. No unfavourable effects on food intakes or weight gains were recorded. The serum zinc content of the RPC group was slightly reduced and the serum tocopherol values significantly lowered in comparison to the control group. Zinc and tocopherol contents of the livers were not changed. Precipitation of sera by dextran sulphate in the presence of calcium ions indicated a reduced level of low density lipoproteins in rats fed RPC diet. In a second experiment, male and female rats were fed diets containing 10% of protein derived either from RPC or casein. Low zinc contents of tibiae indicated a low biological availability of the zinc present in the RPC diet. Rats on RPC diet also showed reduced levels of tocopherol in serum. Despite a lowered zinc status in rats fed RPC diet there was no reduction in food intake, weight gain or growth of tibia in these groups.