Nutrition chemoprevention of gastrointestinal cancers: a critical review

Potential Benefits of Edible Berries in the Management of Aerodigestive and Gastrointestinal Tract Cancers: Preclinical and Clinical Evidence

Epidemiological reports as well as experimental studies have demonstrated the significant health benefits provided by regular berry consumption. Berries possess both prophylactic and therapeutic potential against several chronic illnesses, such as cardiovascular, neurodegenerative, and neoplastic diseases. Berries owe their health benefits to phytoconstituents, such as polyphenolic anthocyanins, ellagic acid, and a diverse array of phytochemicals bestowed with potent antioxidant and anti-inflammatory effects as well as the ability to engage a multitude of signaling pathways. This review highlights the principal chemical constituents present in berries and their primary molecular targets. The article presents and critically analyzes the chemopreventive and therapeutic potential of berry extracts, fractions, and bioactive components on various cancers of the gastrointestinal tract (GIT), including esophageal, stomach, intestinal, and colorectal cancers as well as cancers of the upper aerodigestive tract, such as oral cancer. The current status of clinical studies evaluating berry products in several aforementioned cancers is presented. Various emerging issues including dose-ranging and dosage forms, the role of synergy and the usage of combination therapy as well as other relevant areas essential for the development of berry phytoconstituents as mainstream chemopreventive and therapeutic agents against aerodigestive and GIT cancers are critically discussed.

Primary and secondary prevention of colorectal cancer in the Czech Republic

Colorectal cancer is one of the most frequent malignancies in the Czech Republic and worldwide. Also, a high prevalence of overweight and obesity, a high proportion of smokers in the population, and one of the highest per capita alcohol consumption rates are typical for the Czech population. The role of general practitioners in the prevention of colorectal cancer is crucial. In primary prevention, the doctor should emphasise the importance of a healthy lifestyle – a balanced diet rich in fruits and vegetables, maintaining a normal body weight, adequate physical activity, and non-smoking. In secondary prevention, patients should be informed about the possibilities of colorectal cancer screening and the benefits of early detection of the disease. Participation rates of the target population for colorectal cancer screening are low. Steps leading to increased participation in colorectal cancer screening (including postal invitations) play an important role in influencing the mortality of colorectal cancer.

Antioxidants and prevention of gastrointestinal cancers

PURPOSE OF REVIEW

Gastrointestinal cancers account for 20% of all incident cancers in the United States. Much work has been done to understand the role dietary factors play in the prevention of gastrointestinal cancers, yet evidence regarding the potential preventive effect of antioxidants is conflicting. This review highlights the recent studies investigating the associations between dietary antioxidants and cancers of the gastrointestinal tract.

RECENT FINDINGS

In-vitro and in-vivo studies in animals continue to support the hypothesis that antioxidants reduce the risk of gastrointestinal cancers. Results in human populations are not as supportive. Antioxidant nutrients and fruits and vegetables do not seem to confer protection against colorectal cancer, and certain antioxidants were found to increase the risk of distal colon cancer. Individual antioxidants also do not help prevent pancreatic cancer. Total antioxidant intake and plant-based foods seem promising for stomach cancer prevention, while vitamin C lowers the risk of esophageal cancer. Preventive effects for stomach and esophageal cancers were often limited to or stronger in smokers. Evidence is scarce regarding antioxidants and liver cancer.

SUMMARY

Antioxidants do not aid in the prevention of gastrointestinal cancers in the general population; however, they may act as chemopreventive agents for stomach and esophageal cancers, especially in high-risk populations.

NQO1 C609T polymorphism correlated to colon cancer risk in farmers from western region of Inner Mongolia

OBJECTIVE

To investigate the relationship between NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T polymorphism and colon cancer risk in farmers from western region of Inner Mongolia.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to analyze NQO1 C609T polymorphism from 160 healthy controls and 76 colon cancer patients.

RESULTS

Among the colon cancer patients, the incidence of NQO1 T allele (53.29%) was significantly higher than it in control group (33.75%, P<0.001). The individuals with NQO1 T allele had higher risk [2.239 (95% CI: 
1.510-3.321) times] to develop colon cancer than individuals with NQO1 C allele. The incidence of NQO1
 (T/T) (34.21%) in colon cancer patients was higher than that in control group (15.62%, P<0.001). Odds ratios (OR) analysis suggested that NQO1 (T/T) and NQO1 (T/C) genotype carriers had 3.813 (95% CI: 1.836-7.920) times and 2.080 (1.026-4.219) times risk compared with wild-type NQO1 (C/C) gene carriers in developing colon cancer. Individuals with NQO1 (T/T) genotype had 2.541 (95% CI: 0.990-6.552) times, 3.713 (95% CI: 1.542-8.935) times, and 3.471 (95% CI: 1.356-8.886) times risk than individuals with NQO1 (T/C) or NQO1 (C/C) genotype in well-differentiated, moderately-differentiated, and poorly-differentiated colon cancer patients, respectively.

CONCLUSIONS

NQO1 gene C609T could be one of risk factors of colon cancer in farmers from western region of Inner Mongolia.

