Nutritional factors and colon carcinoma: a case-control study involving French Canadians in Montréal, Quebec, Canada

Interaction between retinol intake and ISX rs5755368 polymorphism in colorectal cancer risk: a case-control study in a Korean population

This study aimed to examine whether the ISX rs5755368 genotypes are associated with the effect of dietary retinol consumption on CRC risk. We recruited 923 CRC patients and 1846 controls to identify the association between dietary retinol and CRC risk. Dietary retinol intake was assessed using a semiquantitative food frequency questionnaire. Genotype data were available for 1419 patients (600 cases and 819 controls) of the total study population. Genotyping was performed using an Illumina MEGA Expanded Array. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression models. Retinol intake was inversely associated with CRC (OR = 0.49; 95% CI = 0.37-0.63). Participants with AA genotype showed lower CRC risk than subjects carrying the G allele (AG + GG) (OR = 0.76; 95% CI = 0.58-0.99). A 68% reduced risk of CRC was related to subjects who had the highest retinol intake and carrying AA genotype compared to the risk of participants consumed the lowest retinol intake and carrying the G allele (OR = 0.32; 95% CI = 0.20-0.53; P interaction = 0.026). Retinol intake could be a protective factor for CRC risk while this association could be strengthened among individuals carrying the homozygous AA genotype.

The role of calcium and vitamin D dietary intake on risk of colorectal cancer: systematic review and meta-analysis of case-control studies

PURPOSE

The aim of this study is to analyze the current evidence about the relationships between calcium/vitamin D and CRC based on case-control studies according to sex, tumor location and continental region to complement the information obtained in meta-analyses of other designs.

METHODS

The articles were located in three databases (PUBMED, EMBASE and SCOPUS), they should be written in English language, with a case and control design and published between 1 January 1970 and 31 October 2019.

RESULTS

There were 37 selected studies, 32 for intake of calcium, that involved 24,353 CRC cases and 30,650 controls, and 23 for that of VIT D, with a total of 19,076 cases and 36.746 controls included. For dietary calcium intake, the overall OR was 0.94 (95% CI 0.92-0.97), suggesting a reducing effect with a 6% decrease in CRC risk for every 300 mg of calcium ingested daily. Regarding vitamin D intake a global OR of 0.96 (95% CI 0.93-0.98) was observed, what means a 4% decrease in the risk of CRC per 100 IU/day of vitamin D.

CONCLUSION

Higher dietary intakes of calcium and vitamin D are associated to a decreased risk of CRC.

Oxidative stress induced by tBHP in human normal colon cells by label free Raman spectroscopy and imaging. The protective role of natural antioxidants in the form of β-carotene

The present study aimed to investigate the protective effect of β-carotene on the oxidative stress injury of human normal colon cell line CCD-18Co triggered by tert-butyl hydroperoxide (tBHP). XTT examination was used to determine cell viability after β-carotene supplementation and to determine the optimal concentration of antioxidant in spectroscopic studies. Cell biochemistry for the CCD-18Co control group, after tBHP addition and for cells in the β-carotene-tBHP model was studied using label-free Raman microspectroscopy. Results for stress treated CCD-18Co human colon normal cells and human colon cancer cells Caco-2 based on vibration features were also compared. Pretreatment with β-carotene alleviated damage in CCD-18Co human normal colon cells induced by tBHP and showed the preventative effect on cell apoptosis. Treatment with β-carotene altered the level of ROS investigated based on intensities of Raman peaks typical for lipids, proteins and nucleic acids. The present study confirmed the antioxidant, protective role of β-carotene against ROS by using spectroscopic label-free Raman techniques.

Is dietary fibre truly protective against colon cancer? A systematic review and meta-analysis

Colorectal cancer is the third most common cancer worldwide. Growing evidence shows that about 47% of cases of colorectal cancer can be prevented by a healthy lifestyle. We performed a systematic review and meta-analysis aimed to evaluate the association between dietary fibre intake and the risk of colon cancer. We performed a structured computer search on PubMed, including epidemiological studies reporting results of dietary fibre intake and risk of colon cancer in women or men. We compared subjects exposed to the highest versus the lowest consumption. The search strategy identified 376 papers. After screening, 25 datasets were included in our meta-analysis. Results suggest a protective role of dietary fibre intake on colon cancer risk ES = 0.74 (95% CI = 0.67-0.82), p value = .000, but, moderate statistical heterogeneity (χ² = 42.73, p value = .011) was found. Due to the high mortality of colorectal cancer, it is important to identify effective preventive measures, especially those of a healthy lifestyle, such as a healthy diet.

The association between dietary protein intake and colorectal cancer risk: a meta-analysis

BACKGROUND

Association between dietary protein intake and colorectal cancer risk has not been fully quantified, while the results were controversial. This study aimed to evaluate the role of protein intake in the development of colorectal cancer.

METHODS

PUBMED and EMBASE were searched up to December 2016. Two independent reviewers independently extracted data from eligible studies. Relative risk (RR) with 95% confidence intervals (CI) was pooled using random-effects model to estimate the result. Besides, publication bias and sensitivity analysis were conducted.

RESULTS

Thirteen articles involving 21 studies comprising 8187 cases were included in this report. The pooled RR of colorectal cancer was 1.006 (95% CI = 0.857-1.179) indicating that there is no significant association between dietary protein intake and colorectal cancer risk. Furthermore, the pooled RRs for colon cancer and rectum cancer were 1.135(95% CI = 0.871-1.480) and 0.773(95% CI = 0.538-1.111), respectively, with the highest category of dietary protein intake. The association was not significant either in subgroup analysis of study design, protein type (animal protein or vegetable protein), sex, and or geographic locations.

