Dietary Acrylamide Intake and the Risks of Renal Cell, Prostate, and Bladder Cancers: A Japan Public Health Center-Based Prospective Study

Acrylamide can be carcinogenic to humans. However, the association between the acrylamide and the risks of renal cell, prostate, and bladder cancers in Asians has not been assessed. We aimed to investigate this association in the Japan Public Health Center-based Prospective Study data in 88,818 Japanese people (41,534 men and 47,284 women) who completed a food frequency questionnaire in the five-year follow-up survey in 1995 and 1998. A validated food frequency questionnaire was used to assess the dietary acrylamide intake. Cox proportional hazard regression models were used to estimate hazard ratios and 95% confidence intervals (CIs). During a mean follow-up of 15.5 years (15.2 years of prostate cancer), 208 renal cell cancers, 1195 prostate cancers, and 392 bladder cancers were diagnosed. Compared to the lowest quintile of acrylamide intake, the multivariate hazard ratios for the highest quintile were 0.71 (95% CI: 0.38–1.34, p for trend = 0.294), 0.96 (95% CI: 0.75–1.22, p for trend = 0.726), and 0.87 (95% CI: 0.59–1.29, p for trend = 0.491) for renal cell, prostate, and bladder cancers, respectively, in the multivariate-adjusted model. No significant associations were observed in the stratified analyses based on smoking. Dietary acrylamide intake was not associated with the risk of renal cell, prostate, and bladder cancers.

Dietary Acrylamide Intake and the Risk of Pancreatic Cancer: The Japan Public Health Center-Based Prospective Study

Acrylamide is a probable carcinogen in humans. Few studies have assessed dietary acrylamide intake and the risk of pancreatic cancer; however, these studies are based on Western populations. Our purpose was to investigate the association of dietary acrylamide intake with the risk of pancreatic cancer utilizing data from the Japan Public Health Center-based Prospective Study. We evaluated the data of 89,729 participants aged 45-74 years, who replied to a questionnaire on past medical history and lifestyle habits from 1995-1998. Dietary acrylamide intake was estimated utilizing a validated food frequency questionnaire. We calculated the hazard ratios and 95% confidence intervals by using Cox proportional-hazards regression models. The average follow-up was 15.2 years, and 576 cases of pancreatic cancer were diagnosed. In the multivariate-adjusted model, an association between dietary acrylamide intake and pancreatic cancer risk was not demonstrated (hazard ratio for the highest vs. lowest quartile = 0.83, 95% confidence interval: 0.65-1.05, p for trend = 0.07). Furthermore, in the analyses stratified by sex, smoking status, coffee consumption, green tea consumption, alcohol consumption, and body mass index, no significant association was detected. Dietary acrylamide intake was not associated with the pancreatic cancer risk in Japanese individuals.

Dietary Acrylamide Intake and Risk of Lung Cancer: The Japan Public Health Center Based Prospective Study

Acrylamide, which forms in heat-treated foods with high carbohydrate content, is a probable human carcinogen. This study aimed to evaluate the association between dietary acrylamide intake and lung cancer using data from the Japan Public Health Center based Prospective Study. Our study included 85,303 participants who completed a food frequency questionnaire. Cox proportional hazards regression models were used to assess hazard ratios and 95% confidence intervals (CIs) after adjusting for confounders. After 14.3 years and 15.4 years of mean follow-up period, 1187 and 485 lung cancer cases were identified in men and women, respectively. The multivariable-adjusted hazard ratios of 10-µg/day increment in acrylamide intake were 1.01 (95% CI, 0.99–1.02) in men and 0.98 (95% CI, 0.95–1.02) in women. Compared with the lowest quartile of acrylamide intake, the hazard ratios for the highest quartile were 1.13 (95% CI, 0.95–1.33; p for trend = 0.12) in men and 1.03 (95% CI, 0.78–1.36; p for trend = 0.86) in women in the multivariable-adjusted model. Moreover, there was also no significant association observed in the stratified analysis for histological subtypes of lung cancer. This study demonstrated that dietary acrylamide intake was not associated with increased lung cancer risk in the Japanese population.

