Prepared Foods September 6, 2005 eNewsletter

The anti-inflammatory effect of soy isoflavones may help prevent bone loss and cancer.

"TNF-alpha is a key mediator of inflammatory responses and may play a pivotal role in the development of cancer and in bone resorption," according to recent research. "This study determined the effect of soy rich in isoflavones on levels of TNF-alpha."

Y. Huang and colleagues described their study: "Twelve postmenopausal women ingested a 36-oz. portion of soymilk containing isoflavones daily for 16 weeks and provided fasting blood samples multiple times before, during and after soy consumption for the analyses of cytokines and monocyte content. Compared with prediet levels (36.3 ±14.0 pg/ml), serum levels of TNF-alpha decreased by 25.1% (27.2 ±10.3 pg/ml; p<0.01) as early as two weeks after soy consumption and by 66.7% (11.6 ±5.3 pg/ml; p<0.01) 10 weeks after soy consumption and recovered to the prediet levels four weeks after the termination of soy consumption (38.6 ±19.6 pg/ml; p=0.66)."

The authors noted, "A similar decrease of up to 56.6 and 14.4% was found for serum IL-1alpha and the mean percentage of blood monocytes during soy consumption, respectively, but not for IL-6. In cultures of monocytes or whole blood from postmenopausal women, soy isoflavones (genistein and daidzein, 10-1000 nm), tamoxifen (10-1000 nm) or 17beta-estradiol (0.1-10 nm) inhibited lipopolysaccharide (1 microg/ml)-induced TNF-alpha production by up to 55.8%."

"Isoflavones may be the active components in soy responsible for the decrease of TNF-alpha found in postmenopausal women during a soy diet," concluded the scientists. "This antiinflammatory effect of the isoflavones may be important in immune modulation and the prevention of bone loss and cancer."

Huang and colleagues published their study in The Journal Of Clinical Endocrinology And Metabolism (“Decreased Circulating Levels of Tumor Necrosis Factor-alpha in Postmenopausal Women During Consumption of Soy-containing Isoflavones.” J Clin Endocrinol Metab, 2005;90(7):3956-62). For additional information, contact L.W. Lu, Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, 700 Harborside Drive, Galveston, Texas 77555-1109. E-mail:

Source: Obesity, Fitness & Wellness Week