Comparison of measured dietary consumption of calcium, phosphorus, iron and potassium with calculated values by "Weighing method", "purchasing method" and "recall method" concerning food consumption

Three survey methods for dietary consumption, i. e. (1) weighing all food stuffs prior to cooking (weighing method), (2) purchasing the same meal as consumed and separating it into food stuffs (purchasing method), and (3) asking the housewives who cooked the meal to recall the composition and weight of food stuffs used (recall method), were concurrently tested on a total of 30 meals served by 10 housewives living in an agricultural village in Oita Prefecture in the southern part of Japan. Using the new version of the Japanese Standard Food Consumption Table (4th edition), calcium, phosphorus, iron and potassium contents of each meal were calculated by each survey method and the values obtained were compared with the measured values. Calcium, phosphorus and iron were simultaneously measured by inductively coupled argon plasma (ICP) spectrophotometer (JY48P JobinYbon) and potassium content in meals was measured by atomic absorption spectrophotometer (Zeeman 180-80 Hitachi). Good correlations between calculated values and the corresponding measured ones were observed, i. e. (1) for calcium content: 0.799, 0.800 and 0.655, (2) for phosphorus content: 0.840, 0.843 and 0.627, (3) for iron content: 0.565, 0.733 and 0.545, (4) for potassium content: 0.857, 0.746 and 0.742 respectively for weighing, purchasing and recall methods. Out of 12 combinations, six comparisons of calculated values versus measured values differed significantly by paired t-test analysis, i. e. (1) for the weighing method, the mean values were larger for phosphorus (p