The effect of serum carotenoids on atrophic gastritis among the inhabitants of a rural area in Hokkaido, Japan

A total of 206 residents (76 males and 130 females) of a rural area of Hokkaido, Japan, attending a health check in August, 1997, were studied to assess the relationship between serum carotenoids and atrophic gastritis (AG). Of the participants, 91 had AG as indicated by their serum levels of pepsinogen I and pepsinogen II. Logistic regression analysis, after adjusting for gender and age, revealed that the odds ratios for serum carotenoid levels were lower for subjects with high serum levels of α-carotene (odds ratio, 0.41; 95% C.I., 0.19-0.88) and β-carotene (odds ratio, 0.41; 95% C.I., 0.18-0.91) than for those with low serum carotenoid levels. In addition, the odds ratios of subjects with high serum levels of β-cryptoxanthin (odds ratio, 0.60; 95% C.I., 0.28-1.31), provitamin A (odds ratio, 0.38; 95% C.I., 0.17-0.85), and retinol (odds ratio, 0.67; 95% C.I., 0.31-1.48) were found to be lower than the odds ratios for those with low serum levels. Odds ratios for subjects with high serum zeaxanthin/lutein levels were higher than odds ratios for those with low serum levels. These results suggest that frequent intake of foods ric, in carotenoids with provitamin A activity may reduce the risk of AG.

Chemopreventive efficacy of hesperetin (citrus flavonone) against 1,2-dimethylhydrazine-induced rat colon carcinogenesis

BACKGROUND

Colorectal carcinogenesis is one of the most common cancers/lethal diseases. Chronic inflammation is considered a risk factor for colorectal cancer. Hesperetin, a flavonone found in citrus fruits and oranges is shown to possess potent growth inhibitory effects against various human cancer cells. It possesses anti-inflammatory and antioxidant properties. AIM OF THE SCOPE: In the present study, we have evaluated the chemopreventive efficacy of hesperetin against rat colon carcinogenesis in male Wistar rats.

METHODS

Group 1 served as control, received modified pellet diet and group 2 rats received 20 mg/kg body weight of hesperetin p.o. every day. Groups 3-6 rats were given subcutaneous injections of 1,2-dimethylhydrazine (DMH, 20 mg/kg body weight) once a week for 15 consecutive weeks. In addition, rats in group 4 received hesperetin as in group 2 for the first 15 weeks (initiation), group 5 rats received hesperetin as in group 2 after the last injection of DMH and continued till the end of the experimental period (postinitiation). Group 6 rats received hesperetin as in group 2 throughout the entire experimental period of 32 weeks.

RESULTS

Detection of cell proliferation markers such as proliferating cell nuclear antigen (PCNA) (immunohistochemistry), argyrophilic nucleolar organizer regions (AgNORs) (silver staining); apoptosis (immunoblotting and immunohistochemistry); angiogenic growth factors (ELISA) indicated decreased cell proliferation and increased apoptotic markers in the colon. In addition, decreased angiogenic growth factors such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and downregulation of mRNA Cyclooxygenase-2 (COX-2) expressions were observed in mucosal and fecal samples of hesperetin-supplemented rats.

CONCLUSIONS

Hesperetin supplementation showed an inhibition of cell proliferation markers, angiogenic growth factors, COX-2 mRNA expression and induction of apoptosis. Thus, hesperetin can be used as a potent chemopreventive agent against DMH-induced colon cancer.

Lifestyle Interventions in the Prevention and Treatment of Cancer

Despite evidence that cancer death rates in the United States are declining, the absolute number of new cancers and cancer deaths continues to increase, and there is clear evidence that certain human behaviors are influencing these increases. The 4 major factors of lifestyle that continue to be causally related to certain cancers—tobacco use, an unhealthy diet, inadequate exercise, and excessive exposure to ultraviolet radiation—are each independently important in their effects on the genetic and molecular processes that result in the malignant transformation of human cells. There is both irrefutable and otherwise strong evidence that 4 common cancers that occur in the United States—lung cancer, colon/rectal cancer, breast cancer, and prostate cancer—and a less common cancer, malignant melanoma, have etiologic factors that are lifestyle based and therefore controllable through alterations in human behavior. These cancers and the evidence that lifestyle is important in the causation and/or prevention of the disease are the subjects of this review.

Fish consumption and risk of major chronic disease in men

BACKGROUND

Although fish consumption may reduce specific disease endpoints, such as sudden cardiac death and prostate cancer, the effects of major chronic disease on total burden, reflecting sums of effects on a variety of endpoints and risk pathways, are not well established. Higher n-6 fatty acid consumption has also been hypothesized to reduce the health benefits of n-3 fatty acids in fish.

OBJECTIVE

The aim was to study the associations of fish and n-3 fatty acid consumption with risk of total major chronic disease (cardiovascular disease, cancer, and death) and to determine whether a high n-6 intake modifies the associations.

DESIGN

Lifestyle and other risk factors were assessed every 2 y and diet every 4 y in 40,230 US male health professionals aged 40-75 y and free of major chronic disease at baseline in 1986. During 18 y of follow-up, 9715 major chronic disease events occurred, including 3639 cardiovascular disease events, 4690 cancers, and 1386 deaths from other causes.

