Associations between Exposure to Tobacco Smoke and Behavioral Problems in Preschool Japanese Children.

Background: A few studies related to pediatric behavior have measured secondhand smoke exposure in children using valid objective biochemical markers. We aimed at investigating the associations between current and cumulative exposure to tobacco smoke, measured both subjectively and objectively, and behavioral problems in children. Methods: Subjects were 437 Japanese children, aged 3-6 years in 2006. Exposure to tobacco smoke was evaluated from a parent-administered questionnaire and urinary cotinine concentrations. The cotinine concentrations were measured using first-void morning urine by liquid chromatography-tandem mass spectrometry. Children's behaviors were assessed by the parent-completed Strengths and Difficulties Questionnaire. Results: After multiple adjustments for covariates, higher total difficulty scores of children were significantly associated with the larger number of cigarettes parents smoke, more smokers among cohabiters, and more pack-years of exposure to tobacco smoke from parents and cohabiters. The total difficulty scores were 8.72, 9.09, and 10.52, respectively, for children in the low, middle, and high tertiles of creatinine-corrected cotinine concentrations in urine (p=0.002, trend p=0.005). There was no substantial sex difference in the positive associations between passive smoking and the SDQ scores. Conclusions: Exposure to tobacco smoke in early childhood may be involved in the development of pediatric behavioral problems. The importance of reducing the exposure of children to tobacco smoke, particularly in the home, was further emphasized for the prevention of psychological and behavioral problems in childhood.

Number of Teeth and All-Cause and Cancer Mortality in a Japanese Community: The Takayama Study.

BACKGROUND: The association between the number of teeth and mortality among community-dwelling people has been examined in many epidemiological studies. However, few Japanese studies have included cancer mortality as an endpoint. We prospectively investigated the association between number of remaining teeth and all-cause and cancer mortality in a Japanese community. METHODS: This study included participants in the Takayama Study who were aged 35-70 years old at baseline in 1992. Information on the number of remaining teeth was obtained from 11,273 participants via questionnaire at the second survey in 2002. The response rate was 66.9%. Deaths and their causes were ascertained during 11.8 years of follow-up. RESULTS: A total of 1,098 deaths (435 cancer-related and 235 cardiovascular-related) were identified during the follow-up period. After adjusting for covariates, participants with 0 to 9 teeth were at moderate but significantly increased risk of all-cause mortality (hazard ratio [HR] 1.19; 95% confidence interval [CI], 1.03-1.39) and cancer mortality (HR 1.31; 95% CI, 1.03-1.67) compared to those with 20 or more teeth. With regard to cancer site, a significant association was observed for lung cancer (HR for 0-9 teeth vs. 20 or more teeth, 1.75; 95% CI, 1.08-2.83). This association was somewhat strengthened among never-smokers (HR 3.56; 95% CI, 1.02-12.45). CONCLUSIONS: We observed that a lower number of remaining teeth was significantly associated with increased risk from all-cause and lung cancer mortality. Further studies on the number of teeth and lung and other types of cancer are needed.

High Intake of Free Sugars, Fructose, and Sucrose Is Associated with Weight Gain in Japanese Men.

BACKGROUND: Available evidence for associations between sugar intake and body weight is largely from short-term controlled trials and studies focusing on sugar-sweetened beverages. Studies on long-term weight change related to the intake of types of sugar are thus needed. OBJECTIVE: We examined the associations between weight change and the intake of various types of carbohydrates, including starch, total sugars, and free or naturally occurring sugars and saccharides (i.e., glucose, fructose, sucrose, and lactose), among Japanese men and women. METHODS: This prospective cohort study included 14,971 residents of Takayama City in Japan who were aged 35-69 y at the first survey in 1992 and responded to a self-administrated questionnaire at the second survey in 2002. We excluded those with cancer, coronary artery disease, stroke, or diabetes on the first survey and those with missing information about body weight on both surveys, leaving 13,229 participants for analysis (5879 men and 7350 women). Mean (95% CI) values of 10-y weight change according to types of carbohydrates were estimated using linear regression models with adjustment for total energy intake and other dietary and lifestyle factors. Dietary intake was assessed at the first survey using a validated FFQ. RESULTS: Among men, free sugar intake was associated with weight gain and the estimated means (95% CIs) of weight change were -0.60 (-0.67, -0.54), -0.31 (-0.38, -0.24), -0.12 (-0.19, -0.05), and 0.20 (0.13, 0.27) kg from the first to fourth quartiles (P-trend = 0.002). Moreover, high intakes of sucrose and fructose were associated with weight gain (P-trend: 0.018 for sucrose and 0.001 for fructose). Among women, the intake of any type of carbohydrate was not significantly associated with weight change. CONCLUSIONS: These results suggested that high intakes of free sugars, sucrose, and fructose were associated with long-term weight gain among Japanese men.

