Laboratory of Nutrition, Faculty of Pharmacy, University Louis Pasteur, Strasbourg, France.
Nutrition. 2012 Feb;28(2):148-53. doi: 10.1016/j.nut.2011.04.009. Epub 2011 Aug 27.
To explain why vegetarian subjects develop morbidity and mortality from cardiovascular diseases unrelated to vitamin B status and Framingham criteria.
A study of 24 rural male subjects 18 to 30 y old and 15 urban male controls was conducted in the Sahel region of Chad. Food consumption was determined from a dietary questionnaire, and overall health status was assessed by body weight, body mass index, serum albumin, plasma transthyretin, urinary nitrogen, and creatinine. Plasma lipids, vitamins B6, B9 and B12, homocysteine, and related sulfur amino acids were measured as selected cardiovascular disease risk factors.
Body weight, body mass index, blood, and urinary markers of protein status were significantly lower, with an estimated 10% decrease of lean body mass in the study group compared with urban controls. Neither lipid fractions nor plasma levels of vitamins B6, B9, and B12 were significantly different between the two groups. Although the mean consumption of sulfur amino acids (10.4 mg·kg(-1)·d(-1)) by rural subjects was significantly below the recommended dietary allowances (13 mg·kg(-1)·d(-1)), plasma methionine values were similar in the two groups. In contrast, homocysteine concentration was significantly increased (18.6 μmol/L, P < 0.001), and the levels of cysteine and glutathione were significantly decreased in the study group, demonstrating inhibition of the trans-sulfuration pathway. The strong negative correlation (r = -0.71) between transthyretin and homocysteine implicated lean body mass as a critical determinant of hyperhomocysteinemia.
The low dietary intake of protein and sulfur amino acids by a plant-eating population leads to subclinical protein malnutrition, explaining the origin of hyperhomocysteinemia and the increased vulnerability of these vegetarian subjects to cardiovascular diseases.
解释素食者为何会出现与维生素 B 状态和弗雷明汉标准无关的心血管疾病发病率和死亡率。
在乍得萨赫勒地区对 24 名 18 至 30 岁的农村男性受试者和 15 名城市男性对照者进行了一项研究。通过饮食问卷确定食物摄入量，通过体重、体重指数、血清白蛋白、血浆转甲状腺素、尿氮和肌酐评估整体健康状况。测量了血浆脂质、维生素 B6、B9 和 B12、同型半胱氨酸和相关硫氨基酸，作为选定的心血管疾病危险因素。
体重、体重指数、血液和尿液蛋白质状况标志物显著降低，与城市对照组相比，研究组的瘦体重估计减少了 10%。两组之间的脂质分数和血浆维生素 B6、B9 和 B12 水平均无显著差异。尽管农村受试者的硫氨基酸平均摄入量（10.4mg·kg(-1)·d(-1)）明显低于推荐的膳食允许量（13mg·kg(-1)·d(-1)），但两组的血浆蛋氨酸值相似。相比之下，同型半胱氨酸浓度显著升高（18.6μmol/L，P<0.001），研究组的半胱氨酸和谷胱甘肽水平显著降低，表明转硫途径受到抑制。转甲状腺素与同型半胱氨酸之间的强负相关（r=-0.71）表明瘦体重是高同型半胱氨酸血症的关键决定因素。
植物性饮食人群的蛋白质和硫氨基酸摄入量低，导致亚临床蛋白质营养不良，解释了这些素食者高同型半胱氨酸血症的发生和心血管疾病易感性增加的原因。
