Analysis of vitamin E, selenium, and other nutrients in planned balanced diets in Taiwan

To obtain insights into the daily supply of vitamin E, Se, minerals, and other nutrients in well-planned Taiwanese balanced diets, six daily diet samples whose formulation and preparation had been planned and supervised by hospital dieticians were collected from a diet/nutrition unit of a university hospital. According to HPLC analysis, the mean daily vitamin E supplied by these diets was 11.7 ± 2.1 mg/day of α-tocopherol equivalent, including 9.8 γ 2.4, 17.4 γ 9.8, and 5.5 γ 1.0 mg/day of α-, γ-, and δ-tocopherol, respectively, and are very close to the RDA value of 12 mg/day. The mean selenium content of the daily diet samples analyzed spectrofluorometrically were 112 ± 7 μg/day, well above the recommended allowance of 55 μg/day. Using inductively coupled plasma emission spectroscopy, the supply of minerals including Ca, P, Fe, Cu, Zn, Na, and K in these diets were found to surpass the recommended allowances or comply with the dietary goals. Unexpectedly, it was found that the mean Mg content was only 258 mg/day which was below the recommended intake of 300 mg/day. The mean proximate compositions were 97, 74, 6.4, 13.2, and 287.4 g/day of crude protein, crude fat, crude fiber, crude ash, and nitrogen-free extract, respectively, from which the mean energy supply was calculated to be 2202 kcal/day. Although the analyzed energy value was 10% higher than the planned target value, the percentages of energy contributed by the three macro-nutrients agreed well to planned values. The pattern of seven essential amino acids analyzed by acid hydrolysis and an amino acid analyzer was found to surpass the requirement patterns for 2-year-old children and adults. The results indicate that vitamin E, Se, and most minerals provided by a well-planned Taiwanese balanced diet meet the recommended allowances except for Mg.