CONCLUSIONS

The present study indicated that the highest category compared to the lowest category of protein intake had no significant association on colorectal cancer risk. Dose-response analysis was not conducted due to limited information provided. Therefore, more studies with large cases and participants as well as detailed amounts of dietary protein intake are wanted to confirm this result.

A meta-analysis between dietary carbohydrate intake and colorectal cancer risk: evidence from 17 observational studies

The association between dietary carbohydrate intake and colorectal cancer (CRC) risk remains controversial. We therefore conducted this meta-analysis to assess the relationship between them. A literature search from the databases of PubMed, Embase, Web of Science and Medline was performed for available articles published in English (up to September 2016). Pooled relative risk (RR) with 95% confidence interval (CI) was calculated to evaluate the association between dietary carbohydrate intake and CRC risk. The random-effect model (REM) was selected as the pooling method. Publication bias was estimated using Egger’s regression asymmetry test and funnel plot. A total of 17 articles involving 14402 CRC patients and 846004 participants were eligible with the inclusion criteria in this meta-analysis. The pooled RR with 95% CI of dietary carbohydrate intake for CRC, colon cancer and rectum cancer risk were 1.08 (95% CI =0.93–1.23, I² =68.3%, P_{heterogeneity}<0.001), 1.09 (95% CI =0.95–1.25, I² =48.3%) and 1.17 (95% CI =0.98–1.39, I² =17.8%) respectively. When we conducted the subgroup analysis by gender, the significant association was found in men’s populations (summary RR =1.23, 95% CI =1.01–1.57), but not in the women’s populations. In the further subgroup analyses for study design and geographic locations, we did not find any association between dietary carbohydrate intake and CRC risk in the subgroup results respectively. No significant publication bias was found either by the Egger’s regression asymmetry test or by the funnel plot. This meta-analysis suggested that higher dietary carbohydrate intake may be an increased factor for CRC risk in men populations. Further studies are wanted to confirm this relationship.

δ- and γ-tocopherols inhibit phIP/DSS-induced colon carcinogenesis by protection against early cellular and DNA damages

Tocopherols, the major forms of vitamin E, are a family of fat-soluble compounds that exist in alpha (α-T), beta (β-T), gamma (γ-T), and delta (δ-T) variants. A cancer preventive effect of vitamin E is suggested by epidemiological studies. However, past animal studies and human intervention trials with α-T, the most active vitamin E form, have yielded disappointing results. A possible explanation is that the cancer preventive activity of α-T is weak compared to other tocopherol forms. In the present study, we investigated the effects of δ-T, γ-T, and α-T (0.2% in diet) in a novel colon cancer model induced by the meat-derived dietary carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and promoted by dextran sodium sulfate (DSS)-induced colitis in CYP1A-humanized (hCYP1A) mice. PhIP/DSS treatments induced multiple polypoid tumors, mainly tubular adenocarcinomas, in the middle to distal colon of the hCYP1A mice after 10 wk. Dietary supplementation with δ-T and γ-T significantly reduced colon tumor formation and suppressed markers of oxidative and nitrosative stress (i.e., 8-oxo-dG and nitrotyrosine) as well as pro-inflammatory mediators (i.e., NF-κB p65 and p-STAT3) in tumors and adjacent tissues. By administering δ-T at different time periods, we obtained results suggesting that the inhibitory effect of δ-T against colon carcinogenesis is mainly due to protection against early cellular and DNA damages caused by PhIP. α-T was found to be ineffective in inhibiting colon tumors and less effective in attenuating the molecular changes. Altogether, we demonstrated strong cancer preventive effects of δ-T and γ-T in a physiologically relevant model of human colon cancer. © 2016 Wiley Periodicals, Inc.

Prevention and treatment of cancers by immune modulating nutrients

Epidemiological and laboratory data support the protective effects of bioactive nutrients in our diets for various diseases. Along with various factors, such as genetic history, alcohol, smoking, exercise, and dietary choices play a vital role in affecting an individual's immune responses toward a transforming cell, by either preventing or accelerating a neoplastic transformation. Ample evidence suggests that dietary nutrients control the inflammatory and protumorigenic responses in immune cells. Immunoprevention is usually associated with the modulation of immune responses that help in resolving the inflammation, thus improving clinical outcome. Various metabolic pathway-related nutrients, including glutamine, arginine, vitamins, minerals, and long-chain fatty acids, are important components of immunonutrient mixes. Epidemiological studies related to these substances have reported different results, with no or minimal effects. However, several studies suggest that these nutrients may have immune-modulating effects that may lower cancer risk. Preclinical studies submit that most of these components may provide beneficial effects. The present review discusses the available data, the immune-modulating functions of these nutrients, and how these substances could be used to study immune modulation in a neoplastic environment. Further research will help to determine whether the mechanistic signaling pathways in immune cells altered by nutrients can be exploited for cancer prevention and treatment.

