Dietary carotenoids and risk of colon cancer: case-control study

Effect Modification of Selenium Supplementation by Intake and Serum Concentrations of Antioxidants on the Development of Metachronous Colorectal Adenoma

BACKGROUND

Selenium (Se) is a trace element that has been investigated as a potential chemopreventive agent for colorectal cancer. Dietary intake of other antioxidant nutrients may modify the effect of Se.

OBJECTIVE

We examined the association between intake and serum concentrations of retinol, β-carotene, β-cryptoxanthin, lycopene, lutein/zeaxanthin, and α- and γ-tocopherol and the development of metachronous colorectal adenoma, and if these nutrients modified the effect of Se.

METHODS

We conducted a prospective study of 1874 participants from the Se Trial with data for antioxidant intake, as well as a subcohort of 508 participants with serum biomarker concentrations.

RESULTS

Statistically significantly lower odds for the development of metachronous adenoma were observed for those participants in the highest tertile of intake for lutein/zeaxanthin compared to the lowest, with an OR (95% CI) of 0.72 (0.56-0.94). No effect modification for intake of any nutrient was observed. However, circulating concentrations of lycopene exhibited statistically significant effect modification of selenium supplementation (p < 0.06).

CONCLUSION

These findings show that intake and circulating concentrations of antioxidant nutrients were not consistently associated with reduced odds for the development of metachronous lesions, although blood concentrations of lycopene may modify the effect of selenium supplementation.

Association between dietary intake of fatty acids and colorectal cancer, a case-control study

Background

The association of dietary fat and colorectal cancer (CRC) was frequently reported. However, few studies assessed the effects of different types of dietary fats on CRC. This study aimed to investigate the association between intakes of different types of dietary fatty acids with colorectal cancer risk.

Methods

This case-control study was conducted on 480 participants including 160 CRC cases and 320 healthy controls in Firoozgar Hospital, Tehran, Iran. The intake of dietary fatty acids of the participants was assessed using a semi quantitative food frequency questionnaire (FFQ).

Results

The mean intake of cholesterol (273.07 ± 53.63 vs. 254.17 ± 61.12, P = 0.001), polyunsaturated fatty acids (PUFA) (16.54 ± 4.20 vs. 15.41 ± 4.44, P = 0.012), and calorie (2,568.76 ± 404.48 vs. 2,493.38 ± 176.03, P = 0.006) was higher and the mean intake of oleic acid (5.59 ± 3.17 vs. 8.21 ± 5.46) and linoleic acid (6.03 ± 3.44 vs. 7.02 ± 4.08, P = 0.01) was lower in the case group compared to the control group. An inverse association was found between colorectal cancer (CRC) and dietary intake of oleic acid (OR: 0.85, CI 95% 0.80–0.90, P = 0.001), linoleic acid (OR: 0.85, CI 95% 0.78–0.93, P = 0.001), and α-linolenic acid (OR: 0.75, CI 95% 0.57–0.98, P = 0.04). The association remained significant after adjusting for age and sex, sleep, smoking, and alcohol consumption, and BMI.

Conclusions

The results of this study support a protective effect of oleic acid, linoleic acid, and α-linolenic acid against CRC. Further longitudinal studies are warranted to confirm these results.

Capsanthin induces death in human prostate cancer cell lines by inducing DNA damage

There is a relationship between a person’s diet and the development and prevention of some cancers. Carotenoids are found as various natural pigments in many fruits and vegetables. Studies on carotenoids and their potential roles in carcinogenesis are increasing in importance day by day. In this study, we aimed to determine the cytotoxic and genotoxic effects of capsanthin, a carotenoid compound, in human prostate cancer cell lines.

After different concentrations of capsanthin were applied to human prostate cancer cell lines (LNCaP and PC-3), the effects of the compound on cell viability were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. The single-cell gel electrophoresis (Comet) assay was then used to reveal the genotoxic effects of probable cytotoxic dosages on cell DNA. After the treatments, apoptotic cell death levels were determined by Tunel staining. At high concentrations, capsanthin dramatically reduced PC-3 and LNCaP cell viability (p<0.05). In addition, capsanthin caused DNA damage and apoptotic cell death in the prostate cancer cells. The results show that capsanthin reduces cell viability by causing genotoxicity in prostate cancer cells.

Association of Retinol and Carotenoids Content in Diet and Serum With Risk for Colorectal Cancer: A Meta-Analysis

Background

Colorectal cancer (CRC) risk is linked to serum and dietary retinol and carotenoids, according to clinical and epidemiological research. However, the findings are not consistent. As a result, we did this meta-analysis to determine the link between them.

