Daily variation in food intake of infants from 2 to 18 months.

This paper examines the day to day variation in energy intake of 48 breast-fed infants studied by 4-day diet records at monthly intervals from 6 weeks to 7 1/2 months and of 37 fully weaned infants studied at 10, 12, 15 and 18 months. Variation was low in the fully breast-fed infants, increased as solids were introduced, and at 18 months, approached values found for adults. Pooled within-subject coefficient of variation (CVw) at 1-3, 3-5, 5-7, 10 + 12, and 15 + 18 months was 10.6, 10.6, 12.0, 13.6, 18.1 per cent. Between-subject coefficient of variation (CVb) was 20.1, 19.3, 16.9, 19.4 and 23.3 per cent at these ages. Some individuals were more variable than others; the range of CVw at each age was wide; at 2-4 and 15-18 months it was 1-21 and 6-30 per cent respectively. The number of daily records needed to assess energy intake of groups of individuals with a specified degree of confidence is discussed together with implications for the planning of dietary surveys.