Dietary intakes of retinol, carotenes, vitamin C, and vitamin E and colorectal cancer risk: the Fukuoka colorectal cancer study

It has long been a matter of interest whether antioxidant vitamins are protective against colorectal cancer as well as human cancers in general, but epidemiological evidence is inconclusive. We investigated associations of dietary intakes of retinol and antioxidant vitamins with colorectal cancer risk in 816 incident cases of histologically confirmed colorectal cancer and 815 controls randomly selected for the Fukuoka colorectal cancer study in Japan. Dietary intakes were assessed by a PC-assisted interview regarding 148 food items. Statistical adjustment was made for body mass index, physical activity, calcium, and n-3 fatty acid intake and other factors. Retinol intake was significantly, inversely associated with colorectal cancer risk; the odds ratio for the highest vs. lowest was 0.55 (95% CI: 0.35, 0.88; P (trend) = 0.01) in women, but a modest increase in the risk was observed among men with the highest intake of retinol. Liver was the major source of retinol intake and showed similar associations with colorectal cancer risk in men and women. Intake of carotenes, vitamin C, and vitamin E were not related to colorectal cancer risk in either men or women. The study did not support a hypothesis that dietary intake of antioxidant vitamins is protective in the development of colorectal cancer.

Cancer prevention by different forms of tocopherols

Many epidemiological studies have suggested that a low vitamin E nutritional status is associated with increased cancer risk. However, several recent large-scale human trials with high doses of α-tocopherol (α-T) have produced disappointing results. This points out the need for a better understanding of the biological activities of the different forms of tocopherols. Using a naturally occurring tocopherol mixture (γ-TmT) that is rich in γ-T, we demonstrated the inhibition of chemically induced lung, colon, and mammary cancer formation as well as the growth of xenograft tumors derived from human lung and prostate cancer cells. This broad anticancer activity of γ-TmT has been attributed mainly to the trapping of reactive oxygen and nitrogen species and inhibition of arachidonic acid metabolism. Activation of peroxisome proliferator-activated receptor γ (PPARγ) and the inhibition of estrogen signaling have also been observed in the inhibition of mammary cancer development. δ-T has been shown to be more active than γ-T in inhibiting the growth of human lung cancer cells in a xenograft tumor model and the development of aberrant crypt foci in azoxymethane-treated rats, whereas α-T is not effective in these models. The higher inhibitory activities of δ-T and γ-T (than α-T) are proposed to be due to their trapping of reactive nitrogen species and their capacity to generate side-chain degradation products, which retain the intact chromanol ring structure and could have cancer preventive activities.

Cancer-preventive activities of tocopherols and tocotrienols

The cancer-preventive activity of vitamin E has been studied. Whereas some epidemiological studies have suggested a protective effect of vitamin E against cancer formation, many large-scale intervention studies with alpha-tocopherol (usually large doses) have not demonstrated a cancer-preventive effect. Studies on alpha-tocopherol in animal models also have not demonstrated robust cancer prevention effects. One possible explanation for the lack of demonstrable cancer-preventive effects is that high doses of alpha-tocopherol decrease the blood and tissue levels of delta-tocopherols. It has been suggested that gamma-tocopherol, due to its strong anti-inflammatory and other activities, may be the more effective form of vitamin E in cancer prevention. Our recent results have demonstrated that a gamma-tocopherol-rich mixture of tocopherols inhibits colon, prostate, mammary and lung tumorigenesis in animal models, suggesting that this mixture may have a high potential for applications in the prevention of human cancer. In this review, we discuss biochemical properties of tocopherols, results of possible cancer-preventive effects in humans and animal models and possible mechanisms involved in the inhibition of carcinogenesis. Based on this information, we propose that a gamma-tocopherol-rich mixture of tocopherols is a very promising cancer-preventive agent and warrants extensive future research.

Primary prevention of colorectal cancer: are we closer to reality?

Colorectal cancer is one of the leading causes of morbidity and mortality worldwide. An early detection of colorectal cancer determines therapeutic outcomes, while primary prevention remains a challenge. Our aim was to review the dietary, geographical and genetic factors in the causation and their possible role in the primary prevention of colorectal cancer. Data from experimental and clinical studies and population screening programmes were analysed to determine the factors responsible for causation of colorectal cancer. The role of dietary constituents, including the consumption of fat, red meat, fibre content, alcohol consumption, and other lifestyle issues, including obesity, lack of exercise and geographical variations in cancer prevalence were reviewed. The role of genetic and lifestyle factors in causation of colorectal cancer is evident from the experimental, clinical and population-based studies. Dietary factors, including the consumption of fat, fibre, red meat and alcohol, seem to have a significant influence in this regard. The role of micronutrients, vitamins, calcium may be relevant but remain largely unclear. In conclusion, there is ample evidence favouring the role of various dietary and lifestyle factors in the aetiology of colorectal cancer. Modification of these factors is an attractive option, which is likely to help in the primary prevention and reduced disease burden.

Meta-analysis of animal fat or animal protein intake and colorectal cancer

BACKGROUND

In the recent World Cancer Research Fund/American Institute for Cancer Research report of diet and cancer, it was concluded that there is limited but suggestive evidence that animal fat intake increases the risk of colorectal cancer.

OBJECTIVE

To clarify this potential relation, we conducted meta-analyses across a variety of subgroups, incorporating data from additional studies.

DESIGN

Analyses of high compared with low animal fat intakes and categorical dose-response evaluations were conducted. Subgroup analyses, consisting of evaluations by study design, sex, and tumor site were also performed.

