Effects of dietary phytoestrogens in postmenopausal women

Abstract

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.

Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials

“…Our literature search identified 31 RCTs. Twenty-two studies were excluded because of lack of indices of interest (Agnusdei et al, 1997a, b;Gambacciani et al, 1997a, b;Potter et al, 1998;Alekel et al, 2000;Wangen et al, 2000;Clifton-Bligh et al, 2001;Katase et al, 2001;Anderson et al, 2002;Chiechi et al, 2002;Lucas et al, 2002;Chen et al, 2003Chen et al, , 2004Jones et al, 2003;Schult et al, 2003;Atkinson et al, 2004;Harkness et al, 2004;Olsen et al, 2004;Mori et al, 2004a, b), non-randomization (Dalais et al, 1998), lack of a control group (Agnusdei et al, 1997a, b), insufficient original data or baseline values (Gambacciani et al, 1997a, b;Khalil et al, 2002). Thus, nine studies with a total of 432 subjects were included in this meta-analysis, in which five studies had quality score of five; three studies had quality score of four and one study had quality score of three (Morabito et al, 2002;Uesugi et al, 2002;Yamori et al, 2002;Arjmandi et al, 2003Arjmandi et al, , 2005Dalais et al, 2003;Brooks et al, 2004;Mori et al, 2004a, b;Nikander et al, 2004) (Table 1).…”

The prevalence and risk factors for age-related macular degeneration in rural–urban India, Sankara Nethralaya Rural–Urban Age-related Macular degeneration study, Report No. 1

“…Sodium adversely affects calcium balance through the promotion of urinary calcium loss (24). There is increasing evidence that phytoestrogens from soy and some other plant sources may account for better bone health than might otherwise be expected for a given calcium intake (25), with effects mediated via the β-estrogen receptor (26). Other nutrients such as vitamin K, through osteocalcin, and essential fatty acids also contribute to bone health.…”

The use of complementary and alternative medications by menopausal women in South East Queensland

“…In relation to menopausal symptoms such as hot flushes, studies have been undertaken on the clinical effectiveness of phytoestrogens (Albertazzi et al, 1998;Dalais et al, 1998;Drapier Faure, Chantre, & Mares, 2002;van de Weijer & Barentsen, 2002) and herbal therapies such as Chinese herbs (Davis et al, 2001), dong quai (Hirata et al, 1997), and evening primrose oil (Chenoy et al, 1994). The effect of nutritional supplements such as calcium on postmenopausal bone loss has also been explored (Aloia et al, 1994;Dawson-Hughes et al, 1990;Reid et al, 1993).…”