Positive or negative effects of isoflavones: Toward the end of a controversy

Effect of thermal processing methods on flavonoid and isoflavone content of decorticated and whole pulses

Legumes have always been consumed as a staple source of proteins, and they are the only dietary source of isoflavones, flavonoid class of secondary plant metabolites. Isoflavones impart physiological effects via estrogenic action in humans and hence, looked upon as potential replacement of hormone estrogen in its deficiency. Legumes are an integral part of the Indian staple diet. Legumes are processed by soaking, germination, and thermal cooking. These methods have been reported to modify the nutrient composition of legumes. The sample population was surveyed to determine the most commonly used household processing methods. Soaking or germination followed by pressure cooking (with or without direct contact of water) or open pan cooking was found to be commonly followed by cooking practice in Indian households. Amongst the decorticated pulses, the highest cooking time was taken by chickpea (Cicer arietinum), and lentil (Lens culinaris) was cooked in the least amount of time. The pressure-cooked decorticated chickpea showed a 63% decrease in TFC and isoflavone content while open pan cooking lowered TFC of chickpea up to 67% and isoflavone content up to 90%. TFC of pressure-cooked and open-pan cooked decorticated lentil was only reduced by 12-17%, while isoflavone content showed 60-80% depletion. TFC of whole legumes was reduced by 30-40% on pressure cooking as well as open pan cooking; however, isoflavone content was variably affected. The black-eyed pea and desi chickpea showed 40% reduced isoflavone content while the loss of isoflavone content was 70% for kidney bean. Germination of green gram significantly increased the TFC and isoflavones, which showed a decrease of 24% and 44%, respectively, on pressure cooking.

New Evaluation of Isoflavone Exposure in the French Population

The study relates the present evaluation of exposure to estrogenic isoflavones of French consumers through two approaches: (1) identification of the isoflavone sources in the French food offering, (2) a consumption-survey on premenopausal women. For the foodstuff approach 150 food-items were analysed for genistein and daidzein. Additionally, 12,707 labels of processed-foods from French supermarket websites and a restaurant-supplier website were screened, and 1616 foodstuffs of interest were retained. The sources of phytoestrogens considered were soy, pea, broad bean and lupine. A price analysis was performed. A total of 270 premenopausal women from the French metropolitan territory were interviewed for their global diet habits and soy consumption and perception. In supermarkets, there were significantly less selected foodstuffs containing soy than in restaurant (11.76% vs. 25.71%, p < 0.01). There was significantly more soy in low price-foodstuff in supermarket (p < 0.01). Isoflavone levels ranged from 81 to 123,871 µg per portion of the analyzed soy containing foodstuff. Among the women inquired 46.3% claimed to have soy regularly. Isoflavone intake >45 mg/day is associated to vegan-diet (p < 0.01). In total, 11.9% of soy-consumers had a calculated isoflavone intake >50 mg/day. This dose can lengthen the menstrual cycles. The actual exposure to phytoestrogen is likely to have an effect in a part of the French population.

Use of dietary supplements containing soy isoflavones and breast cancer risk among women aged >50 y: a prospective study

BACKGROUND

Soy-based dietary supplements have been promoted as natural alternatives to menopausal hormone therapy, but their potential effect on breast cancer development is controversial.

OBJECTIVES

We examined the relation between the consumption of soy supplements and the risk of breast cancer, overall and by tumor hormone receptor status, among women aged >50 y.

METHODS

In total, 76,442 women from the Etude Epidemiologique aupres de Femmes de la Mutuelle Generale de l'Education Nationale (E3N) cohort, born between 1925 and 1950, were followed from 2000 to 2011 (11.2 y on average, starting at a mean age of 59.5 y; 3608 incident breast cancers), with soy supplement use assessed every 2-3 y. HRs of breast cancer were estimated with the use of multivariable Cox models.

RESULTS

Compared with never using soy supplements, the HRs associated with current use of soy supplements were 0.92 (95% CI: 0.76, 1.11) for all, 0.78 (95% CI: 0.60, 0.99) for estrogen receptor (ER)-positive, and 2.01 (95% CI: 1.41, 2.86) for ER-negative breast cancers. There was no association between past use of soy supplements and breast cancer. HRs for current use were 1.36 (95% CI: 0.95, 1.93) and 0.82 (95% CI: 0.65, 1.02) among women with and without a family history of breast cancer, respectively (P-interaction = 0.03) and 1.06 (95% CI: 0.87, 1.30) ≥5 y after menopause compared with 0.50 (95% CI: 0.31, 0.81) in premenopause or ≤5 y postmenopause (P-interaction = 0.04).

CONCLUSIONS

In this cohort of women aged >50 y, we report opposing associations of soy supplements with ER-positive and ER-negative breast cancer risk. Our results also caution against the use of these supplements in women with a family history of breast cancer. Whether the risk profile of soy supplements could be more favorable among premenopausal or recently postmenopausal women deserves further investigation.

Micellar systems of aliphatic alcohol ethoxylates as a sustainable alternative to extract soybean isoflavones

Ethoxylated aliphatic surfactants belonging to the Genapol and Tergitol series were assessed as extraction systems of isoflavones. They showed good extraction properties when compared with different solvents, the Genapol X-080 exhibiting the best performance. Available commercial isoflavone pills were used, as a starting simple matrix, to determine the parameters that affect the extraction procedure. The temperature and the surfactant concentration showed to be factors that favored significantly the extraction performance. The application of optimized variables (Genapol X-080 11% m/m, pH 4.5; extraction temperature of 54 °C and extraction time of 60 min) on soybean flour (natural) allowed extracting 3.237 ± 0.173 mg of isoflavone per gram of treated flour. This result was three times what it was for methanol under identical conditions. Extraction with these micellar systems represents a sustainable alternative methodology for industrial purposes due to its low cost, biodegradability, non-toxicity and easy scaling up.