RESULTS

Six prospective cohort studies with comprehensive dietary assessments, contributing 1070 cases of colorectal cancer and approximately 1.5 million person-years of follow-up, were identified. The summary relative risk estimate (SRRE) for these studies was 1.04 (95% CI: 0.83, 1.31; P for heterogeneity = 0.221) on the basis of high compared with low intakes. When data from case-control studies were combined with the cohort data, the resulting SRRE was 1.15 (95% CI: 0.93, 1.42) with increased variability (P for heterogeneity = 0.015). In our dose-response analysis of the cohort studies, no association between a 20-g/d increment in animal fat intake and colorectal cancer was observed (SRRE: 1.02; 95% CI: 0.95, 1.09). In a separate analysis of 3 prospective cohort studies that reported data for animal protein or meat protein, no significant association with colorectal cancer was observed (SRRE: 0.90; 95% CI: 0.70, 1.15).

CONCLUSION

On the basis of the results of this quantitative assessment, the available epidemiologic evidence does not appear to support an independent association between animal fat intake or animal protein intake and colorectal cancer.

Fruit and vegetable intakes are associated with lower risk of colorectal adenomas

Many phytochemicals in fruits and vegetables have been shown to have cancer-inhibitory effects in animal studies. These effects on cancer, however, have not been clearly demonstrated in human studies. This study investigated the association between fruit and vegetable intakes and the risk of adenomatous polyps. Participants were part of the Tennessee Colorectal Polyp Study. Eligible participants aged 40-75 y were recruited from patients undergoing colonoscopy at 2 medical centers in Nashville, Tennessee from 2003 to 2005. Cases had at least one adenoma and controls were polyp free. Dietary intake was assessed using a self-administered FFQ. Associations between dietary intakes and adenoma risk were evaluated using unconditional logistic regression with restricted cubic function spline. In multivariate analyses of 764 cases and 1517 controls, increased intakes of total fruits, berries, fruit juice, and green leafy vegetables were associated with reduced adenoma risk. The odds ratio for upper tertile intake compared with lower was 0.66 (95% CI = 0.51-0.86) for total fruits, 0.64 (95% CI = 0.47-0.87) for berries, 0.72 (95% CI = 0.56-0.92) for fruit juice, and 0.74 (95% CI = 0.58-0.96) for green vegetables. This study provides additional evidence that high total fruit intake and certain fruit and vegetable intakes may be associated with a reduced risk of colorectal adenomas.

Colon cancer and the elderly: from screening to treatment in management of GI disease in the elderly

Colorectal cancer is one of the commonest tumours in the Westernized world affecting mainly the elderly. This neoplasm in older individuals occurs more often in the right colon and grows more rapidly than in the young, often shows a mucinous histology and mismatch repair gene changes. Effective screening permits discovery of colorectal cancer at an early highly treatable stage and allows for detection and removal of premalignant colorectal adenomas. Screening methods that focus on cancer detection use fecal assays for the presence of blood or altered DNA, those for detection of adenomas (and early cancer) use endoscopic or computerised radiologic techniques. Broad use of screening methods has lowered colorectal cancer development by about 50%. In addition, prevention of the earliest stage of colon carcinogenesis has been shown to be effective in small prospective studies and epidemiologic surveys but have not been employed in the general population. Since 1996 the chemotherapeutic armamentarium for metastatic colorectal cancer has grown beyond 5-fluorouracil to include an oral 5-fluorouracil prodrug, capecitabine as well as irinotecan and oxaliplatin. Three targeted monoclonal antibodies (Moabs), bevacizumab (an anti-vascular endothelial growth factor Moab) and cetuximab/panitumumab, both anti-epidermal growth factor receptor inhibitors, have also earned regulatory approval. Most stage IV patients are treated with all of these drugs over 2 or 3 sequential lines of palliative chemotherapy and attain median survivals approaching 24 months. Lastly, adjuvant oxaliplatin plus 5-fluorouracil for high risk resected stage II and stage III colon cancer patient has led to substantial improvement in cure rates. With appropriate care of age associated comorbidities these treatment modalities are feasible and effective in the geriatric population.

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.

Fiber and colorectal diseases: separating fact from fiction

Whilst fruits and vegetables are an essential part of our dietary intake, the role of fiber in the prevention of colorectal diseases remains controversial. The main feature of a high-fiber diet is its poor digestibility. Soluble fiber like pectins, guar and ispaghula produce viscous solutions in the gastrointestinal tract delaying small bowel absorption and transit. Insoluble fiber, on the other hand, pass largely unaltered through the gut. The more fiber is ingested, the more stools will have to be passed. Fermentation in the intestines results in build up of large amounts of gases in the colon. This article reviews the physiology of ingestion of fiber and defecation. It also looks into the impact of dietary fiber on various colorectal diseases. A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has fiber been found to be useful in chronic constipation and irritable bowel syndrome. It is also not useful in the treatment of perianal conditions. The fiber deficit - diverticulosis theory should also be challenged. The authors urge clinicians to keep an open mind about fiber. One must be aware of the truths and myths about fiber before recommending it.

Major Scientific Advances with Dairy Foods in Nutrition and Health

A large body of scientific evidence collected in recent decades demonstrates that an adequate intake of calcium and other nutrients from dairy foods reduces the risk of osteoporosis by increasing bone acquisition during growth, slowing age-related bone loss, and reducing osteoporotic fractures. These results have culminated in the new (2005) Dietary Guidelines for Americans that now recommend 3 servings of milk products per day to reduce the risk of low bone mass and contribute important amounts of many nutrients that may have additional health attributes beyond bone health. A number of animal, observational, and clinical studies have shown that dairy food consumption can help reduce the risk of hypertension. Clinical trials indicate that the consumption of recommended levels of dairy products, as part of a healthy diet, can contribute to lower blood pressure in individuals with normal and elevated blood pressure. Emerging data also indicate that specific peptides associated with casein and whey proteins can significantly lower blood pressure. In addition, a growing body of evidence has provided support for a beneficial effect of dairy foods on body weight and fat loss. Clinical studies have demonstrated that during caloric restriction, body weight and body fat loss occurs when adequate calcium is provided by supplements and that this effect is further augmented by an equivalent amount of calcium supplied from dairy foods. Several studies support a role for calcium, vitamin D, and dairy foods against colon cancer. Additionally, conjugated linoleic acid, a fatty acid found naturally in dairy fat, confers a wide range of anticarcinogenic benefits in experimental animal models and is especially consistent for protection against breast cancer.