RESULTS

After multivariable adjustment, neither fish nor dietary n-3 fatty acid consumption was significantly associated with risk of total major chronic disease. Compared with fish consumption of <1 serving/mo, consumption of 1 serving/wk and of 2-4 servings/wk was associated with a lower risk of total cardiovascular disease of approximately 15%. No significant associations were seen with cancer risk. Higher or lower n-6 fatty acid intake did not significantly modify the results (P for interaction > 0.10).

CONCLUSIONS

Modest fish consumption was associated with a lower risk of total cardiovascular disease, consistent with cardiac mortality benefits but not with total cancer or overall major chronic disease; n-6 fatty acid consumption did not influence these relations.

Hesperetin exerts dose dependent chemopreventive effect against 1,2-dimethyl hydrazine induced rat colon carcinogenesis

Colon cancer is still one of the leading causes of death in USA and is increasing at an alarming rate in Asia. It is one of the major causes of death in industrialized countries, and its etiology is known to be a combination of hereditary, environmental, dietary factors and lack of physical activity. Chemoprevention plays a potential role in colorectal cancer. The present study was performed to evaluate the efficacy of hesperetin supplementation on colonic aberrant crypt foci, lipid peroxidation and antioxidant defense system in 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis in male Wistar rats. The rats were segregated into six groups viz., group 1, control rats received modified pellet diet; group 2 rats received modified pellet diet along with hesperetin (30 mg/kg body weight/day); groups 3-6 administrated DMH (20 mg/kg body weight) subcutaneous injection once a week for the first 4 weeks; in addition groups 4-6 received hesperetin at three different doses of 10, 20 and 30 mg/kg body weight/day for 16 weeks. All the rats were sacrificed at the end of the experimental period of 16 weeks. Increased tumor incidence and increased number aberrant crypt foci (ACF) accompanied by a decrease in the tissue lipid peroxidation, glutathione S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) activities were observed in DMH-treated rats. Administration of hesperetin to DMH treated rats significantly decreased the tumor incidence, the number of aberrant crypt foci with simultaneous enhancement of tissue lipid peroxidation, GST, GPx, SOD, and CAT activities. The results of this study suggest that hesperetin at a dose of 20 mg/kg body weight showed a significant beneficial effect against chemically induced colonic carcinogenesis in rats as compared to the other two doses.

Content of polyphenolic compounds in the Nigerian stimulants Cola nitida ssp. alba, Cola nitida ssp. rubra A. Chev, and Cola acuminata Schott & Endl and their antioxidant capacity

Varieties of kola nuts (Cola nitida alba, Cola nitida rubra A. Chev, and Cola acuminata Schott & Endl), a group of popular Nigerian and West African stimulants, were analyzed for their content of secondary plant metabolites. The three varieties of the kola nuts contained appreciable levels of (+)-catechin (27-37 g/kg), caffeine (18-24 g/kg), (-)-epicatechin (20-21 g/kg), procyanidin B 1 [epicatechin-(4beta-->8)-catechin] (15-19 g/kg), and procyanidin B2 [epicatechin-(4beta-->8)-epicatechin] (7-10 g/kg). Antioxidant capacity of the extracts and purified metabolites was assessed by two HPLC-based and two colorimetric in vitro assays. Extracts of all varieties exhibited antioxidant capacity with IC 50 values in the range 1.70-2.83 and 2.74-4.08 mg/mL in the hypoxanthine/xanthine oxidase and 2-deoxyguanosine HPLC-based assays, respectively. Utilization of HPLC-based assays designed to reflect in situ generation of free radicals (e.g., HO(*)), as opposed to general assays (DPPH, FRAP) in common use which do not, indicate that, of the major secondary plant metabolites present in kola nut extracts, caffeine is potentially the more effective cancer chemopreventive metabolite in terms of its antioxidant capacity.

Nutrition and Colorectal Cancer Risk

Though no one knows why one person gets cancer and another does not, there are ways to decrease the chances of getting cancer. In the case of colorectal cancers, diet may be a preventative factor. The objective of this literature review was to determine whether a person's nutritional diet has an effect on his or her risk of getting colorectal cancer. Studies done by a number of researchers on the correlation between colorectal cancer risk and diet were reviewed. Research papers investigating dietary patterns and colorectal cancer incidence were examined. A synthesis of this literature suggests a diet high in red meat and fat may increase a person's risk of getting colorectal cancer. Contrary to previous recommendations, there is no strong evidence to suggest that fiber intake (including more fruits and vegetables) has any effect on colorectal cancer risk.

A NAD(P)H:quinone oxidoreductase 1 polymorphism is a risk factor for human colon cancer

Colon cancer is one of the most common cancers in North America and generally develops from colonic epithelial cells following initiation by carcinogens. We have shown that the phase II detoxifying enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1) contributes to the inhibition of carcinogen-induced colon cancer in rats at both the initiation and postinitiation stages. An inactivating polymorphism at base 609 of the NQO1 gene, (609)C (NQO1 *1) --> (609)T (NQO1 *2), occurs at high frequency in the human population. Thus, we carried out a case-control study to determine if this polymorphism is associated with an increased risk of developing colon cancer. A total of 298 patients with colon cancer and 349 healthy controls matched for age, gender, and ethnic origin were enrolled in the study. There was an increased incidence of the NQO1 *2/*2 genotype in patients with colon cancer, with a gender and age-adjusted odds ratio of 2.68 (95% confidence intervals, 1.14-6.28). However, the incidence of the NQO1 *1/*2 genotype was not increased in patients with colon cancer compared with controls. When the patient and control groups were stratified by tobacco and alcohol use, the incidences of the NQO1 *2/*2 genotype were increased in patients with colon cancer for tobacco and alcohol users and nonusers, suggesting that there is no interaction between the NQO1 base 609 polymorphism and tobacco or alcohol use. These results strongly suggest that NQO1 plays a significant role in preventing the development of colon cancer, and individuals with an NQO1 *2/*2 genotype are at an increased risk of developing this disease.

