Relationship of diet to risk of colorectal adenoma in men.

BACKGROUND: Rates of colorectal cancer in various countries are strongly correlated with per-capita consumption of red meat and animal fat and inversely associated with fiber consumption. There have been few studies, however, of dietary risk factors for colorectal adenomas, which are precursors of cancer. PURPOSE: Our purpose was to determine prospectively the relationship between dietary factors and risk of colorectal adenomas. METHODS: Using data from the Health Professionals Follow-up Study, we documented 170 cases of adenomas of the left colon or rectum in 7284 male health professionals who completed a food-frequency questionnaire in 1986 and who had a colonoscopy or sigmoidoscopy between 1986 and 1988. Relative risk (RR) of adenoma was determined according to quintiles of nutrient intakes. RESULTS: After adjustment for total energy intake, saturated fat was positively associated with risk of colorectal adenoma (P for trend = .006); RR for the highest versus the lowest quintile of intake was 2.0 (95% confidence interval [CI] = 1.2-3.2). Dietary fiber was inversely associated with risk of adenoma (P for trend less than .0001); RR for men in the highest versus the lowest quintile was 0.36 (95% CI = 0.22-0.60). All sources of fiber (vegetables, fruits, and grains) were associated with decreased risk of adenoma. For subjects on a high-saturated fat, low-fiber diet, the RR was 3.7 (95% CI = 1.5-8.8) compared with those on a low-saturated fat, high-fiber diet. The ratio of the intake of red meat to the intake of chicken and fish was positively associated with risk of adenoma (P for trend = .02). CONCLUSIONS: These prospective data provide evidence for the hypothesis that a diet high in saturated fat and low in fiber increases the risk of colorectal adenoma. They also support existing recommendations to substitute chicken and fish for red meat in the diet and to increase intake of vegetables, fruits, and grains to reduce risk of colorectal cancer.     

Diet, nutrition, and cancer: interim dietary guidelines

The Committee on Diet, Nutrition, and Cancer of the National Academy of Sciences recently evaluated the role of diet in carcinogenesis. Both epidemiological and laboratory evidence suggests that a high intake of total fat increases susceptibility to cancer of different sites, particularly the breast and colon. In epidemiological studies frequent consumption of certain fruits and vegetables and in laboratory experiments some components of fruits and vegetables, especially cruciferous vegetables, appear to decrease the incidence of cancers at various sites. In contrast, frequent consumption of salt-cured, salt-pickled, or smoked foods, possibly because they may contain nitrosamines or polycyclic aromatic hydrocarbons, appears to increase the risk of esophageal or stomach cancer. Excessive alcohol consumption among smokers appears to be associated with an elevated risk of cancers of the oral cavity, esophagus, larynx, and respiratory tract. Interim dietary guidelines to reduce the risk of cancer were proposed in accordance with these conclusions. No definitive conclusions were reached for other dietary factors, including total calories, cholesterol, fiber, and selenium, nor could the quantitative contribution of diet to overall cancer risk be estimated.     

Dietary patterns,Mediterranean diet,and endometrial cancer risk

This study examines the association between dietary patterns and endometrial cancer risk. A case–control study of endometrial cancer was conducted from 1996 to 1999 in the San Francisco Bay Area in white, African-American, and Latina women age 35–79. Dietary patterns were defined using a principal components analysis; scoring dietary intake based on correspondence to a Mediterranean-style diet; and by jointly categorizing intake of fruits/vegetables and dietary fat. Four dietary patterns were identified and labeled “plant-based,” “western,” “ethnic,” and “phytoestrogen-rich.” None of these dietary patterns nor adherence to a Mediterranean diet (to the extent consumed by this population) was associated with endometrial cancer risk. However, among non-users of supplements, greater consumption of the “western” dietary pattern was associated with a 60% increase in risk (95% CI: 0.95–2.7 per unit change; P-interaction = 0.10). A diet characterized by high fat consumption increased risk, regardless of fruit and vegetable consumption (OR = 1.4, 95% CI: 0.97–2.1 for high fat, low fruit/vegetable intake and OR = 1.4, 95% CI: 0.95–2.1 for high fat, high fruit/vegetable intake compared to low fat, high fruit/vegetable intake). Thus, while like others we found that dietary fat increases endometrial cancer risk, the evaluation of dietary patterns did not provide any additional information regarding risk.     