Dietary calcium, phosphorus, vitamin D, dairy products and the risk of colorectal adenoma and cancer among French women of the E3N-EPIC prospective study

A protective effect of calcium and/or dairy products on colorectal cancer has been reported in epidemiological studies but the findings are considered inconsistent. In particular, it is unclear whether they act at a particular step of the adenoma-carcinoma sequence. To investigate the effect of dairy product consumption and dietary calcium, vitamin D and phosphorus intake on the adenoma-carcinoma sequence in the French E3N-EPIC prospective study. The population for the study of risk factors for adenomas was composed of 516 adenoma cases, including 175 high-risk adenomas, and of 4,804 polyp-free subjects confirmed by colonoscopy. The population for the colorectal cancer study was composed of 172 cases and 67,312 cancer-free subjects. Diet was assessed using a self-administered questionnaire completed at baseline. There was a trend of decreasing risk of both adenoma (ptrend=0.04) and cancer (ptrend=0.08) with increasing calcium intake, with RRs for adenoma and cancer of 0.80 (IC 95%=0.62-1.03) and 0.72 (95% CI=0.47-1.10), respectively, in the fourth quartile compared to the first. A protective effect of dairy products on adenoma (RRQ4 vs. Q1=0.80, 95% CI=0.62-1.05, ptrend=0.04) was observed and of milk consumption on colorectal cancer (RRQ4vs. Q1=0.54, 95% CI=0.33-0.89, ptrend=0.09), although the latter did not reach significance. Phosphorus intake also decreased the risk of adenoma (RRQ4 vs. Q1=0.70, 95% CI=0.54-0.90, ptrend=0.005). No vitamin D effect was identified. Our data support the hypothesis that calcium, dairy products and phosphorus exert a protective effect at certain steps of the adenoma-carcinoma sequence.

Nutritional genomics

Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutrigenetics will provide the basis for personalized dietary recommendations based on the individual's genetic make up. This approach has been used for decades for certain monogenic diseases; however, the challenge is to implement a similar concept for common multifactorial disorders and to develop tools to detect genetic predisposition and to prevent common disorders decades before their manifestation. The preliminary results involving gene-diet interactions for cardiovascular diseases and cancer are promising, but mostly inconclusive. Success in this area will require the integration of different disciplines and investigators working on large population studies designed to adequately investigate gene-environment interactions. Despite the current difficulties, preliminary evidence strongly suggests that the concept should work and that we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes; nutrition will be the cornerstone of this endeavor.

Calcium intake and colorectal adenoma in a US colorectal cancer early detection program

BACKGROUND

Calcium can reduce the risk of colorectal tumors by binding secondary bile and fatty acids, which leads to antiproliferative effects in the bowel, or by acting directly on the colonic epithelium, which affects differentiation and apoptosis.

OBJECTIVE

We investigated calcium intake and risk of colon adenoma to evaluate the association of calcium intake with early stages of colorectal tumor development.

DESIGN

We compared the supplemental and dietary calcium intakes of 3696 participants with histologically verified adenoma of the distal colon (ie, descending colon, sigmoid colon, or rectum) with the calcium intakes of 34 817 sigmoidoscopy-negative control participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Calcium intake was assessed at study entry with a 137-item food-frequency questionnaire and additional questions on the amount and duration of calcium supplement use.

RESULTS

After adjustment for known risk factors, adenoma risk was lower by 12% for participants in the highest quintile of total calcium intake (>1767 mg/d) than for participants in the lowest quintile (<731 mg/d) (odds ratio: 0.88; 95% CI: 0.76, 1.02; P for trend = 0.04). The protective association between total calcium and colorectal adenoma was largely due to calcium supplement use, with a 27% decrease in adenoma risk for participants taking >1200 mg/d than for nonusers of supplements (odds ratio: 0.73; 95% CI: 0.56, 0.91; P for trend = 0.005). The protective associations of total and supplemental calcium were strongest for colon adenoma (descending and sigmoid colon).

CONCLUSION

High calcium intake, particularly from supplements, is associated with a reduced risk of distal colorectal adenoma.

A moderately low phosphate intake may provide health benefits analogous to those conferred by UV light - a further advantage of vegan diets