Differences in characteristics of colorectal neoplasm between young and elderly Thais

AIM: To analyze the differences of clinical characteristics of colorectal neoplasm including polyps between the elderly and young Thai patients.

METHODS: Colonoscopy database from December 2000 to October 2004 was retrospectively analyzed. There were 1822 eligible patients who underwent colonoscopy (with a mean age of 56.6 years). Patients were classified into two groups: the older age group (aged ≥ 60 years; n = 989) and the younger age group (aged < 60 years; n = 833). Data were recorded on age, colonoscopic indications, tumor location, colonoscopic findings and their related histological findings.

RESULTS: Colorectal malignancy related lesions were more often found in the older age group (21%) than in the younger age group (12%). Left-sided lesions were detected more commonly than right-sided in both age groups in approximately two-thirds of all cases. Hematochezia showed greater association with left-sided lesions in the elderly. No relationship was found between age and neoplasm staging and severity.

CONCLUSION: The chance of detecting colorectal neoplasm by colonoscopy was higher in the elderly than in the young Thais. However, both groups had the lesions predominantly located in the left side.

Carbohydrate Digestibility Predicts Colon Carcinogenesis in Azoxymethane-Treated Rats

The purpose of this study was to compare the effect of carbohydrate structure and digestibility on azoxymethane (AOM)-induced colon carcinogenesis. Five groups of male Fischer 344 rats each comprising 30 animals were injected with AOM and fed a high-fat diet with 15% of various carbohydrates. The carbohydrate sources used were sucrose, cornstarch (a linear starch, reference group), potato starch (a branched starch), a short-chained oligofructose (Raftilose), and a long-chained inulin-type fructan (Raftiline). An interim sacrifice was performed after 9 wk to investigate markers of carbohydrate digestibility, including caecal fermentation (caecum weight and pH) and glucose and lipid metabolism [glucose, fructoseamine, HbA1c, triglycerides, and insulin-like growth factor (IGF) 1]. In addition potential early predictors of carcinogenicity [cell proliferation and aberrant crypt foci (ACF)] at 9 wk and their correlation to colon cancer risk after 32 wk were investigated. Tumor incidence was significantly reduced in animals fed oligofructose, and the number of tumors per animal was significantly reduced in animals fed inulin and oligofructose at 32 wk after AOM induction compared to the reference group fed sucrose. Increased caecum weight and decreased caecal pH were seen in groups fed oligofructose, inulin, and potato starch. Plasma triglyceride was decreased in rats fed oligofructose and inulin. Cell proliferation was increased in the proximal colon of rats fed sucrose, oligofructose, and inulin, and the number of cells per crypt decreased in rats fed oligofructose and inulin. The total number of ACF's was unaffected by treatment, and the size and multiplicity of ACF was unrelated to tumor development. It was concluded that less digestible carbohydrates with an early effect on caecum fermentation and plasma triglyceride decreased subsequent tumor incidence and multiplicity. This was unrelated to ACF, cell proliferation, and other markers of glucose and lipid metabolism.

Adequate intake values for dietary fibre based on faecal bulking indexes of 66 foods

OBJECTIVE

To determine an adequate daily intake value for dietary fibre (AIdf) based on faecal bulking indexes (FBIs) for 66 foods of known total dietary fibre (TDF) content.

DESIGN

FBIs of 66 foods were measured and expressed as wheat bran equivalents (WBEfb) per 100 g of food. A daily WBEfb requirement for humans was calculated from faecal bulk generated per gram of wheat bran TDF in humans, using a critical faecal mass of 200 g/day for protection against large bowel disease. TDF content was regressed against WBEfb content for all 66 foods assayed, and an AIdf value obtained by substituting the calculated human WBEfb requirement into the regression equation.

METHOD

FBI was measured using a validated rat assay, with eight large (400+/-50 g) rats per group, preadapted to dietary fibre, and fed adequate restricted diets containing test foods at inclusion rates consistent with human intakes. The critical faecal mass was based on epidemiological studies, and the faecal bulk generated per gram of wheat bran TDF was the mean of 27 published values.

RESULTS

WBEfb requirements for humans were calculated to be 90 g/day, corresponding to a faecal output of 200 g/day. The regression equation relating WBEfb measured in the FBI assay to TDF in all 66 foods was TDF=0.491WBEfb + 3.19, R2=0.81 Substituting the human WBEfb requirement of 90 g into the regression equation gave an AIdf value of 40.9 g TDF/day.

