Serum carotenoids, retinol, and tocopherols, and colorectal cancer risk in a Japanese cohort: effect modification by sex for carotenoids

An overview of vitamins as epidrugs for colorectal cancer prevention

Gene expression altering epigenomic modifications such as DNA methylation, histone modification, and chromosome remodeling is crucial to regulating many biological processes. Several lifestyle factors, such as diet and natural, bioactive food compounds, such as vitamins, modify epigenetic patterns. However, epigenetic dysregulation can increase the risk of many diseases, including cancer. Various studies have provided supporting and contrasting evidence on the relationship between vitamins and cancer risk. Though there is a gap in knowledge about whether dietary vitamins can induce epigenetic modifications in the context of colorectal cancer (CRC), the possibility of using them as epidrugs for CRC treatment is being explored. This is promising because such studies might be informative about the most effective way to use vitamins in combination with DNA methyltransferase inhibitors and other approved therapies to prevent and treat CRC. This review summarizes the available epidemiological and observational studies involving dietary, circulating levels, and supplementation of vitamins and their relationship with CRC risk. Additionally, using available in vitro, in vivo, and human observational studies, the role of vitamins as potential epigenetic modifiers in CRC is discussed. This review is focused on the action of vitamins as modifiers of DNA methylation because aberrant DNA methylation, together with genetic alterations, can induce the initiation and progression of CRC. Although this review presents some studies with promising results, studies with better study designs are necessary. A thorough understanding of the underlying molecular mechanisms of vitamin-mediated epigenetic regulation of CRC genes can help identify effective therapeutic targets for CRC prevention and treatment.

Association between serum carotenoids and premature mortality in a population-based case-control study

Carotenoids are abundant pigments mainly contained in vegetables and fruits, and show antioxidant properties by quenching free radicals in human body. Few studies have investigated associations between serum carotenoid levels and premature mortality. The objective of this study was to investigate the association between serum carotenoid level and premature mortality in a Japanese population. This study included 446 Japanese adults (174 men, aged of 40-64) recruited as participants in the Japan Collaborative Cohort (JACC) Study. Serum carotenoid level was measured by high-performance liquid chromatography. Premature mortality was defined as death before 65 years old during the follow-up period. Premature mortality was ascertained in 60 men (34.5%) and 65 women (23.9%). In men, compared to the 1^st tertile of serum β-cryptoxanthin and provitamin A, those who were in the 3^rd tertile had lower risks of premature all-cause mortality (OR, 95% CI: 0.19, 0.07-0.47 for β-cryptoxanthin, and 0.24, 0.09-0.61 for provitamin A). In women, compared to the 1^st tertile of serum β-cryptoxanthin, those who were in the 3^rd tertile had higher risks of premature all-cause mortality (OR, 95% CI: 1.94, 1.00-4.03). These significant associations were observed in analyses for premature cancer mortality. We found significant associations between higher levels of serum β-cryptoxanthin and provitamin A and lower risks of premature mortality among Japanese men, while a different directional association was found in women. Although these findings suggest roles of serum carotenoids on premature mortality, further studies are needed to validate this association in other populations.

Association of Dietary Carrot/Carotene Intakes With Colorectal Cancer Incidence and Mortality in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

Background:

The evidence of dietary carrot/carotene intake's effect on the association with colorectal cancer (CRC) risk is conflicted. We sought to examine the association of carrot/carotene intake with CRC incidence and mortality in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening cohort.

Methods

In all, 101,680 participants were enrolled between November 1993 and July 2001 from the PLCO cohort. We employed the multivariable Cox regression analyses to estimate the hazard ratios and 95% confidence interval. Subgroup analyses and interaction tests were performed to examine the potential effect modifiers. We further applied the generalized additive model to explore the non-linear trend of the exposure to cancer-related outcomes.

Results

A total of 1,100 CRC cases and 443 cancer-related deaths were documented. We noted that the 4th quintile of dietary carrot intakes was associated with a 21% lower risk of CRC incidence, compared with the lowest quintile group (full-adjusted HR_{quintile4vs.quintile1} = 0.79, 95%CI = 0.65–0.97, p for trend = 0.05), while the adjusted-HR was 0.95 (95%CI = 0.89–1.02) with per SD increment of carrot intakes, and no statistically significant associations were detected between dietary α-, and β-carotene intake and CRC incidence. There were no statistically significant associations observed between carrot/carotene intakes and CRC mortality. Furthermore, there were no non-linear dose-response relationships between dietary carrot, α-, and β-carotene intake and CRC incidence and mortality (all p_nonlinearity > 0.05). Of note, smoking status as a modifier on the association of dietary carrot intakes with CRC incidence but not mortality was observed.

