Ribeka Takachi

Consumption of n-3 Fatty Acids and Fish Reduces Risk of Hepatocellular Carcinoma

BACKGROUND & AIMS Fish is a rich source of n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). Although consumption of fish and n-3 PUFA has been reported to protect against the development of some types of cancer, little is known about its association with hepatocellular carcinoma (HCC). METHODS We investigated the association between fish and n-3 PUFA consumption and HCC incidence (n = 398) in a population-based prospective cohort study of 90,296 Japanese subjects (aged, 45-74 y). Hazard ratios and 95% confidence intervals (CIs) for the highest vs the lowest quintile were estimated from multivariable adjusted Cox proportional hazards regression models. We also conducted subanalyses of subjects with known hepatitis B virus (HBV) or hepatitis C virus (HCV) status, and of subjects who were anti-HCV and/or hepatitis B surface antigen positive. All tests of statistical significance were 2-sided. RESULTS Among all subjects, consumption of n-3 PUFA-rich fish and individual n-3 PUFAs was associated inversely with HCC, in a dose-dependent manner. Hazard ratios for the highest vs lowest quintiles were 0.64 (95% CI, 0.42-0.96) for n-3 PUFA-rich fish, 0.56 (95% CI, 0.36-0.85) for EPA, 0.64 (95% CI, 0.41-0.98) for DPA, and 0.56 (95% CI, 0.35-0.87) for DHA. These inverse associations were similar irrespective of HCV or HBV status. CONCLUSIONS Consumption of n-3 PUFA-rich fish or n-3 PUFAs, particularly EPA, DPA, and DHA, appears to protect against the development of HCC, even among subjects with HBV and/or HCV infection.

Consumption of sodium and salted foods in relation to cancer and cardiovascular disease: the Japan Public Health Center-based Prospective Study.

BACKGROUND Although the influence of salt, per se, on the risk of cancer or cardiovascular disease (CVD) might differ from that of salt-preserved foods, few studies have simultaneously examined the effects of sodium and salted foods on the risk of either cancer or CVD. OBJECTIVE We simultaneously examined associations between sodium and salted food consumption and the risk of cancer and CVD. DESIGN During 1995-1998, a validated food-frequency questionnaire was administered to 77,500 men and women aged 45-74 y. During up to 598,763 person-years of follow-up until the end of 2004, 4476 cases of cancer and 2066 cases of CVD were identified. RESULTS Higher consumption of sodium was associated with a higher risk of CVD but not with the risk of total cancer: multivariate hazard ratios for the highest compared with lowest quintiles of intake were 1.19 (95% CI: 1.01, 1.40; P for trend: 0.06) for CVD and 1.04 (95% CI: 0.93, 1.16; P for trend: 0.63) for total cancer. Higher consumption of salted fish roe was associated with higher risk of total cancer, and higher consumption of cooking and table salt was associated with higher risk of CVD. Similar results were seen for the risk of gastric or colorectal cancer and stroke. CONCLUSIONS Sodium intake as a whole salt equivalent may not increase the risk of cancer but may increase that of CVD. In contrast, salted food intake may increase the risk of cancer. Our findings support the notion that sodium and salted foods have differential influences on the development of cancer and CVD.

Dietary cadmium intake and breast cancer risk in Japanese women: a case-control study.

