Yuri Yokoyama

Association of body mass index with lifestyle and rotating shift work in Japanese female nurses

Higher body mass index (BMI) values have been reported in rotating shift workers compared with regular daytime workers. This study examines the relationship between work schedule and BMI, and considers whether lifestyle habits could explain the relationship.

Influence of dietary behavior on the circadian rhythm of the autonomic nervous system as assessed by heart rate variability

BACKGROUND Misalignment of circadian systems is detrimental to human health. However, only a few studies have examined the influence of late meals on the human circadian system. The purpose of this study was to investigate whether delayed meals affect circadian rhythm as assessed by heart rate variability (HRV). METHODS Seven healthy men (aged 22.4±0.4years) participated in this study, which involved delaying mealtimes by 5h for two weeks. Prior to this study, the regular mealtimes of participants were at 08:00, 13:00, and 18:00 (Baseline). During the intervention, each meal was provided at 13:00, 18:00 and 23:00 (Late mealtimes). Circadian variation was assessed by HRV based on R-R intervals calculated from a pulse at the rising phase of each spike in the QRS complex in a 24-h electrocardiograph record. The ratio of low frequency (LF) to high frequency (HF) power (LF/HF) and the ratio of HF power to total power (%HF) were calculated using spectral analysis. The phase and amplitude of HRV variables in a 24-h period were mathematically obtained with double cosinor analysis. RESULTS The acrophase and amplitude for LF power, HF power and %HF in a 24-h period were not significantly different between Baseline and Late mealtimes. On the other hand, the acrophase significantly differed between Baseline and Late mealtimes for heart rate (95%CI, 1.1-3.8h), standard deviation of R-R intervals (95%CI, 2.5-4.4h) and LF/HF (95%CI, 1.1-2.3h). CONCLUSIONS Our findings suggest that delayed mealtimes shift the phase of circadian rhythm of the autonomic nervous system.

Association of dietary variety with body composition and physical function in community-dwelling elderly Japanese

ObjectivesTo examine the associations of dietary variety with body composition and physical function in community-dwelling elderly JapaneseDesignCross-sectional study.SettingCommunity-based.ParticipantsA total of 1184 community-dwelling elderly adults aged 65 and over.MeasurementsDietary variety was assessed with a food frequency questionnaire (maximum, 10 points) that encompassed the 10 main food components of Japanese meals (meat, fish/shellfish, eggs, milk, soybean products, green/yellow vegetables, potatoes, fruit, seaweed, and fats/oils). Body composition was determined by multifrequency bioelectrical impedance analysis. Physical function was assessed by measuring grip strength and usual walking speed. Multiple linear regression analysis was used to examine the associations of dietary variety with body composition and physical function.ResultsAfter adjusting for potential confounders, higher dietary variety scores were independently associated with higher lean mass (β (SE): 0.176 (0.049), p<0.001) and appendicular lean mass (β (SE): 0.114 (0.027), p<0.001) but not with body fat mass. Elders with a higher dietary variety score had greater grip strength and faster usual walking speed (β (SE): 0.204 (0.071), p=0.004, and β (SE): 0.008 (0.003), p=0.012, respectively).ConclusionGreater dietary variety was significantly associated with greater lean mass and better physical function in Japanese elders. The causal relationship warrants investigation in a prospective study.

Association of eating behaviours with diurnal preference and rotating shift work in Japanese female nurses: a cross-sectional study

Objectives Our study examines differences in eating behaviour between day workers and rotating shift workers, and considers whether diurnal preference could explain the differences. Methods Japanese female nurses were studied (39 day workers and 123 rotating shift workers, aged 21–63 years) using self-administered questionnaires. The questionnaires assessed eating behaviours, diurnal preference and demographic characteristics. The questionnaire in the Guidelines for the management of obesity disease issued by the Japan Society for the Study of Obesity was used to obtain scores for the levels of obesity-related eating behaviours, including cognition of constitution, motivation for eating, eating as a diversion, feeling of satiety, eating style, meal contents and temporal eating patterns. The Japanese version of the Morningness–Eveningness (ME) questionnaire was used to measure self-rated preference for the degree to which people prefer to be active in the morning or the evening (ME). Results The scores for meal contents and temporal eating patterns in rotating shift workers were significantly higher than those in day workers. The ME score of rotating shift workers was significantly lower, indicating greater eveningness/less morningness among rotating shift workers. Multivariate linear regression revealed that the ME score was significantly negatively associated with temporal eating patterns and showed a negative association with the score for meal contents at a trend level, while current work shift was not significantly correlated with the scores. Conclusions These results suggest that eating behaviours for rotating shift workers are associated with a more unbalanced diet and abnormal temporal eating patterns and that the associations may be explained by diurnal preference rather than by rotating shift work.

