Table 5.
Randomized, Controlled Trials of Soy or red clover for cognition in postmenopausal women
Author, year | Design | Subjects | Intervention type and duration | Outcome |
---|---|---|---|---|
Duffy, 2003 69 | RCT with 2 groups: soy isoflavone supplement or placebo |
|
Supplement contained total of 60mg isoflavones.
Duration: 12 weeks |
Significant improvements in recall of pictures and sustained attention tasks compared to placebo.
Significantly greater improvements in learning rule reversals and a planning task |
File, 2005 70 | RCT with 2 groups: soy isoflavone supplement or placebo |
|
Supplement contained total of 60mg isoflavones.
Duration: 6 weeks |
Significant improvements in short-term memory, frontal lobe function, mental flexibility, and planning ability in soy group compared to placebo. |
Kritz-Sliverstein, 2003 71 | RCT with 2 groups: isoflavone supplement or placebo |
|
Supplement contained a total of 110 mg/day of isoflavones
Duration: 6 months |
Significant improvement in cognitive function, for women on supplement compared to placebo. |
Kreijkamp-Kaspers, 2004 34 | RCT with 2 groups: ISP or casein protein |
|
ISP contained 25.6 g/day of soy protein and 99mg/day of isoflavones.
Duration: 12 months |
No differences in cognitive function between the two groups |
Howes, 2005 46 | RCT with 2 groups: Red clover isoflavones or placebo |
|
Supplement contained total of 28.5mg of isoflavones, took 2 tablets a day.
Duration: 6 months |
No effects (after correction for multiple comparisons) of isoflavones on cognitive function. |
Abbreviations: RCT=Randomized Controlled Trial, ISP=Isolated Soy Protein