Food and botanical groupings and risk of breast cancer: a case-control study in Shanghai, China.

Breast cancer incidence rates more than double in Chinese women as they migrate from China to Hong Kong to the United States, suggesting that environmental factors contribute to the international variation in breast cancer incidence. Several dietary factors, which differ between the United States and the Chinese population, including intake of soy, meat, and fruits and vegetables, have been suggested to affect breast cancer risk. This report describes results from a case-control study of diet and risk of breast cancer nested in a randomized trial of breast self exam in Shanghai, China. Participating breast cancer cases (n = 378) and frequency age-matched controls (n = 1,070) completed a comprehensive food frequency questionnaire and a risk factor questionnaire. After adjustment for age, total energy intake, and total years of breast-feeding, women in the highest quartile of fruit and vegetable intake (> or =3.8 servings/d) were significantly less likely to have breast cancer (odds ratio, 0.48; 95% confidence interval, 0.29-0.78) as compared with women in the lowest quartile of intake (< or =2.3 servings/d). Egg consumption was also significantly inversely associated with risk of breast cancer (odds ratio for > or =6.0 eggs/wk versus < or =2.0 eggs/wk is 0.56; 95% confidence interval, 0.35-0.91). There was no difference in soy consumption between cases and controls. None of the associations with a single botanical family explained the strong inverse relationship between fruits and vegetables and breast cancer risk. These results provide additional evidence in support of the important role of fruits and vegetables in breast cancer prevention.     

Diet and risk of colorectal cancer in a cohort of Finnish men

Objectives: Based on previous epidemiological studies, high fat and meat consumption may increase and fiber, calcium, and vegetable consumption may decrease the risk of colorectal cancer. We sought to address these hypotheses in a male Finnish cohort.Methods: We analyzed data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) where 27, 111 male smokers completed a validated dietary questionnaire at baseline. After an average of 8 years of follow-up, we documented 185 cases of colorectal cancer. The analyses were carried out using the Cox proportional hazards model.Results: The relative risk (RR) for men in the highest quartile of calcium intake compared with men in the lowest quartile was 0.6 (95% CI 0.4–0.9, p for trend 0.04). Likewise, the intake of milk protein and the consumption of milk products was inversely associated with risk of colorectal cancer. However, intake of dietary fiber was not associated with risk, nor was fat intake. Consumption of meat or different types of meat, and fried meat, fruits or vegetables were not associated with risk.Conclusions: In this cohort of men consuming a diet high in fat, meat, and fiber and low in vegetables, high calcium intake was associated with lowered risk of colorectal cancer.     

Diet and ovarian cancer risk: a case-control study in China

This case-control study, conducted in Zhejiang, China during 1999-2000, investigated whether dietary factors have an aetiological association with ovarian cancer. Cases were 254 patients with histologically confirmed epithelial ovary cancer. The 652 controls comprised 340 hospital visitors, 261 non-neoplasm hospital outpatients without long-term diet modifications and 51 women recruited from the community. A validated food frequency questionnaire was used to measure the habitual diet of cases and controls. The risks of ovarian cancer for the dietary factors were assessed by adjusted odds ratios based on multivariate logistic regression analysis, accounting for potential confounding demographic, lifestyle, familial factors and hormonal status, family ovarian cancer history and total energy intake. The ovarian cancer risk declined with increasing consumption of vegetables and fruits but vice versa with high intakes of animal fat and salted vegetables. The adjusted upper quartile odds ratio compared to the lower quartile was 0.24 (0.1-0.5) for vegetables, 0.36 (0.2-0.7) for fruits, 4.6 (2.2-9.3) for animal fat and 3.4 (2.0-5.8) for preserved (salted) vegetables with significant dose-response relationship. The risk of ovarian cancer also appeared to increase for those women preferring fat, fried, cured and smoked food.     

