Dietary Fat Intake and Cancer

Association between dietary fiber and endometrial cancer: a dose-response meta-analysis

BACKGROUND

Endometrial cancer is the most common female gynecologic cancer in the United States. Excessive and prolonged exposure of the endometrium to estrogens unopposed by progesterone and a high body mass are well-established risk factors for endometrial cancer. Although dietary fiber has been shown to beneficially reduce estrogen concentrations and prevent obesity, its role in endometrial cancer has received relatively little attention.

OBJECTIVE

The objective was to summarize and quantify the current evidence of a role of dietary fiber consumption in endometrial cancer risk and to identify research gaps in this field.

DESIGN

We conducted a systematic literature review of articles published through February 2007 to summarize the current evidence of a relation between dietary fiber consumption and endometrial cancer risk and to quantify the magnitude of the association by conducting a dose-response meta-analysis.

RESULTS

Ten articles representing 1 case-cohort study and 9 case-control studies that evaluated several aspects of fiber consumption and endometrial cancer risk were identified through searches in various databases. On the basis of 7 case-control studies, the random-effects summary risk estimate was 0.82 (95% CI: 0.75, 0.90) per 5 g/1000 kcal dietary fiber, with no evidence of heterogeneity (I(2): 0%, P for heterogeneity: 0.55). The random-effects summary estimate was 0.71 (95% CI: 0.59, 0.85) for the comparison of the highest with the lowest dietary fiber intake in 8 case-control studies, with little evidence of heterogeneity (I(2): 20.8%, P for heterogeneity: 0.26). In contrast, the only prospective study that evaluated this association did not find an association.

CONCLUSIONS

Although the current evidence, based on data from case-control studies, supports an inverse association between dietary fiber and endometrial cancer, additional population-based studies, particularly cohort studies, are needed before definitive conclusions can be drawn.

Nutrition and pharyngeal cancer: results from a case-control study in Spain

BACKGROUND

Oropharyngeal and hypopharyngeal cancer is increasing all over the world, frequently affecting more and more women and younger individuals and not only the typical 50- to 60-year-old heavy smoker and drinking man. In addition, 5-year overall survival rate remains poor (30% to 40% in most series), despite advances in treatment. Therefore, it is crucial to understand as accurately as possible the risk factors for these malignancies to improve primary prevention.

METHODS

We report the results from a case-control study of pharyngeal cancer risk factors conducted in Spain involving 232 consecutive patients who were gender- and age-matched with 232 controls. Data were collected by interviewer-administered personal interview.

RESULTS

Our results show that low intake of fruit, fruit juice, uncooked vegetables, dietary fiber-containing foods (legume and cereals), fish, milk, and dairy products is an independent risk factor for pharyngeal cancer and that high consumption of meat and fried foods also increases the risk once data are adjusted for tobacco smoking and alcohol drinking.

CONCLUSIONS

Although findings for fruit, juice, and uncooked vegetables are in accordance with those from other authors and can be explained on a biologic basis, the relationship between pharyngeal cancer and dietary excess of saturated fatty acids needs experimental investigation. Findings for milk, dairy products, and fish also warrant more detailed epidemiologic research because of conflicting data reported in the literature and because of the reportedly ambiguous role of retinol in human cancers. No conclusive explanations for the protective effect of dietary fiber-containing foods can be put forward today. Our results are uniquely attributable to oropharyngeal and hypopharyngeal cancers because of the small size of our nasopharyngeal cancer subsample.

Are there age-dependent effects of diet on prostate cancer risk?

OBJECTIVES

To examine whether there are age-dependent effects of diet on prostate cancer risk.

METHODS

We have postulated that nutritional factors that may affect the risk of initiation would be more likely to be identified among younger patients, whereas those that may affect the risk of progression would be more clearly identifiable among older patients. Study subjects were 320 patients with prostate cancer and 246 controls with no systematic disease, hospitalised in six major hospitals in Athens, Greece. Logistic regression models were fitted separately for men under 70 years and 70 years or older.