Although exposure to ultraviolet light is often viewed as pathogenic owing to its role in the genesis of skin cancer and skin aging, there is growing epidemiological evidence that such exposure may decrease risk for a number of more serious cancers, may have a favorable impact on blood pressure and vascular health, and may help to prevent certain autoimmune disorders - in addition to its well-known influence on bone density. Most likely, these health benefits are reflective of improved vitamin D status. Increased synthesis or intake of vitamin D can be expected to down-regulate parathyroid hormone (PTH), and to increase autocrine synthesis of its active metabolite calcitriol in certain tissues; these effects, in turn, may impact cancer risk, vascular health, immune regulation, and bone density through a variety of mechanisms. Presumably, a truly adequate supplemental intake of vitamin D - manyfold higher than the grossly inadequate current RDA - could replicate the benefits of optimal UV exposure, without however damaging the skin. Diets moderately low in bioavailable phosphate - like many vegan diets - might be expected to have a complementary impact on disease risks, inasmuch as serum phosphate suppresses renal calcitriol synthesis while up-regulating that of PTH. A proviso is that the impact of dietary phosphorus on bone health is more equivocal than that of vitamin D. Increased intakes of calcium, on the other hand, down-regulate the production of both PTH and calcitriol - the latter effect may explain why the impact of dietary calcium on cancer risk (excepting colon cancer), hypertension, and autoimmunity is not clearly positive. An overview suggests that a vegan diet supplemented with high-dose vitamin D should increase both systemic and autocrine calcitriol production while suppressing PTH secretion, and thus should represent a highly effective way to achieve the wide-ranging health protection conferred by optimal UV exposure.

Glycemic Index, Glycemic Load, and Carbohydrate Intake in Relation to Risk of Distal Colorectal Adenoma in Women

Case-control studies and a cohort study have shown inconsistent associations between a high glycemic index or a high glycemic load and risk of colorectal cancer. These dietary variables have not been examined in relation to risk of colorectal adenoma. We thus examined the associations between dietary glycemic index, glycemic load, and carbohydrate intake with risk of adenoma of the distal colon or rectum among 34,428 US women who were initially free of cancer or polyps, who completed a semi-quantitative food-frequency questionnaire in 1980, and who underwent endoscopy from 1980 through 1998. 1,715 adenoma cases (704 large adenomas, 894 small adenomas, 1,277 distal colon adenomas, and 504 rectal adenomas) were documented during 18 years of follow-up. Dietary glycemic index, glycemic load, and carbohydrate intake were not related to risk of total colorectal adenoma after adjustment for age and established risk factors [relative risk (RR) for extreme quintiles of glycemic index = 1.11, 95% confidence interval (CI) 0.94-1.32, P for trend = 0.66; RR for glycemic load = 0.92, 95% CI 0.76-1.11, P for trend = 0.63; RR for carbohydrate intake = 0.90, 95% CI 0.73-1.11, P for trend = 0.64]. In addition, no significant associations were found for large or small adenoma, distal colon or rectal adenoma, or across strata of body mass index. Our findings do not support the hypothesis that a high glycemic index diet, a high glycemic load diet, or high carbohydrate intake overall are associated with risk of colorectal adenoma.

Calcium or resistant starch does not affect colonic epithelial cell proliferation throughout the colon in adenoma patients: a randomized controlled trial

Patients with a history of sporadic adenomas have increased epithelial cell proliferative activity, an intermediate risk marker for colorectal cancer. Reduction of proliferation by dietary intervention may reflect a decreased colorectal cancer risk. To evaluate whether calcium or resistant starch could reduce proliferative activity throughout the colon, we performed a randomized controlled trial in 111 sporadic adenoma patients. Patients received two placebos, 1 g of calcium + placebo, or 30 g of amylomaize (19 g of resistant starch) + placebo. After 2 mo, biopsies were collected from the cecum, transverse and sigmoid colon, and rectum during colonoscopy. Epithelial cell proliferation was determined by dividing the number of 5-bromo-2-deoxyuridine-labeled nuclei by the total number of nuclei x 100 (labeling index, LI). LI of luminal, mid, and basal compartments was determined. Twenty-five patients dropped out. In the remaining 86 patients (28 treated with placebo, 30 with calcium + placebo, and 28 with resistant starch + placebo), no difference was observed in total LI, the LI of the three compartments, or the crypt length in the four areas of the colorectum. Colonic epithelial cell proliferative activity throughout the colon of sporadic adenoma patients is not affected by supplementation with 1 g of calcium or 19 g of resistant starch.

Assessment of risk associated with specific fatty acids and colorectal cancer among French-Canadians in Montreal: a case-control study

BACKGROUND

Discrepancies in findings on the association between dietary fats and colorectal cancer (CRC) persist, and it is hypothesized that fatty acids (FA) may modulate CRC risk because of their physiological functions.

METHODS

Between 1989 and 1993, a case-control study involving 402 cases and 668 population-based controls was conducted among French-Canadians. Dietary intake was assessed by a food frequency questionnaire.

RESULTS

Oleic acid was the major FA consumed by the study population. A significant inverse association was found among females between CRC and butyrate (OR = 0.57; 95% CI: 0.34-0.96; P = 0.006), alpha-linoleic acid (ALA) (OR = 0.78; 95% CI: 0.46-1.32; P = 0.016), and w-3 FA (OR = 0.84; 95% CI: 0.50-1.41; P = 0.028), comparing the upper to the lower quartiles of intake. An increased risk was associated with arachidonic acid (AA) (OR = 2.03; 95% CI: 1.16-3.54; P = 0.001) among males, and with the w6/w3 ratio (OR = 1.47; 95% CI: 0.86-2.50; P = 0.001) among females. Arachidonic acid was linked with up to fivefold increased risk (OR = 5.33; 95% CI: 2.04-13.95; P = 0.0004 for trend) among men with high vitamin C intake. Females with low carotenoids intake were at elevated risk associated with AA (OR = 4.07; 95% CI: 1.84-8.99; P = 0.003); eicosapentaenoic acid (OR = 3.50; 95% CI: 1.59-7.71; P = 0.015), and docosahexaenoic acid (OR = 5.77; 95% CI: 2.50-13.33; P = 0.002), comparing the upper with the lower quartiles of intake.