Dietary variety and decline in lean mass and physical performance in community-dwelling older Japanese: A 4-year follow-up study

ObjectivesTo examine associations of dietary variety with changes in lean mass and physical performance during a 4-year period in an elderly Japanese population. Design: Four-year prospective study.SettingThe Hatoyama Cohort Study and Kusatsu Longitudinal Study, Japan.Participants935 community-dwelling Japanese aged 65 years or older.MeasurementsDietary variety was assessed using a 10-item food frequency questionnaire. Body composition was determined by multifrequency bioelectrical impedance analysis, and physical performance (grip strength and usual gait speed) was measured in surveys at baseline and 4 years later. Longitudinal analysis included only participants who were originally in the upper three quartiles of lean body mass, appendicular lean mass, grip strength, and usual gait speed. The outcome measures were decline in lean body mass, appendicular lean mass, grip strength, and usual gait speed, defined as a decrease to the lowest baseline quartile level at the 4-year follow-up survey. Associations of dietary variety with the outcome measures were examined by logistic regression analysis adjusted for potential confounders.ResultsIn the fully adjusted model, the odds ratios for decline in grip strength and usual gait speed were 0.43 (95% confidence interval, 0.19–0.99) and 0.43 (confidence interval, 0.19–0.99), respectively, for participants in the highest category of dietary variety score as compared with those in the lowest category. Dietary variety was not significantly associated with changes in lean body mass or appendicular lean mass.ConclusionAmong older adults, greater dietary variety may help maintain physical performance, such as grip strength and usual gait speed, but not lean mass.

Validity of a Semi-Quantitative Food Frequency Questionnaire for Collegiate Athletes

BACKGROUND Food frequency questionnaires (FFQs) have been developed and validated for various populations. To our knowledge, however, no FFQ has been validated for young athletes. Here, we investigated whether an FFQ that was developed and validated to estimate dietary intake in middle-aged persons was also valid for estimating that in young athletes. METHODS We applied an FFQ that had been developed for the Japan Public Health Center-based Prospective Cohort Study with modification to the duration of recollection. A total of 156 participants (92 males) completed the FFQ and a 3-day non-consecutive 24-hour dietary recall (24hDR). Validity of the mean estimates was evaluated by calculating the percentage differences between the 24hDR and FFQ. Ranking estimation was validated using Spearmans correlation coefficient (CC), and the degree of miscategorization was determined by joint classification. RESULTS The FFQ underestimated energy intake by approximately 10% for both males and females. For 35 nutrients, the median (range) deattenuated CC was 0.30 (0.10 to 0.57) for males and 0.32 (-0.08 to 0.62) for females. For 19 food groups, the median (range) deattenuated CC was 0.32 (0.17 to 0.72) for males and 0.34 (-0.11 to 0.58) for females. For both nutrient and food group intakes, cross-classification analysis indicated extreme miscategorization rates of 3% to 5%. CONCLUSIONS An FFQ developed and validated for middle-aged persons had comparable validity among young athletes. This FFQ might be useful for assessing habitual dietary intake in collegiate athletes, especially for calcium, vitamin C, vegetables, fruits, and milk and dairy products.

The Impact of Menstrual Cycle Phases on Cardiac Autonomic Nervous System Activity : An Observational Study Considering Lifestyle (Diet, Physical Activity, and Sleep) among Female College Students

Studies examining the impact of menstrual cycle phases on the cardiac autonomic nervous system have produced inconsistent results. This study aimed to investigate this relationship, controlling for the confounding effects of diet, physical activity, and sleep, which can be affected by the menstrual cycle. Fifteen female college students with regular menses were enrolled. Data regarding 24-h heart rate variability (HRV), dietary intake, eating behavior, menstrual distress, and sleep and activity parameters were obtained during the follicular and luteal phases. Power spectral analysis of HRV was used to calculate low-frequency (0.04-0.15 Hz, LF), high-frequency (>0.15 Hz, HF), and total spectral power (TP). Cardiac sympathetic and parasympathetic nervous system activity indicators were evaluated as LF/HF and HF/TP, respectively. Intake of protein and fat, as well as total sleep time and number of awakenings, were higher in the luteal phase than in the follicular phase (p<0.05). Tendencies for increased mean activity counts, emotional eating scores, and behavioral change scores in the Menstrual Distress Questionnaire were observed in the luteal phase (p<0.10). Although LF/HF was higher in the luteal phase (p=0.036), the relationship was weakened after controlling for diet, physical activity, and sleep (p=0.113). Our findings suggest that altering sympathetic nervous system activity during the menstrual cycle was not independent from major lifestyle factors (diet, physical activity, and sleep). Menstrual cycle phase and changes of these parameters should be considered when assessing the cardiac autonomic function among menstruating woman.