Associations of Cell Phone Use and Screen Viewing with Overweight in Children.

Background: Effects of using mobile devices on childhood obesity have not been well studied. We aimed to ascertain whether cell phone use and screen viewing are associated with excess body weight in a cross-sectional study of Japanese school children. Methods: Subjects were 3141 students, ages 6 to 7 years, who participated in the Hekinan Children's Study conducted during 2011-2015. Participants were asked to submit a parent-administered questionnaire on child and parent demographics, health status, and lifestyles, including cell phone use and screen time. Heights and weights were measured at the schools. Being overweight was defined according to the cutoff point for children specified by the Extended International Obesity Task Force. Among 2596 analytic children, the odds ratios (ORs) for being overweight were estimated according to cell phone use, time spent watching television, and time spent on games and computers using the logistic regression models. Analyses were conducted after adjustments for potential confounders, including dietary intake, physical activities, sleep duration, and quality of sleep. Results: After multivariate adjustments, cell phone users were found to have an OR of 1.74 for being overweight compared with nonusers. Cell phone use of longer duration was associated with higher risk of being overweight (trend p = 0.018). Time spent watching television was positively associated with the risk of being overweight (trend p = 0.003). Conclusions: Just as earlier studies have shown for television viewing, cell phone use might be a risk factor related to being overweight among children.

Associations between coffee consumption and all-cause and cause-specific mortality in a Japanese city: the Takayama study.

OBJECTIVE: Epidemiological studies suggest that coffee consumption is inversely associated with all-cause and cause-specific mortality. Evidence from studies targeting non-white, non-Western populations is still sparse, although coffee is popular and widely consumed in Asian countries. DESIGN: Population-based, prospective cohort study. We used Cox proportional hazards models with adjustment for dietary and lifestyle factors to estimate associations between coffee consumption and all-cause and cause-specific mortality. Dietary intake including coffee consumption was assessed only at baseline using a validated FFQ. SETTING: A Japanese city. PARTICIPANTS: Individuals aged 35 years or older without cancer, CHD and stroke at baseline (n 29 079) and followed from 1992 to 2008. RESULTS: From 410 352 person-years, 5339 deaths were identified (mean follow-up = 14·1 years). Coffee consumption was inversely associated with mortality from all causes and CVD among all participants, but not from cancer. Compared with the category of 'none', the multivariate hazard ratio (95 % CI) for all-cause mortality was 0·93 (0·86, 1·00) for <1 cup/d, 0·84 (0·76, 0·93) for 1 cup/d and 0·81 (0·71, 0·92) for 2-3 cups/d. The multivariate hazard ratio (95 % CI) for cardiovascular mortality were 0·87 (0·77, 0·99) for <1 cup/d, 0·76 (0·63, 0·92) for 1 cup/d and 0·67 (0·50, 0·89) for 2-3 cups/d. Inverse associations were also observed for mortality from other causes, specifically infectious and digestive diseases. CONCLUSION: Drinking coffee, even 1 cup/d, was inversely associated with all-cause mortality and mortality from cardiovascular, infectious and digestive diseases.

Dietary Soy Intake Is Inversely Associated with Risk of Type 2 Diabetes in Japanese Women but Not in Men.

