Tempe is a fermented soy bean product originally made by Central Javanese people through fermentation with Rhizopus species. Although there is evidence of earlier fermentation of soy, tempe had appeared in the Central Javanese food pattern in the 1700s. Through its extensive use in main meals and snacks, it has led to people in the Jakarta prectinct having the highest known soy intake in the world and accordingly of the isoflavones contained. This provides an unique opportunity to consider the health effects of tempe (and soy), both beneficial and potentially toxic. Apparent health benefits are bowel health, protection against cardiovascular disease, certain cancers (e.g. breast and prostate) and menopausal health (including bone health). The long use of tempe at all stages of life, without recognised adverse effects, suggests it is relatively safe at the levels of intake seen in Central Java. However, further research on soy, both fermented and non-fermented, in Central Java should yield more insight into the mechanisms of action and the safe ranges of intake.

The aim of this study was to test the hypothesis that increased dietary intake of phytoestrogens reduces the health impact of the menopause. To test this hypothesis, a double-blind, randomized, entry-exit, cross-over study was conducted to assess the effects of three dietary manipulations--soy and linseed diets (high in phytoestrogens) and a wheat diet (low in phytoestrogens). Postmenopausal women were recruited and randomly assigned to one of the three dietary regimens. Urinary phytoestrogen concentrations, hot flush rate, vaginal smears, bone mineral density and bone mineral content were assessed for two 12-week periods. Comparative analysis showed no significant differences, but, when analyzed separately, groups consuming high phytoestrogen diets had between 10 and 30 times higher urinary excretion of phytoestrogens compared to those consuming the low phytoestrogen diet (p < 0.01). Study participants consuming soy, linseed and wheat diets had a 22% (not significant, n.s.), 41% (p < 0.009) and 51% (p < 0.001) reduction in hot flush rate; a 103% (p < 0.04), 5.5% (n.s.) and 11% (n.s.) increase in vaginal cytology maturation index; and a 5.2% (p < 0.04), 5.2% (n.s.) and 3.8% (n.s.) increase in bone mineral content, respectively. No changes were detected in bone mineral density. The differential effects of high phytoestrogen dietary manipulations on outcomes may represent tissue-specific responses to isoflavones and lignans contained in soy and linseed, respectively. Whilst health outcome measures were not significantly different between groups, the data obtained from separate analysis suggest that phytoestrogens in soy and linseed may be of use in ameliorating some of the symptoms of menopause. Furthermore, the significant decrease in hot flush rate in the wheat group cannot be attributable to phytoestrogens measured in this study. Due to subject variability, larger studies are still needed to evaluate population benefit.

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