RESULTS

Polyunsaturated lipids substantially increased the risk among younger subjects, but played little role among older ones (p for interaction 0.21). Cooked tomatoes had a strong protective effect among older persons, but not among younger subjects (p for interaction 0.009). Last, vitamin E was strongly inversely related to prostate cancer risk among younger subjects, but not among older subjects (p for interaction 0.15).

CONCLUSIONS

Even a simple straight forward interpretation of the data, i.e., that older cases of prostate cancer have a different dietary risk profile than younger ones, has potentially useful implications.

Cancers, mainly male, as population biomarkers for breast cancer mortality

BACKGROUND

BCM correlates significantly with mor tality from other site-specific cancers and cardiovascular diseases for both sexes. These other mortalities could be used as independent biomarkers (predictors) of BCM allowing an evaluation of the importance of common etiological factors.

METHODS

BCM (age-adjusted, 45-74 years), obtained around 1992 from 37 countries worldwide, was estimated in multivariate regression to identify the best predictors.

RESULTS

Male and female biomarkers predicted BCM with a R(2) of 0.80 and 0. 69, respectively. Strongest correlation was obtained with male colon, prostate, lung, and rectum cancer and female esophagus cancer (R(2) = 0.84, P < 0.0001). The estimated independent mean percentage contribution +/- SD to BCM was 40 +/- 7 from prostate cancer, 38 +/- 9 from male colon, 13 +/- 6 from male lung and rectum cancer combined, and 9 +/- 3 from female esophagus cancer. The regression equation (1992 data) predicted mean BCM in 28 available countries from 1967 to 1991 with a mean error of 5%. BCM in individual countries was also reliably predicted from 1967 to 1991, r = 0.86 to 0.90 (P < 0.0001). In 1953, r was 0.74 (P < 0.0001).

CONCLUSIONS

The evidence suggests a major influence of modifiable environmental factors common to BCM, its biomarkers, and both sexes: most likely nutrition, smoking, and alcohol intake. The results obtained with male data suggest a minor impact of sex-linked risk factors and, until recently, of treatment and early detection on BCM at the population level.

The effects of varying dietary fat on the nutrient intake in male and female runners

OBJECTIVE

The present study examined the effects of varying dietary fat levels on nutrients in female and male endurance runners.

METHODS

Three diets (low, medium and high fat) were designed for each subject using their food preferences and three-day food records. Each diet was eaten for 28 to 31 days. The diets were self-selected from seven-day sample menus. Twelve male and 13 female runners between 18 and 55 years of age who averaged 42 miles/week participated in the study. Daily food intakes, activity records and weekly palatability/hunger scales were completed.

RESULTS

Dietary fat intakes, as a percent of total energy intake (%E), averaged 17%E, 31%E, and 44%E on the low, medium and high fat diets, respectively. Energy consumption was less than their estimated energy expenditure (EEE) on all diets. On the low fat diet, the female runners were consuming approximately 60% of their EEE. As dietary fat increased, the difference between calorie intake and estimated energy expenditure became less and the subjects were less hungry on the two higher fat diets. For all subjects, as energy intakes increased, so did carbohydrate intake. Therefore, carbohydrate intake was not different on the two lower fat diets. Irrespective of gender, calcium and zinc intakes, which were below 1989 RDAs, increased with increasing fat intakes, between the low and medium fat diets. Zinc intake was also higher on the highest fat diet. Essential fatty acid intakes for females on the low fat diet were less than 2.5%E. Half of the female runners ate less than the RDA of calcium and zinc on the low fat diet and Fe on the medium fat diet.

CONCLUSION

This study suggests that endurance runners may not be consuming enough calories on a low fat diet and that increasing dietary fat increased energy consumption. On the low fat diet, essential fatty acids and some minerals (especially zinc) may be too low. A low fat diet could compromise health and performance.

