Dietary Intakes of Selected Nutrients and Food Groups and Risk of Cervical Cancer

We investigated the relationships between intakes of selected dietary nutrients and food groups and risk of cervical cancer in a hospital-based, case-control study including 239 cases diagnosed with squamous cell carcinoma of the cervix and 979 hospital patients with nonneoplastic diagnoses who completed a self-administered questionnaire between 1982 and 1998 at Roswell Park Cancer Institute. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression adjusting for age, education, smoking status, use of oral contraceptives, barrier contraceptives and spermicides, family history of cervical cancer, year questionnaire completed, and energy intake. Significant reductions in risk of approximately 40–60% were observed for women in the highest vs. lowest tertiles of dietary fiber (OR = 0.59, 95% CI = 0.37–0.94), vitamin C (OR = 0.52, 95% CI = 0.33–0.80), vitamin E (OR = 0.44, 95% CI = 0.27–0.72), vitamin A (OR = 0.47, 95% CI = 0.30–0.73), α -carotene (OR = 0.41, 95% CI = 0.27–0.63), β -carotene (OR = 0.44, 95% CI = 0.29–0.68), lutein (OR = 0.51, 95% CI = 0.33–0.79), folate (OR = 0.55, 95% CI = 0.34–0.88), and total fruit and vegetable intake (OR = 0.52, 95% CI = 0.34–0.77). Our findings suggest that a diet rich in plant-based nutrients may be important in reducing the risk of cervical cancer.     

Intakes of selected nutrients, foods, and phytochemicals and prostate cancer risk in western New York

A number of epidemiological studies have suggested that diet may affect the etiology of prostate cancer, but few have investigated the impact of phytochemical intakes on this cancer. We conducted a case-control study of diet and prostate cancer in western New York involving 433 men with primary, histologically confirmed prostate cancer and 538 population-based controls, frequency matched to cases on age and county of residence. Diet was assessed with a detailed food-frequency questionnaire. We calculated daily intakes of nutrients and the phytochemicals beta-sitosterol, campesterol, stigmasterol, total phytosterols, total lignan precursors, quercetin, and kaempferol based on published food composition data. Odds ratios (ORs) and 95% confidence intervals (CIs) describing the association of prostate cancer risk with selected nutrients, phytochemicals, and food groups were estimated with unconditional logistic regression. Compared with men in the lowest quartile of intake, reduced risks were observed for men in the highest quartile of intake of vitamin C (OR = 0.49; 95% CI = 0.33-0.74), beta-carotene (OR = 0.53; 95% CI = 0.36-0.79), alpha-carotene (OR = 0.67; 95% CI = 0.47-0.97), lutein (OR = 0.55; 95% CI = 0.37-0.81), lycopene (OR = 0.62; 95% CI = 0.42-0.92), total lignan precursors (OR = 0.66; 95% CI = 0.47-0.94), quercetin (OR = 0.64; 95% CI = 0.44-0.92), and total vegetables (OR = 0.53; 95% CI = 0.36-0.79), but weak increased risks were observed for snacks and sweets (OR = 1.46; 95% CI = 0.95-2.23). Estimates associated with nutrients and phytochemicals were attenuated after adjustment for total vegetable intake. Nevertheless, our results support the hypothesis that a phytochemical-rich, plant-based diet is of importance in reducing risks of hormone-related neoplasms.     

Effect of nutrient intake and Helicobacter pylori infection on gastric cancer in Korea: a case-control study