Variations in the estimated intake of acrylamide from food in the Japanese population

BACKGROUND

Due to concerns of carcinogenicity, it is necessary to assess long-term acrylamide exposure in individuals. Whether the available methods of estimating acrylamide intake can indicate long-term exposure remains unknown. We examined variations in the estimated dietary acrylamide intake of the Japanese population.

METHODS

The study included 240 participants aged 40-74 years who were a part of the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT). Twelve-day dietary records (DRs) were collected over a one-year period, and food frequency questionnaires (FFQs) were collected twice during the year. Dietary acrylamide intake was estimated from an acrylamide content database. Within-individual variations and between-individual variations were calculated using the random effects model. A linear regression analysis was performed to identify foods with large between-individual variations.

RESULTS

The ratios of within-individual variance to between-individual variation were 3.2 for men and 4.3 for women. Days of DRs required to estimate the usual individual intake within 20% of the true mean intake with 95% confidence were 60 days for men and 66 days for women. Coffee/cocoa, potato, and green tea contributed to between-individual variations, in that order, and seven foods contributed to 93% of the between-individual variation.

CONCLUSIONS

Estimating the acrylamide intake using DRs requires an extended data collection period to estimate the intragroup ranking and habitual intake of individuals. Long-term exposure assessments should be based on methods with less potential for measurement errors, such as the use of biomarkers.

Dietary Acrylamide Intake and Risk of Esophageal, Gastric, and Colorectal Cancer: The Japan Public Health Center-Based Prospective Study

BACKGROUND

Acrylamide has been classified as a probable human carcinogen based chiefly on laboratory evidence. However, the influence of dietary acrylamide intake on risk of esophageal, gastric, and colorectal cancer has not been extensively studied. We aimed to evaluate the association between dietary acrylamide intake and esophageal, gastric, and colorectal cancer using data from the Japan Public Health Center-based Prospective Study.

METHODS

Our study included 87,628 participants who completed a food-frequency questionnaire at enrollment in 1990 and 1993. We used Cox proportional hazards regression models to estimate hazards ratios and 95% confidence intervals (CI) after adjusting for confounding factors.

RESULTS

After 15.5, 15.3, and 15.3 mean years of follow-up for esophageal, gastric, and colorectal cancer, we identified and analyzed 391 esophageal, 2,218 gastric, and 2,470 colorectal cancer cases, respectively. Compared with the lowest quintile of acrylamide intake, the multivariate HR for the highest quintile was 0.86 (95% CI, 0.53-1.39; P _trend = 0.814), 0.84 (95% CI, 0.69-1.01; P _trend = 0.301), and 0.93 (95% CI, 0.79-1.08; P _trend = 0.165) for esophageal, gastric, and colorectal cancer, respectively, in the multivariable-adjusted model. Furthermore, no significant associations were observed when the participants were stratified by cancer subsites.

CONCLUSIONS

In conclusion, this study demonstrated that dietary acrylamide intake was not associated with increased risk of esophageal, gastric, or colorectal cancer among the Japanese population.

IMPACT

It is the first time to assess the effect of dietary acrylamide intake on risk of digestive system cancer in Asian populations.

Validity of Estimated Acrylamide Intake by the Dietary Record Method and Food Frequency Questionnaire in Comparison with a Duplicate Method: A Pilot Study

