Change in USDA food composition data for 43 garden crops, 1950 to 1999

Change in USDA food composition data for 43 garden crops, 1950 to 1999

2004

E00182

A study was conducted to evaluate possible changes in USDA nutrient content data for 43 garden crops between 1950 and 1999 and consider their potential causes. USDA nutrient content data published in 1950 and 1999 were compared for 13 nutrients and water in 43 garden crops, mostly vegetables. After adjusting for differences in moisture content, the ratios of nutrient contents, R (1999/1950), were calculated for each food and nutrient. To evaluate the foods as a group, the median and geometric mean R-values for the 13 nutrients and water were calculated. To evaluate R-values for individual foods and nutrients, with hypothetical confidence intervals, the USDA's standard errors (SEs) of the 1999 values were used, from which 2 estimates for the SEs of the 1950 values were generated. As a group, the 43 foods show apparent, statistically reliable declines (R<1) for 6 nutrients (protein, Ca, P, Fe, riboflavin and ascorbic acid), but no statistically reliable changes for 7 other nutrients. The medians range declined from 6% for protein to 38% for riboflavin. When evaluated for individual foods and nutrients, R-values were usually not distinguishable from one with current data. Depending on whether we use low or high estimates of the 1950 SEs, respectively, 33 or 20% of the apparent R-values differed reliably from one. Significantly, about 28% of these R-values exceeded one. It is suggested that any real declines are generally most easily explained by changes in cultivated varieties between 1950 and 1999, in which there may be trade-offs between yield and nutrient content.

v.23(6):669-682, JOURNAL OT THE AMERICAN COLLEGE OF NUTRITION

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