To examine the effects of dietary factor and Helicobacter pylori (H. pylori) infection with emphasis on vitamin intake on the risk of gastric cancer (GC), we conducted a case-control study in South Korea, a high-risk area for GC. Trained dietitians interviewed 136 cases histologically diagnosed with GC. An equal number of hospital controls was selected by matching sex and age. High dietary intakes of vegetable fat [odds ratio (OR) = 0.35; 95% confidence interval (CI) = 0.15-0.83], folate (OR = 0.35; 95% CI = 0.13-0.96), and antioxidants, such as vitamin A (OR = 0.34; 95% CI = 0.13-0.83), beta-carotene (OR = 0.33; 95% CI = 0.13-0.82), vitamin C (OR = 0.26; 95% CI = 0.09-0.72), and vitamin E (OR = 0.41; 95% CI = 0.17-1.01), were shown to have a protective effect on GC risk using a multivariate model adjusting for foods significantly related to GC in our previous study (charcoal grilled beef, spinach, garlic, mushroom, and a number of types of kimchi) and supplement use. When stratified according to H. pylori infection, high intakes of vitamin C (OR = 0.10; 95% CI = 0.02-0.63) and vitamin E (OR = 0.16; 95% CI = 0.03-0.83) exhibited highly significant inverse associations with GC among the H. pylori-infected subjects compared with noninfected individuals. GC risk was significantly decreased only when consumption levels for two of these vitamins were high. Our findings suggest that high intake of antioxidant vitamins contribute to the reduction of GC risk and that GC risk in Korea may be decreased by encouraging those with H. pylori infection to increase their intake of antioxidant vitamins.     

Intakes of selected nutrients and food groups and risk of ovarian cancer

In a hospital-based case-control study, we examined dietary intakes of selected nutrients and food groups and ovarian cancer risk among 496 women with primary, histologically confirmed epithelial ovarian cancer and 1,425 women with nonneoplastic diagnoses, ages 20-87 years, admitted to Roswell Park Cancer Institute between 1982 and 1998. Data on diet and other relevant risk factors in the few years before admission were collected with a self-administered questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression adjusting for age, education, region of residence, regularity of menstruation, family history of ovarian cancer, parity, age at menarche, oral contraceptive use, and energy intake. Women in the highest vs. the lowest quartile of total energy had a weak increase in risk (OR = 1.25, 95% CI = 0.90-1.73). Significantly reduced risks were associated with higher intakes of dietary fiber (OR = 0.57, 95% CI = 0.38-0.87), vitamin A (OR = 0.66, 95% CI = 0.45-0.98), carotenoid (OR = 0.64, 95% CI = 0.43-0.93), vitamin E (OR = 0.58, 95% CI = 0.38-0.88), beta-carotene (OR = 0.68, 95% CI = 0.46-0.98), and total fruit and vegetable intake (OR = 0.62, 95% CI = 0.42-0.92). Our findings suggest that a diet high in plant foods may be important in reducing risk of ovarian cancer.     

Dietary vitamin D and calcium intake and premenopausal breast cancer risk in a German case-control study

Epidemiological studies and laboratory data suggest that vitamin D may protect against the development of cancer, including breast cancer. Vitamin D supply affects the bioavailability of dietary calcium, which might also have anticarcinogenic effects. However, few studies considered them jointly. We used a population-based case-control study in Germany to examine the independent and joint effects of dietary vitamin D and calcium on premenopausal breast cancer risk. Dietary information was assessed using a validated food frequency questionnaire from 278 premenopausal cases and 666 age-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariate models adjusting vitamin D models for calcium intake and vice versa. Breast cancer risk was significantly inversely associated with vitamin D intake. The OR and 95% CI for the highest intake category (> or = 5 microg/day) was 0.50 (95% CI = 0.26-0.96) compared with the lowest (< 2 microg/day; P(trend) = 0.02). Dietary calcium intake was not associated with breast cancer (OR = 0.73, 95% CI = 0.41-1.29) for the highest (> or = 1,300 mg/day) versus the lowest category (< 700 mg/day), P(trend) = 0.29). No statistically significant interaction between the 2 nutrients was observed. Our data support a protective effect of dietary vitamin D on premenopausal breast cancer risk independent of dietary calcium intake.     