Conclusions

In summary, this large U.S. prospective cohort study indicated that a moderate consumption of carrots was associated with a lower CRC incidence, which suggested that a certain dose-range of carrots consumed might contribute to a potential cancer-prevention effect, not the more the better.

The development of knee osteoarthritis and serum carotenoid levels among community-dwelling people in Japan

OBJECTIVES

Carotenoids are plant pigments found in many vegetables, functioning as antioxidants scavenging singlet molecular oxygen and peroxyl radicals. No longitudinal study exists on the relationship between carotenoids and knee osteoarthritis (KOA) development. We aimed to determine the incidence of KOA development for 10 years in community-dwelling people in Japan and assess its association with serum carotenoids.

METHODS

Data of 440 participants (174 men, 266 women) with health-screening records for at least 10 years were analysed. We defined KOA development as advancing from K/L grade 0/1 at the initial check-up to grade ≥2 in a unilateral knee during a 10-year follow-up period. Serum carotenoid levels were measured using high-performance liquid chromatography. We used the Cox hazard model for multivariate analysis and investigated each carotenoid's impact on KOA development.

RESULTS

KOA developed in 33.4% of patients; the annual KOA development rate was significantly higher among women than among men (p < .01; 3.4% vs. 1.6%). Among the carotenoids measured, only retinol was associated with KOA development in women using multivariable analysis. KOA development was not associated with any carotenoids in men.

CONCLUSION

The annual rate of KOA development was higher in women, and retinol was associated with KOA development in women.

Serum carotenoids and colorectal cancer risk: A case-control study in Guangdong, China

SCOPE

Previous epidemiological studies on the association between circulating carotenoids and the risk of colorectal cancer drew inconclusive conclusions. This study aimed to examine serum carotenoids in relation to colorectal cancer risk in a Chinese population.

METHODS AND RESULTS

One case-control study beginning from July 2010, consecutively recruited 538 eligible colorectal cancer cases and 564 age (5-year interval) and sex frequency-matched controls. Serum levels of α-carotene, β-carotene, β-cryptoxanthin, lycopene and lutein/zeaxanthin were detected by HPLC. Unconditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence internal (CI) after adjusting for various confounders. Serum levels of α-carotene, β-cryptoxanthin and lycopene were found to be inversely associated with colorectal cancer risk. The adjusted ORs of the highest quartile relative to the lowest quartile serum level were 0.49 (95% CIs 0.33-0.72) for α-carotene, 0.44 (95% CIs 0.29-0.66) for β-cryptoxanthin, and 0.36 (95% CIs 0.24-0.54) for lycopene, respectively. The association between serum β-carotene, lutein/zeaxanthin and colorectal cancer risk was not statistically significant.

CONCLUSION

The results indicated that the incidence of colorectal cancer was associated with lower serum levels of α-carotene, β-cryptoxanthin and lycopene among Chinese population residing in Guangdong.

Mediterranean diet and colorectal cancer: A systematic review

Colorectal cancer is the third most common cancer worldwide, especially in developed countries where an estimated 60% of all cases occur. There is evidence of a higher risk for CRC in Western society, where people tend to eat more red and processed meat than those living along the Mediterranean coast, who have a decreased overall cancer mortality, which is correlated to their eating habits, such as Mediterranean diet. The aim of this review was to evaluate the correlation between three components of the Mediterranean diet (olive oil, red wine, and tomatoes) and incidence and progression of colorectal cancer. As such, we conducted a literature search using keywords "colorectal cancer," "dietary pattern," "Mediterranean diet," "olive oil," "protective effects," "resveratrol," and "lycopene." Olive oil polyphenols, red wine resveratrol, and tomato lycopene showed several characteristics in vitro that interfere with molecular cancer pathways. At the same time, many clinical studies have reported an association of these components with a reduction in cancer initiation and progression. More clinical studies are needed to identify the precise dose and administration of single agents or their combination to produce a coadjutant treatment to those already applied in chemoprevention and oncologic treatment.