Dietary fruit and vegetables protect against somatic mutation in vivo,but low or high intake of carotenoids does not

Epidemiological studies have demonstrated protective effects of vegetables and fruit on risk of cancer, but underlying mechanisms remain unclear. Intervention studies have in some cases contradicted previous epidemiological evidence, e.g. for beta-carotene supplementation and lung cancer, emphasizing the need for mechanistic data. We assessed in vivo mutagenic effects of several dietary items using the HPRT (hypoxanthine-guanine phosphoribosyl transferase) gene assay with T-lymphocytes from 312 individuals (158 lung cancer cases, 154 population controls), who provided information on diet and smoking habits. HPRT mutant frequency (MF) was significantly decreased in relation to intake of vegetables, citrus fruits and berries, respectively, as well as calculated vitamin C intake from diet. There was a significant U-shaped association with dietary carotenoid intake, with lowest MF near population average carotenoid intakes and higher mutation frequencies both at low and high intakes, and a similar borderline significant association was observed for beta-carotene. Our study is consistent with known diet-cancer associations and provides novel human in vivo mechanistic support for a cancer-protective effect of vegetables and fruit by modulation of somatic mutagenesis. Our results also provide support for the increase in lung cancer risk observed particularly in smokers in studies of beta-carotene supplementation.     

Red meat consumption in Australia: intakes, contributions to nutrient intake and associated dietary patterns.

In the past few decades, increasing concern about the role of diet in the aetiology of diseases such as heart disease and certain cancers, including colon cancer and the hormone-related cancers, has led to a number of studies assessing the role of various food components. Many of these studies, particularly those in the 1970s and 1980s looked at individual foods or nutrients without assessing their role in relation to other dietary components. Thus the role of red meat was often examined in isolation from energy, fat or fibre intake or from consumption of other food groups such as vegetables or fruit. Epidemiological studies of the dietary aetiology of colon cancer have been undertaken in a number of communities with varying meat and dietary intake profiles and with varying results. To provide background information for an assessment of the potential role of red meat consumption in the aetiology of colon cancer in the Australian context, an analysis of current consumption patterns of red meat in the population was undertaken. The results show that red meat consumption, which had been falling since the 1970s, continued to decline in Australia at a time when colon cancer rates were rising. Red meat intake in 1995/6 averaged 88 g a day for men and 45 g a day for women and was contributing less than one-fifth of the dietary fat and saturated fat in the Australian diet. Those with the highest intakes of red meat on the day of the survey had intakes of vegetables and fruits closer to those of non-red meat eaters, with the low-to-moderate red meat consumers having the lower intakes of fruits and vegetables.     

Risk factors for esophageal cancer in Shanghai,China. II. Role of diet and nutrients

A population-based case-control study of esophageal cancer (902 cases, 1,552 controls) in Shanghai, China, investigated the etiologic role of diet. After adjustment for cigarette smoking, alcohol consumption and other risk factors, increasing consumption of fruits, dark orange vegetables and beef or mutton was associated with statistically significant decreasing trends in risk for esophageal cancer. In general, risks were about 40% lower among those in the upper vs. lower quartiles of intake of these foods. Fivefold increases in risk were observed among those who consumed burning hot soup or porridge, with smaller excesses for preserved vegetables, salty and deep fried foods. Nutrient analysis revealed that increased dietary intake of protein, carotene, vitamins C and E and riboflavin was associated with reduced esophageal cancer risk. Our findings support the notion that the reported temporal increases in the per capita consumption of fruits, vegetables and animal products contribute to the substantial reduction in the incidence of esophageal cancer in Shanghai, particularly since cigarette and alcohol use has not decreased.     

Food and cancer: state of the art about the protective effect of fruits and vegetables

Epidemiological studies performed during the last 20 years support an inverse relationship between the individual intake of fruits and vegetables and the risk of cancer. In taking into account some recent conflicting data, a working group of the Nacre network, the French Network for Food and Cancer Research, has conduced a critical analysis of epidemiological and experimental studies, including the preliminary data from the Epic cohort, the European Prospective Investigation into Cancer and Nutrition, to clarify the role of fruits and vegetables to prevent cancer. To date, a high intake of fruits and vegetables (at least, 400 g per day) is appropriate to lower the risk of cancer. Fruits and vegetables provide numerous phytochemicals which, in part, may explain their beneficial effect. Thus, studies in animal models and in cell-culture systems have furnished a lot of information about the potential mechanism by which a diet high in fruits and vegetables may reduce the risk of cancer in humans. However, more investigation in the identification of the biologically active constituents, in the knowledge of their availability and the mechanism by which they contribute to lower the risk of cancer, will increase the scientific support of a public health policy.     