Nutritional factors and breast cancer in Mexico

Breast cancer (BC) morbidity and mortality in Mexico are on the rise, affecting younger women with more frequency. Nutritional factors are often mentioned as determinants of BC but their relevance is not well established in Latin-American countries, where dietary habits show great variation. From a study population previously assembled in Mexico City, 141 histologically confirmed cases of BC were matched by age (+/-3 yr) to an equal number of hospital controls. A food frequency questionnaire was administered to all subjects and the risk of BC was estimated in relation to the intake of selected nutrients. The findings of this study show a protective effect against BC due to a high intake of polyunsaturated fat (odds ratio, OR = 0.10, 95% CI = 0.02-0.40, P for trend = 0.001) and vitamin E (OR = 0.10, 95% CI = 0.02-0.44, P for trend = 0.003) among postmenopausal women. In addition, our findings also suggest that a high intake of total fiber (OR = 0.29, 95% CI = 0.08-1.10, P for trend = 0.080) and carotenes (OR = 0.42, 95% CI = 0.16-1.14, P for trend = 0.088) lowers BC risk among premenopausal women. The relationship between the intake of nutrients and BC risk needs further confirmation.     

Dietary Vitamin D and Calcium Intake and Premenopausal Breast Cancer Risk in a German Case-Control Study

Epidemiological studies and laboratory data suggest that vitamin D may protect against the development of cancer, including breast cancer. Vitamin D supply affects the bioavailability of dietary calcium, which might also have anticarcinogenic effects. However, few studies considered them jointly. We used a population-based case-control study in Germany to examine the independent and joint effects of dietary vitamin D and calcium on premenopausal breast cancer risk. Dietary information was assessed using a validated food frequency questionnaire from 278 premenopausal cases and 666 age-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariate models adjusting vitamin D models for calcium intake and vice versa. Breast cancer risk was significantly inversely associated with vitamin D intake. The OR and 95% CI for the highest intake category (≥ 5 μ g/day) was 0.50 (95% CI = 0.26–0.96) compared with the lowest (< 2 μ g/day; P_trend = 0.02). Dietary calcium intake was not associated with breast cancer (OR = 0.73, 95% CI = 0.41–1.29) for the highest (≥ 1,300 mg/day) versus the lowest category (< 700 mg/day), P_trend = 0.29). No statistically significant interaction between the 2 nutrients was observed. Our data support a protective effect of dietary vitamin D on premenopausal breast cancer risk independent of dietary calcium intake.     

Intakes of Vitamin A,C, and E,and β-Carotene Are Associated With Risk of Cervical Cancer: A Case-Control Study in Korea

Cervical cancer is one of the most common gynecological malignancies in Korea, although the incidence has been declining in recent years. This study explored whether antioxidant vitamin intakes influenced the risk of cervical cancer. The association between antioxidant vitamin intakes and cervical cancer risk was calculated for 144 cervical cancer cases and 288 age-matched, hospital-based controls using unconditional logistic regression models. Cases reported statistically lower mean dietary intakes of vitamin A, β -carotene, and vitamin C than did controls. Total intakes of vitamins A and E, which included both dietary and supplement intake, were also lower in cases. Those patients in the highest quartiles of dietary vitamin A, β -carotene, and vitamin C intakes had statistically significantly lower cervical cancer risks than those in the lowest quartiles for vitamin A, β -carotene, and vitamin C: odds ratio (OR) = 0.36 [95% confidence interval (CI) = 0.19–0.69), OR = 0.48 (CI = 0.26–0.88), and OR = 0.36 (CI = 0.18–0.69), respectively. Total intakes of vitamins A, C, and E were strongly inversely associated with cervical cancer risk: OR = 0.35 (CI = 0.19–0.65), OR = 0.35 (CI = 0.19–0.66), and OR = 0.53 (CI = 0.28–0.99), respectively. The findings support a role for increased antioxidant vitamin intake in decreasing the risk of cervical cancer. These associations need to be assessed in large prospective studies with long-term follow-up.     