Methods

From 2000 through 2022, the PubMed, Web of Science, and Embase databases, as well as pertinent article references, were searched and filtered based on inclusion and exclusion criteria and literature quality ratings. High and low intake were used as controls, and OR (odds ratio) or RR (relative risk) and 95% confidence interval were extracted. The extracted data were plotted and analyzed using Stata12.0 software.

Results

A total of 22 relevant studies were included, including 18 studies related to diet and 4 studies related to serum. For high and low intake or concentration controls, the pooled OR was as follows: β-carotene (OR = 0.89, 95% CI: 0.78–1.03), α-carotene (OR = 0.87, 95% CI: 0.72–1.03), lycopene (OR = 0.93, 95% CI: 0.81–1.07), lutein/zeaxanthin (OR = 0.96, 95% CI: 0.87–1.07), β-cryptoxanthin (OR = 0.70, 95% CI: 0.48–1.01), total carotenoids (OR = 0.97, 95% CI: 0.81–1.15), retinol (OR = 0.99, 95% CI: 0.89–1.10), serum carotenoids (OR = 0.73, 95% CI: 0.58–0.93), serum retinol (OR = 0.62, 95% CI: 0.26–1.49). Subgroup analysis was performed according to tumor type, study type and sex.

Conclusion

Total carotenoid intake and Lutein/Zeaxanthin intake were not associated with CRC risk. High β-carotene, α-carotene, lycopene, and β-cryptoxanthin all tended to reduce CRC risk. Serum carotenoid concentrations were significantly inversely associated with CRC risk.

The association among calorie, macronutrient, and micronutrient intake with colorectal cancer: A case-control study

The risk of colorectal cancer (CRC) can be influenced by dietary components. This study aims to investigate the association between dietary intake and CRC in Iranian adults. This hospital‐based case–control study was performed on 160 patients with CRC and 320 healthy people. General and pathological data were collected through face‐to‐face interviews. A validated food frequency questionnaire (FFQ) was used to assess the intake of calories, macronutrients, and micronutrients. The case group had a significantly higher intake of calories, carbohydrates, vitamin A, vitamin K, fluoride, and molybdenum and a lower intake of vitamin E, vitamin B1, beta carotene, biotin, folate, magnesium, selenium, manganese, and fiber (all p < .001). CRC was positively associated with the intake of carbohydrate (OR: 1.01, CI% 1.03–1.01, p = .001), and vitamin A (OR: 1.009, CI 95% 1.006–1.01, p = .001) and negatively associated with intake of fiber (OR: 0.67, CI 95% 0.59–0.76, p = .001), beta carotene (OR: 0.99, CI 95% 0.99–0.99, p = .001), vitamin E (OR: 0.27, CI 95% 0.15–0.47, p = .001), folate (OR: 0.98 CI 95% 0.97–0.98, p = .001), and biotin (OR: 0.83, CI 95% 0.77–0.90, p = .001). The associations remained significant after adjusting for age and sex. Further adjustments for physical activity, alcohol consumption, and smoking did not change the results. The results identified that the risk of colorectal cancer can be influenced by dietary intake. Further longitudinal studies are needed to confirm these findings and to identify the underlying mechanisms of the effects of dietary components on the risk of colorectal cancer.

Ethanol Extract of Eryngium Foetidum Leaves Induces Mitochondrial Associated Apoptosis via ROS Generation in Human Gastric Cancer Cells

Background: Eryngium foetidum has long been used as a food ingredient and folk medicine in tropical regions. The anticancer activity of EF extract and the mechanisms remains unclear. Herein, we prepared four solvent extracts of EF leaves, detected the cytotoxic effects, and explored the potential mechanism by which these extracts induce cell death. Methods: The anticancer activity of the EF extracts was measured by MTT, CCK-8 and BrdU assays. The cell cycle was evaluated by flow cytometry and western blot. Apoptotic events were investigated with Hoechst, Annexin V/PI assays and western blot. The mitochondrial membrane potential was monitored using JC-1 staining, and ROS production was assessed with immunofluorescence. Results: The ethanol extract of EF leaves exhibited the strongest cytotoxic effect against SGC-7901 cells. The EFE extract significantly inhibited the SGC-7901 cells viability, arrested the cell cycle, increased the numbers of apoptotic cells, caused the loss of MMP, increased the Bax/Bcl-2 ratio, and led to cytochrome c release, and triggered ROS production. Conclusion: Our findings demonstrated for the first time that EFE extract induces mitochondrial associated apoptosis via ROS generation in SGC-7901 cells. Thus, EFE extract could be identified as a potential edible phytotherapy for the treatment of human gastric cancer.