A Low Fat Diet Rich in Fruits and Vegetables May Reduce the Risk of Developing Prostate Cancer

Background: Diet has been implicated in prostate cancer risk and there is evidence of risk reduction with a ‍healthy diet. The objective of this population-based case control study was to examine whether a low fat diet rich in ‍fruits and vegetables can reduce the risk of developing prostate cancer in Mumbai, India. Methods: Included in this ‍study were microscopically proved cases of prostate cancer diagnosed during 1998 to 2000 and registered by Bombay ‍Population Based Cancer Registry (n=594). The controls were healthy men belonging to the resident general population ‍of Mumbai, India. Two controls for each case matched by age and place of residence were selected as the comparison ‍group. Data on oil/fat consumption, fruits and vegetable consumption and other probable confounding factors were ‍obtained by structured face-to-face interview. After exclusions, 390 cases and 780 controls were available for final ‍analysis and confounding was controlled by multiple logistic regression. Results: 58.7% of the control group consumed ‍more than 3 kg of fruits and vegetables per week compared to 52.1% of the case group. Controlling for age and ‍probable confounding factors, a statistically significant protective effect for prostate cancer was observed for those ‍who consumed fruits and vegetables 2 to 3 kg (OR 0.5, 95%CI 0.3-0.8) and more than 3 kg (OR 0.4, 95% CI 0.3-0.6) ‍per week compared to those who consumed less than 2 kg per week. The linear trend for the protective effect was ‍highly significant with increase in the consumption of fruits and vegetables (p = 0.001). Even though not statistically ‍significant, oil/fat consumption showed an elevated risk (OR 1.7, 95%CI 0.9-3.3) for those who consumed more than ‍2kg of oil/fat per month compared to those who consumed less than 1kg. Conclusion: The findings from this study ‍support the hypothesis that a low fat diet rich in fruits and vegetables may reduce the risk of prostate cancer.     

A review of association of dietary factors in gallbladder cancer

Gallbladder cancer (GBC) is the prominent malignancy of hepato-biliary tract, being the fifth most common carcinoma for gastrointestinal tract in United States. Epidemiological studies world wide have implicated dietary factors in the development of gallbladder cancer. The ecological evidences indicate considerable geographic variation in the incidence of gallbladder cancer. However the variations in GBC incidence of different populations might be partly determined by their dietary variations. Higher intake of energy and carbohydrate possibly increase the risk of gallbladder cancer. Obesity plays an important role in the causation of GBC. Adequate intake of fruits and vegetables probably reduce the risk of GBC. This nutritional preventive effect against GBC could be attributed to high content of vitamins, carotenes and fibers. They can not be too emphatically stated as the sole determinants of GBC. It is apparently clear that a variety of essential nutrients can significantly modify the carcinogenic process. Furthermore, an attempt has been made to establish an association between dietary factors and the occurrence of gallbladder cancer.     

Diet and vitamin or mineral supplementation and risk of rectal cancer in Canada

The study examines the relation of diet and vitamin or mineral supplementation with risk of rectal cancer. Mailed questionnaires were completed by 1 380 newly diagnosed patients with histologically confirmed rectal cancer and 3 097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socio-economic status, lifestyle, diet and vitamin or mineral supplementation. We derived odds ratios and 95% confidence intervals through unconditional logistic regression. Total of consumption of vegetables, fruit and whole-grain products did not reduce the risk of rectal cancer. Consumption of cruciferous vegetables was inversely associated with risk of rectal cancer among women only, as did chicken intake among men. The strongest dietary association with increased rectal cancer risk appeared in males with increasing total fat intake and in females with bacon intake. Vitamin and mineral supplementation showed significant inverse associations with rectal cancer in women only. These findings suggest that dietary risk factors for rectal cancer in women may differ from those in men.     

