Preventive nutritional factors in epidemiology: Interaction between sodiumand calcium

1. It is generally believed, though difficult to prove, that diet plays a r ole in the risk of various diseases. Components of difficulties include sev eral issues such as dietary assessment method, regression dilution bias, mu lticolinearity and interaction among nutrients, 2. The present study focuses on colinearity and interaction between sodium and calcium, which should be cautiously examined in nutritional epidemiolog ical studies in relation to blood pressure and bone mineral density. 3. The World Health Organization's International Cooperative Cardiovascular Diseases and Alimentary Comparison study showed significant multicolineari ty among urinary sodium, calcium and urea nitrogen as well as urinary calci um and magnesium, Urinary sodium and calcium had significant correlation (r = 0.438, P < 0.05, n = 48) by cross-centre analysis, 4. Interaction between sodium and calcium on bone mineral density is studie d using the data set from bone mineral density screening for 1658 females, aged 20-40 years, in Yokohama, Japan, Among those who have lower calcium in take (< 600 mg/day), higher calcium intake (%) from small fish, which is li kely to be associated with a high salt diet, related to significantly lower mineral bone density. 5. Interaction between sodium and calcium on bone mineral density among you ng Japanese females is suggested. Moderate sodium restriction is needed for prevention of not only cardiovascular diseases but also osteoporosis.