Comparison of plasma levels of nutrient-related biomarkers among Japanese populations in Tokyo, Japan, São Paulo, Brazil, and Hawaii, USA

Previous studies of Japanese migrants have suggested that the increase in colorectal cancer rates occurring after migration is slower among Japanese Brazilians than among Japanese Americans. We hypothesized that this difference may partly reflect differences in vegetable and fruit intake between the populations. Using data from validation studies of food frequency questionnaires being used in comparative case-control studies of colorectal adenoma in Tokyo, São Paulo, and Hawaii, plasma carotenoid, retinol, tocopherol, and coenzyme Q10 levels were measured by high-performance liquid chromatography, and 25-hydroxy vitamin D levels were estimated by enzyme-linked immunosorbent assay. Plasma levels were compared by analysis of covariance between 142 Japanese in Tokyo, 79 Japanese Brazilians in São Paulo, and 78 Japanese Americans in Hawaii. Overall, we found significantly lower plasma carotenoid levels, except for lycopene levels, and retinol levels in Japanese Americans compared with Japanese in Tokyo and Japanese Brazilians. The plasma total carotenoid level was highest in Japanese Brazilians. Compared with the mean level among Japanese Brazilians (1741.2 ng/ml), P for difference was 0.03 among Japanese in Tokyo (1514.4 ng/ml) and less than 0.01 for Japanese Americans (1257.7 ng/ml). Plasma lycopene and tocopherol levels did not substantially differ between the three populations. We also found significantly lower plasma levels of 25-hydroxy vitamin D and total coenzyme Q10 in Japanese in Tokyo than in Japanese Americans and Japanese Brazilians. Higher levels of plasma carotenoids among Japanese Brazilians than among Japanese in Tokyo and Hawaii may have contributed to the slower pace of the increase in colorectal cancer rates observed in that population after migration.

Plasma and dietary carotenoids and vitamins A, C and E and risk of colon and rectal cancer in the European Prospective Investigation into Cancer and Nutrition

Carotenoids and vitamins A, C and E are possibly associated with a reduced colorectal cancer (CRC) risk through antioxidative properties. The association of prediagnostic plasma concentrations and dietary consumption of carotenoids and vitamins A, C and E with the risk of colon and rectal cancer was examined in this case-control study, nested within the European Prospective Investigation into Cancer and Nutrition study. Plasma concentrations of carotenoids (α- and β-carotene, canthaxanthin, β-cryptoxanthin, lutein, lycopene, zeaxanthin) and vitamins A (retinol), C and E (α-, β- and γ- and δ-tocopherol) and dietary consumption of β-carotene and vitamins A, C and E were determined in 898 colon cancer cases, 501 rectal cancer cases and 1,399 matched controls. Multivariable conditional logistic regression models were performed to estimate incidence rate ratios (IRR) and corresponding 95% confidence intervals (CIs). An association was observed between higher prediagnostic plasma retinol concentration and a lower risk of colon cancer (IRR for highest quartile = 0.63, 95% CI: 0.46, 0.87, p for trend = 0.01), most notably proximal colon cancer (IRR for highest quartile = 0.46, 95% CI: 0.27, 0.77, p for trend = 0.01). Additionally, inverse associations for dietary β-carotene and dietary vitamins C and E with (distal) colon cancer were observed. Although other associations were suggested, there seems little evidence for a role of these selected compounds in preventing CRC through their antioxidative properties.

Plasma carotenoids and retinol and overall and breast cancer risk: a nested case-control study

Experimental studies suggest that carotenoids and retinol may play a role in carcinogenesis, but epidemiological evidence is lacking. We investigated the prospective associations between plasma concentrations of major carotenoids and retinol, and overall and breast cancer risk. A nested case-control study included all first incident cancer cases diagnosed in the SU.VI.MAX cohort between 1994 and 2002 (n = 159 cases, 1 matched control/case). Baseline plasma concentrations of carotenoids and retinol were measured by high-performance liquid chromatography. Conditional logistic regression was used to assess odds ratios for an increase of 0.1 μmol/L [odds ratio (OR)] and 95% confidence intervals (CI). Plasma β-carotene (OR = 0.95, 95% CI = 0.90-0.99, Ptrend = 0.04) and β-cryptoxanthin concentrations (OR = 0.89, 95% CI = 0.81-0.99, Ptrend = 0.03) were inversely associated with overall cancer risk. Plasma β-cryptoxanthin concentration was inversely associated with breast cancer risk (OR = 0.83, 95% CI = 0.71-0.96, Ptrend = 0.02). The OR between plasma lycopene concentration and overall cancer risk was 1.07 (0.99-1.15), Ptrend = 0.06. This association turned significant (Ptrend = 0.01) when excluding cancer cases diagnosed during the first year of follow-up. This prospective study suggests an inverse association between plasma concentrations of β-cryptoxanthin and both overall and breast cancer risk, and an inverse association between β-carotene and overall cancer risk. The direct association between lycopene concentration and cancer risk deserves further investigation.