Relationship Between Dietary Factors and Bodily Iron Status Among Japanese Collegiate Elite Female Rhythmic Gymnasts.

This cross-sectional study explored the prevalence of iron deficiency (ID) and associations between dietary factors and incidence of ID in female rhythmic gymnasts during preseason periods. Participants were 60 elite collegiate rhythmic gymnasts (18.1 ± 0.3 years [M ± SD]) who were recruited every August over the course of 8 years. Participants were divided into 2 groups according to the presence or absence of ID. Presence of ID was defined either by ferritin less than 12 μg/L or percentage of transferrin saturation less than 16%. Anthropometric and hematologic data, as well as dietary intake, which was estimated via a semiquantitative food frequency questionnaire, were compared. ID was noted in 48.3% of participants. No significant group-dependent differences were observed in physical characteristics, red blood cell counts, hemoglobin, hematocrit, haptoglobin, or erythropoietin concentrations. The ID group had a significantly lower total iron-binding capacity; serum-free iron; percentage of transferrin saturation; ferritin; and intake of protein, fat, zinc, vitamin B2, vitamin B6, beans, and eggs but not iron or vitamin C. The recommended dietary allowance for intake of protein, iron, zinc, and various vitamins was not met by 30%, 90%, 70%, and 22%-87% of all participants, respectively. Multiple logistic analysis showed that protein intake was significantly associated with the incidence of ID (odds ratio = 0.814, 95% confidence interval [0.669, 0.990], p = .039). Participants in the preseasons weight-loss periods showed a tendency toward insufficient nutrient intake and were at a high risk for ID, particularly because of lower protein intake.

Effects of a multifactorial intervention comprising resistance exercise, nutritional and psychosocial programs on frailty and functional health in community‐dwelling older adults: A randomized, controlled, cross‐over trial

To examine the effects of a multifactorial intervention on frailty and functional health among community‐dwelling older adults, a 6‐month randomized, controlled, cross‐over trial was carried out within the Hatoyama Cohort Study.

Association of Trajectories of Higher-Level Functional Capacity with Mortality and Medical and Long-Term Care Costs Among Community-Dwelling Older Japanese

Background Higher-level functional capacity is crucial component for independent living in later life. We used repeated-measures analysis to identify aging trajectories in higher-level functional capacity. We then determined whether these trajectories were associated with all-cause mortality and examined differences in medical and long-term care costs between trajectories among community-dwelling older Japanese. Methods 2,675 adults aged 65-90 years participated in annual geriatric health assessments and biennial health monitoring surveys during the period from October 2001 through August 2011. The average number of follow-up assessments was 4.0, and the total number of observations was 10,609. Higher-level functional capacity, which correspond to the fourth and fifth sublevels of Lawtons hierarchical model, was assessed with the Tokyo Metropolitan Institute of Gerontology-Index of Competence (TMIG-IC). Results We identified four distinct trajectory patterns (high-stable, late-onset decreasing, early-onset decreasing, and low-decreasing) on the TMIG-IC through age 65-90 years. As compared with the high-stable trajectory group, participants in the late-onset decreasing, early-onset decreasing, and low-decreasing TMIG-IC trajectory groups had adjusted hazard ratios for mortality of 1.22 (95% confidence interval: 1.01-1.47), 1.90 (1.53-2.36), and 2.87 (2.14-3.84), respectively. Participants with high-stable and late-onset decreasing higher-level functional capacity trajectories had lower mean monthly medical costs and long-term care costs. In contrast, mean total costs were higher for those with low-decreasing trajectories, after excluding the large increase in such costs at the end of life. Conclusions People with a low-decreasing aging trajectory in higher-level functional capacity had higher risks of death and had high monthly total costs.