BACKGROUND: Whole soy foods, as well as their components, including protein and isoflavones, have garnered attention because they may have beneficial effects against diabetes. OBJECTIVES: We examined associations between the intake of soy foods, soy protein, and soy isoflavones and the risk of diabetes in the Japanese population. METHODS: This prospective cohort study included 13,521 residents (5883 men and 7638 women; 35-69 y old) of Takayama City, Japan. The subjects responded to a self-administered baseline questionnaire in 1992 and to a follow-up questionnaire seeking information about diabetes in 2002. Their mean ± SD body mass index was 22.6 ± 2.6 kg/m2 (men) and 22.1 ± 2.7 (women). The intakes of total soy foods, fried soy foods, nonfried soy foods, soy protein, and soy isoflavones were estimated through the use of a validated food-frequency questionnaire administered in 1992. Associations between soy intake and the risk of diabetes were evaluated through the use of Cox proportional hazards models incorporating age, education level, physical activity, smoking status, alcohol consumption, history of hypertension, use of vitamin supplements, menopausal status, and dietary factors including glycemic load, total energy, total fat, meat, fruit, vegetables, and coffee. RESULTS: During a 10-y follow-up, 438 participants reported physician-diagnosed diabetes. Women in the highest tertile of intakes of total soy foods, fried soy foods, nonfried soy foods, soy protein, and soy isoflavone had significantly lower HRs, after controlling for covariates, than those with the lowest intakes. For example, HRs were 0.45 (95% CI: 0.30, 0.68; P-trend <0.001) for total soy food intake. In men, there were no significant associations between soy intake and the risk of diabetes. CONCLUSIONS: These results suggest that a high soy intake may be associated with a lower risk of diabetes in Japanese women.

Green tea intake and colorectal cancer risk in Japan: the Takayama study.

BACKGROUND: Reportedly, green tea has a preventive effect against colorectal cancer in animal models. Nevertheless, results from epidemiological studies of the association between green tea consumption and colorectal cancer have been inconsistent. We aimed to evaluate colorectal cancer risk in relation to green tea consumption in a population-based prospective cohort study. METHODS: Subjects were 13 957 men and 16 374 women aged ≥35 years in September 1992. The participants' green tea consumption was elicited by administering a food frequency questionnaire. The colorectal cancer incidence was confirmed through regional population-based cancer registries and histological identification from colonoscopy in two main hospitals in the study area. Colorectal cancer was defined as the sum of code C18 (colon cancer) and codes C19 and C20 (rectal cancer) according to ICD-10. RESULTS: Up to March 2008, 429 men and 343 women were diagnosed with colorectal cancer. No significant association was found between green tea consumption and colorectal cancer in men and women, respectively. However, for men, compared with the group of 'none or less than once per day' of green tea consumption, the multiple-adjusted relative risks (95% CIs) for colon cancer were 1.32 (0.90, 1.94), 0.76 (0.57, 1.02), and 0.78 (0.49, 1.22), respectively, in the group of 'once per day,' '2-3 times per day', and 'four times per day or more' (trend P = 0.045). CONCLUSIONS: This study observed no overall significant associations between green tea consumption and colorectal cancer risk, except that there was a weak trend for greater consumption of green tea with decreased risk of male colon cancer.

Association between exposure to household smoking and dental caries in preschool children: a cross-sectional study.

BACKGROUND: We aimed to examine the association of exposure to environmental tobacco smoke with dental caries among preschool children. Exposure to environmental tobacco smoke was assessed in terms of urinary cotinine concentrations and pack-years of exposure to smoking by parents and other family members at home. METHODS: This cross-sectional study included 405 preschool children aged 3-6 years from two preschools in Japan in 2006. Information on the smoking habits of family members living with the child was obtained from parent-administered questionnaires. Dental examination was conducted to assess dental caries, that is, decayed and/or filled teeth. Urinary cotinine levels were measured using first-void morning urine samples. RESULTS: Overall, 31.1% of the children had dental caries, and 29.5% had decayed teeth. Exposure to current maternal and paternal smoking was positively associated with the presence of dental caries after controlling for covariates. More than three pack-years of exposure to maternal smoking and more than five pack-years of exposure to smoking by all family members were significantly associated with the presence of dental caries as compared with no exposure (odds ratio [OR] = 5.55, 95% confidence interval [CI] = 2.17-14.22, P for trend < 0.001 and OR = 2.00, 95% CI = 1.12-3.58, P for trend = 0.004, respectively). These exposure variables were similarly associated with the presence of decayed teeth (OR = 2.92, 95% CI = 1.23-6.96, P for trend = 0.01 and OR = 1.75, 95% CI = 0.96-3.20, P for trend = 0.03, respectively). As compared with lowest tertile of the urinary cotinine level, the highest tertile of the urinary cotinine level was significantly associated with the presence of dental caries as well as decayed teeth; the ORs for the highest vs. lowest tertile of urinary cotinine levels were 3.10 (95% CI = 1.71-5.63, P for trend = 0.012) and 2.02 (95% CI = 1.10-3.70, P for trend = 0.10), respectively. CONCLUSIONS: These data suggest that exposure to tobacco smoke may have a dose-dependent influence on the development of caries.