The Benefits and Risks of Certain Dietary Carotenoids that Exhibit both Anti- and Pro-Oxidative Mechanisms-A Comprehensive Review

Carotenoid pigments, particularly β-carotene and lycopene, are consumed in human foodstuffs and play a vital role in maintaining health. β-carotene is known to quench singlet oxygen and can have strong antioxidant activity. As such, it was proposed that β-carotene might reduce the risk of cancer. Epidemiological studies found inverse relationships between cancer risk and β-carotene intake or blood levels. However, clinical trials failed to support those findings and β-carotene supplementation actually increased lung cancer incidence in male smokers. Early experimental animal studies found dietary β-carotene inhibited UV-induced skin cancers. Later studies found that β-carotene supplementation exacerbated UV-carcinogenic expression. The discrepancies of these results were related to the type of diet the animals consumed. Lycopene has been associated with reduced risk of lethal stage prostate cancer. Other carotenoids, e.g., lutein and zeaxanthin, play a vital role in visual health. Numerous studies of molecular mechanisms to explain the carotenoids' mode of action have centered on singlet oxygen, as well as radical reactions. In cellular systems, singlet oxygen quenching by carotenoids has been reported but is more complex than in organic solvents. In dietary β-carotene supplement studies, damaging pro-oxidant reactivity can also arise. Reasons for this switch are likely due to the properties of the carotenoid radicals themselves. Understanding singlet oxygen reactions and the anti-/pro-oxidant roles of carotenoids are of importance to photosynthesis, vision and cancer.

Carotenoid intake from natural sources and colorectal cancer: a systematic review and meta-analysis of epidemiological studies

Carotenoid intake from natural sources has been hypothesized to reduce the risk of colorectal cancer (CRC). The aim of this study was to systematically review the epidemiological evidence for the association between carotenoid intake from natural sources and CRC development. We carried out a systematic review and meta-analysis of epidemiological studies to investigate whether the intake of specific carotenoids from natural sources, as well as combined carotenoids, is associated with the risk of CRC overall and by anatomic subsite. A comprehensive literature search of MEDLINE and Scopus databases was performed. Twenty-two articles were identified from the literature search, of which 16 were case-control studies and 6 were cohort studies. In the random-effects meta-analysis of case-control and cohort studies, we found no association between the intake of individual and total carotenoids and the risk of CRC overall and by anatomic subsite. Overall, our findings do not support a significant association between intake of specific carotenoids from dietary sources, as well as combined carotenoids, and the risk of CRC overall and by anatomic subsite.

Chemopreventive Effects of Eryngium foetidum L. Leaves on COX-2 Reduction in Mice Induced Colorectal Carcinogenesis

To investigate the potential effects of Eryngium foetidum Linn. leaves (EF) in colitis-induced colorectal carcinogenesis in mice by azoxymethane (AOM) and dextran sulfate sodium (DSS), 39 ICR male mice were studied and divided into 6 groups. The mice were received a modified AIN-76 diet in Group 1, whereas Group 2 was given an AOM, DSS, and AIN-76 diet. Groups 3 and 4 were fed with 0.8% and 3.2% freeze-dried EF with AIN-76 diets, for 5 wk. Groups 5 and 6 were fed with 0.8% and 3.2% EF diets for 5 wk during AOM/DSS administration. The mice were necropsied at Week 20 and their colons were collected. The results indicated that the incidences of tumors in Groups 2, 5, and 6 was 100%, 75%, and 88%, with multiplicities (mean ±SE) of 3.75 ±0.92, 2.38 ± 0.96 and 4.25 ± 0.79, respectively. Interestingly, there was a significant difference in COX-2 expression in mice received 3.2% EF in their diet, but the proliferative cell nuclear antigen index and iNOS protein expression were not significantly different. We concluded that EF at a dose level of 3.2% in their diet had a preventive effect on colorectal carcinogenesis via the proinflammatory cytokine, COX-2.

Effects of smoking and antioxidant micronutrients on risk of colorectal cancer

BACKGROUND & AIMS

Antioxidant intake has been reported to increase the risk of colorectal cancer (CRC) for smokers, yet reduce the risk for nonsmokers. We investigated the association between tobacco smoking and risk of colon or rectal cancer, and whether dietary and supplemental intake of the antioxidant vitamins A, C, E, β-carotene, selenium, zinc, and manganese affects the risk of CRC among smokers.

