Elsevier

American Heart Journal

Volume 145, Issue 2, February 2003, Pages N1-N4
American Heart Journal

Clinical Investigations: Prevention and Rehabilitation
Effects of oral soy protein on markers of inflammation in postmenopausal women with mild hypercholesterolemia,☆☆,,★★

https://doi.org/10.1067/mhj.2003.115Get rights and content

Abstract

Background Nitric oxide (NO) may protect arteries against atherosclerosis, as suggested by experimental studies. Estrogen therapy enhances the bioactivity of NO in the vasculature of healthy postmenopausal women, but is not acceptable for long-term use by many women. Observational studies have demonstrated beneficial cardiovascular effects of soy protein in premenopausal and postmenopausal women. We examined whether the consumption of isolated soy protein may improve markers of vascular inflammation in postmenopausal women with hypercholesterolemia. Methods and Results In a randomized, double-blind, placebo-controlled, crossover study, 24 postmenopausal women with hypercholesterolemia received 25 g of soy protein or a placebo daily for 6 weeks, with treatment periods separated by 1 month. Markers of vascular inflammation were measured by enzyme-linked immunosorbent assay methods, including: soluble interleukin-2 receptor (sIL-2r), E-selectin, P-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1). There was no effect of soy protein in comparison with placebo on the inflammatory markers: the sIL-2r level was 942.2 ± 335.3 pg/mL with soy protein and 868.5 ± 226.9 pg/mL with placebo (P =.311); E-selectin was 39.6 ± 16.5 ng/mL with soy protein and 42.1 ± 17.6 ng/mL with placebo (P =.323); P-selectin was 157.9 ± 67.9 ng/mL with soy protein and 157.5 ± 47.6 ng/mL with placebo, (P =.977); ICAM-1 was 266.0 ± 81.3 ng/mL with soy protein and 252.5 ± 82.7 ng/mL with placebo (P =.435); VCAM-1 was 402.7 ± 102.1 ng/mL with soy protein and 416.4 ± 114.8 ng/mL with placebo (P =.53). Conclusions Consumption of 25 g of isolated soy protein daily for 6 weeks does not substantially affect markers of vascular inflammation in postmenopausal women with hypercholesterolemia. (Am Heart J 2003;145:e7.)

Section snippets

Methods

Women were randomly assigned dietary treatments of either 25 g of isolated isoflavones (Protein Technologies International, St Louis, Mo) or 25 g of total milk protein (Protein Technologies International), with each treatment period lasting 6 weeks and separated by 1 month in which the patients were off treatment. The only differences between the 2 products were the protein source and isoflavone content. All study participants returned to the hospital for blood drawing and brachial artery

Results

Thirty postmenopausal women with hypercholesterolemia (age 55 ± 5 years) who had not taken hormone replacement, antioxidant vitamins, or lipid-lowering therapies in the preceding 2 months and who had low-density lipoprotein (LDL) cholesterol levels >130 mg/dL were enrolled in the study. All had plasma 17β-estradiol levels <50 pg/mL and follicle stimulating hormone levels >50 pg/mL. No subject had hypertension or diabetes mellitus or was a current cigarette smoker. The baseline lipid profile

Discussion

The intake of soy protein (25 g daily for 6 weeks) did not affect markers of vascular inflammation in 24 postmenopausal women with hypercholesterolemia, compared with a placebo (milk protein). We focused on isolated soy protein containing naturally occuring isoflavones because of observational, epidemiologic, population-based studies that have demonstrated cardiac protection and antiatherogenic effects resulting from soybean isoflavones. “Dietary estrogens” are adsorbed from the intestinal

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  • Cited by (0)

    Supported by a grant from Protein Technologies International, St Louis, Mo.

    ☆☆

    Reprint requests: Arnon Blum, MD, Director, Department of Internal Medicine A, Tel-Aviv Sourasky Medical Center, Tel-Aviv 64239, Israel.

    E-mail: [email protected]

    ★★

    1097-6744/2003/$30.00 + 0

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