Acrylamide, classified as a probable carcinogen to humans, forms during high- temperature cooking. Dietary exposure among the Japanese is unknown. To evaluate the validity of estimated acrylamide intake using a dietary record (DR) and the food frequency questionnaire (FFQ) in comparison with the duplicate diet method (DM) in a Japanese population. Design: A validation study was performed with 14 participants (age, 32-50 y; 11 women) from 11 households. Food samples were simultaneously collected for the DM and DR on the same day over 2 consecutive days. The FFQ was administered after collecting samples for the DM and DR. For the DM, dietary acrylamide was calculated from chemical analyses of each food. For the DR and FFQ, acrylamide intake for each food was calculated using the database of acrylamide contents of foods. Correlation coefficients were calculated using the Spearman rank method. Average acrylamide intake values calculated using the DM, DR, and FFQ were 0.106, 0.233, and 0.128 μg/kg body weight/d, respectively; these values showed a marginally positive correlation between the DM and DR (r=0.52), but a low correlation between the DM and FFQ (r=-0.011). For the DR, non-alcoholic drinks had the highest contribution, followed by confectionery and vegetables. For the DM, the contribution of confectionery was the highest, followed by vegetables and non-alcoholic drinks. In conclusion, the validity of acrylamide intake estimation using the DR was reasonably high when compared to the analytical value of the simultaneous DM. However, further improvement is required for estimating acrylamide intake using the FFQ.

Validity of a Self-administered Food Frequency Questionnaire for the Estimation of Acrylamide Intake in the Japanese Population: The JPHC FFQ Validation Study

BACKGROUND

Acrylamide, a probable carcinogen to humans, forms during high temperature cooking. Dietary exposure to acrylamide among the Japanese population is unknown. We aimed to establish and validate a method to assess acrylamide exposure among the Japanese population using a food frequency questionnaire (FFQ) from the Japan Public Health Center-based prospective study.

METHODS

Validation studies for the FFQ were conducted in 1994 (Cohort I, n = 215) and 1996 (Cohort II, n = 350). The 28-day dietary records (DRs) were collected over 1 year. The FFQ was distributed before and after DR collection. Data for acrylamide exposure were based on reported measurements in Japan, and calculations considered the cooking process for specific vegetables in a home setting. Spearman's rank correlation and weighted kappa coefficients were calculated from energy-adjusted data.

RESULTS

Mean acrylamide intake levels estimated from DRs for Cohorts I and II were 6.78 (standard deviation [SD], 3.89) µg/day and 7.25 (SD, 3.33) µg/day, and corresponding levels estimated from the FFQ were 7.03 (SD, 4.30) µg/day and 7.14 (SD, 3.38) µg/day, respectively. Deattenuated correlation coefficients for men and women were 0.54 and 0.48 in Cohort I and 0.40 and 0.37 in Cohort II, respectively. Weighted kappa coefficients were over 0.80 in all cases. The main contributing food groups from DRs were beverages, confectioneries, vegetables, potatoes and starches, and cereals.

CONCLUSIONS

High kappa values validate the use of FFQ in epidemiological studies. The marked contribution of cooked vegetables indicates the importance of considering household cooking methods in assessing acrylamide intake levels in the Japanese population.

Dietary acrylamide intake and the risk of endometrial or ovarian cancers in Japanese women

A meta-analysis published in 2015 noted a marginally increased risk of endometrial and ovarian cancers in non-smoking women with dietary acrylamide intake, but only a few studies were included, and they were limited to Western countries. The aim of this study was to investigate the association between dietary acrylamide intake and endometrial or ovarian cancer risk in the Japan Public Health Center-based Prospective Study (JPHC Study). In this prospective cohort study, 47 185 participants aged 45-74 years at the follow-up starting point in the JPHC Study were enrolled. Dietary acrylamide intake was assessed using a validated food frequency questionnaire. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (95%CI). In participants with endometrial and ovarian cancer, the average follow-up periods were 15.5 and 15.6 years, respectively, and 161 and 122 cases of endometrial and ovarian cancer were diagnosed, respectively. Energy-adjusted dietary acrylamide intake was negatively associated with endometrial cancer, but the association disappeared after adjusting for coffee consumption with an adjusted HR for the highest vs lowest tertile of 0.85 (95%CI: 0.54-1.33). No association was observed, however, for ovarian cancer (adjusted HR, 0.77; 95%CI: 0.49-1.23). Furthermore, after stratifying by smoking status, coffee consumption, alcohol consumption, body mass index, and menopause status, no association was observed. Dietary acrylamide intake was not associated with the risk of endometrial or ovarian cancer in Japanese women with a relatively lower dietary intake of acrylamide compared with Western populations.