METHODS

Data on smoking habits and antioxidant intake were analyzed for 54,208 participants in the Danish Prospective Diet, Cancer and Health Study. Of these participants, 642 were diagnosed with colon cancer and 348 were diagnosed with rectal cancer. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazard models. Principal components were used to analyze intake of combinations of antioxidants.

RESULTS

Ever smoking increased the risk for CRC (hazard ratio, 1.19; 95% confidence interval, 1.03-1.37), especially for rectal cancer. Smoking for at least 20 years was associated with a 26% increase in risk of CRC, compared with never smokers, and smoking 20 g tobacco or more each day was associated with a 30% increase in risk. Smoking for more than 30 years, or more than 20 g tobacco each day, was associated with a 48% increase in risk of rectal cancer. We did not observe an interaction between smoking and antioxidant consumption on risk of CRC.

CONCLUSIONS

Tobacco smoking increases the risk for CRC. We did not observe that consumption of antioxidant micronutrients modulates the effects of smoking on CRC risk.

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.

Fruit and vegetable consumption is inversely associated with having pancreatic cancer

OBJECTIVE

Studies on fruit, vegetable, fiber, and grain consumption and pancreatic cancer risk are inconclusive. We used a clinic-based case-control study specifically designed to address limitations of both cohort and case-control studies to examine the relationship.

METHODS

Participants were excluded who reported changing their diet within 5 years prior to study entry. And 384 rapidly ascertained cases and 983 controls (frequency matched on age (±5 years), race, sex, and residence) completed epidemiologic surveys and 144-item food frequency questionnaires. Odds ratios (OR) and 95% confidence intervals were calculated using logistic regression adjusted for age, sex, smoking, body mass index, energy intake, and alcohol consumption.

RESULTS

Comparing highest to lowest quintiles, we observed significant inverse associations (OR < 0.8) with significant trends (p (trend) < 0.05) for citrus, melon, and berries, other fruits, dark green vegetables, deep yellow vegetables, tomato, other vegetables, dry bean and pea, insoluble fiber, soluble fiber, whole grains, and orange/grapefruit juice, and an increased association with non-whole grains. Results were similar after adjusting for diabetes or total sugar intake.

CONCLUSIONS

We provide evidence that lower consumption of fruits, vegetables, whole grains, and fiber is associated with having pancreatic cancer. This may have a role in developing prevention strategies.

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.

Smoking attenuates the negative association between carotenoids consumption and colorectal cancer risk

OBJECTIVES

Consumption of vegetables and fruits, physical activity, obesity and caloric intake are all strongly related to the risk of colorectal cancer (CRC). The association between dietary intake of carotenoids from vegetables/fruits and risk of CRC in the context of cigarette smoking was studied in a nutritionally diverse population.

METHODS

The study included 1,817 age sex residence-matched case-control pairs from a population-based study in Northern Israel. Data were acquired by food-frequency questionnaire. Individual intake of carotenoid isomers was calculated using an Israeli food content database. Odds ratios (ORs) were calculated using conditional logistic regression models adjusted for known risk factors.

RESULTS

Strong inverse associations were found with consumption of 9-cis-beta-carotene (OR = 0.35, 0.26-0.47), all-trans-beta-carotene (OR = 0.58, 0.44-0.76), cis-beta-cryptoxanthin (OR = 0.67, 0.50-0.90), all-trans-zeaxanthin (OR = 0.64, 0.48-0.86), and lutein (OR = 0.74, 0.57-0.96). Lycopene (OR = 2.22, 1.71-2.89) and all-trans-beta-cryptoxanthin (OR = 2.01, 1.48-2.73) were associated with increased risk of CRC. Inverse associations of most carotenoids with CRC, demonstrated in non-smokers, were much attenuated or reversed in past or current smokers with a highly significant interaction term.

CONCLUSIONS

Consumption of most dietary carotenoids was found to be strongly associated with reduced risk of CRC. However, smoking significantly attenuated or reversed this observed protective effect on CRC occurrence. Smokers should be advised that smoking also hampers the potential health promoting effects of high fruit and vegetable consumption.

Carotenoid intake and colorectal cancer risk: the multiethnic cohort study

Background

A protective effect of fruits and vegetables against colorectal cancer has been supported by many epidemiologic studies. This suggests that the carotenoids frequently found in these foods play a role in the prevention of this common cancer. To examine associations between the intake of individual and total carotenoids and the risk of colorectal cancer, we analyzed prospective data from the Multiethnic Cohort Study.