Cadmium, an environmental pollutant, may act like an estrogen and be a potential risk factor for estrogen-dependent diseases such as breast cancer. We examined the hypothesis that higher dietary cadmium intake is associated with risk of overall and hormone receptor-defined breast cancer in Japanese women, a population with a relatively high cadmium intake. The study was conducted under a case-control design in 405 eligible matched pairs from May 2001 to September 2005 at four hospitals in Nagano Prefecture, Japan. Dietary cadmium intake was estimated using a food frequency questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer and its hormone-receptor-defined subtypes were calculated by tertile of dietary cadmium intake. We found no significant association between dietary cadmium and risk of total breast cancer in either crude or multivariable-adjusted analysis. Adjusted ORs for tertiles of cadmium intake were 1.00, 1.19, and 1.23 (95% CI, 0.76-2.00; P for trend=0.39) for whole breast cancer. Further, no significant associations were seen across strata of menopausal status, smoking, and diabetes in multivariable-adjusted models except for adjusted OR for continuous cadmium intake in postmenopausal women. A statistically significant association was found for estrogen receptor-positive (ER+) tumors among postmenopausal women (adjusted OR=1.00, 1.16, and 1.94 [95% CI, 1.04-3.63; P for trend=0.032]). Although the present study found no overall association between dietary cadmium intake and breast cancer risk, higher cadmium intake was associated with increased risk of ER+ breast cancer in postmenopausal women, at least at regular intake levels in Japanese women in the general population. Further studies are needed to confirm this association.

Reproducibility and Validity of Dietary Patterns Assessed by a Food Frequency Questionnaire Used in the 5-Year Follow-Up Survey of the Japan Public Health Center-Based Prospective Study

Background Analysis of dietary pattern is increasingly popular in nutritional epidemiology. However, few studies have examined the validity and reproducibility of dietary patterns. We assessed the reproducibility and validity of dietary patterns identified by a food frequency questionnaire (FFQ) used in the 5-year follow-up survey of the Japan Public Health Center-Based Prospective Study (JPHC Study). Methods The participants were a subsample (244 men and 254 women) from the JPHC Study. Principal component analysis was used to identify dietary patterns from 28- or 14-day dietary records and 2 FFQs. To assess reproducibility and validity, we calculated Spearman correlation coefficients between dietary pattern scores derived from FFQs separated by a 1-year interval, and between dietary pattern scores derived from dietary records and those derived from a FFQ completed after the dietary records, respectively. Results We identified 3 Japanese dietary patterns from the dietary records and 2 FFQs: prudent, westernized, and traditional. Regarding reproducibility, Spearman correlation coefficients between the 2 FFQs ranged from 0.55 for the westernized Japanese pattern in men and the prudent Japanese pattern in women to 0.77 for the traditional Japanese pattern in men. Regarding validity, the corresponding values between dietary records and the FFQ ranged from 0.32 for the westernized Japanese pattern in men to 0.63 for the traditional Japanese pattern in women. Conclusions Acceptable reproducibility and validity was shown by the 3 dietary patterns identified by principal component analysis based on the FFQ used in the 5-year follow-up survey of the JPHC Study.

Long-term Dietary Cadmium Intake and Cancer Incidence

Background: Cadmium, a ubiquitous environmental pollutant, is classified as a carcinogenic substance. Several laboratory and epidemiologic studies of workers and subjects in polluted areas have suggested a positive association between cadmium exposure and risk of several cancers. However, data from general populations are sparse. We prospectively examined the association between cadmium exposure and incidence of cancer in a Japanese population with a relatively high dietary intake of cadmium. Methods: We conducted a population-based prospective study in 90,383 Japanese men and women 45–74 years of age. Participants responded to a validated questionnaire that included 138 food items. We estimated dietary cadmium intake from 6 food groups, based on the questionnaire data. During 9 years of follow-up, 5849 cancer cases were identified. Hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer were calculated by Cox proportional hazards modeling. Results: There was no evidence of an association of cadmium consumption and total cancer, with HRs in the highest versus lowest cadmium intake group of 0.94 (95% CI = 0.82 to 1.08; test for trend, P = 0.46) for men and 0.96 (0.81 to 1.15; 0.60) for women. No site-specific cancers were associated with cadmium intake in men or women. Conclusion: We found no associations of cancer with cadmium, at least at the exposure levels observed in a general population in Japan.

