Study of 27,000 adults finds bean products and soy compounds tied to lower kidney disease risk

Scientists analyzed the diets and kidney health of more than 27,000 Chinese adults and found notable differences between whole beans, processed soy foods, and the patterns seen in women and men.

Study: Associations of beans, bean products, and soy isoflavone intake with chronic kidney disease: a cross-sectional study. Image Credit: Norwood Audrey Jared / Shutterstock

A study published in Nutrition Journal found that greater intake of soy isoflavones and bean products was linked with lower odds of chronic kidney disease (CKD). Each standard deviation increase in bean product intake corresponded to a 15% lower likelihood of CKD. The highest soy isoflavone intake group had 30% lower odds than the lowest-intake group. By contrast, plain bean intake was not significantly associated with CKD. The results may help shape future research into dietary strategies for kidney health.

Previous laboratory work has identified compounds in beans and soy that may reduce inflammation and oxidative stress in the kidneys. However, whether these foods provide similar benefits in people remains uncertain, since large population-based studies are still limited. Earlier epidemiological studies have largely focused on rural Chinese populations, and research examining soy isoflavones on their own has been scarce.

About the study

In this cross-sectional analysis, the researchers assessed whether intake of beans, bean products, and soy isoflavones was associated with CKD prevalence among adults in the Northeast China Biobank (NEC-Biobank) study.

The NEC-Biobank initially enrolled 36,376 adults from Heilongjiang, Jilin, Liaoning, and Inner Mongolia. After excluding participants with missing information, cancer, implausible calorie intake, extreme values, or self-reported CKD, 27,003 adults remained for analysis. Dietary intake over the previous year was collected using a validated 110-item Food Frequency Questionnaire (FFQ). The researchers adjusted intake estimates for total energy using data from the sixth edition of China's food composition database.

Beans included mung beans, soybeans, snap beans, and bean sprouts. Bean products such as dried tofu, soy milk, and tofu pudding were also included. Participants were divided into four groups according to combined bean and bean product intake. The same method was used for soy isoflavones, with energy-adjusted estimates separating lower and higher intake groups. These categories were created for statistical analysis rather than as dietary recommendations.

Participants with eGFR below 60 mL/min/1.73 m² or protein in urine were classified as having CKD in the analysis. eGFR was calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation. Blood samples were used to measure glucose and serum creatinine, while urine samples were collected to detect protein, red blood cells, and occult blood.

The researchers identified major dietary patterns and used statistical models to test associations between bean, bean product, and soy isoflavone intake and CKD prevalence, including whether the relationships changed across intake levels. They adjusted for age, sex, ethnicity, body mass index, comorbidities, smoking, alcohol use, education, income, physical activity, calorie intake, and dietary patterns.

In sensitivity analyses, the team excluded participants younger than 40 years and those with recent dietary changes. They also adjusted for red meat, protein, and sodium intake and for hyperuricemia diagnosis. In another sensitivity analysis, the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines were used to examine the findings under different diagnostic criteria. Proteinuria and reduced eGFR were also analyzed separately.

Results and discussion

Among the 27,003 participants, 900 (3.3%) were classified as having CKD. Nearly 65% were women, and most were older than 50 years. People with higher soy isoflavone intake were more often older women with lower incomes and less education, and they had a higher prevalence of hypertension and diabetes, but lower rates of drinking and smoking. They also reported lower carbohydrate and total calorie intake, along with higher protein and fat intake overall. Fasting blood glucose was higher in this group, while serum uric acid was lower.

After adjustment for demographic, clinical, and dietary factors, participants in the highest quartile of combined bean and bean product intake had 33% lower odds of CKD than those in the lowest quartile. For bean products alone, the reduction was 37%. Plain bean intake was not significantly linked to CKD. The highest soy isoflavone intake group also had 30% lower odds of CKD than the lowest group.

Daidzein, glycitein, and genistein were each associated with lower odds of CKD. The inverse associations for bean products, daidzein, and glycitein were strongest at lower intake levels before flattening out. Combined bean and bean product intake, as well as total soy isoflavone intake, showed roughly linear patterns. Estimates at very high intake levels were less certain.

Sensitivity analyses produced similar findings. Subgroup analyses showed broadly consistent inverse associations for total bean and bean product intake, although these were not statistically significant among participants younger than 50 years, those of Han ethnicity, or those with a body mass index below 24 kg/m². For soy isoflavones, the inverse association was stronger in women than in men, and the difference between sexes was statistically significant.

Earlier experimental studies suggest that soy isoflavones such as genistein and daidzein may affect kidney inflammation, tissue scarring, and protein loss in urine. Genistein has also been studied for its influence on nuclear factor kappa B (NF-κB) and extracellular signal-regulated kinase (ERK) signaling. These pathways were not directly examined in the NEC-Biobank participants.

The findings indicate that people with higher bean product and soy isoflavone intake were less likely to have CKD at the time of assessment, but the study cannot show that these foods prevent kidney disease. Its reliance on self-reported diet and a single kidney assessment raises the possibility of recall bias and CKD misclassification, since a diagnosis requires persistent abnormalities for at least three months. Missing data, unmeasured factors, and the regional nature of the study population also limit interpretation.

Further large prospective studies are needed to determine whether these associations may translate into real benefits for kidney health in adults. Research involving people with diabetes or hypertension could be especially useful, since both conditions raise the risk of kidney disease.

Source:

Journal reference:

• Zhang, S., Ji, C., Xia, Y. et al. (2026). Associations of beans, bean products, and soy isoflavone intake with chronic kidney disease: a cross-sectional study. Nutrition Journal, 25, 119.