Gallaher D D, Johnson P E, Hunt J R, Lykken G I, Marchello M J
Department of Food and Nutrition, North Dakota State University, Fargo 58105.
Am J Clin Nutr. 1988 Aug;48(2):350-4. doi: 10.1093/ajcn/48.2.350.
Beef is a concentrated source of zinc. However, the bioavailability of Zn from beef has not been clearly established. It is also unclear whether there is a difference in absorption between intrinsic and extrinsic Zn. To address these questions, a calf was labeled with 65ZnCl2 and the meat was used as a source of intrinsically labeled beef. Twelve subjects were given a meal containing 100 g beef labeled either intrinsically or extrinsically with 65ZnCl2. Gamma-ray emissions, as determined by whole-body counting, were used to calculate Zn absorption. Absorption values were 20.9 +/- 5.5% from the extrinsic meal and 26.4 +/- 10.6% from the intrinsic meal, a difference that was not statistically significant (p greater than 0.05). Zn absorption was thus much less than the 40% assumed in establishing the 1980 Recommended Dietary Allowance for Zn. These results also indicate that extrinsic labels of Zn are valid markers of zinc absorption in beef.
牛肉是锌的浓缩来源。然而，牛肉中锌的生物利用度尚未明确确定。内在锌和外在锌在吸收方面是否存在差异也不清楚。为了解决这些问题，用65ZnCl2标记一头小牛，其肉用作内在标记牛肉的来源。给12名受试者提供一顿含有100克用65ZnCl2内在或外在标记的牛肉的餐食。通过全身计数测定的γ射线发射用于计算锌的吸收。外在餐食的吸收值为20.9±5.5%，内在餐食的吸收值为26.4±10.6%，差异无统计学意义（p>0.05）。因此，锌的吸收远低于1980年确定锌的推荐膳食摄入量时所假定的40%。这些结果还表明，锌的外在标记是牛肉中锌吸收的有效标志物。