Formation of DNA adducts of the food-derived mutagen 2-amino-9H-pyrido-[2,3-b]indole (A(alpha)C) and bioassay of mammary gland carcinogenicity in Sprague-Dawley rats

2-amino-9H-pyrido[2,3-b]indole (AalphaC) is a heterocyclic amine found at relatively high concentrations in barbecued or grilled meats. In the current study, the mammary gland carcinogenicity of AalphaC was examined in female Sprague-Dawley rats given 10 doses of AalphaC (75 mg/kg, orally, once per day starting at 43 days of age) and placed on a defined high-fat diet (23.5% corn oil), a strong promotional factor for rat mammary gland carcinogenesis. Within 1 year, one out of 20 rats dosed with AalphaC developed a tubulopapillary carcinoma, indicating that the bioassay was largely negative. As DNA adduct formation is considered to play a role in carcinogenesis, AalphaC-DNA adduct levels were measured in the mammary gland and other tissues by the 32P-postlabelling method. Under intensification conditions, one major adduct and up to three minor adducts were detected in isolated mammary gland epithelial cells and other tissues (liver, stomach, small intestine, colon and kidney) of AalphaC-treated rats; the adduct patterns were similar in all tissues examined. The major adduct, comprising 60-100% of total DNA adduct levels in tissues, was chromatographically identical to the principal adduct found in 3'-dGp-AalphaC (synthesized by reacting 3'-phospho-2'-deoxyguanosine (3'-dGp) with N-acetoxy-AalphaC). Of the tissues examined, the highest AalphaC-DNA adduct levels were found in the liver. In male rats given a single dose of AalphaC (75 mg/kg, orally, 3 hr prior to necropsy), no AalphaC-DNA adducts were detected in extrahepatic tissues. In female rats given a single dose or 12 daily doses of AalphaC, hepatic DNA adduct levels were at least 12-13-fold higher than those in any other tissue. Mean total AalphaC-DNA adduct levels in mammary gland epithelial cells and liver from female rats given multiple doses of AalphaC were 3.5 and 50.7 (RAL x 10(7)), respectively. Although factors in addition to DNA adduct formation are likely to play a role in mammary gland carcinogenesis, the results suggest that the weak mammary gland carcinogenicity of AalphaC may in part be associated with low AalphaC-DNA adduct levels in the mammary gland epithelium.

Olive oil and human cancer: an assessment of the evidence

BACKGROUND

We have attempted to summarize the evidence concerning the association of olive oil intake with cancer risk in humans.

METHODS

We reviewed all the studies that met the following criteria: (1) they have directly examined olive oil in the context of an extensive food frequency questionnaire or have evaluated the role of monounsaturated fat in populations of Mediterranean countries where a large fraction of monounsaturated fat originates from olive oil and (2) they have analyzed the data with explicit or implicit control for energy intake to accommodate the likely confounding influence of caloric consumption and to account to a certain extent for differential completeness of reporting between cases and controls. Ecologic studies were also considered and relevant experimental data were invoked.

RESULTS

With respect to breast cancer, there is converging evidence for a protective effect, although the data are not definitive. For other cancer types, the overall epidemiologic evidence, although promising, is quantitatively limited and qualitatively suboptimal.

CONCLUSIONS

The issue is of major public health importance and deserves additional study.

You won't know unless you ask: the biopsychosocial interview for adolescents

In order to impact morbidity and mortality of adolescents, the health care provider must not only determine the risk status of the teenager but also take time to provide appropriate guidance and interventions. We have developed the West Virginia University Adolescent Risk Score, which is more inclusive than similar screening techniques and requires an 8 +/- 3-minute interview. This format facilitates specific guidance, provides documentation of risk status, and is readily accessible on future visits. Our data provide the basis for planning and research regarding the effectiveness of interventions.

Environmental dietary factors in colorectal cancer. Some unresolved issues

BACKGROUND

Unresolved epidemiologic issues in large bowel cancer include reasons for changes in incidence rates, differences in epidemiology of cancer in the distal and proximal colon and rectal cancer, and the optimal fat and fiber levels for low rates.

METHODS

The authors examined questions of suitable procedures for the assessment of intake of specific key nutrients and mode of cooking. International data by site and nutritional factors were compared.

RESULTS

Fat and fiber intake in the United States, Japan, and Finland related to differences in rates. Laboratory animal model studies indicated that type of fat affected carcinogenesis. Colon cancer rates in men in the United States increased slightly, but started to decline slightly, as in women.

CONCLUSIONS

Dietary factors play a key role in causation and prevention of large bowel cancer, with a diet of 25% fat and 25 g fiber recommended. Comprehensive school health education should be used to modify the nutritional habits of children.