Inverse associations between serum concentrations of zeaxanthin and other carotenoids and colorectal neoplasm in Japanese

BACKGROUND

To investigate the associations between serum concentrations of carotenoids and the presence of colorectal polyps and cancers in Japanese using a cross-sectional study.

METHODS

893 subjects who underwent colorectal endoscopy between 2001 and 2002 provided serum samples and information on lifestyle factors. Serum concentrations of six carotenoids were compared among patients with polyps, cancers, and controls.

RESULTS

In males, high serum zeaxanthin was associated with decreased rates of polyps [odds ratio (OR) = 0.48, 95 % confidence interval (CI) 0.27-0.87] and cancer (OR = 0.35, 95 % CI 0.12-1.06), adjusting for age, body mass index, serum cholesterol, smoking status, and alcohol intake. In females, zeaxanthin (OR = 0.25, 95 % CI 0.07-0.82), lutein (OR = 0.30, 95 % CI 0.10-0.94), alpha-carotene (OR = 0.30, 95 % CI 0.10-0.90), and beta-carotene (OR = 0.27, 95 % CI 0.09-0.85) showed significant inverse associations with cancer development. These associations were consistent with findings of inverse associations between the ingestion of green-yellow vegetables (OR = 0.44, 95 % CI 0.23-0.84), carrots and pumpkins (OR = 0.46, 95 % CI 0.25-0.86), and fruits (OR = 0.53, 95 % CI 0.30-0.94) and polyp in males, and between carrots and pumpkins (OR = 0.30, 95 % CI 0.09-0.99), legumes (OR = 0.14, 95 % CI 0.04-0.44), and seaweed (OR = 0.23, 95 % CI 0.07-0.75) and cancer development in females.

CONCLUSIONS

These results provide further support for the protective effects of carotenoids contained in green-yellow vegetables and fruits against colorectal neoplasm in Japanese.

Phytochemicals and cancer risk: a review of the epidemiological evidence

A number of epidemiological studies have investigated associations between various phytochemicals and cancer risk. Phytoestrogens and carotenoids are the two most commonly studied classes of phytochemicals; phytosterols, isothiocyanates, and chlorophyll also have been investigated, although to a much lesser extent. Because there have been no systematic reviews of the literature on all phytochemicals and cancer risk to date, this article systematically reviews 96 published epidemiological studies that examined associations between phytochemicals and cancer risk. Most studies found null associations between individual phytochemicals and cancer risk at various sites. In addition, results from past studies have been largely inconsistent, and observed associations have been of relatively modest magnitude. The most consistent protective effects were observed for higher levels--dietary intake, serum, plasma, or urinary metabolites--of β-carotene and renal cell cancer, β-cryptoxanthin and lung cancer, isothiocyanates and lung cancer, isothiocyanates and gastrointestinal cancer, lignans and postmenopausal breast cancer, and flavonoids and lung cancer. Although elevated risk of certain cancers with higher levels of certain phytochemicals was observed, an insufficient pool of studies examining the same associations or inconsistent findings across studies limit the ability to conclude that any one phytochemical increases cancer risk. Additional research is needed to support previously identified associations in cases where only one study has examined a particular relationship. Importantly, continued research efforts are needed to evaluate the cumulative and interactive effects of numerous phytochemicals and phytochemical-rich foods on cancer risk.

Effect of clinical condition and mycophenolate mofetil on plasma retinol, α-tocopherol and β-carotene in renal transplant recipients

INTRODUCTION

Plasma antioxidant vitamins (retinol, α-tocopherol, β-carotene) were measured to establish the influence of clinical condition and mycophenolate mofetil (MMF) treatment on the nutritional status of renal transplant recipients.

MATERIAL AND METHODS

In 106 adult patients plasma vitamins were measured and 24-h diet history questionnaires were conducted. The MMF influence on plasma vitamins was verified in 61 patients.

