Dietary Factors Influence Production of the Soy Isoflavone Metabolite S-(-)Equol in Healthy Adults

Abstract

S-(-)equol, an intestinally derived metabolite of the soy isoflavone daidzein, is proposed to enhance the efficacy of soy diets. Adults differ in their ability to produce equol when consuming soy foods for reasons that remain unclear. Therefore, we performed a comprehensive dietary analysis of 143 macro- and micronutrients in 159 healthy adults in the United States (n = 89) and Australia (n = 70) to determine whether the intake of specific nutrients favors equol production. Three-d diet records were collected and analyzed using Nutrition Data System for Research software and S-(-)equol was measured in urine by mass spectrometry. Additionally, in a subset of equol producers and nonproducers (n = 10/group), we examined the long-term stability of equol producer status by retesting 12, 18, and 24 mo later. Finally, the effect of oral administration of the antibiotic metronidazole (500 mg/d for 7 d) on equol production was examined in 5 adults monitored during a 4-mo follow-up period. Equol producers accounted for 30.3% and 28.6% of the United States and Australian participants, respectively (overall frequency, 29.6%). No significant differences were observed for total protein, carbohydrate, fat, saturated fat, or fiber intakes between equol producers and nonproducers. However, principal component analysis revealed differences in several nutrients, including higher intakes of polyunsaturated fatty acids (P = 0.039), maltose (P = 0.02), and vitamins A (P = 0.01) and E (P = 0.035) and a lower intake of total cholesterol (P = 0.010) in equol producers. During a 2-y period, equol producer status remained unchanged in all nonproducers and in 80% of equol producers, whereas metronidazole abolished equol production in only 20% of participants. In conclusion, these findings suggest that major differences in the macronutrient content of the diet appear not to influence equol production, but subtle differences in some nutrients may influence the ability to produce equol, which was a relatively stable phenomenon.

Effect of Daidzein 120 Mg Supplementation to Menopausal Symptoms and Quality of Life in Non Equol Producer Women

“…Setchell stated that duration and amount of daidzein-containing food, type of intestinal microbiota population, such as bacteria with ability to reduce sulfa, amount of polyunsaturated fatty acid, and vitamin A and E in food influenced level of equol in vivo. Elimination of equol within plasma was 7-8 hrs [28]. This may be the reason the previous studies conducted "challenge" by giving soycontaining food prior examining respondent's equol level just to be assessed by urine collection or blood withdraw.…”

S-(−)equol production is developmentally regulated and related to early diet composition

“…The 3-day diet records were analyzed using the Nutrition Data System for Research software (Nutrition Coordinating Center, University of Minnesota, Minneapolis, MN, USA), as described previously [29,30]. …”

Plasma equol concentration is not associated with breast cancer and fibrocystic breast conditions among women in Shanghai, China

“…Furthermore, in our study, equol was assessed at only one time point. Although equol production has been shown to be relatively stable within individuals over time in some studies [42, 43], others have suggested that around 6 to 20% of individuals vary or crossover equol phenotypes over relatively short periods of time [44, 45]. However, the evidence to date suggests there is more often a producer to non-producer shift than vice versa [42–45].…”