Antioxidants, carotenoids, and risk of rectal cancer

Numerous properties suggest that antioxidants and carotenoids may be valuable chemopreventive agents. A population-based case-control study of 952 rectal cancer cases and 1,205 controls from Northern California and Utah was conducted between September 1997 and February 2002. Detailed diet history, medical history, and lifestyle factors interviews were conducted. Dietary antioxidants were not associated with rectal cancer risk in men. For women, relative to the highest level of intake, low intake of dietary lycopene (odds ratio (OR) = 1.7, 95% confidence interval (CI): 1.0, 2.8) or vitamin E (OR = 2.2, 95% CI: 1.1, 4.3) was associated with an increased risk of rectal cancer. Alpha-, beta-, and gamma-tocopherol were associated with an approximate twofold increased risk of rectal cancer in women. Associations were stronger for women aged > or = 60 years for vitamin E and tocopherols (alpha-tocopherol OR = 3.6, 95% CI: 1.4, 9.4; gamma-tocopherol OR = 5.3, 95% CI: 2.1, 13.2; delta-tocopherol OR = 1.9, 95% CI: 0.9, 4.0), except for beta-tocopherol, for which risk increased twofold for all women. Associations differed by estrogen status for beta-carotene, lycopene, and vitamin E. These results suggest that vitamin E and lycopene may modestly reduce the risk of rectal cancer in women.     

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.     

Dietary carotenoids and genetic instability modify bladder cancer risk

In vitro and in vivo studies have shown that carotenoid supplementation is associated with decreased DNA damage, but the role of dietary carotenoids in cancer risk remains controversial because epidemiologic studies have yielded conflicting results. Limited data exist regarding the role of dietary carotenoids in the context of constitutional genetic instability in cancer risk. This case-control study estimated dietary carotenoid intake [microg/(kJ . d)] from a FFQ for 423 patients with bladder cancer and 467 healthy controls, and quantified baseline and benzo[a]pyrene diol epoxide (BPDE)- and gamma-radiation-induced DNA damage in the peripheral blood lymphocytes using the comet assay. Overall, intake of total carotenoids was lower (P < 0.01) for bladder cancer cases (mean +/- SD: 1273.4 +/- 688.9) compared with healthy controls (1501.3 +/- 791.5). When categorized into quartiles, there was an inverse association between increasing levels of carotenoid intake and bladder cancer risk with greatest protective effect [odds ratio (OR) = 0.56, 95% CI, 0.37-0.85] in the quartile with the highest level of intake. Baseline and mutagen-induced DNA damage was significantly higher in cases than in controls; when analyzed jointly with carotenoid intake, high DNA damage and low carotenoid intake were associated with the highest risk. For example, with high baseline DNA damage and low total carotenoid intake, the OR was 3.08 (95% CI, 1.64-5.77); with high baseline DNA damage and high total carotenoid intake, the risk was somewhat attenuated (OR = 2.49, 95% CI, 1.28-4.84). The risk was decreased further for low baseline DNA damage and low total carotenoid intake (OR = 2.18; 95% CI, 1.13-4.22). This study provides evidence of a preventive role for carotenoids in bladder cancer, and these data may have important implications for cancer prevention, especially for individuals susceptible to DNA damage.     

Plant foods, antioxidants, and prostate cancer risk: findings from case-control studies in Canada

Epidemiological data on most cancer sites suggest that consumption of plant foods, which contain high levels of antioxidants, might slow or prevent the appearance of cancer. We used data from three case-control studies to test this hypothesis. The total study population consisted of 617 incident cases of prostate cancer and 636 population controls from Ontario, Quebec, and British Columbia. Dietary information was collected by an in-person interview with a detailed quantitative dietary history. Unconditional logistic regression analyses were performed to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A decreasing, statistically significant association was found with increasing intakes of green vegetables (OR = 0.54, 95% CI = 0.40-0.71 for 4th quartile), tomatoes (OR = 0.64, 95% CI = 0.45-0.91), beans/lentils/nuts (OR = 0.69, 95% CI = 0.53-0.91), and cruciferous vegetables (OR = 0.69, 95% CI = 0.52-0.91 for 3rd quartile). Higher intakes of fruit were associated with higher ORs (OR = 1.51, 95% CI = 1.14-2.01 for 4th quartile), an effect that was seen for total fruit and citrus fruit, as well as for all other noncitrus fruits. Among the grains, refined-grain bread intake was associated with a decrease in risk (OR = 0.65 for 4th quartile), whereas whole-grain breakfast cereals were associated with a higher risk for prostate cancer. Of all the antioxidant nutrients studied, the ORs were higher with higher intakes of cryptoxanthin (OR = 1.44, 95% CI = 1.09-1.89 for 4th quartile). Exposure to certain dietary components of plant origin, which are potentially modifiable, indicates the theoretical scope for reducing the risk from prostate cancer. Future experimental studies or trials are warranted for further understanding.     