Raw and cooked vegetables, fruits, selected micronutrients, and breast cancer risk: a case-control study in Germany

In 1998-2000, a case-control study of breast cancer was conducted in Heidelberg, Germany. Three hundred ten consecutively recruited cases with primary breast cancer were matched according to 10-yr age groups to 353 controls with conditions unrelated to diet or endocrine disorders. Intake of raw vegetables, total vegetables, and whole-grain products was inversely associated with breast cancer risk (highest vs. lowest quartile adjusted odds ratio [OR] 0.51, 95% confidence interval [CI] 0.31-0.84; OR = 0.62, 95% CI = 0.38-1.02; and OR = 0.57; 95% CI = 0.34-0.95, respectively). Also, high intake of some selected vitamins and minerals possessing putative DNA-stabilizing properties displayed significant inverse risk associations. Adjusted ORs were as follows: vitamin C (OR = 0.49, 95% CI = 0.2-0.88), folate equivalents (OR = 0.47, 95% CI = 0.25-0.88), b-carotene (OR = 0.46, 95% CI = 0.27-0.80), zinc (OR = 0.35, 95% CI = 0.15-0.78), and copper (OR = 0.51, 95% CI = 0.31-1.03). In contrast, no significant association with risk was seen for an increased intake of fruits, cooked vegetables, fiber, calcium, manganese, or iron. In this population of German women, components of raw vegetables and some micronutrients appear to decrease breast cancer risk.     

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.     

Fiber Intake and Risk of Nasopharyngeal Carcinoma: A Case-Control Study

Some studies examined the inverse relation between nasopharyngeal carcinoma (NPC) risk and dietary fibers in endemic populations. By means of a hospital-based case-control study, we verified whether this association was also present in Italy in connection with various types of dietary fibers. Cases were 198 patients with incident, histologically confirmed, NPC admitted to major teaching and general hospitals during 1992–2008. Controls were 594 patients admitted for acute, nonneoplastic conditions to the same hospital network of cases. Information was elicited using a validated food frequency questionnaire including 78 foods, food groups, or dishes. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were estimated for quartiles of intake of different types of fiber after allowance for energy intake and other potential confounding factors. Total fiber intake was inversely related to risk of NPC (OR = 0.58 for the highest vs. the lowest quartile of intake; 95% CI: 0.34–0.96). We found an inverse association for total soluble (OR = 0.58; 95% CI: 0.35–0.96) and total insoluble fiber (OR = 0.56; 95% CI: 0.33–0.95), in particular cellulose (OR = 0.57; 95% CI: 0.33–0.96), and lignin (OR = 0.51; 95% CI: 0.31–0.85). In conclusion, this study suggests that dietary intake of soluble and insoluble fibers is inversely related to NPC risk in a nonendemic southern population.     

Antioxidant supplements and risk of breast cancer recurrence and breast cancer-related mortality among postmenopausal women

Despite widespread use, only a few clinical or epidemiological studies have examined the relationship between antioxidant supplements and risk of breast cancer recurrence or breast cancer-related mortality. We used proportional hazards and logistic regression modeling to estimate rate ratios and odds ratios (ORs) for recurrence and mortality among 385 postmenopausal women diagnosed with breast cancer between 1986 and 1988 enrolled into a case-control study on diet and cancer. Women were recontacted with a single questionnaire to ascertain the use of nutritional supplements during 12-14 yr of follow-up time. In multivariable models, antioxidant supplement users compared with nonusers were less likely to have a breast cancer recurrence or breast cancer-related death (OR = 0.54, 95% CI = 0.27-1.04). Vitamin E supplements showed a modest protective effect when used for more than 3 yr (OR = 0.33, 95% CI = 0.10-1.07). Premorbid dietary intake of vitamins C or E from diet, supplements, or both showed no relationship with risk. Risks of recurrence and disease-related mortality were reduced among women using vitamin C and vitamin E supplements for more than 3 yr. Recall bias among proxy respondents for women who died during follow-up may have contributed to these findings. This study provides limited support for the hypothesis that antioxidant supplements may reduce the risk of breast cancer recurrence or breast cancer-related mortality.     

