The purpose of the present study was to examine the association between soya food consumption and insulin resistance using baseline data of the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study in Tokushima, Japan.

This cross-sectional study included 1274 subjects, aged 34–70 years at baseline, living in Tokushima Prefecture between 2008 and 2013. Fasting blood samples were collected and information on lifestyle characteristics including soya food intake and medical history were obtained using a structured self-administered questionnaire. The homeostasis model assessment of insulin resistance (HOMA-IR) was measured and those with HOMA-IR≥2·5 were defined as having insulin resistance. Multiple logistic regression models were used to analyse the association between soya product intake and the prevalence of insulin resistance.

Rural communities located in Tokushima Prefecture, Japan, between 2008 and 2013.

A total of 1148 adults (565 men and 583 women), aged 34–70 years.

The frequency of intake of miso soup, total non-fried soya products and total soya products showed significant inverse dose–response relationships with insulin resistance, after adjustments for potential confounders. When soya product intake was calculated as soya protein and isoflavone, the odds ratios of insulin resistance decreased significantly as the estimated intake of soya protein increased. Furthermore, significant inverse dose–response relationships were observed for total non-fried soya products and total soya products, after adjustment for total vegetable or total fibre consumption.

The present results indicate that the intake of soya products and non-fried soya products is associated with reduced insulin resistance in the Japanese population.

To examine cross-sectional relationships between plasma vitamin D and cardiometabolic risk factors in young adults.

Data were collected from interviews, physical examinations and biomarker measurements. Total plasma 25-hydroxyvitamin D (25(OH)D) was measured using LC–tandem MS. Associations between 25(OH)D and cardiometabolic risk factors were modelled using weighted linear regression with robust estimates of standard errors.

Individuals born in Jerusalem during 1974–1976.

Participants of the Jerusalem Perinatal Study (n 1204) interviewed and examined at age 32 years. Participants were oversampled for low and high birth weight and for maternal pre-pregnancy obesity.

Mean total 25(OH)D concentration among participants was 21·7 (sd 8·9) ng/ml. Among males, 25(OH)D was associated with homeostatic model assessment of insulin resistance (natural log-transformed, β=−0·011, P=0·004) after adjustment for BMI. However, these associations were not present among females (P for sex interaction=0·005).

We found evidence for inverse associations of 25(OH)D with markers of insulin resistance among males, but not females, in a healthy, young adult Caucasian population. Prospective studies and studies conducted on other populations investigating sex-specific effects of vitamin D on cardiometabolic risk factors are warranted.