Validity of a Self-Administered Food Frequency Questionnaire for Middle-Aged Urban Cancer Screenees: Comparison With 4-Day Weighed Dietary Records

Background The validity of estimates of dietary intake calculated using a food frequency questionnaire (FFQ) depends on the specific population. The 138-item FFQ used in the 5-year follow-up survey for the Japan Public Health Center-based Prospective Study was initially developed for and validated in rural residents. However, the validity of estimates based on this FFQ for urban residents, whose diet and lifestyle differ from those of rural residents, has not been clarified. We examined the validity of ranking individuals according to level of dietary consumption, as estimated by this FFQ, among an urban population in Japan. Methods Among 896 candidates randomly selected from examinees of cancer screening provided by the National Cancer Center, Japan, 144 participated in the study. In 2007–2008, at an average 2.7 years after cancer screening, participants were asked to respond to the questionnaire and to provide 4-day weighed diet records (4d-DRs) for use as the reference intake. Spearman correlation coefficients (CCs) between the FFQ and 4d-DR estimates were calculated, after correction for intraindividual variation of 4d-DRs. Results The median (range) deattenuated CC for men and women was 0.57 (0.23 to 0.89) and 0.47 (0.08 to 0.94), respectively, across 45 nutrients and 0.51 (0.10 to 0.98) and 0.51 (−0.36 to 0.88) for 43 food groups. Conclusions Although the FFQ was developed for a rural population, it provided reasonably valid measures of consumption for many nutrients and food groups in middle-aged screenees living in urban areas in Japan.

High Dietary Intake of Magnesium May Decrease Risk of Colorectal Cancer in Japanese Men

Magnesium maintains genomic stability and is an essential cofactor for DNA synthesis and repair. Magnesium intake has been reported to be inversely associated with colorectal cancer (CRC) risk in Western populations. This study examined the association between dietary intake of magnesium and CRC risk in Japanese men and women aged 45-74 y. Data from 40,830 men and 46,287 women, at the 5-y follow-up of the Japan Public Health Center-based Prospective Study, who responded to a 138-item FFQ were used in this analysis. A total of 689 and 440 CRC events were observed during the mean follow-up of 7.9 and 8.3 y for men and women, respectively. When adjusted for potential confounders, the hazard ratio and 95% CI in the highest quintile of magnesium intake compared with the lowest quintile in men were 0.65 (95% CI, 0.40-1.03) for CRC (P-trend = 0.04), 0.48 (95% CI, 0.26-0.89) for colon cancer (P-trend = 0.01), and 0.97 (95% CI, 0.47-2.02) for rectal cancer (P-trend = 0.93). Borderline inverse associations were also observed in men who consumed alcohol regularly (P-trend = 0.07) or had a BMI <25 kg/m(2) (P-trend = 0.06). There were similar inverse associations for invasive colon cancer and distal colon cancer. There were no significant associations between magnesium intake and cancer risk in women. Higher dietary intake of magnesium may decrease the risk of CRC in Japanese men.

Dietary patterns and type 2 diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study

Background/objective:Dietary patterns in Western populations have been linked to type 2 diabetes, but the association of distinctive dietary patterns of Japanese population remains unclear. We prospectively investigated the association between dietary patterns and risk of developing type 2 diabetes among Japanese adults.Subjects/methods:Participants were 27 816 men and 36 889 women aged 45–74 years who participated in the second survey of the Japan Public Health Center-based prospective study and had no history of diabetes. Dietary patterns were derived by using principal component analysis of the consumption of 134 food and beverage items ascertained by a food frequency questionnaire. Odds ratios of self-reported physician-diagnosed type 2 diabetes over 5 year were estimated using logistic regression analysis.Results:A total of 1194 new cases (692 men and 502 women) of type 2 diabetes were self-reported. We identified three dietary patterns: prudent, westernized and traditional Japanese patterns. Any dietary pattern was not significantly associated with type 2 diabetes risk after adjustment for covariates in both men and women. The multivariate-adjusted odds ratios (95% confidence interval) for type 2 diabetes for the highest versus lowest quartile of each dietary pattern score in men and women, respectively, were 0.93 (0.74–1.16) and 0.90 (0.69–1.16) for the prudent pattern, 1.15 (0.90–1.46) and 0.81 (0.61–1.08) for the westernized pattern, and 0.97 (0.74–1.27) and 0.87 (0.66–1.15) for the traditional pattern.Conclusions:Although a small protective effect of the prudent dietary pattern cannot be excluded, dietary patterns may not be appreciably associated with type 2 diabetes risk in Japanese.

