Long-term Individual Dietary Surveys

It is known that the amounts of food consumed by individual men vary from day to day and that this variation may be considerable.Literature shows that surveys of short duration cannot be relied on to give a true picture of the normal dietary pattern.Seven-day studies are commonly taken as sufficient, although Wait & Roberts (1932), McHenry, Ferguson & Gurland (1945) and Yudkin (1951) conclude that I week cannot be considered a long enough period to give an accurate assessment of the average intake of nutrients by the individual.T h e survey made by Roberts, Kerr & Ohlson (1948) of the food intake of older women lasted for 6 months, and this appears to be the longest period recorded.I n view of the sparsity of information on this subject it was decided to record for long periods the intakes of foods and nutrients in the normal diet of two healthy adults pursuing their customary occupations.'Healthy' is taken, in this context, to mean freedom from any apparent symptoms or signs of illness or malnutrition, and the existence of a feeling of well-being, a steady body-weight, good physique and sufficient energy to perform the normal activities of the subjects concerned. EXPERIMENTAL Duration of surveyTO obtain an estimate of the average intake the duration of any survey should be sufficient to reflect the normal dietary of the subject and, preferably, the effect on it of seasonal influence.For this reason one survey lasted 70 weeks and the other 13.The longer one was divided into two periods of 61 weeks and 9 weeks.A break of 13 weeks during this survey was made to test the subject's reaction to freedom from weighing food.Food records were not obtained for weeks 10 and 14 in this study.