CONCLUSION

The AIdf value of 40.9 g TDF/day based on faecal bulking supports the AIdf of 38 g TDF/day recently set by the Institute of Medicine (USA), for young men, based on protection against heart disease. The AIdf value is obtained from the relation between the effects of foods and their content of mixed function, plant cell wall dietary fibres within the food matrices, and should not be used to guide intakes of extrinsic functional polysaccharides.

The contribution of epidemiology

Epidemiologic studies directly contribute data on risk (or benefit) in humans as the investigated species, and in the full food intake range normally encountered by humans. This paper starts with introducing the epidemiologic approach, followed by a discussion of perceived differences between toxicological and epidemiologic risk assessment. Areas of contribution of epidemiology to the risk assessment process are identified, and ideas for tailoring epidemiologic studies to the risk assessment procedures are suggested, dealing with data collection, analyses and reporting of both existing and new epidemiologic studies. The dietary habits and subsequent disease occurrence of over three million people are currently under observation worldwide in cohort studies, offering great potential for use in risk assessment. The use of biomarkers and data on genetic susceptibility are discussed. The paper describes a scheme to classify epidemiologic studies for use in risk assessment, and deals with combining evidence from multiple studies. Using a matrix approach, the potential contribution to each of the steps in the risk assessment process is evaluated for categories of food substances. The contribution to risk assessment of specific food substances depends on the quality of the exposure information. Strengths and weaknesses are summarized. It is concluded that epidemiology can contribute significantly to hazard identification, hazard characterisation and exposure assessment.

Methods of in vitro toxicology

In vitro methods are common and widely used for screening and ranking chemicals, and have also been taken into account sporadically for risk assessment purposes in the case of food additives. However, the range of food-associated compounds amenable to in vitro toxicology is considered much broader, comprising not only natural ingredients, including those from food preparation, but also compounds formed endogenously after exposure, permissible/authorised chemicals including additives, residues, supplements, chemicals from processing and packaging and contaminants. A major promise of in vitro systems is to obtain mechanism-derived information that is considered pivotal for adequate risk assessment. This paper critically reviews the entire process of risk assessment by in vitro toxicology, encompassing ongoing and future developments, with major emphasis on cytotoxicity, cellular responses, toxicokinetics, modelling, metabolism, cancer-related endpoints, developmental toxicity, prediction of allergenicity, and finally, development and application of biomarkers. It describes in depth the use of in vitro methods in strategies for characterising and predicting hazards to the human. Major weaknesses and strengths of these assay systems are addressed, together with some key issues concerning major research priorities to improve hazard identification and characterisation of food-associated chemicals.

A protective role of dietary vitamin D3 in rat colon carcinogenesis

The aim of the present work was to gain insight into a putative anticancer effect of dietary vitamin D3 (cholecalciferol) in a rat model of colon carcinogenesis. Male rats were assigned to three different dietary groups. The dietary regimens were based on a standard murine-defined diet (AIN-76A) or a stress diet containing 20% fat, reduced Ca2+ concentration, a high phosphorus-to-Ca2+ ratio, and either low or high vitamin D3 content. Colorectal cancer was induced by administration of the procarcinogen 1,2-dimethylhydrazine (DMH). Blood Ca2+, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and 25-hydroxyvitamin D3 [25(OH)D3] levels were measured in DMH-treated rats and in respective weight- and age-matched dietary control groups. Colonic epithelial proliferation was assessed by determining thymidine kinase (TK) activity, bromodeoxyuridine (BrdUrd) incorporation into crypt cell DNA, and the mean labeling index along the colonic crypt continuum. Maintenance of rats on the stress diet either unmodified or supplemented with vitamin D3 in the absence of carcinogen treatment provoked a time-dependent rise in colonic TK activity and hyperproliferation of colonic epithelium. DMH treatment of rats maintained on the standard diet caused a marked increase in the proliferative indexes of colonic epithelium and in expansion of the crypt proliferative compartment. TK activity and the crypt mitotic zone were significantly augmented in the animal group fed the stress diet. Supplementary vitamin D3 abrogated the stress diet-enhanced colonic responses to the carcinogenic insult. Colon tumor multiplicity was fourfold higher in animals fed the stress diet than in animals maintained on a standard diet. The marked rise in colonic tumor multiplicity and adenocarcinoma incidence in rats fed the stress diet was obliterated by supplemental dietary vitamin D3. Cumulatively, the present results indicate that dietary vitamin D3 impedes the neoplastic process in murine large intestine and strengthen the view that inappropriate changes in dietary components and micronutrients are contributory determinants of colorectal cancer.

Biomarkers in disease and health

Biomarkers have considerable potential in aiding the understanding of the relationship between diet and disease or health. However, to assess the role, relevance and importance of biomarkers on a case by case basis it is essential to understand and prioritise the principal diet and health issues. In the majority of cases, dietary compounds are only weakly biologically active in the short term, have multiple targets and can be both beneficial and deleterious. This poses particular problems in determining the net effect of types of foods on health. In principle, a biomarker should be able to contribute to this debate by allowing the measurement of exposure and by acting as an indicator either of a deleterious or of an enhanced health effect prior to the final outcome. In this review, the examples chosen - cancer (stomach, colon/rectal, breast); coronary heart disease and osteoporosis - reflect three major diet-related disease issues. In each case the onset of the disease has a genetic determinant which may be exacerbated or delayed by diet. Perhaps the most important factor is that in each case the disease, once manifest, is difficult to influence in a positive way by diet alone. This then suggests that the emphasis for biomarker studies should focus on predictive biomarkers which can be used to help in the development of dietary strategies which will minimise the risk and be of greater benefit.