Antioxidant vitamins and risk of gastric cancer: a case-control study in Portugal

We quantified the effect of antioxidant vitamins in gastric cancer risk, taking into account Helicobacter pylori seropositivity and overall fruit and vegetable intake. Incident cases were identified in two large hospitals in Porto, Portugal, and controls were randomly sampled among city dwellers. Food intake was assessed with a previously validated semiquantitative food-frequency questionnaire. A commercially available chromatographic immunoassay was used for the detection of immunoglobulin G antibodies. Complete questionnaire information and serum samples were available for 233 cases and 311 controls. Compared with subjects in the lowest tertile of dietary intake, the odds ratios (ORs) for those in the highest were 0.85 (95% confidence interval, CI = 0.45-1.60) for vitamin C, 1.04 (95% CI = 0.60-1.80) for vitamin E, and 1.33 (95% CI = 0.77-2.30) for provitamin A carotenoids after further adjusting for fruit and vegetable consumption. Fruit and vegetables remained an independent protective factor (OR = 0.45; 95% CI = 0.23-0.89) after further adjustment for the intake of antioxidant vitamins. H. pylori status had no significant interaction with dietary items. Factors other than H. pylori infection and intake of vitamin C and provitamin A carotenoids seem to account for the inverse association between fruit and vegetable consumption and gastric cancer.     

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 folate, vitamin B6, vitamin B12 and methionine intake and the risk of breast cancer by oestrogen and progesterone receptor status

Few studies have evaluated the relationship between the consumption of dietary folate and one-carbon metabolism-related nutrients and breast cancer risk defined by oestrogen receptor (ER) and progesterone receptor (PR) status. The objective of the present study was to examine the associations between dietary folate, vitamin B6, vitamin B12, and methionine intake and the risk of breast cancer by ER and PR status among Chinese women in Guangdong. A hospital-based case-control study was conducted from June 2007 to August 2008, with 438 cases and 438 age (5-year interval)- and residence (rural/urban)-matched controls. Dietary intake information was assessed using a validated FFQ administered through a face-to-face interview. Unconditional logistic regression models were used to calculate multivariate-adjusted OR and 95 % CI. A significant inverse association was found between dietary folate and vitamin B6 intake and breast cancer risk. The adjusted OR of the highest v. the lowest quartile were 0·32 (95 % CI 0·21, 0·49; P(trend) < 0·001) for dietary folate and 0·46 (95 % CI 0·30, 0·69; P(trend) < 0·001) for vitamin B6. No associations were observed for vitamin B12 and methionine intake. A significant inverse association between dietary folate intake and breast cancer risk was observed in all subtypes of ER and PR status. These findings suggest that dietary folate and vitamin B6 intakes were inversely associated with breast cancer risk. The inverse association did not differ by ER and/or PR status.     

Dietary intake and risk of lung cancer in women who never smoked.

A case-control study was conducted to examine the influence of dietary factors on the risk of developing lung cancer among women who have never smoked cigarettes. This study included 124 cases of histologically confirmed carcinoma of the lung and 263 community-based controls. Dietary data were collected utilizing the reduced version of the National Cancer Institute (Block) food frequency questionnaire. The results of this analysis, adjusted for age, education, and total calories, indicated a strong protective effect associated with total vegetable consumption and intake of carotene. Individuals in the highest quartile of vegetable consumption experienced the greatest decreased risk with an odds ratio (OR) of 0.2, [confidence interval (CI) 0.1-0.5]. The effect of all vegetables combined was greater than that of green and yellow vegetables alone (highest quartile OR 0.4, CI 0.2-0.7). Similarly, the protective effect of total carotene (highest quartile OR 0.3, CI 0.1-0.6) was somewhat greater than that of beta-carotene alone (highest quartile OR 0.4, CI 0.2-0.8). Retinol intake was not associated with a decreased risk of lung cancer in our population. There was an inverse association between lung cancer risk and vitamin C intake, which was not significant, although a statistically significant trend was noted.     

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), alpha-carotene (OR=0.41, 95% CI=0.27-0.63), beta-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.     

Development of a comprehensive dietary antioxidant index and application to lung cancer risk in a cohort of male smokers

In many observational studies, a higher intake of individual antioxidants is inversely associated with lung cancer risk. Data from in vitro and animal experiments suggest that there are biochemical interactions among antioxidant nutrients; therefore, consideration of multiple antioxidants simultaneously may be important in terms of risk estimation. The authors constructed a dietary antioxidant index and evaluated its ability to predict lung cancer risk within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. At baseline (1985-1988), 27,111 Finnish male smokers aged 50-69 years completed a dietary questionnaire that assessed usual frequency of consumption and portion sizes for the previous 12 months. A total of 1,787 incident cases of lung cancer were identified during a follow-up period of up to 14.4 years (1985-1999). Principal components analyses were individually applied to the carotenoid, flavonoid, and vitamin E nutrient groups, and summation of retained principal component scores, plus selenium and vitamin C, yielded the composite antioxidant index. In multivariate proportional hazards models, the relative risks for lung cancer according to increasing quintiles of the antioxidant index were 1.00 (referent), 1.00 (95% confidence interval (CI): 0.87, 1.14), 0.91 (95% CI: 0.79, 1.05), 0.79 (95% CI: 0.68, 0.92), and 0.84 (95% CI: 0.72, 0.98) (p for trend = 0.002). These findings support the hypothesis that a combination of dietary antioxidants reduces lung cancer risk in male smokers.     