Methods

This analysis includes 85 898 men and 105 106 women who completed a quantitative food frequency questionnaire in 1993–1996. The participants were African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites aged 45–75 years at cohort entry. After an average follow-up of 8.2 years, 1292 and 1086 incident cases of colorectal cancer were identified in men and women, respectively. Cox proportional hazard models were used to estimate relative risks of colorectal cancer.

Results

No significant associations were found between intake of individual and total carotenoids and colorectal cancer risk either in men or women, except for β-cryptoxanthin, which showed a mild protective effect in men. When the associations were investigated separately for colon and rectal cancer, lycopene intake was related to an increased risk of rectal cancer in men. A decreased risk was seen for total β-carotene in male current smokers, but the test for interaction with smoking status was not significant. No association was observed in each ethnic-sex group.

Conclusion

Overall, our findings do not support a significant association between carotenoid intake and colorectal cancer, although some associations were seen in subgroup analyses.

Site specific delivery of microencapsulated fish oil to the gastrointestinal tract of the rat

The aim of this study was to design food grade matrices to deliver microencapsulated fish oil to the large bowel of the rat where the potential exists to retard inflammation and cancer development. Digestion in simulated gastric fluid and intestinal fluid demonstrated that only 4-6% of oil was released from the following dried emulsion formulations: 50% fish oil encapsulated in heated casein-glucose-dried glucose syrup (1:1:1) (Cas-Glu-DGS-50); 25% fish oil in casein-modified resistant starch (Hylon VII) (1:1) (Cas-Hylon-25); or 25% fish oil in Cas-Glu-Hylon (1:1:1) (Cas-Glu-Hylon-25). A short-term gavage study (0-12 h) with fish oil and Cas-Glu-DGS-50 demonstrated the appearance of fish oil long chain (LC) n-3 polyunsaturated fatty acids (PUFA) into the plasma indicating specific small intestinal absorption with little LC n-3 PUFA reaching the large bowel. In a 2-week-long term, daily gavage study, the bioavailability of fish oil and fish oil in Cas-Glu-DGS-50 or Cas-Hylon-25 demonstrated that fish oil and Cas-Glu-DGS-50 LC n-3 PUFA were incorporated into the tissue of the small intestine and colon, whereas Cas-Hylon-25 was resistant to degradation in the small intestine. The use of modified Hylon VII for targeted colonic delivery was confirmed in the final short-term gavage study (0-14 h) using Cas-Glu-Hylon-25 with [(14)C]-trilinolenin as a marker incorporated into the microcapsules, where up to 60% of the labeled oil reached the large bowel. Depending on the microencapsulating matrix employed, fish oil can be delivered selectively to the small intestine or to a high degree to the large bowel.

Dietary fatty acids and recurrence of colorectal adenomas in a European intervention trial

Epidemiological studies have provided inconsistent data about the role of dietary fatty acids in colorectal cancer, and few studies have addressed their role in colorectal adenoma. The aim of the study was to assess the risk of overall adenoma recurrence associated with dietary consumption of total fat, subtypes of fat, and specific fatty acids (oleic acid, linoleic acid, alpha-linolenic acid). The study sample was composed of 523 patients with confirmed adenomas at the index colonoscopy, 35 to 75 yr old, who completed the European fiber-calcium intervention trial and had an initial dietary assessment using a qualitative and quantitative food questionnaire. The overall 3-yr recurrence rate was 22.6% (118 out of 523 patients). There were no significant associations between overall adenoma recurrence and either total fat, subtypes of fat, or specific fatty acids. However, polyunsaturated fatty acids and linoleic acid were both moderately but significantly associated with distal and multiple recurrence. No significant associations were observed with recurrence of proximal or advanced adenomas. Our findings do not support the hypothesis of strong associations between dietary fatty acids and recurrence of colorectal adenomas. The hypothesis of a differential role of specific fatty acids according to colorectal subsites deserves further investigation.