The Women’s Health Initiative Randomized Controlled Dietary Modification Trial: a post-mortem

Ecological correlations derived from national mortality data and case–control studies have suggested a positive relation between dietary fat and risk of breast cancer. However, in the many large prospective studies that have been conducted more recently, little or no association has been found between total fat intake and breast cancer incidence. The recently released results from the Women’s Health Initiative Fat Reduction Trial found no significant effect of a low-fat diet on risk of breast cancer or total cancer incidence. However, methodologic limitations of this trial, particularly low compliance with the dietary intervention, make these data difficult to interpret, and in the end this massive trial contributes little to our understanding of the role of fat intake in the risk of breast cancer. A substantial body of available evidence now suggests that the percentage of energy derived from fat intake during midlife does not appear to be an important risk factor for breast cancer and is not the primary reason for the large international differences in disease incidence. Diet has a major impact on breast cancer risk, mainly mediated through childhood growth rates and weight gain in later life. Minimizing weight gain during midlife or weight loss after menopause reduces the risk of postmenopausal breast cancer. Massive randomized trials of behavior change to prevent cancer will usually not be a good investment, as clear answers are unlikely. The best information on prevention by diet and lifestyle will generally come from long-term prospective studies combined with controlled trials of intermediate endpoints.     

Dietary factors and risk of lung cancer in never-smokers

We studied dietary risk factors for lung cancer among never-smokers in a population-based case–control study in Stockholm, 1989–1995. Study subjects were older than 30 years of age and had never smoked regularly. A total of 124 cases (35 men, 89 women) and 235 controls (72 men, 163 women) participated. Exposure information was obtained at interview with study subjects. The never-smoking status was validated by interviews with next-of-kin. A protective effect was suggested for vegetables, mediated primarily by carrots (relative risk [RR], 0.7; 95% confidence interval [CI], 0.4–1.3, and 0.6, 0.3–1.1 for intermediate and high consumption of carrots, respectively). Non-citrus fruits appeared to lower the risk as well, with RR 0.6, 95% CI 0.3–1.3 and 0.5, 0.3–1.0 for intermediate and high consumption, respectively. A protective effect with dose-response was also seen for intake of beta-carotene and total carotenoids. Increased risks were seen for cultured milk products in both genders (RR 2.0, 95% CI 1.1–3.9 for intermediate and 1.6, 0.9–2.9 for high consumption), but for milk only among male high consumers. Our results support evidence linking a diet rich in vegetables and non-citrus fruit with decreased lung cancer risk and suggests that among vegetables, carrot consumption is the most important component or marker for this effect in Sweden. The results regarding milk products could be consistent with dietary fat as a risk factor for lung cancer, although a more comprehensive assessment of fat intake is necessary to explore this relation. Int. J. Cancer 78:430–436, 1998. © 1998 Wiley-Liss, Inc.     

The influence of dietary patterns on the development of thyroid cancer

To elucidate the role of diet in the development of thyroid cancer, we conducted a case-control study of 113 persons with histologically-verified thyroid cancer and 138 controls, matched by age, gender and health unit. Socio-economic data, known risk factors and food consumption of more than 100 items were recorded by interviewer-administered prestructured questionnaire. Factor analysis was used to identify possible dietary patterns and logistic regression analysis was used to explore the effect of food items or dietary patterns on thyroid cancer. After adjustment for age, gender, body mass index (BMI), and total energy intake, significant positive associations were observed for pork consumption, while negative ones were observed for tomatoes, lemons and pasta. Dietary patterns of fruits, raw vegetables and mixed raw vegetables and fruits, led to a reduced risk (corresponding odds ratios (ORs) 0.68, 0.71, 0.73) for all thyroid cancers and similar figures were obtained for papillary thyroid cancers. A dietary pattern of fish and cooked vegetables led to an increased risk (OR 2.79) of follicular cancer.     