Cedar Pollinosis and Mortality: A Population-Based Prospective Cohort Study in Japan.

BACKGROUND: Cedar pollinosis is one of the most prevalent forms of seasonal allergic reaction in Japan. Only one prospective study has examined the association between cedar pollinosis and mortality. Using a symptom-based questionnaire on cedar pollinosis, we investigated the association of cedar pollinosis with all-cause and cause-specific mortality. METHODS: Data came from the Takayama Study, which recruited residents aged ≥35 years in 1992 from Takayama city in Gifu Prefecture, Japan. The current study used information on cedar pollinosis that was obtained from the second survey in 2002. A total of 12,471 persons who were 45-80 years old and had no history of cancer, coronary heart disease, or stroke responded to a questionnaire asking about four symptoms related to cedar pollinosis. Mortality and migration data were obtained throughout the follow-up period up to March 2013. Cox proportional hazard models were used to examine the relation between cedar pollinosis and mortality. RESULTS: A total of 1,276 persons died during follow-up period. Among these, there were 504 neoplasm, 278 cardiovascular, and 181 respiratory deaths. After adjusting for potential confounders, cedar pollinosis was associated with significantly lower all-cause mortality (hazard ratio [HR] 0.79; 95% confidence interval [CI], 0.65-0.95) and respiratory mortality (HR 0.38; 95% CI, 0.18-0.82). There was no significant association between cedar pollinosis and mortality due to neoplasm or cardiovascular disease. CONCLUSIONS: We found an inverse association between cedar pollinosis and the risk of all-cause and respiratory mortality. Further research is needed to elucidate the association between cedar pollinosis and mortality.

The Hekinan Children's Study: Design and Profile of Participants at Baseline.

BACKGROUND: The early life environment is now recognized as a key factor contributing to susceptibility to certain diseases in later life. METHODS: We initiated a cohort study among school children in 2011 to primarily investigate the associations between lifestyle and environmental factors and some surrogate markers of chronic diseases, such as cardiometabolic risk factors (ie, obesity, high blood pressure, high blood glucose, insulin, or lipids) and cancer risk factors (ie, height and age at menarche). A baseline questionnaire asked for information, including demographic variables, medical history and use of medication, dietary habits, physical activity, sleep habits, and behavioral and emotional problems of children. Follow-up surveys are planned for the fourth grade of elementary school and the first grade of junior high school. At these follow-up surveys, fasting blood samples will be obtained to measure cardiometabolic markers. We also checked the validity of a food frequency questionnaire, which was originally created for 6-year-olds but was modified for use in older children. RESULTS: A total of 3,141 first-year students at elementary schools in Hekinan City, Aichi Prefecture, participated in the study. The response rate was 87.4%. The means of age and body mass index were 6.99 (standard deviation, 0.28) years and 15.3 (standard deviation, 1.7) kg/m2, respectively, in the 3,067 Japanese children (1,639 boys and 1,428 girls). CONCLUSIONS: This cohort will reveal determinants of cardiometabolic risk factors and cancer risk factors during childhood.

Maternal Acrylamide Intake during Pregnancy and Sex Hormone Levels in Maternal and Umbilical Cord Blood and Birth Size of Offspring.

Exposure to acrylamide during pregnancy may disturb pregnancy hormones and the growth of the fetus. The present study aimed to examine the association of maternal acrylamide intake with maternal and cord sex hormone levels during pregnancy and at birth and birth size of offspring. The study subjects were 204 pregnant Japanese women and their newborn girls. Intake of acrylamide was assessed based on 5-day diet records at approximately the 29th week of pregnancy. The concentrations of estradiol, estriol, and testosterone were measured in maternal serum at the 29th weeks of pregnancy and at delivery and umbilical cord blood at delivery. Birth weight, length, and head circumference were measured at the delivery. After controlling for covariates, higher intake of acrylamide was significantly positively associated with higher level of umbilical cord estradiol at the delivery (p for trend = .01), but not with any hormone levels measured in maternal blood. A positive association between acrylamide intake and head circumference was of borderline significance (p for trend = .06). Overall, there were no consistent associations between maternal acrylamide intake and sex hormone levels during pregnancy. However, as this is the first study to examine these associations, additional studies are needed.