Self-Reported Taste Preference Can Be a Proxy for Daily Sodium Intake in Middle-Aged Japanese Adults

Reducing dietary salt intake remains a challenging issue in the management of chronic disease. Taste preference is suspected to be an important proxy index of daily sodium consumption. This study examined the difference in daily sodium intake according to self-reported taste preference for miso soup as representative of homemade cooking in middle-aged urban Japanese adults. Among 896 candidates randomly selected from examinees of cancer screening provided by the National Cancer Center, Japan, 143 men and women participated in this cross-sectional study. During the period from May 2007 through April 2008, participants provided a food frequency questionnaire, which included information on taste preference and dietary behaviors, a weighed food record over 4 consecutive days, a simultaneous 24-hour urine collection, and a sample of miso soup as it is usually prepared in the home. Mean 24-hour urinary sodium excretion and daily sodium intake were compared according to the self-reported taste preference for miso soup. Taste preference was significantly associated with both 24-hour urinary sodium excretion (trend P<0.01) and daily sodium intake (trend P=0.01), with a corresponding regression coefficient per 1 rank preference increment of 403 mg and 315 mg/day, respectively. The observed association between preference and urinary excretion was attenuated by further adjustment for discretionary salt-related behaviors. These findings suggest that self-reported taste preference for homemade cooking is a defining feature of daily sodium intake through discretionary salt-related dietary behaviors. A reduction in daily sodium consumption per 1 rank light preference was estimated to equate to approximately 1 g salt/day.

Effect of low-dose calcium supplements on bone loss in perimenopausal and postmenopausal Asian women: A randomized controlled trial

Current standard‐dose calcium supplements (eg, 1000 mg/d) may increase the risk for cardiovascular events. Effectiveness of lower‐dose supplements in preventing bone loss should thus be considered. This study aimed to assess whether calcium supplements of 500 or 250 mg/d effectively prevent bone loss in perimenopausal and postmenopausal Japanese women. We recruited 450 Japanese women between 50 and 75 years of age. They were randomly assigned to receive 500 mg of calcium (as calcium carbonate), 250 mg of calcium, or placebo daily. Medical examinations conducted three times over a 2‐year follow‐up period assessed bone mineral density (BMD) of the lumbar spine and femoral neck. One‐factor repeated measures ANOVA was used for statistical tests. Subgroup analyses were also conducted. Average total daily calcium intake at baseline for the 418 subjects who underwent follow‐up examinations was 493 mg/d. Intention‐to‐treat analysis showed less dramatic decreases in spinal BMD for the 500‐mg/d calcium supplement group compared to the placebo group (1.2% difference over 2 years, p = 0.027). Per‐protocol analysis (≥80% compliance) revealed that spinal BMD for the 500‐mg/d and 250‐mg/d calcium supplement groups decreased less than the placebo group (1.6%, p = 0.010 and 1.0%, p = 0.078, respectively), and that femoral neck BMD for the 500‐mg/d calcium supplement group decreased less relative to the placebo group (1.0%, p = 0.077). A low‐dose calcium supplement of 500 mg/d can effectively slow lumbar spine bone loss in perimenopausal and postmenopausal women with habitually low calcium intake, but its effect on the femoral neck is less certain. Calcium supplementation dosage should thus be reassessed. (Clinical Trials Registry number: UMIN000001176).