Diet and vitamin or mineral supplementation and risk of colon cancer by subsite in Canada

The study assesses the association of diet and vitamin or mineral supplementation with risk of proximal or distal colon cancer. Mailed questionnaires were completed by 1723 newly diagnosed, histologically confirmed colon cancer cases and 3097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socio-economic status, physical activity, smoking habits, alcohol use, diet and vitamin or mineral supplementation. Odds ratios and 95% confidence intervals were derived through unconditional logistic regression. Linear regression was used to examine that dietary factors affect body mass index. The strongest positive associations between colon cancer risk and increasing total fat intake were observed for proximal colon cancer in men and for distal colon cancer in both men and women. Increased consumption of vegetables, fruit and whole-grain products did not reduce the risk of colon cancer. A modest reduction in distal colon cancer risk was noted in women who consumed yellow-orange vegetables. Significant positive associations were observed between proximal colon cancer risk in men and consumption of red meat and dairy products, and between distal colon cancer risk in women and total intake of meat and processed meat. We also saw strong associations between bacon intake and both subsites of colon cancer in women. When men were compared with women directly by subsite however, the results did not show a corresponding association. A significantly reduced risk of distal colon cancer was noted in women only with increasing intake of dairy products and of milk. Among men and women taking vitamin and mineral supplements for more than 5 years, significant inverse associations with colon cancer were most pronounced among women with distal colon cancer. These findings suggest that dietary risk factors for proximal colon cancer may differ from those for distal colon cancer.

Halocynthiaxanthin and Peridinin Sensitize Colon Cancer Cell Lines to Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand

Carotenoids are compounds contained in foods and possess anticarcinogenic activity. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising candidate for cancer therapeutics due to its ability to induce apoptosis selectively in cancer cells. However, some tumors remain tolerant to TRAIL-induced apoptosis. Therefore, it is important to develop agents that overcome this resistance. We show, for the first time, that certain carotenoids sensitize cancer cells to TRAIL-induced apoptosis. Combined treatment with halocynthiaxanthin, a dietary carotenoid contained in oysters and sea squirts, and TRAIL drastically induced apoptosis in colon cancer DLD-1 cells, whereas each agent alone only slightly induced apoptosis. The combination induced nuclear condensation and poly(ADP-ribose) polymerase cleavage, which are major features of apoptosis. Various caspase inhibitors could attenuate the apoptosis induced by this combination. Furthermore, the dominant-negative form of a TRAIL receptor could block the apoptosis, suggesting that halocynthiaxanthin specifically facilitated the TRAIL signaling pathway. To examine the molecular mechanism of the synergistic effect of the combined treatment, we did an RNase protection assay. Halocynthiaxanthin markedly up-regulated a TRAIL receptor, death receptor 5 (DR5), among the death receptor-related genes, suggesting a possible mechanism for the combined effects. Moreover, we examined whether other carotenoids also possess the same effects. Peridinin, but not alloxanthin, diadinochrome, and pyrrhoxanthin, induced DR5 expression and sensitized DLD-1 cells to TRAIL-induced apoptosis. These results indicate that the combination of certain carotenoids and TRAIL is a new strategy to overcome TRAIL resistance in cancer cells.

DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.

The introduction of the stilbene synthase gene enhances the natural antiradical activity of Lycopersicon esculentum mill

Tomato (Lycopersicon esculentum) is a vegetable rich in antioxidants, such as lycopene, lutein, and zeaxanthin. Their presence is responsible for the characteristic ability of this product to inhibit the formation of reactive oxygen species, including singlet oxygen. The grapes and wines derived from grapes also contain powerful antioxidants. The antioxidant effect is derived from the polyphenols such as resveratrol and proanthocyanidin. Resveratrol is phytoalexin that is synthesized via the activation of the gene, stilbene synthase (STS). We decided to determine if the introduction of this gene into Lycopersicon esculentum Mill could modify its antioxidant activity. Using Electronic Paramagnetic Resonance (EPR) spectroscopy, which permits the detection of antiradical activity, especially *OH (hydroxyl radical), we showed that the antioxidant activity of the products, into which the gene STS had been introduced, was almost double than that of natural products and that their activity was especially pronounced due to ripening. Moreover, resveratrol concentrations in modified tomatoes were much higher than that found in the individual fruit. In the isolated hearts subjected to ischemia/reperfusion, the rats fed with modified tomato exhibited better cardiac performance, reduced myocardial infarct size and decreased number of apoptotic cardiomyocytes, and reduced oxidative stress compared to unmodified tomato or resveratrol alone indicating superior cardioprotective abilities of modified tomatoes.

Modifying Cancer Risk Factors: The Gene-Environment Interaction

OBJECTIVES

To examine the concept of risk modification in the context of cancer prevention.

DATA SOURCES

Published articles and research studies on genetic and environmental factors.

CONCLUSION

How the environment is defined frames how the gene-environment interaction is studied and understood. The development of a workable model for risk modification flexible enough to be individualized for a patient is an important step in making primary prevention the goal in cancer care.

