Forsythe W A
School of Home Economics, University of Southern Mississippi, Hattiesburg 39406.
J Nutr. 1995 Mar;125(3 Suppl):619S-623S. doi: 10.1093/jn/125.3_Suppl.619S.
The effects of dietary protein on plasma cholesterol concentrations are well documented: animal proteins (casein) are hypercholesterolemic compared with plant proteins (soy protein). Although this effect of protein source on plasma cholesterol has been shown in many species, the mechanism is not completely understood. This paper reviews the relationship between dietary protein source and plasma thyroxine concentration. The basic premise is that feeding soy protein lowers plasma cholesterol concentration by causing an increase in plasma thyroxine concentrations. The metabolic changes involving cholesterol that occur when soy protein is fed are discussed. These changes are consistent with changes induced by elevating thyroxine. Data are presented from animal studies showing that feeding soy protein to laboratory animals consistently elevates plasma thyroxine concentrations. Furthermore, this elevation in plasma thyroxine concentrations precedes the change in plasma cholesterol concentrations: a necessary requirement for hypothesizing a causative effect. Possible mechanisms as to how a dietary protein source affects plasma thyroxine are also presented.
与植物蛋白（大豆蛋白）相比，动物蛋白（酪蛋白）会使胆固醇升高。尽管蛋白质来源对血浆胆固醇的这种影响已在许多物种中得到证实，但其机制尚未完全明确。本文综述了饮食蛋白质来源与血浆甲状腺素浓度之间的关系。基本前提是，摄入大豆蛋白会通过使血浆甲状腺素浓度升高来降低血浆胆固醇浓度。文中讨论了喂食大豆蛋白时发生的涉及胆固醇的代谢变化。这些变化与甲状腺素升高引起的变化一致。文中给出了动物研究的数据，表明给实验动物喂食大豆蛋白会持续提高血浆甲状腺素浓度。此外，血浆甲状腺素浓度的升高先于血浆胆固醇浓度的变化：这是假设存在因果关系的必要条件。文中还介绍了饮食蛋白质来源影响血浆甲状腺素的可能机制。