Intake of starch and sugars and total and cause-specific mortality in a Japanese community: the Takayama Study.

Studies on the intake of different types of carbohydrates and long-term mortality are sparse. We examined the association of starch, total and each type of sugar and free sugars with the risk of total and cause-specific mortality in a cohort of the general population in Japan. Study subjects were 29 079 residents from the Takayama Study, Japan, who responded to a self-administered questionnaire in 1992. Diet was assessed by a validated FFQ at the baseline. Mortality was ascertained during 16 years of follow-up. We noted 2901 deaths (974 cancer related and 775 cardiovascular related) in men and 2438 death (646 cancer related and 903 cardiovascular related) in women. In men, intake of starch was inversely associated with total mortality after controlling for covariates (hazard ratio (HR) for the highest quartile v. lowest quartile: 0·71; 95 % CI 0·60, 0·84; Ptrend < 0·001). Intakes of total sugars, glucose, fructose, sucrose, maltose and free and naturally occurring sugars were significantly positively associated with total mortality in men (HR for the highest v. lowest quartile of total sugar: 1·27; 95 % CI 1·12, 1·45; Ptrend < 0·0001). Similar relations were observed for cardiovascular mortality and non-cancer, non-cardiovascular mortality in men. In women, there was no significant association between any type of carbohydrates and mortality except that intake of free sugars was significantly positively associated with total and non-cancer, non-cardiovascular mortality. Data suggest that the high intake of starch reduces mortality, whereas the high intake of sugars, including glucose, fructose and sucrose, increases mortality in Japanese men.

Coffee, Green Tea, and Caffeine Intake and Liver Cancer Risk: A Prospective Cohort Study.

We aimed to investigate whether coffee, green tea, and caffeine intake are associated with liver cancer risk, using data of a prospective cohort study. This study included 30,824 participants (14,240 men and 16,584 women) aged 35 years or older in the Takayama study, which was launched on September 1, 1992. The consumption frequencies of coffee and green tea were assessed using a self-administered questionnaire. Caffeine intake was estimated from the consumption frequencies of caffeine-containing beverages and foods and their caffeine content per serving. The incidence of liver cancer was confirmed using regional population-based cancer registries. During the follow-up period of 16 years, a total of 172 participants developed liver cancer. The adjusted hazard ratios and 95% confidence intervals (CIs) in relation to coffee consumption were 0.65 (95% CI: 0.46-0.93) for less than once per day, 0.63 (95% CI: 0.39-1.02) for once per day, and 0.40 (95% CI: 0.20-0.79) for twice per day or more, compared with nondrinkers. No associations with green tea, black tea and caffeine intake were observed. The present study confirmed that coffee consumption significantly reduces liver cancer risk and raises the possibility that caffeine intake might not account for the association.

Soy Isoflavone Intake and Bladder Cancer Risk in Japan: From the Takayama Study.

Background: There is growing evidence suggesting that soy isoflavones play a protective role in the development of cancer. However, few epidemiological studies have investigated the association between soy isoflavone intake and bladder cancer.Methods: We evaluated the associations of soy and isoflavone intakes with bladder cancer incidence in a population-based prospective study in Japan. Subjects were 14,233 men and 16,584 women age 35 years or older in September 1992. Soy and isoflavone intakes were assessed via a validated food-frequency questionnaire, while controlling for total energy intake. Cancer incidence was mainly confirmed through regional population-based cancer registries. Bladder cancer was defined as code C67 according to the International Classification of Diseases and Health Related Problems, 10th Revision.Results: During mean follow-up of 13.6 years, 120 men and 41 women had developed bladder cancer. After adjustments for multiple confounders, compared with the lowest quartile of soy food intake, the estimated hazard ratios for the second, third, and highest quartiles of soy food intake were 0.74, 0.52, and 0.55, respectively, in men (P-trend: 0.023). The corresponding values were 0.60, 0.75, and 0.64, respectively, in women (P-trend: 0.43). Similar inverse associations were observed between isoflavone intake and bladder cancer risk.Conclusions: A significant decreased risk of bladder cancer was observed among men who had higher intakes of total soy and isoflavones.Impact: Our finding on the potential benefit of consuming soy foods against bladder cancer is promising and warrants further studies. Cancer Epidemiol Biomarkers Prev; 27(11); 1371-5. ©2018 AACR.