RESULTS

The current dietary intakes of vitamins in daily food rations were lower than recommended. Plasma retinol was lower in patients suffering from gastrointestinal disorders (1.25 ±0.48 mg/l vs. 1.55 ±0.70 mg/l) and inversely associated with aminotransferases activity (p = 0.019) and creatinine clearance (p = 0.021). Retinol concentrations were positively associated with plasma creatinine (p = 0.027) and pharmacokinetic parameters of MMF phenyl glucuronide. β-Carotene concentrations were higher in women (0.39 ±0.46 mg/l vs. 0.28 ±0.23 mg/l; p = 0.041) and when MMF was co-administered with cyclosporine vs. tacrolimus (0.45 ±0.62 mg/l vs. 0.25 ±0.19 mg/l). Plasma α-tocopherol correlated negatively with the mycophenolic acid pre-dose concentration (p = 0.027) and was significantly lower in patients treated with calcineurin inhibitors (8.90 ±5.23 mg/l vs. 12.25 ±5.62 mg/l). A positive correlation was observed between α-tocopherol levels and aspartate aminotransferase (p = 0.006). In multivariate regression aspartate aminotransferase and MMF treatment significantly influenced retinol (p < 0.001).

CONCLUSIONS

The MMF treatment was associated with significantly lower retinol concentrations. The gastrointestinal disorders occurrence in MMF-treated patients may cause a decrease in retinol absorption. Diet adjustment and/or vitamin A supplementation should be considered.

The effect of β-carotene on lumbar osteophyte formation

STUDY DESIGN

Cross-sectional cohort study of elderly people.

OBJECTIVE

The relationships of osteophyte formation on plain lumbar radiographs with serum levels of antioxidants (carotenoids, vitamin A, vitamin E) and other factors were investigated to examine whether antioxidants are involved in lumbar spine degeneration.

SUMMARY OF BACKGROUND DATA

Antioxidants have inhibitory effects on the onset of many diseases. However, the association of lumbar osteophyte formation with antioxidant levels in the general population has not been investigated.

METHODS

The subjects were 286 people (103 men and 183 women; mean age = 68 years) who underwent resident health screening. Osteophyte formation on lumbar lateral radiographs (Nathan classification), lumbar lordosis angles, sacral inclination angles, serum levels of antioxidants, triglyceride levels, body mass index, osteoporosis, back muscle strength, history of alcohol intake, and smoking history were studied in these subjects.

RESULTS

Lumbar osteophyte formation was detected in 48 subjects (17%). Osteophyte formation was significantly more common in elderly persons, men, and subjects with a history of alcohol intake; and had a significant correlation with sacral inclination angle. The levels of α-tocopherol, β-tocopherol, zeaxanthin/lutein, cryptoxanthin, lycopene, α-carotene, and β-carotene were significantly lower in subjects with osteophytes. Logistic regression analysis adjusted for all factors showed that a higher age (odds ratio [OR] = 1.1, 95% confidence interval [CI] = 1.02-1.16; P = 0.02) and a low β-carotene level (OR = 6.7, 95% CI = 1.39-32.6; P = 0.02) were risk factors for osteophyte formation.

CONCLUSION

The serum levels of carotenoids and vitamin E were significantly lower in subjects with lumbar osteophyte formation, and a low β-carotene level was the strongest risk factor for lumbar osteophytes. This is the first evidence of an association between carotenoids and lumbar osteophyte formation. This finding suggests that appropriate dietary intake of antioxidants is important for inhibition of lumbar spine degeneration in a rapidly aging society.

A carotenoid health index based on plasma carotenoids and health outcomes

While there have been many studies on health outcomes that have included measurements of plasma carotenoids, this data has not been reviewed and assembled into a useful form. In this review sixty-two studies of plasma carotenoids and health outcomes, mostly prospective cohort studies or population-based case-control studies, are analyzed together to establish a carotenoid health index. Five cutoff points are established across the percentiles of carotenoid concentrations in populations, from the tenth to ninetieth percentile. The cutoff points (mean ± standard error of the mean) are 1.11 ± 0.08, 1.47 ± 0.08, 1.89 ± 0.08, 2.52 ± 0.13, and 3.07 ± 0.20 µM. For all cause mortality there seems to be a low threshold effect with protection above every cutoff point but the lowest. But for metabolic syndrome and cancer outcomes there tends to be significant positive health outcomes only above the higher cutoff points, perhaps as a triage effect. Based on this data a carotenoid health index is proposed with risk categories as follows: very high risk: <1 µM, high risk: 1-1.5 µM, moderate risk: 1.5-2.5 µM, low risk: 2.5-4 µM, and very low risk: >4 µM. Over 95 percent of the USA population falls into the moderate or high risk category of the carotenoid health index.

