Intake of isoflavone and lignan phytoestrogens and associated demographic and lifestyle factors in older Australian women.

The purpose was to determine intake of phytoestrogens in a sample of older Australian women, and to investigate associated lifestyle factors. Subjects were an age-stratified sample of 511 women aged 40-80 y, randomly selected from the electoral roll and participating in the Longitudinal Assessment of Ageing in Women at the Royal Brisbane and Women's Hospital. A cross-sectional study was conducted to assess isoflavone and lignan intake over the past month from food and supplements using a 112-item phytoestrogen frequency questionnaire. Data were also collected on nutrient intakes, physical activity, smoking, alcohol, non-prescription supplements, hormone therapy, education and occupation. Logistic regression was used to evaluate associations between demographic and lifestyle variables and soy/linseed consumption while controlling for age. Isoflavone intakes were significantly higher in the younger compared to older age groups (p<0.001); there were no age-related differences in lignan intake. Forty-five percent of women consumed at least one serve of a soy and/or linseed item and were defined as a soy/linseed consumer. Median (range) intakes by consumers for isoflavones and lignans (3.9 (0-172) mg/d and 2.4 (0.1-33) mg/d) were higher than intakes by non-consumers (0.004 (0-2.6) mg/d and 1.57 (0.44-4.7) mg/d), respectively (p<0.001). Consumers had higher intakes of dietary fibre (p=0.003), energy (p=0.04) and polyunsaturated fat (p=0.004), and higher levels of physical activity (p=0.006), socio-economic position (p<0.001), education (p<0.001) and supplement use (p<0.001). Women who consumed soy or linseed foods differed in lifestyle and demographic characteristics suggesting these factors should be considered when investigating associations with chronic disease outcomes.

Development and validation of a short questionnaire for estimating the intake of zinc.

Zinc is an essential nutrient required for numerous metabolic functions. The aim of the present study was to develop a zinc-specific food frequency questionnaire (FFQ) and to determine its relative validity. A 74-item FFQ was designed for the measurement of zinc intake. Food items were included in the FFQ if their zinc content was >0.5 mg/100 g, and the food item contributed >5% of the recommended dietary intake. Female subjects (n = 22) were recruited to complete the questionnaire in addition to maintaining a weighed food record for 7 days. Mean intake of zinc obtained from the weighed records (8.8 +/- 2.3 mg/day; mean +/- SD) was significantly lower than that obtained from the FFQ (10.5 +/- 3.1 mg/day; P < 0.01). Ranked zinc intakes obtained from the two instruments were significantly correlated (r (s) = 0.81, P < 0.001). Evaluation of progressively shortened versions of the FFQ, containing 23-61 food items and representing 60-90% of the contribution to total zinc intake, yielded correspondingly decreasing magnitudes of zinc intake, but the rank correlation with the weighed records was significant (P < 0.01). Rank correlations and analysis of plots from Bland-Altman analyses suggest that a shortened 37-item FFQ has comparable validity to the full FFQ. A shortened FFQ is likely to produce lower demands on the interviewer and/or respondent when assessing zinc intake.

Red clover (Trifolium pratense) isoflavones and serum homocysteine in premenopausal women: a pilot study.

BACKGROUND: There is limited information on the effect of isoflavones on homocysteine concentrations, a risk factor for a number of chronic diseases. METHODS: Twenty-three premenopausal women participated in a double-blind, randomized, parallel study for four menstrual cycles. Subjects consumed either placebo or purified red clover (Trifolium pratense) isoflavone (86 mg/day) tablets. Blood samples were collected weekly during cycles 1, 3, and 4 for determination of serum folate and total homocysteine concentrations. Dietary intake was monitored monthly. RESULTS: Concentrations of folate and homocysteine in serum did not change significantly in either group, and there were no significant differences observed between the follicular and luteal phases of the menstrual cycle. The participants' dietary records indicated that nutrient intake was constant, and compliance was confirmed by analysis of urinary isoflavone concentrations and tablet counts in returned containers. CONCLUSIONS: These results suggest that in the absence of any dietary modification, supplementation with purified isoflavones that are predominantly methoxylated has no effect on serum homocysteine or folate in premenopausal women.

Phytoestrogens and indicators of breast cancer prognosis.

Breast cancer incidence is lower and survival is longer in Asian women residing in Japan, China, or the Philippines than Caucasian women residing in the United States. Phytoestrogen intake has been examined as a possible reason for the disparity in breast cancer incidence and survival. This study examined the association between phytoestrogen intake prior to diagnosis of breast cancer and indicators of breast cancer prognosis (tumor size, estrogen and progesterone receptor status, histological grade, lymphovascular invasion, nodal spread, and stage) in 128 women, aged 40-79 yr, newly diagnosed with invasive breast cancer. After controlling for significant confounding factors, higher intakes of phytoestrogens were associated with favorable indicators of breast cancer. In women with higher intakes of phytoestrogens, there was a 32% reduction in the odds of being diagnosed with any stage of cancer other than stage 1 (95% confidence interval, CI = 0.49-0.93; P = 0.02), a 38% reduction in odds of being diagnosed with positive lymphovascular invasion (95% CI = 0.40-0.95; P = 0.03), and a 66% increase in the odds of being diagnosed with a positive progesterone receptor (95% CI = 1.06-2.58; P = 0.03). We conclude that phytoestrogen intake prior to diagnosis may improve prognosis of breast cancer.

Effects of supplementation with purified red clover (Trifolium pratense) isoflavones on plasma lipids and insulin resistance in healthy premenopausal women.

Consumption of isoflavone-rich soyabean protein is reported to reduce total and LDL-cholesterol, but the specific components responsible are undetermined. In a previous crossover trial we showed that purified isoflavones, derived from red clover (Trifolium pratense), raised HDL3-cholesterol in premenopausal women; however, these findings were inconclusive due to period and carryover effects. In an attempt to overcome this problem, we utilised a parallel study designed to re-examine the effects of purified isoflavones on plasma lipoproteins and markers of insulin resistance in premenopausal women. Twenty-five healthy premenopausal women participated in a double-blind, randomised, parallel study. The treatment group (n 12) consumed a placebo for the first menstrual cycle and an isoflavone supplement (86 mg/d, derived from red clover) for three cycles, while the placebo group (n 13) consumed a placebo supplement for four menstrual cycles. Blood samples were collected weekly during cycles 1, 3 and 4. Supplementation with isoflavones resulted in a 15-fold increase in urinary isoflavone excretion (P<0.0001). There were no significant effects on total cholesterol, LDL- and HDL-cholesterol, HDL subfractions, triacylglycerol, lipoprotein(a), glucose or insulin concentrations. Our present results indicate that purified isoflavones derived from red clover have no effect on cholesterol homeostasis or insulin resistance in premenopausal women, a group which is at low risk of CHD.