Soya isoflavones and obesity in Chinese adults
What it found
In a large group of Chinese adults in Shanghai, those who ate the most soya isoflavones were less likely to be obese than those who ate the least.
The link was seen in men and in women after menopause.
What they found
Studies in people
Obesity overall
People in the highest group for soya isoflavone intake had a lower prevalence of obesity than those in the lowest group (12.0% vs. 13.4%). The authors report a lower chance of being obese in the highest intake group.
Central obesity
The highest intake group also had a lower prevalence of central obesity (29.3% vs. 31.1%). But when other factors were taken into account, the overall link with central obesity was not significant.
Men and women
The link between soya isoflavones and obesity differed by sex. In men, the chance of obesity went down as intake rose, then stayed flat. In women, a negative link was seen for both overall and central obesity.
After menopause
The negative link with obesity was seen in women after menopause but not before it. The authors say postmenopausal women may benefit more from soya isoflavones in the diet.
Physical activity
No significant interaction was found between soya isoflavone intake and physical activity level for obesity or central obesity.
What the authors conclude
“Our results suggest that Chinese adults with higher dietary intake of SI may be less likely to be obese, particularly for postmenopausal women.”
Also in their conclusions
- They say Chinese adults with higher dietary intake of soya isoflavones may be less likely to be obese, particularly postmenopausal women.
- They suggest that postmenopausal women taking higher dietary soya isoflavones may be less likely to be obese.
- They say their results provide further evidence for dietary guidelines to recommend soya-rich foods such as soy bean and soy products in postmenopausal women to prevent obesity.
How it was done
The authors wanted to see whether the amount of soya isoflavones people usually eat is linked to obesity, since most human evidence comes from small supplement trials rather than normal diets.
They looked at 53,711 adults aged 20 to 74 in Shanghai who were part of a cohort study. Food questionnaires were used to estimate soya isoflavone intake over the past 12 months, and body measurements were taken three times.
What it can’t tell you
- This was a cross-sectional study, so it can show a link but cannot prove that soya isoflavones cause less obesity.
- Soya isoflavone intake was estimated from food questionnaires, which can be misremembered and do not always reflect how much is actually used by the body.
- The study did not include soya isoflavone supplements, so it cannot say what effect supplements might have.
Who paid
- Funding
- Funded by National Nature Science Foundation of China; Fudan University (from the PubMed record).
- Conflicts
- The authors declare that they have no conflict of interest.
- Authors work at
- Fudan University, China; Dali University, China; Shanxi Medical University, China
The paper
- Title
- Soy Isoflavones Intake and Obesity in Chinese Adults: A Cross-Sectional Study in Shanghai, China
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Zhu J, Zhao Q, Qiu Y, et al (2021). Soy Isoflavones Intake and Obesity in Chinese Adults: A Cross-Sectional Study in Shanghai, China. Nutrients. doi:10.3390/nu13082715Free full textPubMed 34444874DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error