Estimation of long-term dietary exposure to acrylamide of the Japanese people

Acrylamide is a probable human carcinogen and known human neurotoxin. This study estimated hypothetical long-term dietary exposure to acrylamide of the Japanese people using probabilistic and deterministic approaches by combining the concentration of acrylamide in foods with the amount and frequency of food consumption in the population. Data included acrylamide concentrations in more than 2400 individual food samples from a national survey and the literature from 2004 to 2013. Food consumption amounts were derived from the data of 24,293 Japanese citizens aged 1 year and older in the 2012 National Health and Nutrition Survey. Median lifetime average dietary exposure to acrylamide was estimated as 147-154 ng/kg body weight (bw)/day (95th percentile, 226-261 ng/kg bw/day). The deterministic estimate of lifetime exposure was 158 ng/kg bw/day and ranged from 119 ng/kg bw/day for the period of life after 60 years old to 409 ng/kg bw/day for the period between 1 and 6 years old. This study found that vegetables cooked at a high temperature, coffee and cooked potato were the major food groups contributing to long-term dietary acrylamide exposure of the Japanese people.

Dietary acrylamide intake and risk of breast cancer: The Japan Public Health Center-based Prospective Study

Acrylamide forms during cooking and is classified as a probable carcinogen in humans, mandating the need for epidemiological studies of dietary acrylamide and cancers. However, the risk of dietary acrylamide exposure to breast cancer in Japanese women has not been assessed. We investigated the association between dietary acrylamide intake and risk of breast cancer in the Japan Public Health Center-based Prospective Study. The present study included 48 910 women aged 45-74 years who responded to a 5-year follow-up survey questionnaire. Dietary acrylamide intake was assessed using a validated food frequency questionnaire. Cox proportional hazards regression models were used to estimate hazard ratios and 95% confidence intervals. During an average of 15.4 years of follow up, 792 breast cancers were diagnosed. Energy-adjusted dietary acrylamide intake was not associated with the risk of breast cancer (adjusted hazard ratio for highest versus lowest tertile = .95, 95% confidence intervals: 0.79-1.14, P-trend = .58). Further, no significant associations were observed when stratified analyses were conducted by smoking status, coffee consumption, alcohol consumption, body mass index, menopausal status, estrogen receptor status, and progesterone receptor status. In conclusion, dietary acrylamide intake was not associated with the risk of breast cancer in this population-based prospective cohort study of Japanese women.

Acrylamide in Foods Generated through Heating (Contaminants)

The Food Safety Commission of Japan (FSCJ) conducted a risk assessment on acrylamide (AA) (CAS No. 79-06-1) in foods generated through heating, as a self-tasking risk assessment. In rodent toxicity studies, major adverse effects were observed on neurotoxicity and male reproductive toxicity. Statistically significant increases in incidences were observed in the carcinogenicity studies in Harderian gland, mammary gland, lung and forestomach in mice, and in mammary gland, thyroid and testis in rats. Positive results were also obtained from in vitro and in vivo genotoxicity studies of AA and glycidamide (GA). Therefore, FSCJ recognized AA as a genotoxic carcinogen. Judging from the dietary AA intake among Japanese people, the non-neoplastic risk is extremely low because of sufficient margins of exposure (MOEs). The neoplastic risk, however, could not be excluded due to the insufficient MOEs, although no clear evidence on human health effect have been provided from the epidemiological studies. It is important to note that no consistent relationships between AA exposure and cancer incidences have been observed even in the studies focusing on the highly exposed populations in occupational settings. FSCJ thus concluded that continual efforts are necessary to reduce dietary AA intakes in accordance with the principle of ALARA (as low as reasonably achievable) from the viewpoint of public health.