Influence of observational study design on the interpretation of cancer risk reduction by carotenoids

Recently published literature has been reviewed to determine whether lycopene, beta-carotene, alpha-carotene, and beta-cryptoxanthin are associated with reductions in cancer risk and whether study findings differ by study design. A total of 57 publications meeting pre-defined inclusion and exclusion criteria were identified, with the majority (55) being observational studies. None of the intervention studies supported a significant reduction in cancer risk with carotenoid (beta-carotene) supplementation. The majority of observational studies did not support significant reductions in cancer risk with increased carotenoid dietary intakes/circulating levels. A larger percentage of case-control studies supported significant associations between increased dietary intakes/circulating levels of carotenoids relative to prospective (cohort and nested case-control) studies. Compared to prospective studies, case-control studies cannot be used to establish temporality and may be more susceptible to selection and recall biases. Thus, diet-disease relationships suggested by case-control studies should ideally be confirmed by additional evidence from prospective studies.

Trends in dietary intakes of vitamins A, C and E among Japanese men and women from 1974 to 2001

OBJECTIVE

To investigate long-term trends in dietary intakes of vitamins A, C and E in Japanese adults.

DESIGN

Time series by community-based nutrition survey.

SETTING

Two rural communities (Ikawa and Kyowa) between 1974 and 2001 in Japan.

SUBJECTS

A total of 3713 men and 3726 women aged 40-69 years.

METHODS

Dietary intake data were collected by the 24 h dietary recall.

RESULTS

In Ikawa, mean intake of vitamin A (beta-carotene and retinol) increased by 13-40%; vitamins C and E increased by approximately 23-33% among men and women from 1974-1977 to 1998-2000. In Kyowa, mean intake of vitamin A, primarily retinol, increased by 13-21% among men and women; vitamin C from fruits decreased by 16% among men; and vitamin E increased by 29% among women from 1982-1986 to 1998-2001. Mean intake of vitamin E in the latest survey period was lower than the Adequate Intake among men and women in both communities. Generally, there were increased intakes of beta-carotene and vitamin C from green/yellow and other vegetables; increased retinol intake from fish/shellfish, eggs, milk/dairy products and fats/oils; and increased vitamin E intake from green/yellow and other vegetables, fish/shellfish, eggs, milk/dairy products and fats/oils.

CONCLUSIONS

Mean intakes of the antioxidant vitamins A, C and E increased among middle-aged Japanese men and women between the 1970s and the 1990s except for decreased vitamin C among Kyowa men. The lower mean intake of vitamin E than the Adequate Intake should be considered a potential public health issue for the prevention of CVD.

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Association of Serum Carotenoid Concentration and Dietary Habits among the JACC Study Subjects

BACKGROUND: We wished to determine the validity of the association between serum carotenoid concentrations and dietary habits obtained from a food frequency questionnaire in the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho).

METHODS: The subjects were 866 male and 569 female controls in nested case-control studies for evaluating the risk of lung, colorectal, and urothelial cancers as parts of the JACC Study. Dietary habits were assessed using a food frequency questionnaire, and serum samples were obtained at baseline. Serum carotenoid concentrations of frozen-stored sera were measured and compared with the results of the survey.

RESULTS: In males, consumption of dairy products, some oily foods, vegetables, fruits, and boiled beans correlated positively with serum carotenoid concentrations, whereas ingestion of boiled rice and sansai (edible wild plants) was negatively correlated with serum carotenoids. In females, only fruit consumption was positively correlated with serum carotenoid concentration, whereas ingestion of butter, sansai, and potatoes were negatively correlated. Some specific associations, between serum lycopene and tomato consumption and between serum β-cryptoxanthin and ingestion of oranges, were observed in both sexes.

CONCLUSIONS: In males, serum carotenoid concentrations were slightly associated with intake of foods rich in carotenoids. The lack of associations in females suggests that the food frequency questionnaire did not validly evaluate females’ dietary habits concerning carotenoids in the JACC Study.