CONCLUSION

The results of this study suggest that independently of total energy intake, substituting AA by butyrate, ALA, or omega-3 FA may reduce CRC risk. The role of interactions between vitamin C, total carotenoids, and polyunsaturated FA requires further investigation.

Dietary and serum alpha-tocopherol, beta-carotene and retinol, and risk for colorectal cancer in male smokers

OBJECTIVE

To study the association between dietary and serum antioxidant vitamins and carotenoids and risk for colorectal cancer in male smokers.

DESIGN

A prospective cohort study within a randomised, double-blind, placebo-controlled trial testing supplementation with alpha-tocopherol (50 mg/day), beta-carotene (20 mg/day) or both in preventing cancer.

SUBJECTS AND METHODS

Participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study with complete dietary data and serum samples available from baseline. These included 26,951 middle-aged male smokers among whom 184 colorectal cancer cases were diagnosed during 8 y of follow-up. Relative risks were calculated with Cox proportional hazards models adjusting for trial supplementation, age, body mass index, serum cholesterol, cigarettes smoked per day and physical activity.

RESULTS

There was no significant association between dietary vitamin C or E, alpha-or gamma-tocopherol, retinol, alpha- or beta-carotene, lycopene or lutein+zeaxanthin and risk for colorectal cancer. Serum alpha-tocopherol, beta-carotene or retinol was also not associated with the risk, neither did the season when baseline blood was drawn modify the relationship between serum beta-carotene and colorectal cancer risk.

CONCLUSIONS

Our data support the results from previous studies in which no association between dietary antioxidant vitamins and carotenoids and risk for colorectal cancer has been observed. Likewise, no association between baseline serum antioxidant concentrations and colorectal cancer risk was evident.

SPONSORSHIP

The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study was supported by a contract with the US National Cancer Institute (N01-CN-45165).

Colorectal cancer in an African city population in transition

An enquiry has been made on a series of African patients with colorectal cancer who were admitted in 1995-1999 to Chris Hani Baragwanath Hospital (3200 beds), and who lived in Soweto (population about 1 million), Johannesburg, South Africa. In the urban context described, Africans have considerably more advantages, socio-economically, dietarily and in other respects, than their rural counterparts. The 126 patients comprised 58 males and 68 females, giving calculated incidence rates in their communities for colorectal cancer of 1.7 and 2.0, respectively, per 100,000 'world' population. In contrast, as indicated in the South African Cancer Registry for 1993-1995, the corresponding rates for white males and females were 24.7 and 19.3, respectively, per 100,000. The proportion of African patients under 40 years was 19.0%; but was only 4.0% in the white population. In contrast to this major disparity, there was only a minor interethnic disparity regarding cancers that are very common in Africans, namely, those of the oesophagus and lung. Hence, with ongoing transitional changes - in diet and other respects - the relatively high proportion of younger African patients probably indicates a rising occurrence of colorectal cancer in the urban African population.

Relations between vegetable, fruit and micronutrient intake. Implications for odds ratios in a case-control study

OBJECTIVE

To investigate whether the protection observed for some micronutrients, such as beta-carotene, in several observational studies may simply reflect vegetable and fruit intake.

DESIGN

A case-control study conducted in Italy.

SUBJECTS

The subjects were 1225 colon cancer patients, 728 rectal cancer patients and 4154 hospital controls.

RESULTS

For the 16 micronutrients considered, the more closely a micronutrient was correlated with total vegetable and fruit intake, the more it appeared protective against colorectal cancer.

CONCLUSION

When studying the effect of a nutrient on disease risk in an observational setting, its relation to other nutrients and foods must be taken into account.

Dietary fiber and colorectal neoplasia

PURPOSE

Dietary fiber has been implicated in colorectal neoplasia, despite conflicting evidence. This is a review of the currently available data on the role of dietary fiber in colorectal carcinogenesis.

METHODS

A literature search was conducted using the MEDLINE database. All case-control, longitudinal, and randomized, controlled studies published in English between 1988 and 2000 were identified, as were animal model studies in the period 1986 to 2000. Data from the various studies were tabulated and systematically analyzed, with particular emphasis on the effect of dietary fiber on tumor incidence and luminal parameters such as short chain fatty acids.

RESULTS

Epidemiologic correlation studies show a high intake of dietary fiber to be associated with a lower risk of colorectal neoplasia. Thirteen of the 24 case-control studies reviewed demonstrated a protective effect of dietary fiber against colorectal neoplasia, and 16 showed a protective effect of vegetables or vegetable fiber. On the other hand, of 13 longitudinal studies in various cohorts, only 3 demonstrated a protective effect of fiber and 4 a protective effect of vegetables or vegetable fiber. The five published randomized, controlled trials all investigated the effect of increased fiber intake on short-term adenoma recurrence; however, none showed any significant protective effect. Among 19 experimental studies in animal models, 15 showed a protective effect of fiber against tumor induction compared with controls. Animal studies also showed that poorly fermentable fibers (e.g., wheat bran and cellulose) were more protective than soluble fibers (e.g., guar gum and oat bran), which sometimes enhanced carcinogenesis. No clear correlation was found between luminal pH or short chain fatty acids and tumor induction.

CONCLUSIONS

On the basis of current data, there is little evidence to support the use of dietary fiber supplements to reduce the risk of colorectal neoplasia. Lifelong and early exposure may be important but are difficult to study. Other risk factors interact with the effects of dietary fiber.

Low serum retinol levels are associated with hepatocellular carcinoma in patients with chronic liver disease

BACKGROUND

Retinol and other vitamin A derivatives affect the differentiation and growth of many tissues and have anti-tumour properties.

