Soy proteins and isoflavones reduce interleukin-6 but not serum lipids in older women: a randomized controlled trial

Abstract

Soy foods contain several components, notably, isoflavones and amino acids, that may improve cardiovascular health. We evaluated the long-term effect of soy protein and/or soy isoflavones supplementation on serum lipids and inflammatory markers using a 1-year randomized, double-blind, placebo-control, clinical trial in 131 healthy ambulatory women older than 60 years. We hypothesized that soy protein, in combination with isoflavones, would have the largest positive effect on coronary heart disease risk factors (serum lipids and inflammatory markers) compared with either intervention alone and that, within groups receiving isoflavones, equol producers would have more positive effects on coronary heart disease risk factors than nonequol producers. After a 1-month baseline period, participants were randomized into 1 of 4 intervention groups: soy protein (18 g/d) and isoflavone tablets (105 mg/d isoflavone aglycone equivalents), soy protein and placebo tablets, control protein and isoflavone tablets, or control protein and placebo tablets. T Tests were used to assess differences between equol and nonequol producers. Ninety-seven women completed the trial. Consumption of protein powder and isoflavone tablets did not differ among groups, and compliance with study powder and tablets was 79% and 90%, respectively. After 1 year, in the entire population, there were either no or little effects on serum lipids and inflammatory markers, regardless of treatment group. Equol producers, when analyzed separately, had significant improvements in total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios (−5.9%, P = .02; −7.2%, P = .04 respectively). Soy protein and isoflavone (either alone or together) did not impact serum lipids or inflammatory markers. Therefore, they should not be considered an effective intervention to prevent cardiovascular disease because of lipid modification in healthy late postmenopausal women lacking the ability to produce equol.

Associations between intake of dietary fermented soy food and concentrations of inflammatory markers: a cross‐sectional study in Japanese workers

“…Interestingly, it was found that soy protein significantly decreased the level of the inflammatory maker IL-6 and that soy isoflavones tended to decrease IL-6 level. No difference was found in the inflammatory maker CRP (44). In our study, an inverse association was not found between intake of soy foods and/or soy isoflavone and inflammatory markers ( Table 2).…”

Effect of Genistein on Cholesterol Metabolism‐Related Genes in HepG2 Cell

“…Extensive epidemiology studies (Zhuo, Melby, & Watanabe, 2004;Li, Liu, Wang, Zhao, & Feng, 2016) and animal studies (Rosier & Saes, 2006;Sbarouni, Iliodromitis, Zoga, Theodorakis, & Kremastinos, 2007) have shown that genistein can significantly decrease plasma LDL-C, TC, total triglycerides, as well as homocysteine levels, and also increase plasma HDL-C levels, which improves endothelial function and reduces the risk factors of atherosclerosis. However, others consider that soy protein and isoflavone (either alone or together) have no effect on plasma lipids or inflammatory biomarkers to prevent cardiovascular disease, even though isoflavone levels are substantially increased in blood and urine (Meyer et al, 2004;Mangano et al, 2013). We previously showed that genistein had benefits on plasma and hepatic lipid metabolism in high-fat-diet induced nonalcoholic steatohepatitis (NASH) rats through modulating the key transcription factors, including SREBP, PPAR, and AMPK (Liu, Zhong, Yin, & Jiang, 2017).…”

Beneficial effects of rice endosperm protein intake in Japanese men with risk factors for metabolic syndrome: a randomized, crossover clinical trial

“…Recent clinical trials with soy protein were performed using doses of 15-56 g of protein/day [39][40][41][42]; however to date, no clinical reports have investigated rice protein intake. Consequently, in the present study, we used a smaller amount of protein, i.e., 10 g/day, to avoid potential health hazards.…”