Background:
Soy isoflavones (ISFs) are regularly consumed in Japan and other Asian countries where some studies showed a significant inverse association of ISFs intake with incident coronary heart disease (CHD). However, a US randomized clinical trial did not find ISFs as anti-atherogenic. This discrepancy may be due to the higher capacity of people in Japan than in the US to produce equol, a metabolite of ISF by the gut microbiome. Equol may have greater anti-atherogenic properties than ISFs. It is unknown whether equol producers (EP), people who produce equol after consuming ISF, have lower aortic calcification (AC), a biomarker of atherosclerosis, as compared to non-EP.
Aim:
To determine the association between equol producing status and AC in Japanese men.
Method:
This cross-sectional, population-based study included 302 Japanese men aged 40-49, free of CHD. EP was defined as participants with serum levels of equol ≥20 nM. AC was measured in the entire aorta and quantified by the Agatston method. The presence of AC was defined as AC score ≥10. We analyzed the association between equol producing status and AC using the Tobit and the logistic regressions.
Result:
We observed 125 participants as EP. In multivariable analyses, EP had non-significantly lower AC score by 147 (95% confidence interval (CI): -386, 92) units and an odds ratio of 0.71 (95% CI: 0.40, 1.26) for the AC presence as compared to non-EP. As significant interaction of equol producing status with age was present, we stratified the analyses by the median age. In men aged 45-49 years, EP had non-significantly lower AC score by 246 units and a non-significant 0.62 times the odds of AC presence as compared to non-EP; the corresponding values in men aged 40-44 were 12 units and 0.91 times (Table). Such an association was not observed with serum ISFs (data not shown).
Conclusion:
Japanese middle-aged men who were EP had non-significantly lower AC than non-EP and such association was stronger in men aged 45-49 than 40-44 years. Further study with much larger sample size is warranted.
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