Zinc in Potatoes Study

Zinc is important in biology and allows the proper function of proteins in living organisms. Severe zinc deficiency in animals and humans over long periods of time can therefore cause adverse effects. In the UK, the zinc status of most people is adequate, but about 20% of the population, especially adolescents in deprived communities and vegetarians/vegans, are likely marginally zinc deficient. Because potatoes are a favoured food in adolescents and vegetarians/vegans, the investigators have improved the zinc content of Saxon potatoes by biofortification, which involves spraying potato plant leaves with zinc salts. The potato zinc concentration is about three times the level in unfortified potatoes of the same variety. This level of zinc can boost the zinc intake of people who are marginally zinc deficient so that they become zinc adequate. Indeed, in rat studies, the investigators have shown that addition of some zinc-biofortified potato to a low zinc diet improves the zinc and health status of the animals. In the present study, the investigators propose to investigate whether the potato biofortification can improve the zinc and health status of volunteers. Because most of the volunteers (healthy adult men and women after the menopause) might have normal or variable zinc status at recruitment, it might not be possible to see the benefits of the potato diets and therefore, the investigators shall reduce the zinc intake of all 45 participants to 1 mg Zn/d for a period of two weeks prior to feeding 15 randomly selected individuals the biofortified potato diets (4 mg Zn/d) for two weeks. Zinc and health status will be measured by blood tests before and after zinc depletion and after feeding the potato diets. Results will be compared with data from 15 volunteers eating unfortified potato diets with a daily placebo and 15 volunteers consuming the unfortified potato diets with a zinc supplement (18 mg/d) as a positive control.