Effects of polyunsaturated fatty acids on atrophic gastritis in a Japanese population

In the present study, 92 people were found to have atrophic gastritis (AG) according to depressed serum levels of pepsinogen I and pepsinogen II in a screening involving 208 Japanese people, participating in a group health check. Serum levels of n-3 polyunsaturated fatty acids, especially docosahexaenoic acid (DHA), were higher in AG than in non-AG individuals, while those of gamma-linolenic acid (GLA) were significantly lower in AG individuals. The odds ratios for high serum DHA and GLA levels in AG subjects were 2.20 (95% C.I.: 1.10-4.39) and 0.34 (95% C.I.: 0.17-0.68), respectively. The above results suggested that GLA plays a role in reducing the incidence of AG, whereas DHA may increase a risk of AG.

Protective effect of folic acid against oxidative stress produced in 21-day postpartum rats by maternal-ethanol chronic consumption during pregnancy and lactation period

In this paper we show the protective effect of folic acid on oxidative stress in offspring caused by chronic maternal ethanol consumption during pregnancy and the lactation period. Glutathione reductase (GR) specific activity was assayed in liver and pancreas of offspring and mothers. In the offspring, these tissues were also assayed for markers of oxidative damage to lipids and proteins. The results show that ethanol exposure during pregnancy and lactation increased the specific activity of GR in tissues of the mothers (32-34% increase) as well as in the liver of their progeny (24%). Thiobarbituric acid reactive substances (TBARS) were also increased in the liver and pancreas of 21-day-old rats (37- and 54%, respectively). Alcohol also increased the amount of carbonyl groups in proteins in both tissues. These measures of ethanol-mediated oxidative stress were mitigated when pregnant rats were treated with folic acid concomitantly to ethanol administration. The antioxidant capacity of folic acid seems to be involved in its protective effect. The results obtained in the present work suggest that folic acid may be useful in the prevention of damage and promotion of health of the progeny of ethanol-treated rats.

The relation between fish consumption, death from all causes, and incidence of coronary heart disease. the NHANES I Epidemiologic Follow-up Study

1 time/week (adjusted relative risk 0.85, 95% CI 0.68-1.06). Similar but nonsignificant trends were seen in white and black women, but not black men. In white men, risk of noncardiovascular death but not cardiovascular death was also significantly reduced in those consuming fish once or more a week. No consistent association of fish consumption and coronary heart disease incidence or mortality was seen. White men consuming fish once a week had significantly lower risk of death over a 22-year follow-up than those never consuming fish. This was mostly attributable to reductions in death from noncardiovascular causes. Similar patterns, though not significant, were seen in women. Further studies are needed to confirm these findings and to elucidate mechanisms for the effect of fish consumption on noncardiovascular mortality.

Effects of dietary broccoli on rat testicular xenobiotic metabolizing enzymes

The effects of vegetables on the activities of various metabolizing enzymes in liver and intestine have been studied intensively, whereas studies on effects on testicular metabolizing enzymes are lacking. The present report is the first describing the effects of dietary broccoli on the activities of a number of xenobiotic metabolizing enzymes from rat testes. Groups of male Wistar rats were fed a semisynthetic diet with 10% (w/w) freeze-dried broccoli for 1 week. Different broccoli samples with varying content of glucosinolates were used. Dietary broccoli significantly increased the activities of two testicular phase II enzymes--glutathione S-transferase (1.6-fold) and UDP-glucuronosyl transferase (1.8-fold). The activities of these enzymes differed significantly depending on the conditions during cultivation of the broccoli, because of differences in the content of glucosinolates and other secondary plant metabolites. The levels of two glutathione S-transferase subunits, rGSTM2 and rGSTA, were determined using Western blotting analysis and the levels of both subunits were reduced in animals fed broccoli grown at low S-fertilizer level. Broccoli did not statistically significantly modulate the activities of the phase I enzymes, epoxide hydrolase or NAD(P)H quinone-oxidoreductase, or the phase II enzyme p-sulphotransferase, or the anti-oxidative enzymes catalase and total glutathione peroxidase in rat testes. In general, dietary broccoli affects phase I and phase II enzyme levels in rat testes much less than found in liver, however, two rat testicular phase II xenobiotic metabolizing enzymes were induced.

The Chemical Ecology of Human Ingestive Behaviors

▪ Abstract  Ingested nutrients and nonnutrients are presented as determinants in human evolution. The amount and quality of energy, including fat, various foods supply are important criteria in governing selection. Oxidative stress associated with respiration of energy is a factor in the etiology of dietary diseases, such as cardiovascular disease and cancer, and in aging. Evolutionary trends such as gains in brain and body sizes, greater ingestion of long-chain polyunsaturated fatty acids and cholesterol, heating of fatty food, and greater longevity increased oxidative stress while greater reliance on animals foods and less on plants decreased ingestion of exogenous antioxidants. The hypothesis that selection for nonnutrient ingestive behaviors was a compensatory mechanism for increasing antioxidants is presented within the context of a four-factor model on the origins of human medicine.