Dietary antioxidants and lung cancer risk: a case-control study in Uruguay.

To examine the protective role of dietary antioxidants (carotenoids, vitamin C, vitamin E, glutathione, and flavonoids) in lung cancer risk, a case-control study involving 541 cases of lung cancer and 540 hospitalized controls was carried out in Uruguay. The relevant variables were energy adjusted using the residuals method and then categorized in quartiles. Adjusted odds ratios (ORs) for antioxidants were calculated through unconditional logistic regression. With the exception of lycopene and vitamin C, the remaining antioxidants were associated with significant reductions in risk of lung cancer. Of particular interest was the inverse association between dietary glutathione and lung cancer [OR of quartile with highest intake compared with lowest quartile = 0.42, 95% confidence interval (CI) = 0.27-0.63]. Also, carotenoids and vitamin E were associated with significant reductions in risk of lung cancer (OR = 0.43, 95% CI = 0.29-0.64 for total carotenoids and OR = 0.50, 95% CI = 0.39-0.85 for vitamin E). A joint effect for high vs. low intakes of beta-carotene and glutathione was associated with a significant reduction in risk (OR = 0.32, 95% CI = 0.22-0.46). It could be concluded that dietary antioxidants are associated with a significant protective effect in lung carcinogenesis and that the inverse association for glutathione persisted after controlling for total vegetables and fruits.     

Dietary antioxidants, supplements, and risk of epithelial ovarian cancer

Several studies of dietary and serum antioxidant micronutrients (vitamins A, C, and E and beta-carotene) suggest that higher levels may be protective for ovarian cancer. None of these has examined supplements. We used a food frequency questionnaire and additional questions on supplements to study 168 histologically confirmed epithelial ovarian cancer cases, 159 community controls, and 92 hospital-based controls. Antioxidant consumption from diet or supplements was calculated in milligrams or international units per day. In multivariate analyses using only community controls, the highest levels of intake of vitamins C and E from supplements were protective: odds ratio (OR) = 0.40 [95% confidence interval (CI) = 0.21-0.78] and OR = 0.33 (95% CI = 0.18-0.60), respectively. Consumption of antioxidants from diet was unrelated to risk. In analyses combining antioxidant intake from diet and supplements, vitamins C (> 363 mg/day) and E (> 75 mg/day) were associated with reduced risks: OR = 0.45 (95% CI = 0.22-0.91) and OR = 0.44 (95% CI = 0.21-0.94), respectively. Results were similar, with some attenuation toward the null, in analyses combining both control groups. The levels of vitamins C and E associated with the protective effect were well above the current US Recommended Dietary Allowances. These findings support the hypothesis that antioxidant vitamins C and E from supplements are related to a reduced risk of ovarian cancer.     

Effect of dietary intake of phytoestrogens on estrogen receptor status in premenopausal women with breast cancer

Although many dietary studies have focused on breast cancer risk, few have examined dietary influence on tumor characteristics such as estrogen receptor (ER) status. Because phytoestrogens may modulate hormone levels and ER expression, we analyzed ER status and phytoestrogen intake in a case-case study of 124 premenopausal breast cancer patients. We assessed intake with a food-frequency questionnaire and obtained ER status from medical records. Rather than focusing on risk, we evaluated whether low intakes were more strongly associated with ER-negative tumors than with ER-positive disease. In logistic regression adjusting for potential confounders, threefold greater risks of ER-negative tumors relative to ER-positive tumors were associated with low intake of the isoflavones genistein (odds ratio, OR=3.50; 95% confidence interval, CI=1.43-8.58) and daidzein (OR=3.10; 95% CI=1.31-7.30). Low intake of the flavonoid kaempferol (OR=0.36; 95% CI=0.16-0.83), the trace element boron (OR=0.33; 95% CI=0.13-0.83), and the phytosterol beta-sitosterol (OR=0.42; 95% CI=0.18-0.98) were associated with decreased risk of ER-negative tumors relative to ER-positive disease. Other phytoestrogens were not significantly associated with ER status. Thus, in premenopausal patients, some phytoestrogens may affect breast carcinogenesis by influencing ER status. Such findings suggest new directions for mechanistic research on dietary factors in breast carcinogenesis that may have relevance for prevention and clinical treatment.     