IMPLICATIONS FOR NURSING PRACTICE

Nurses working in cancer care are well placed to advise patients on risk-management strategies, and to increase public awareness of the interdependence of environment and genomics on cancer risk.

Tobacco use and associations of beta-carotene and vitamin intakes with colorectal adenoma risk

The effects of vitamins and beta-carotene on the risk of colorectal adenomas have not been fully investigated. Recent data suggest that smoking could modulate the effect of beta-carotene supplements on adenoma recurrence. We investigated the effect of dietary vitamins and beta-carotene on the risk of adenomas, and a potential interaction with smoking status as part of a case-control study of environmental factors associated with the risk of colorectal adenomas and cancers. We compared nutrient intakes in polyp-free controls (n = 427) and adenoma cases (n = 362) globally and using models stratified by smoking status, adjusted for age, sex, BMI, and energy and alcohol intakes. Folate and vitamins C and B-6 were inversely related to adenoma risk (P for trend = 0.005, 0.03, and 0.02, respectively), whereas vitamin D tended to be inversely associated with risk (P for trend = 0.05). There was a significant interaction between beta-carotene and smoking (P interaction = 0.04). In nonsmokers, beta-carotene was inversely associated with adenoma risk, especially that of colon adenomas [odds ratios (ORs) in low vs. high consumers and 95% CI 0.4 (0.2-0.9)], whereas in past or current smokers, beta-carotene was associated with a nonsignificant (P for trend = 0.19) increase in the risk of colon adenomas [corresponding OR = 1.9 (95% CI = 0.9-4.1)]. Our findings support a protective effect of folate and vitamins C and B-6 irrespective of smoking habits, and a protective effect of beta-carotene in nonsmokers only. They suggest an adverse effect of beta-carotene in smokers, who should be cautious about taking high doses of this micronutrient.

Dual Association of beta-carotene with risk of tobacco-related cancers in a cohort of French women

BACKGROUND

Intervention studies have demonstrated that, in smokers, beta-carotene supplements had a deleterious effect on risk of lung cancer and may have a deleterious effect on digestive cancers as well. We investigated a potential interaction between beta-carotene intake and smoking on the risk of tobacco-related cancers in women.

METHODS

A total of 59,910 women from the French Etude Epidémiologique de Femmes de la Mutuelle Générale de l'Education Nationale (E3N) prospective investigation were studied from 1994. After a median follow-up of 7.4 years, 700 women had developed cancers known to be associated with smoking. Diet, supplement use, and smoking status at baseline were assessed by self-report. beta-carotene intake was classified into four groups: first (low intake), second, and third tertiles of dietary intake, and use of supplements (high intake). Unadjusted and multivariable Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals (CIs) for cancer risk. All statistical tests were two-sided.

RESULTS

Among never smokers, multivariable hazard ratios of all smoking-related cancers were 0.72 (95% CI = 0.57 to 0.92), 0.80 (95% CI = 0.64 to 1.01), and 0.44 (95% CI = 0.18 to 1.07) for the second and third tertiles of dietary intake, and high beta-carotene intake, respectively, compared with low intake (Ptrend = .03). Among ever smokers, multivariable hazard ratios were 1.43 (95% CI = 1.05 to 1.96), 1.20 (95% CI = 0.86 to 1.67), and 2.14 (95% CI = 1.16 to 3.97) for the second and third tertiles of dietary intake, and high beta-carotene intake, respectively, compared with low intake (Ptrend = .09). Tests for interaction between beta-carotene intake and smoking were statistically significant (Ptrend =.017). In this population, the absolute rates over 10 years in those with low and high beta-carotene intake were 181.8 and 81.7 cases per 10,000 women in never smokers and 174.0 and 368.3 cases per 10,000 women in ever smokers.

CONCLUSIONS

beta-carotene intake was inversely associated with risk of tobacco-related cancers among nonsmokers with a statistically significant dose-dependent relationship, whereas high beta-carotene intake was directly associated with risk among smokers.

Plasma carotenoid, alpha-tocopherol and retinol concentrations and risk of colorectal adenomas: A case-control study in Japan

To investigate associations between plasma carotenoids, alpha-tocopherol and retinol with colorectal adenomas risk, we measured concentrations in 224 asymptomatic colorectal adenoma cases and 230 population-based controls matched for age and sex. After adjustment for age, history of colorectal adenomas and cancers, BMI, smoking, drinking status, multivitamin consumption and plasma total cholesterol, the risk of colorectal adenomas in the highest quartile was approximately half of that of men in the lowest quartile for alpha-carotene (OR=0.38; 95% CI: 0.18-0.84; P(trend)=0.01), beta-carotene (OR=0.51; 95% CI: 0.24-1.07; P(trend)=0.03) and total carotenoids (OR=0.48; 95% CI: 0.22-1.03; P(trend)=0.04). In addition, a protective association for alpha-carotene in women was also indicated, but which did not reach statistical significance (OR=0.53; 95% CI: 0.19-1.52; P(trend)=0.35). Our findings suggest a protective effect of carotenoids against the development of colorectal adenomas.