Nutritional strategies in the prevention of colorectal cancer

A variety of dietary factors have been implicated as agents that can modulate the development of malignancies of the gastrointestinal tract, particularly colorectal cancer. The effects of fat, red meat, fruits, vegetables, and alcohol on colorectal carcinogenesis have been examined extensively and appear to play substantial roles. Although fiber may play a protective role, recent studies raise the question of whether the protection is conveyed by other components in fiber-laden foods. Folate, selenium, calcium, and omega-3 fatty acids have emerged as factors more recently but may be equally important agents in nutritional chemoprevention, whereas the role of antioxidant vitamins is less certain. Until more firm data are available, the dietary recommendations provided by the American Cancer Society and the National Cancer Institute are appropriate for use in counseling patients on this issue.

Sphingolipids in food and the emerging importance of sphingolipids to nutrition

Eukaryotic organisms as well as some prokaryotes and viruses contain sphingolipids, which are defined by a common structural feature, i.e. , a "sphingoid base" backbone such as D-erythro-1,3-dihydroxy, 2-aminooctadec-4-ene (sphingosine). The sphingolipids of mammalian tissues, lipoproteins, and milk include ceramides, sphingomyelins, cerebrosides, gangliosides and sulfatides; plants, fungi and yeast have mainly cerebrosides and phosphoinositides. The total amounts of sphingolipids in food vary considerably, from a few micromoles per kilogram (fruits) to several millimoles per kilogram in rich sources such as dairy products, eggs and soybeans. With the use of the limited data available, per capita sphingolipid consumption in the United States can be estimated to be on the order of 150-180 mmol (approximately 115-140 g) per year, or 0.3-0.4 g/d. There is no known nutritional requirement for sphingolipids; nonetheless, they are hydrolyzed throughout the gastrointestinal tract to the same categories of metabolites (ceramides and sphingoid bases) that are used by cells to regulate growth, differentiation, apoptosis and other cellular functions. Studies with experimental animals have shown that feeding sphingolipids inhibits colon carcinogenesis, reduces serum LDL cholesterol and elevates HDL, suggesting that sphingolipids represent a "functional" constituent of food. Sphingolipid metabolism can also be modified by constituents of the diet, such as cholesterol, fatty acids and mycotoxins (fumonisins), with consequences for cell regulation and disease. Additional associations among diet, sphingolipids and health are certain to emerge as more is learned about these compounds.

Comparative effects of secondary bile acids, deoxycholic and lithocholic acids, on aberrant crypt foci growth in the postinitiation phases of colon carcinogenesis

The objective of this study was to investigate the effect of deoxycholic (DCA) and lithocholic (LCA) acids on the postinitiation phases of colon cancer. Male Sprague-Dawley rats (n = 170) were injected with azoxymethane (2 injections at 15 mg/kg body wt sc given 1 wk apart) and fed a control (CON) AIN-93 diet. Two weeks after the second azoxymethane injection, 10 animals were killed and aberrant crypt foci (ACF) were enumerated. The remaining animals were randomly assigned to four diet groups: 1) CON, 2) DCA, 3) LCA, and 4) high fat (HF, a positive control group). Bile acid diets consisted of 0.2% by weight DCA or LCA; HF diets consisted of 20% fat (5% soybean oil + 15% beef tallow by weight). Animals were killed at Weeks 3, 12, and 20 (from 1st carcinogen injection), and number and growth features of ACF and adenomatous lesions were enumerated in the colon. At Week 12, ACF number and small, medium, and large (1-3, 4-6, and > or = 7 crypts/focus, respectively) ACF were higher in the HF group than in the DCA, LCA, and CON groups (p < or = 0.05). By Week 20, ACF number and small, medium, and large ACF were similar in the LCA and HF groups, whereas the response was similar in the DCA and CON groups. Average crypt multiplicity was higher in the HF and LCA groups than in the DCA and CON groups (p < or = 0.05). Microadenoma (MA) incidence was higher in the HF group than in the CON and LCA groups (p < or = 0.05). Regional distribution patterns for ACF number were similar to MA and tumor distribution patterns within the CON, DCA, and HF groups. In the LCA group, ACF number and MA showed a proximal predominance in regional distribution, whereas tumors showed a distal predominance. HF diets provided the most stimulatory environment, immediately enhancing the number and growth of ACF and MA incidence. In conclusion, HF and LCA diets exerted distinct effects on postinitiation phases of colon cancer, whereas the DCA diet did not.

Diet, lifestyle, and colorectal cancer: is hyperinsulinemia the missing link?

Several dietary and other lifestyle factors have been implicated in the development of colorectal cancer. However, the precise nature and actual magnitude of the relationship between individual nutrient intakes and other lifestyle factors and colorectal cancer risk are not clear. A unifying hypothesis has recently been proposed that explains why obesity, physical inactivity, alcohol, and consumption of a typical Western diet increase colorectal cancer risk. This hypothesis suggests that these dietary and other lifestyle factors are associated with insulin resistance and hyperinsulinemia and that hyperinsulinemia, in turn, may stimulate growth of colorectal tumors. Two recently published large prospective epidemiologic studies indicate a significant increase in colorectal cancer risk in subjects with diabetes mellitus, thereby supporting this hypothesis.

