Calcium, Vitamin D and Bone Health (The Gambia)

Lead Research Organisation: MRC Unit, The Gambia

Abstract

Rural Gambians have extraordinarily low intakes (about 350 mg/day) of dietary calcium judged against international recommendations (which range from about 800-1200 mg/day). The overall aim of this research programme is to investigate the importance of calcium, vitamin D (and related nutrients) to bone health in developing countries. The specific objectives of the programme are: to determine the impact of very low calcium intakes on child health (stunting, low bone mineral content, rickets) and reproductive health (high blood pressure during pregnancy, calcium content of breast-milk, maternal bone health, build-up of calcium in fetal and infant bones); to test if giving calcium supplements has any effect; and to investigate the biochemical and genetic mechanisms of adaptation to low calcium intakes, with reference to parallel studies in UK, China and Bangladesh. The results from Keneba contribute to cross-cultural comparisons designed to gain insight into the nature of the adaptive response to a low calcium intake, the mechanisms of skeletal growth and maintenance, and ethnic differences in bone disease risk (e.g. osteoporosis and rickets). The work contributes to decisions made by policy-makers in the UK and internationally.

Technical Summary

The role of nutrition in bone health, optimal skeletal growth and the prevention of osteoporosis, rickets and osteomalacia, is of considerable public health concern world-wide. Development of public health strategies for the prevention of osteoporosis and the optimisation of bone health needs robust research to underpin the evidence-base, as recognised by governments and agencies. Like many non-dairy consuming populations in the developing world, rural Gambians have extraordinarily low intakes of dietary calcium judged against international recommendations. The overall aim of this research programme is to investigate the importance of calcium, vitamin D (and related nutrients) to bone health in developing countries. The rapid changes occurring in developing countries from traditional ways of life towards those of the western world are associated with increases in the chronic diseases of affluence, including osteoporosis. The protection afforded by traditional diets and lifestyles may hold the key to future prevention, but opportunities to gain such insights are rapidly disappearing. The CDBH sub-programme is an integral part of the MRC Nutrition and Bone Health programme led by Dr Ann Prentice at MRC HNR (U.1059.00.017); studies are conducted in UK, The Gambia, China, Bangladesh and South Africa, addresses health issues of demographic transition and takes advantage of the cross-cultural perspectives gained. The objectives of the sub-programme at MRC Keneba are aligned with those of the overall Nutrition and Bone Health programme couched in terms of priority needs for health research in Africa, Specific objectives are: To determine the impact of a very low Ca intake on child health (stunting, low bone mineral accretion, rickets, blood pressure, susceptibility to infection), lactational performance, maternal bone health, fetal and infant bone accretion) and health in old age (bone and vascular disease); To test the long-term effects, beneficial or otherwise, of interventions to raise Ca intakes to internationally accepted norms, in order to provide an evidence-base for international policy decisions; To investigate the metabolic, biochemical and genetic mechanisms of adaptation to a low Ca intake and its impact on the metabolic handling and nutritional requirements for Ca, phosphate and vitamin D; To provide authoritative synthesis of research findings and active engagement with academics, governments and agencies in order to inform nutrition policy and practice. Many of the projects are based around well-established cohorts of children, adolescents, mothers and their infants. A series of studies is planned to continue the investigation of the aetiology of rickets and testing our hypothesis that low calcium intakes result in phosphate dysregulation. A new cohort of older Gambian men and women is planned to extend our studies of lifecourse bone health into ageing. A new project area has commenced focused on developing a field method for the measurement of 25-hydroxyvitamin D half-life in order to advance understanding of vitamin D requirements. Collaborative work with other scientists in the ING programme includes the effects of nutritional interventions in mothers and children, contributing to the collection of local reference anthropometric and biochemical data, to understanding relationships between nutritional and genetic factors and to the measurement of whole-body and regional body composition by DXA.

Publications

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