Prevalence of the equol-producer phenotype and its relationship with dietary isoflavone and serum lipids in healthy Chinese adults.

BACKGROUND: Studies have suggested that daidzein-metabolizing phenotypes have beneficial effects on a range of health outcomes. We investigated the prevalence of equol producers and the relationship of equol phenotype with habitual isoflavone consumption and serum lipid concentrations in 200 Chinese adults in Beijing. METHODS: After the baseline survey and dietary records, 200 healthy adults in Beijing were challenged with a soy-isoflavone supplement for 3 days; 24-hour urine samples were collected before and after the challenge. Isoflavones and their metabolites in urine were measured to determine equol phenotype. Serum lipids, uric acid, and other biochemical markers were also measured. RESULTS: Only 26.8% of the participants excreted equol when on a regular diet, as compared with 60.4% after the challenge. After the challenge, urinary isoflavonoid excretion increased in all participants, while equol excretion increased only in equol producers. Isoflavone intake was correlated with urinary isoflavone (range r = 0.49-0.58, P < 0.01). As compared with nonproducers, equol producers were less likely to consume cereals (P < 0.001). There was no significant correlation between serum lipids and isoflavone intake. Serum lipids were not significantly affected by equol phenotype. CONCLUSIONS: Urinary equol excretion was detected in about 25% of participants under their usual dietary conditions. Their potential to produce equol was increased after the challenge. Urinary isoflavone levels may serve as a useful biomarker for isoflavone intake in populations. We observed an association between equol phenotype and cereal intake. Our findings also suggest that dietary isoflavone intake has no significant effect on serum lipids in healthy participants, regardless of equol phenotype.

[Prevalence of equol producer phenotype and its relations to lifestyle factors and dietary intakes among lifestyle factors and dietary intakes among healthy Chinese adults in Beijing].

OBJECTIVE: To investigate the prevalence of equol producers and the physiological range of urinary equol excretion, and also to evaluate relations between equol phenotype and lifestyle among Chinese adults in Beijing. METHODS: 100 male and 100 female adults participated in a cross-sectional study and provided twice 1d urine samples on regular diet and after 3d soy isoflavone challenge respectively. A health and demographics questionnaire, and 2d food record were completed before the urine collections. Isoflavones and their metabolites in urine were measured to determine equol phenotype by HPLC. RESULTS: The physiological range of 24h urinary equol excretion was 0-76.56 micromol/24h, and the percentage of the equol producer phenotype was 26.8% on regular diet and 60.4% after soy isofavone challenge, respectively. There was no indication that habitual consumption of soy foods is associated with the equol producer phenotype. The correlations of isoflavone intake from 2d food record with those from urinary isoflavone levels were 0.58 for total isoflavones, 0.49 for daidzein, 0.56 for genistein, and 0.50 for glycitein (P < 0.01). CONCLUSION: About one fourth of Chinese adults in Beijing were detected equol excretion in urine under the usually lifestyle. However, equol_producing potential was higher.

[Determination of sennosides and degraded products in the process of sennoside metabolism by HPLC].

A method for the separation and determination of sennosides A and B and the main composition (sennidins A and B) in degraded products of sennosides by linear gradient high performance liquid chromatography has been developed. Separation conditions were as follows: column, a Spherisorb C18 column (250 mm x 4.6 mm i.d., 10 microm); column temperature, 40 degrees C; detection wavelength, 360 nm; mobile phase A, 1.25% acetic acid aqueous solution; mobile phase B, methanol; linear gradient, 100% A --> (20 min) 100% B. The method is effective, quick, accurate and reproducible. The satisfactory results show that this new method has certain practical values as an approach of real-time analysis in the process of sennoside metabolism.