Associations of Acrylamide Intake With Urinary Sex Hormone Levels Among Preschool-Age Japanese Children.

Acrylamide may affect the sex hormone system in the prepubertal period. This study examined the cross-sectional associations between dietary acrylamide intake and sex hormone levels among preschool-age Japanese children. The study was conducted in 2006 among 230 boys and 198 girls aged 3-6 years in Aichi, Japan. Acrylamide intake was assessed using 3-day diet records. Urinary concentrations of estrone, estradiol, testosterone, and androst-5-ene-3ß, 17ß diol (hereafter referred to as androstenediol) were measured by liquid chromatography-electrospray ionization-tandem mass spectrometry. Sex hormone levels were adjusted for urinary creatinine levels. The estimated acrylamide intake was 1.00 µg/kg of body weight per day. After controlling for age and other covariates, acrylamide intake was significantly positively associated with urinary levels of testosterone and androstenediol in boys. On average, boys in the highest quartile of acrylamide intake had 96.9% higher testosterone (95% confidence interval: -1.8, 295; P for trend = 0.048) and 34.5% higher androstenediol levels (95% confidence interval: -5.9, 92.3; P for trend = 0.04) than boys in the lowest quartile. In girls, there were no significant associations between acrylamide intake and the hormones measured. Acrylamide intake may alter androgen metabolism in preschool-age boys. Because this is a first observation, our findings require confirmation in additional studies.

Meat consumption and colorectal cancer risk in Japan: The Takayama study.

Compared with the abundant data from Western countries, evidence regarding meat consumption and colorectal cancer is limited in the Japanese population. We evaluated colorectal cancer risk in relation to meat consumption in a population-based prospective cohort study in Japan. Participants were 13 957 men and 16 374 women aged ≥35 years in September 1992. Meat intake, assessed with a validated food frequency questionnaire, was controlled for the total energy intake. The incidence of colorectal cancer was confirmed through regional population-based cancer registries and histological identification from colonoscopy in two main hospitals in the study area. From September 1992 to March 2008, 429 men and 343 women developed colorectal cancer. After adjustments for multiple confounders, a significantly increased relative risk of colorectal cancer was observed in the highest versus lowest quartile of the intake of total and red meat among men; the estimated hazard ratios were 1.36 (95% CI: 1.03, 1.79) for total meat (P for trend = 0.022), and 1.44 (95% CI: 1.10, 1.89) for red meat (P for trend = 0.009). A positive association between processed meat intake and colon cancer risk was also observed in men. There was no significant association between colorectal cancer and meat consumption in women. These results suggest that the intake of red and processed meat increases the risk of colorectal or colon cancer among Japanese men. Abstaining from excessive consumption of meat might be protective against developing colorectal cancer.

Relationship of equol production between children aged 5-7 years and their mothers.

PURPOSE: The factors responsible for the production of isoflavone metabolites have not yet been identified. We aimed to examine the relationships of equol production between mother and child in a birth cohort in Japan. METHODS: Subjects were a part of the participants in a longitudinal study on pregnant women and their offspring. When children were 5-7 years old, mothers and children were asked to reply to a questionnaire on lifestyles and a 3-day child's dietary record. Mothers and children were given a bar-shaped soy snack (Soyjoy®) daily on two consecutive days (soy challenge). The snack contained 14 mg of overall soy isoflavones as the sum of aglycones and the glucosides for mothers and 7.5 mg for children. On the morning of day 0 and 3, they were asked to mail their first-void urines. Urinary isoflavone metabolites of 159 mother-child pairs were measured by a high-performance liquid chromatography method. RESULTS: Equol producers were 35.5 % among mothers and 13.8 % among children. Equol producer status of a child was neither associated with dietary intake nor with urinary levels of daidzein and genistein. After multiple adjustments for potential confounders, the estimated relative risk of equol producer was 2.75 (95 % confidence interval 1.00, 7.52) among children whose mother was an equol producer, compared with children whose mother was a non-producer. CONCLUSION: Child's equol production was associated with the mother's equol producer status. The effects of maternal factors on child's equol production should be studied further.