Hot flashes and other symptoms

The Menopause and Osteoporosis Center in Italy conducted an experiment in which they divided 104 post-menopausal women into two groups: one to receive 60 grams of isolated soy protein (containing 76 mg isoflavones) or 60 grams of casein (no isoflavones) each day for 12 weeks. Each patient was assessed at week 4, 8 and 12 by diary entries of menopausal symptoms according to the Kupperman index. The soy group showed a significant reduction in hot flash frequencies when compared to baseline and placebo (casein).

A similar study was performed using soy isoflavone extracts standardized to contain genistein and daidzein (50 mg of a 1:1 mixture per day). They found a significant decrease in both the number and severity of hot flash episodes over the 12 week study period. A concomitant drop in night sweats was also noted. They further noted that no change was seen between the two groups in endometrial thickness, lipoproteins, bone markers, sex hormone-binding globulin, FSH or vaginal cytology. These results supported what many researches had believed, that certain phytoestrogens have selective estrogen modifying activities, preventing them from increasing the types of risks associated with unopposed estrogens (as in conventionally HRT). Similar findings have been reported by other groups.

Cancer

The exact role of soy isoflavones (or other phytoestrogens) in cancer prevention is difficult to assess at the present time, but current research is very promising. Current epidemiological studies taken together with both in vitro and animal studies suggest that several isoflavones and lignans have anti-carcinogenic activities. One study suggests that soy's breast cancer prevention stems from early (pre-pubertal) exposure to isoflavones that affects the proliferative potential of these tissues in later years.

Lancet published a case-control study to test the dietary intake of phytoestrogens and breast cancer risk. They found that women in the highest quartile of urinary equol (converted from dietary intake of genistein and daidzein) and enterlactone (converted from dietary intake of lignans) had a 73% and 64% reduction in breast cancer risk respectively. Furthermore, the role of lignans in flaxseeds has been linked to structural changes in mammary tissues that potentially reduce mammary cancer risk and flaxseed consumption in postmenopausal women altered urinary excretion of estrogen metabolites suggesting it has a chemoprotective role in postmenopausal women.

These data, taken with similar data reflecting the protective nature of alpha-linolenic acid in breast tissues (flaxseed in the richest source of ALA) suggests that the intake of flaxseed has tremendous health potential, especially in menopausal women.

Cardiovascular Health

The role of phytoestrogens in reducing atherosclerosis and other heart diseases has been under investigation for some time. Several mechanisms have been proposed for these molecules in general and specifically to the soy based genistein and daidzein molecules. They include antioxidant, anti-estrogenic, alterations in liver metabolism, inhibition of smooth muscle cells that lead to Atherosclerotic progression, and suppression of thrombus formation. Lipid profiles in hypercholesterolemic patients are, in some studies, unchanged when compared to placebo, while others report finding hyperlipidmic affects. Since most of these studies involved dietary intakes of soy proteins or food preparations (standardized to isoflavone content), these inconsistencies may be attributable to product variability, individual dosing variations or a result of non-isoflavone soy components.

A recent study found that the isoflavones derived from red clover were able to improve arterial compliance, an index of elasticity of large arteries (known to decrease with age and menopause). This experiment was conducted with a red clover extract providing 40 mg of isoflavones per day. The researches reported a 10% drop in LDL/HDL ratios, although LDL levels themselves were not significantly reduced over placebo. It is clear that, while promising, more studies need to be done in order to assess the role of soy isoflavones or other phytoestrogens in the prevention of cardiac diseases.

Bone Health

For many years, estrogen replacement therapy has been the treatment of choice for improving bone mass in postmenopausal women. As with other estrogen deficiency-related conditions, osteoporosis may be a candidate fro phytoestrogen intervention. Several models postulate a role for phytoestrogens in the prevention of osteoporosis but few studies have found conclusive evidence that naturally occurring phytoestrogens dramatically alter bone mass. One recent study showed a significant increase in both bone mineral content and density in the lumbar spine (although not elsewhere) when 40 grams per day of soy protein were taken for 6 months. Animal studies using soy fed animals suggest that the isoflavone portion is required for bone sparing effects. Again, epidemiology would suggest that dietary phytoestrogens plays a role in preventing osteoporotic factures, but other factors like overall diet and physical labor may play an equal role I the failure of Western women reaching peak bone mass prior to the menopausal years.