Milk consumption in older Americans

OBJECTIVES

The purpose of this study was to identify individual characteristics associated with types and frequency of milk consumption in older American adults.

METHODS

A national probability-based sample (response rate = 91%) completed a telephone survey. Generalized logit and cumulative logit analyses were used to identify predictors of and barriers to fluid milk consumption in 494 elderly people.

RESULTS

The likelihood of drinking skim or 1% milk rather than whole milk increased with nutrition knowledge, income, trying to reduce cholesterol intake, and being female (P < .05). Frequency of milk consumption was higher with nutrition knowledge, frequency of milk consumption during adolescence, and following a diabetic diet but was lower with milk intolerance.

CONCLUSIONS

The present results could be used to develop intervention strategies for improving milk consumption rates among older adults. These strategies might focus on increasing elderly people's awareness of milk intolerance and lactose-reduced milk products and their concern about cholesterol. The relationship between current and adolescent milk consumption suggests that intervention strategies should begin early in life.

Modulation of colonic xenobiotic metabolizing enzymes by feeding bile acids: comparative effects of cholic, deoxycholic, lithocholic and ursodeoxycholic acids

Primary and secondary bile acids such as cholic (CHA), deoxycholic (DCA) and lithocholic (LCA) acids have been shown to increase colon tumorigenesis. It has been suggested that inhibition of xenobiotic metabolizing enzymes such as glutathione S-transferase (GST) and UDP-glucuronyltransferase (UGT) by bile acids may be a factor in the development of colon cancer. While enzyme inhibition has been demonstrated in vitro, it is unclear whether feeding bile acids modulates colonic GST and UGT in vivo. To test this notion, male, Sprague-Dawley rats (n = 100) were assigned to a control (CON) or test diets containing 0.2% CHA, DCA, LCA or ursodeoxycholic acid (UDCA). After 5 weeks, colonic tissue was harvested and used for enzyme and cell proliferation measurements. The response to bile acids varied with the enzyme measured and appeared isoenzyme specific. GST-alpha activity was lower in the bile acid fed groups compared with CON. While GST-mu was lower in the LCA-fed group, GST-pi was lower in the DCA-, CHA- and UDCA-fed groups. Unlike GST, both UGT and NADPH-cytochrome P-450 reductase (CYC) activities were increased by bile acids. The proliferative response of the colonic epithelium varied with the bile acids and was regionally specific. These data demonstrate that feeding bile acids alters the activity of colonic phase I and II enzymes; however, the physiological effect of these enzymatic perturbations is yet to be determined.

Inhibitory effect of 1alpha-hydroxyvitamin D3 on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal carcinogenesis in Wistar rats

The effect of 1alpha-hydroxyvitamin D3 (1alpha(OH)D3) on gastrointestinal carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in male Wistar rats. After oral treatment with 0.01% MNNG for 24 weeks, rats were given 0.04 microg of 1alpha(OH)D3 or its vehicle by gastric intubation three times a week for 24 weeks. The incidence of gastrointestinal tumors was 16/30 (53%) in rats treated with MNNG alone, 16/30 (53%) in those treated with MNNG plus vehicle and 8/30 (27%, P < 0.05) in those treated with MNNG plus 1alpha(OH)D3. The number of tumors per rat in the group treated with MNNG plus 1alpha(OH)D3 was half those in the control groups (P < 0.05). Results indicated that a non-hypercalcemic dose of 1alpha(OH)D3 had an inhibitory effect on MNNG-induced duodeno-intestinal carcinogenesis.

Vitamins E plus C and interacting conutrients required for optimal health. A critical and constructive review of epidemiology and supplementation data regarding cardiovascular disease and cancer

Antioxidants are crucial components of fruit/vegetable rich diets preventing cardiovascular disease (CVD) and cancer: plasma vitamins C, E, carotenoids from diet correlate prevalence of CVD and cancer inversely, low levels predict an increased risk of individuals which is potentiated by combined inadequacy (e.g., vitamins C + E, C + carotene, A + carotene); self-prescribed rectification of vitamins C and E at adequacy of other micronutrients reduce forthcoming CVD, of vitamins A, C, E, carotene and conutrients also cancer; randomized exclusive supplementation of beta-carotene +/- vitamin A or E lack benefits except prostate cancer reduction by vitamin E, and overall cancer reduction by selenium; randomized intervention with synchronous rectification of vitamins A + C + E + B + minerals reduces CVD and counteracts precancerous lesions; high vitamin E supplements reveal potentials in secondary CVD prevention. Plasma values desirable for primary prevention: > or = 30 mumol/l lipid-standardized vitamin E (alpha-tocopherol/cholesterol > or = 5.0 mumol/mmol); > or = 50 mumol/l vitamin C aiming at vitamin C/vitamin E ratio > 1.3-1.5; > or = 0.4 mumol/l beta- (> or = 0.5 mumol/l alpha+ beta-) carotene.

CONCLUSIONS

In CVD vitamin E acts as first risk discriminator, vitamin C as second one; optimal health requires synchronously optimized vitamins C + E, A, carotenoids and vegetable conutrients.