Neurology：大豆蛋白无益提高妇女整体认知能力

与早先的报道相反，一项新的研究表明大豆蛋白或许并不能有助维持45岁以上妇女的整体思维能力，但可能会提高妇女大脑进行面部识别的记忆容量。这项研究发表在2012年6月5日的Neurology杂志上。

大豆是许多亚洲传统饮食的主食，并一直被认为可能改善绝经后妇女的认知能力。近日，加利福尼亚州斯坦福大学的Victor W. Henderson博士发表研究报告说，研究发现长期使用大豆蛋白既不完善也不会损害妇女的整体认知功能。

在这项研究中，313名年龄在45和92岁之间的绝经后健康妇女为受试人员，分别给予25克大豆蛋白或牛奶蛋白匹配的安慰剂。研究人员分别在研究开始和2.5年后对参试人员进行记忆和思维能力测量。

研究发现两组妇女之间的记忆和思维能力并没有显著变化。然而，在视觉记忆或面部识别能力上有些小改善，服用大豆蛋白组的妇女相比于安慰机组提高了约13％。

该研究为大豆补充剂不应该被用于提高绝经后妇女整体认知能力提供了强有力的证据。另一方面饮食中的高大豆蛋白并不会对思维能力有任何有害的影响。

doi:10.1212/WNL.0b013e318258f822
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Long-term soy isoflavone supplementation and cognition in women

V.W. Henderson, MD, MS, J.A. St. John, MPH, H.N. Hodis, MD, N. Kono, MPH, C.A. McCleary, PhD, A.A. Franke, PhD and W.J. Mack, PhD For the WISH Research Group

Objective: To determine the cognitive effects of long-term dietary soy isoflavones in a daily dose comparable to that of traditional Asian diets.

Methods: In the double-blind Women's Isoflavone Soy Health trial, healthy postmenopausal women were randomly allocated to receive daily 25 g of isoflavone-rich soy protein (91 mg of aglycone weight of isoflavones: 52 mg of genistein, 36 mg of daidzein, and 3 mg glycitein) or milk proteinmatched placebo. The primary cognitive endpoint compared between groups at 2.5 years was change from baseline on global cognition, a composite of the weighted sum of 14 neuropsychological test score changes. Secondary outcomes compared changes in cognitive factors and individual tests.

Results: A total of 350 healthy postmenopausal women aged 45–92 years enrolled in this trial; 313 women with baseline and endpoint cognitive test data were included in intention-to-treat analyses. Adherence in both groups was nearly 90%. There was no significant between-group difference on change from baseline in global cognition (mean standardized improvement of 0.42 in the isoflavone group and 0.31 in the placebo group; mean standardized difference 0.11, 95% confidence interval [CI] 0.13 to 0.35). Secondary analyses indicated greater improvement on a visual memory factor in the isoflavone group (mean standardized difference 0.33, 95% CI 0.06–0.60) but no significant between-group differences on 3 other cognitive factors or individual test scores, and no significant difference within a subgroup of younger postmenopausal women.

Conclusion: For healthy postmenopausal women, long-term dietary soy isoflavone supplementation in a dose comparable to that of traditional Asian diets has no effect on global cognition but may improve visual memory.

Classification of evidence: This study provides Class I evidence that long-term dietary supplementation with isoflavone-rich soy protein does not improve global cognition of healthy postmenopausal women.