Nestel P, Cehun M, Chronopoulos A, DaSilva L, Teede H, McGrath B
Baker Medical Research Institute Wynn Domain, Monash University, Melbourne, Australia.
Eur J Clin Nutr. 2004 Mar;58(3):403-8. doi: 10.1038/sj.ejcn.1601796.
To determine whether the two major isoflavones in red clover differ in their effect on low-density lipoprotein cholesterol (LDL-C).
A randomised, placebo-controlled, double-blind trial; two parallel groups taking one of the two isoflavones within which treatment and placebo were administered in a crossover design.
Free-living volunteers.
A total of 46 middle-aged men and 34 postmenopausal women.
Two mixtures of red clover isoflavones enriched in either biochanin (n=40) or formononetin (n=40) were compared. Placebo and active treatment (40 mg/day) were administered for 6 weeks each in a crossover design within the two parallel groups.
Plasma lipids were measured twice at the end of each period.
Baseline LDL-C concentrations did not differ significantly between men (n=46) and women (n=34), nor between those randomised to biochanin or formononetin. Interaction between time and treatments, biochanin, formononetin and corresponding placebos (two-way ANOVA) on LDL-C showed a significant effect of biochanin treatment alone. The biochanin effect was confined to men; median LDL-C was 3.61 (3.05-4.14) mmol/l with biochanin and 3.99 (3.16-4.29) mmol/l with the corresponding placebo (RM ANOVA with Dunnett's adjustment P<0.05). The difference between placebo and biochanin effects on LDL-C was 9.5%. No other lipid was affected and women failed to respond significantly to treatment.
Isolated isoflavones from red clover enriched in biochanin (genistein precursor) but not in formononetin (daidzein precursor), lowered LDL-C in men. This may partly explain the previous failure to demonstrate cholesterol-lowering effects with mixed isoflavones studied predominantly in women.
Novogen Ltd, North Ryde NSW, Australia, provided partial support including provision of tablets and outside monitoring.
确定红三叶草中的两种主要异黄酮对低密度脂蛋白胆固醇（LDL-C）的影响是否存在差异。
一项随机、安慰剂对照、双盲试验；两个平行组，分别服用两种异黄酮中的一种，治疗和安慰剂采用交叉设计给药。
自由生活的志愿者。
共46名中年男性和34名绝经后女性。
比较了两种富含生物chanin（n = 40）或芒柄花黄素（n = 40）的红三叶草异黄酮混合物。在两个平行组内采用交叉设计，安慰剂和活性治疗（40毫克/天）各给药6周。
在每个周期结束时测量两次血脂。
男性（n = 46）和女性（n = 34）之间的基线LDL-C浓度无显著差异，随机分配至生物chanin或芒柄花黄素组的受试者之间也无显著差异。时间与治疗、生物chanin、芒柄花黄素及相应安慰剂之间对LDL-C的相互作用（双向方差分析）显示，仅生物chanin治疗有显著效果。生物chanin的作用仅限于男性；服用生物chanin时LDL-C中位数为3.61（3.05 - 4.14）毫摩尔/升，服用相应安慰剂时为3.99（3.16 - 4.29）毫摩尔/升（采用Dunnett校正的重复测量方差分析，P < 0.05）。安慰剂和生物chanin对LDL-C的作用差异为9.5%。没有其他血脂受到影响，女性对治疗无显著反应。
从红三叶草中分离出的富含生物chanin（染料木黄酮前体）而非芒柄花黄素（大豆苷元前体）的异黄酮可降低男性的LDL-C。这可能部分解释了之前主要在女性中研究的混合异黄酮未能显示出降胆固醇作用的原因。
澳大利亚新南威尔士州北莱德的Novogen有限公司提供了部分支持，包括提供片剂和外部监测。