AIM

To investigate serum retinol levels in patients with liver disease and hepatocellular carcinoma (HCC) and to assess its importance as a risk factor for the development of HCC.

METHODS

Serum retinol levels were measured in healthy volunteers and 175 patients (34 with chronic hepatitis C, 117 with cirrhosis, and 24 with HCC.

RESULTS

The serum retinol levels (mean +/- s.e.) in ng/mL, were 972.1 +/- 37.7 in the control group and 647 +/- 41.1 in patients with chronic hepatitis C. Serum retinol levels in patients with cirrhosis and HCC were lower than in patients with cirrhosis alone (365.8 +/- 43.1 vs. 438.9 +/- 22.1, P < 0.04). In particular, there was a more significant difference in serum retinol levels between Child-Pugh grade A patients with cirrhosis and Child-Pugh grade A patients with cirrhosis/HCC (serum retinol levels 532.4 +/- 26.7 vs. 366.1 +/- 86.4, P < 0.03). There was a significant difference in serum retinol levels between normal controls and all patients' groups (P < 0.001). There were significantly lower serum retinol levels in cholestatic Child-Pugh grade A patients with cirrhosis compared with noncholestatic Child-Pugh grade A patients with cirrhosis/HCC (411.5 +/- 30.3 vs. 579.7 +/- 32.7, P < 0.0004). Sixty percent of patients with Child-Pugh grade A cirrhosis/HCC had serum retinol levels below 350 ng/mL compared with only 18.4% of cirrhotics without HCC (chi 2-test, P=0.01). No correlation was found between serum retinol levels and alpha FP or any other liver function tests, apart from serum albumin, which showed a positive correlation (r=0.61 P < 0.018).

CONCLUSIONS

There was a progressive reduction in serum retinol levels from controls to patients with liver cirrhosis. Those patients with cirrhosis and HCC had significantly lower values than patients with cirrhosis alone. Serum retinol levels may be a risk factor for the development of HCC.

Diet and prevention of colorectal cancer

There is a 20-fold difference in incidence rates of colorectal cancer between the areas of highest incidence (North America and Australia) and lowest incidence (India). Animal studies, epidemiologic research, and clinical trials continue to focus on diet in the search for responsible environmental factors. Between 1997 and 1999, a number of research areas have had considerable activity, and they provide the focus for this review. Among foods, vegetables, cereals, and soy have been topics of recent research. Nutrients from foods and supplements have also gained attention, including n-3 fatty acids, calcium, and B vitamins. Gene-environment interactions are beginning to be studied in populations. Studies of the interaction between polymorphisms in the gene for methylenetetrahydrofolate reductase (MTHFR) and dietary components for risk of both colorectal cancer and adenomatous polyps provide a glimpse into the future of diet and cancer research.

Chronic alcohol consumption induces genomic but not p53-specific DNA hypomethylation in rat colon

Alcohol consumption has been implicated as an etiologic agent in colorectal carcinogenesis, but the mechanism by which alcohol enhances the development of colorectal cancer is not yet known. Recent reports indicate that alcohol consumption can diminish cellular S-adenosylmethionine levels, thus possibly altering normal patterns of DNA methylation, a phenomenon that is mediated by S-adenosylmethionine and whose abnormalities are observed in colonic neoplasia. This study investigated the effect of chronic alcohol consumption on genomic DNA methylation of rat colonic epithelium and methylation of the p53 tumor suppressor gene, abnormalities of which have been implicated in colonic carcinogenesis. Two groups of rats (n = 10/group) were pair-fed either an alcohol-containing or an isocaloric control Lieber-DeCarli diet for 4 wk. The extent of genomic DNA methylation was assessed by incubating the extracted DNA with [(3)H]S-adenosylmethionine and Sss1 methyltransferase. Gene-specific methylation was assessed by using semiquantitative polymerase chain reaction (PCR). Tritiated methyl uptake by colonic DNA (which is inversely correlated with genomic methylation) from alcohol-fed rats was 57% less than that in control DNA (P < 0.05). However, gene-specific DNA methylation, both in the p53 gene (exons 5-8) and in the beta-actin gene, a control gene, did not differ between the two groups. In conclusion, this study indicates that chronic alcohol consumption produces genomic DNA hypomethylation in the colonic mucosa. This may constitute a means by which carcinogenesis is enhanced, although further studies are required to establish causality.

Cardiovascular and renal benefits of dry bean and soybean intake

Dry beans and soybeans are nutrient-dense, fiber-rich, and are high-quality sources of protein. Protective and therapeutic effects of both dry bean and soybean intake have been documented. Studies show that dry bean intake has the potential to decrease serum cholesterol concentrations, improve many aspects of the diabetic state, and provide metabolic benefits that aid in weight control. Soybeans are a unique source of the isoflavones genistein and diadzein, which have numerous biological functions. Soybeans and soyfoods potentially have multifaceted health-promoting effects, including cholesterol reduction, improved vascular health, preserved bone mineral density, and reduction of menopausal symptoms. Soy appears to have salutary effects on renal function, although these effects are not well understood. Whereas populations consuming high intakes of soy have lower prevalences of certain cancers, definitive experimental data are insufficient to clarify a protective role of soy. The availability of legume products and resources is increasing, incorporating dry beans and soyfoods into the diet can be practical and enjoyable. With the shift toward a more plant-based diet, dry beans and soy will be potent tools in the treatment and prevention of chronic disease.