Food Intake and the Risk of Endometrial Endometrioid Adenocarcinoma in Japanese Women

The present study examined the association between food intake and endometrial cancer restricted to endometrial endometrioid adenocarcinoma (EEA) using a case-control study in Japanese women. One hundred sixty-one cases and 380 controls who completed a questionnaire regarding demographic, lifestyle, and food frequency questionnaire were analyzed. Odds ratio (OR) between selected food intakes and EEA were calculated by logistic regression analysis. After adjustment putative confounding factors, the higher intakes of vegetables [odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.26–0.83], peanuts (OR = 0.48, CI = 0.27–0.86), fish (OR = 0.52, CI = 0.29–0.93), boiled egg (OR = 0.24, CI = 0.33–0.92), instant noodles (OR = 1.94, CI = 1.12–3.34), instant food items (OR = 2.21, CI = 1.31–3.74), and deep-fried foods (OR = 2.87, CI = 1.58–5.21) were associated with a risk for EEA. The inverse association with a risk of EEA was also seen in higher intakes (g/1000 kcal) for vegetables (0.45, CI = 0.25–0.81) and fish (0.53, CI = 0.30–0.94) as compare to lower intake. Higher intake of vegetables, peanuts, fish, and boiled egg was associated with a reduced risk for EEA, whereas instant noodles, instant food items, and deep-fried foods was associated with an increased risk for EAA as compared to lower levels of intake.     

Fruits, vegetables, soy foods and breast cancer in pre- and postmenopausal Korean women: a case-control study

We carried out a case-control study to examine the relationship between fruits, vegetables, and soy foods intake with breast cancer risk in Korean women. Incident cases (n = 359) were identified through cancer biopsies and hospital-based controls (n = 708) were selected in the same hospitals. Subjects were asked to indicate usual dietary habits, which were assessed using a semi-quantitative food frequency questionnaire (98 items). Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated by unconditional logistic regression after adjustment for additional confounding factors according to the menopausal status. High grape intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.59, 95% CI = 0.35-0.95; p for trend = 0.05). High tomato intake was associated with reduced breast cancer risk in premenopausal women (OR = 0.59, 95% CI = 0.38-0.89, p for trend = 0.04). In postmenopausal women, green pepper intake showed an inverse association of breast cancer risk (OR = 0.60, 95% CI = 0.43-0.96, p for trend = 0.03). High soybean intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.61, 95% CI = 0.34-0.89, p for trend = 0.02). Our study suggests that high intake of some fruits, vegetables, and soybeans may be associated with a reduced breast cancer risk.     

Dietary and adipose tissue gamma-tocopherol and risk of myocardial infarction

BACKGROUND: Gamma-tocopherol, the most abundant form of dietary vitamin E, may lower the risk of coronary heart disease. METHODS: We investigated whether dietary and adipose tissue gamma-tocopherol are associated with myocardial infarction (MI) in 475 survivors of a first MI and 479 controls from a population-based study carried out between 1994 and 1998 in Costa Rica. Dietary intake was assessed with a validated food-frequency questionnaire and an adipose tissue sample. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Subjects in the highest quintile of dietary gamma-tocopherol had a lower risk of MI compared with those in the lowest quintile (OR = 0.76; 95% CI = 0.50-1.17, P = 0.02 for trend). This trend was no longer statistically substantial in multivariate analysis (P = 0.44). A weak association was found for adipose tissue gamma-tocopherol in univariate (OR = 1.46; 95% CI = 0.94-2.27) and multivariate (OR = 1.31; 95% CI = 0.62-2.76) models. A substantial inverse association with MI was found for total dietary vitamin E whether supplement users were included or excluded (P = 0.01 and 0.05 for trend, respectively). CONCLUSION: These data suggest that gamma-tocopherol does not protect against nonfatal MI.     