Proceedings from the “Third International Conference on Mechanism of Action of Nutraceuticals”

The "Third International Conference on Mechanisms of Action of Nutraceuticals" (ICMAN 3) was held to bring investigators from around the world together to find answers and share experience relevant to the role of nutraceuticals in health and disease. Dietary supplements are currently receiving recognition as being beneficial in coronary heart disease, cancer, osteoporosis and other chronic and degenerative diseases such as diabetes, Parkinson's and Alzheimer's diseases. This gave impetus to investigate the mechanisms of action of nutraceuticals and related bioactive compounds in disease pathologies. Many lines of evidence indicate that the mechanistic actions of natural compounds involve a wide array of biological processes, including activation of antioxidant defenses, signal transduction pathways, cell survival-associated gene expression, cell proliferation and differentiation and preservation of mitochondrial integrity. Furthermore, many of these compounds exert anti-inflammatory actions through inhibition of oxidative stress-induced transcription factors (e.g., NF-kappaB, AP-1), cytotoxic cytokines and cyclooxygenase-2. It appears that these properties play a crucial role in the protection against the pathologies of numerous age-related or chronic diseases. This review summarizes the latest research finding in functional foods and micronutrients in the promotion of health and reduction of risk for major chronic diseases as presented in this symposium.

Hispanic and non-Hispanic white elders from Massachusetts have different patterns of carotenoid intake and plasma concentrations

Carotenoids have been linked with protective roles against diseases associated with aging, including cancer, cardiovascular disease, cataracts, and age-related macular degeneration. With data from a semiquantitative, validated FFQ, we examined carotenoid intake of 340 Puerto Ricans, 98 Dominicans, and 146 non-Hispanic whites (>60 y old) in Massachusetts. Compared with non-Hispanic white men, Hispanic men reported a higher intake of lycopene and lower intakes of alpha-carotene, lutein + zeaxanthin, beta-carotene (from diet only), and total beta-carotene (diet and supplements) (P < 0.001). Hispanic women reported higher intakes of beta-cryptoxanthin and lycopene but lower intakes of lutein + zeaxanthin (P < 0.001) than non-Hispanic white women. The frequency of consumption of fruit and vegetables was higher among Hispanic women, relative to non-Hispanic white women (P < 0.05). Plasma concentrations of alpha-carotene and lycopene were higher in Hispanic than in non-Hispanic white men and women. For both ethnic groups, higher intakes of carotenoids were associated with higher plasma concentrations of the respective carotenoids, except for lycopene (Hispanics) and lutein + zeaxanthin (non-Hispanic whites). Food sources contributing most to total intakes differed among the groups. The major sources of alpha- and beta-carotene were carrots for non-Hispanic whites and winter squash for Hispanics. The major source of lycopene was cooked tomato products for Hispanics, and pasta dishes for non-Hispanic whites. Traditional foods such as beans and plantains were also important contributors of carotenoids for Hispanics. Because of the potential importance of carotenoids as protective factors against chronic diseases, more attention to food-related practices associated with carotenoid intake in differing population groups is warranted.

Association between 6-n-propylthiouracil (PROP) bitterness and colonic neoplasms

Inadequate vegetable intake appears to increase colon cancer risk. Since genetic variation in taste influences vegetable preference, we tested associations between bitterness of 6-n-propylthiouracil (PROP), a measure of taste genetics, and number of colonic polyps, a measure of colon cancer risk, in 251 men who underwent screening lower endoscopy. Patients used the general Labeled Magnitude Scale to rate bitterness of 1.6 mg PROP delivered via filter paper. A subset of 86 patients reported weekly vegetable intakes, excluding salad or potatoes. PROP bitterness correlated significantly with polyp number, an effect separate from age-associated increases in polyp number. The PROP-polyp relationship was strongest in men over 66 years, and older men with polyps were most likely to be overweight or obese. In the subset reporting vegetable intake, men who tasted PROP as more bitter consumed fewer vegetables. These preliminary findings suggest that taste genetics may influence colon cancer risk, possibly through intake of vegetables.