Trace nutrients. 3 Magnesium, copper, zinc, vitamin B6, vitamin B12 and folic acid in the British household food supply.

1. Intakes of magnesium, copper, zinc, vitamin B6, vitamin B12 and folic acid in Britain were calculated by applying the values selected for the 4th edition of McCance and Widdowson's The Composition of Foods (Paul & Southgate, 1978) to the amounts of food recorded in the National Food Survey made during 1976 (Ministry of Agriculture, Fisheries and Food, 1977). 2. National average intakes were (/person per d): Mg 249 mg, Cu 1.51 mg, Zn 9.1 mg, vitamin B6 1.36 mg, vitamin B12 6.6 micrograms free folic acid 105 microgram and total folic acid 190 micrograms. Corresponding intakes (/person) in families with four or more children were 10-20% lower. 3. A comparison of intakes with those recommended in Canada (Department of National Health and Welfare, 1976) and the USA (National Research Council, 1974) or by WHO (1973) indicated that for folic acid average values were particularly low, and only for vitamin B12 were the recommendations significantly exceeded. 4. Contributions from alcoholic drinks and confectionery were also calculated and found, on average, to be significant for cu, vitamin B12 and folic acid. 5. The losses of B-vitamins which might occur on cooking are discussed.