Case-control analysis of dietary folate and risk of bladder cancer

Dietary folate, a water-soluble B vitamin found in a variety of fruits and vegetables, is of particular interest as a chemopreventive agent due to its role in DNA methylation and DNA synthesis and repair. We hypothesized that individuals with low folate intake would be at an increased risk for bladder cancer. Using an ongoing case-control study we assessed dietary folate in 409 incident bladder cancer patients and 451 healthy control subjects. A food-frequency questionnaire was used to estimate naturally occurring food folate (microg/kcal/day), dietary folate equivalents (DFE) from food sources (microg DFE/kcal/day), and DFE from all sources (microg DFE/kcal/day). Unconditional logistic regression analyses were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Bladder cancer patients reported a statistically significant lower intake of folate than control subjects for food folate and DFE from food sources (P < 0.001) but not for DFE from all sources (P = 0.061). In the highest quartile of food folate intake there was a 54% reduced risk for bladder cancer (OR = 0.46; 95% CI = 0.29-0.73) after adjusting for age, gender, ethnicity, smoking, and total energy intake. Similarly, the highest quartile of intake was associated with a 59% reduced risk for DFE from food sources (OR = 0.41; 95% CI = 0.26-0.65) and a 35% reduced risk for DFE from all sources (OR = 0.65; 95% CI = 0.42-1.00). In the joint-effects analyses using never smokers with high folate intake as the reference group (OR = 1.0), heavy smokers with low food folate intake had a 2.31-fold (95% CI = 1.11-4.82) increased risk, whereas heavy smokers with high folate intake had a reduced OR of 1.31 (95% CI = 0.53-3.26). Although the ORs were not statistically significant, light smokers and high folate intake exhibited a protective effect (OR = 0.62; 95% CI = 0.20-1.94), whereas an increased risk was observed for light smoking and low folate intake (OR = 1.41; 95% CI = 0.57-3.45). These patterns were consistent for the joint effects of smoking and DFE from food sources and DFE from all sources. In summary, high intake of dietary folate was associated with an overall decrease in bladder cancer risk. These data may have important implications for cancer prevention; however, large, hypothesis-driven, population-based clinical trials will be required to confirm these findings.     

Relationship of folate,vitamin B-6, vitamin B-12, and methionine intake to incidence of colorectal cancers

It is hypothesized that diets deficient in folate, methionine, and vitamins B-6 and B-12 cause DNA hypomethylation and, as a result, increase risk of colorectal cancers. Furthermore, it is proposed that alcohol, a methyl group antagonist, increases risk of colorectal cancers among those with low intake of folate. Data from the Iowa Women's Health Study, a population-based cohort of incident cancer, were used to examine the relationship of folate, methionine, and vitamins B-6 and B-12 to occurrence of cancers of the colon (n = 598) and rectum (n = 123) over 13 yr of follow-up. There were no independent associations of folate, methionine, or vitamins B-6 and B-12 derived from a food frequency questionnaire with incidence of colon cancer. Adjusted relative risks (RRs) of rectal cancer were similar across categories of folate, vitamin B-12, and methionine intake, but RRs increased progressively with increasing intake of vitamin B-6 [P (for trend) = 0.03]. RRs suggested that incidence of cancer of the proximal colon was lower among those with 1) high folate and high vitamin B-12 intake [RR = 0.59, 95% confidence interval (CI) = 0.39-0.89] and 2) high folate and high vitamin B-6 intake (RR = 0.65, 95% CI = 0.50-0.84) than among those with the lowest intake of these nutrients. Incidence of cancer of the proximal colon was also somewhat lower among those with high folate and low alcohol intake (RR = 0.44, 95% CI = 0.22-0.89). Findings provide limited support for an association between dietary factors involved in DNA methylation and risk of cancers of the colon and rectum.