Eussen Simone J, de Groot Lisette C, Joosten Liesbeth W, Bloo Rubia J, Clarke Robert, Ueland Per M, Schneede Jörn, Blom Henk J, Hoefnagels Willibrord H, van Staveren Wija A
Division of Human Nutrition, Wageningen University, Wageningen, Netherlands.
Am J Clin Nutr. 2006 Aug;84(2):361-70. doi: 10.1093/ajcn/84.1.361.
Vitamin B-12 deficiency is associated with cognitive impairment in older people. However, evidence from randomized trials of the effects of vitamin B-12 supplementation on cognitive function is limited and inconclusive.
The objective was to investigate whether daily supplementation with high doses of oral vitamin B-12 alone or in combination with folic acid has any beneficial effects on cognitive function in persons aged >/=70 y with mild vitamin B-12 deficiency.
In a double-blind, placebo-controlled trial, 195 subjects were randomly assigned to receive 1000 microg vitamin B-12, 1000 microg vitamin B-12 + 400 microg folic acid, or placebo for 24 wk. Vitamin B-12 status was assessed on the basis of methylmalonic acid, total homocysteine (tHcy), and holotranscobalamin (holoTC) concentrations before and after 12 and 24 wk of treatment. Cognitive function was assessed before and after 24 wk of treatment with the use of an extensive neuropsychologic test battery that included the domains of attention, construction, sensomotor speed, memory, and executive function.
Vitamin B-12 status did not change significantly after treatment in the placebo group; however, oral vitamin B-12 supplementation corrected mild vitamin B-12 deficiency. Vitamin B-12 + folic acid supplementation increased red blood cell folate concentrations and decreased tHcy concentrations by 36%. Improvement in memory function was greater in the placebo group than in the group who received vitamin B-12 alone (P = 0.0036). Neither supplementation with vitamin B-12 alone nor that in combination with folic acid was accompanied by any improvement in other cognitive domains.
Oral supplementation with vitamin B-12 alone or in combination with folic acid for 24 wk does not improve cognitive function.
维生素B12缺乏与老年人认知功能损害有关。然而，关于补充维生素B12对认知功能影响的随机试验证据有限且尚无定论。
探讨每日单独补充高剂量口服维生素B12或联合叶酸对70岁及以上轻度维生素B12缺乏者的认知功能是否有任何有益影响。
在一项双盲、安慰剂对照试验中，195名受试者被随机分配接受1000微克维生素B12、1000微克维生素B12 + 400微克叶酸或安慰剂，为期24周。在治疗12周和24周前后，根据甲基丙二酸、总同型半胱氨酸（tHcy）和全转钴胺素（holoTC）浓度评估维生素B12状态。在治疗24周前后，使用包括注意力、构建、感觉运动速度、记忆和执行功能等领域的广泛神经心理测试组合评估认知功能。
安慰剂组治疗后维生素B12状态无显著变化；然而，口服补充维生素B12纠正了轻度维生素B12缺乏。补充维生素B12 + 叶酸可提高红细胞叶酸浓度，并使tHcy浓度降低36%。安慰剂组的记忆功能改善大于单独接受维生素B12的组（P = 0.0036）。单独补充维生素B12或联合叶酸均未伴随其他认知领域的任何改善。
单独口服补充维生素B12或联合叶酸24周不能改善认知功能。