Goals for nutrition in the year 2000

Ongoing research continues to support the hypothesis that dietary factors significantly influence the incidence of many human malignancies. Despite some conflicting and confusing studies reported over the past two decades, it is becoming increasingly clear that maintenance of a healthy adult weight, through proper balance of caloric intake and physical activity, is key to cancer prevention. Moreover, current nutritional recommendations for the prevention of cancer include increased consumption of fruits and vegetables; reduced consumption of red meat and animal fat; and avoidance of excessive alcohol use. For many individuals, a daily multivitamin that contains folic acid may also be part of a reasonable overall cancer prevention strategy.     

Dietary and lifestyle characteristics of colorectal cancer in Jordan: a case-control study

Objectives: We evaluated dietary pattern and lifestyle characteristics of patients with colorectal cancer (CRC) in Jordan. Design: The case-control study included 220 recently diagnosed CRC cases and 220 age and gender matched healthy subjects as a control group. Results: The participating CRC cases had lower dietary intake of fibre, folate, vitamin B12, β-carotene, vitamin C and selenium as compared to controls (P<0.05). The frequency of consumption of fruits and vegetables was also lower among CRC cases, while the frequency of consumption of red meat and saturated fat was higher and positively associated with CRC risk. Furthermore, family history for CRC played a positive role and the majority of CRC cases and controls had a low physical activity level. Conclusions: A sedentary lifestyle and a diet low in fruits and vegetables, and high in animal red meat and saturated fat, appeared associated with CRC among the studied Jordanian subjects. This is consistent with the reported CRC studies in developed nations indicating global causal effects for this tumour type.     

Nutrition and breast cancer

Epidemiologic evidence on the relation between nutrition and breast cancer is reviewed. After several decades of study, many aspects of the role of diet in breast cancer etiology are still unclear. Results from large prospective studies do not support the concept developed from animal and ecologic evidence that dietary fat intake in mid-life is associated with breast cancer risk. Thus, if fat intake is relevant to breast cancer, it is probably only at extremely low fat intakes or during early life. An emerging hypothesis that higher energy intake and growth rate in childhood and adolescence increases risk deserves further study. The possibility that diets rich in olive oil may be protective is also intriguing. Considerable evidence suggests that low intake of vegetables modestly increases the risk of breast cancer; however, the nutrients responsible remain elusive. The positive relation of alcohol intake with breast cancer risk has been seen repeatedly, and recently has been buttressed by studies showing that moderate alcohol intake increases estrogen endogenous levels. Advice to increase vegetable intake and limit alcohol consumption would probably have a modest, at best, effect on breast cancer risk. Future studies of the relation of nutrition during early life to subsequent breast cancer risk are needed.This work was supported, in part, by research grants CA 40456, CA 50598, and CA 55075 from the US National Institutes of Health, and a grant from the American Cancer Society (SIG-18). Dr Hunter is partially supported by a Faculty Research Scholar Award (FRA-455) from the American Cancer Society.     

Cancer preventive role of selected dietary factors

Dietary behavior seems to be an important modifiable determinant for the risk of cancer. The evidences from several epidemiological studies suggest that higher intakes of fruits and vegetables have been associated with lower risk of cancer. Dietary phenolic and polyphenolic substances, terpenoids, dietary fibers, fish oils, some micronutrients present in foods of both plant and animal origin, and a reduction of caloric intake appear to inhibit the process of cancer development. Many dietary factors possess antioxidant and anti-inflammatory properties and cause induction of phase II enzymes like glutathione-S-transferases. It has been suggested that cruciferous vegetables play an important role in cancer prevention, and their chemopreventive effects are due to high glucosinolate content which under enzymatic hydrolysis produces bioactive compound isothiocyanates. Further, isothiocyanates of a wide variety of cruciferous vegetables are powerful inhibitors of carcinogenesis in experimental animal models. Several flavonoids present in fruits, tea, soya beans, etc. may be useful as cancer preventive agents. Similarly, ellagic acid, perillyl alcohol and resveratrol found in various fruits may have chemoprotective effect. Moreover, different vanilloids such as curcumin and gingerol have been shown to possess antioxidative properties. Nevertheless, in spite of several studies, still the effects of various ingredients are not clearly distinguished. In human, little convincing evidence has been established for the proposed protective effects of dietary constituents. It is an important future research goal to provide necessary evidences to support the chemopreventive role of different dietary factors, and also to clarify misunderstandings in this perplexing area.