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.     

Dietary intake and risk of lung cancer in women who never smoked

A case‐control study was conducted to examine the influence of dietary factors on the risk of developing lung cancer among women who have never smoked cigarettes. This study included 124 cases of histologically confirmed carcinoma of the lung and 263 community‐based controls. Dietary data were collected utilizing the reduced version of the National Cancer Institute (Block) food frequency questionnaire. The results of this analysis, adjusted for age, education, and total calories, indicated a strong protective effect associated with total vegetable consumption and intake of carotene. Individuals in the highest quartile of vegetable consumption experienced the greatest decreased risk with an odds ratio (OR) of 0.2, [confidence interval (CI) 0.1–0.5]. The effect of all vegetables combined was greater than that of green and yellow vegetables alone (highest quartile OR 0.4, CI 0.2–0.7). Similarly, the protective effect of total carotene (highest quartile OR 0.3, CI 0.1–0.6) was somewhat greater than that of ß‐carotene alone (highest quartile OR 0.4, CI 0.2–0.8). Retinol intake was not associated with a decreased risk of lung cancer in our population. There was an inverse association between lung cancer risk and vitamin C intake, which was not significant, although a statistically significant trend was noted.     

Case-control study of lifetime physical activity and breast cancer risk

A population-based case-control study of 1,233 incident breast cancer cases and 1,237 controls was conducted in Alberta, Canada, in 1995-1997 to examine the effect of lifetime physical activity patterns on breast cancer risk. No associations between physical activity and breast cancer were found for premenopausal women. For postmenopausal women in the highest quartile (> or =161 metabolic equivalent (MET)-hours/week per year) versus the lowest quartile (<104.8 MET-hours/week per year) of lifetime total physical activity, the adjusted odds ratio was 0.70 (95% confidence interval (CI): 0.52, 0.94). When the risks associated with each type of activity were examined for postmenopausal women, household and occupational activity conferred the largest risk reductions (odds ratio (OR) = 0.57, 95% CI: 0.41, 0.79 and OR = 0.59, 95% CI: 0.44, 0.81, respectively, for highest vs. lowest quartiles of activity), while recreational activity was not associated with any risk reductions. For postmenopausal women, the authors found stronger risk reductions for those who were also nonsmokers (OR = 0.64, 95% CI: 0.46, 0.88), non-alcohol-drinkers (OR = 0.39, 95% CI: 0.11, 0.77), or nulliparous (OR = 0.22, 95% CI: 0.07, 0.70) when they compared the highest with the lowest quartile of lifetime total physical activity. This study provides evidence that lifetime total activity reduces risk of postmenopausal breast cancer.     

Serum selenium and risk of prostate cancer-a nested case-control study

BACKGROUND: Selenium is a potential chemopreventive agent against prostate cancer, whose chemoprotective effects are possibly mediated through the antioxidative properties of selenoenzymes. Interrelations with other antioxidative agents and oxidative stressors, such as smoking, are poorly understood. OBJECTIVES: The aims were to investigate the association between serum selenium and prostate cancer risk and to examine interactions with other antioxidants and tobacco use. DESIGN: A nested case-control study was performed within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Serum selenium in prospectively collected samples was compared between 724 incident prostate cancer case subjects and 879 control subjects, frequency-matched for age, time since initial screen, and year of blood draw. The men were followed for up to 8 y. RESULTS: Overall, serum selenium was not associated with prostate cancer risk (P for trend = 0.70); however, higher serum selenium was associated with lower risks in men reporting a high (more than the median: 28.0 IU/d) vitamin E intake [odds ratio (OR) for the highest compared with the lowest quartile of selenium: 0.58; 95% CI: 0.37, 0.91; P for trend = 0.05; P for interaction = 0.01] and in multivitamin users (OR for highest compared with the lowest quartile of selenium: 0.61; 95% CI: 0.36, 1.04; P for trend = 0.06; P for interaction = 0.05). Furthermore, among smokers, high serum selenium concentrations were related to reduced prostate cancer risk (OR for the highest compared with the lowest quartile of selenium: 0.65; 95% CI: 0.44, 0.97; P for trend = 0.09; P for interaction = 0.007). CONCLUSION: Greater prediagnostic serum selenium concentrations were not associated with prostate cancer risk in this large cohort, although greater concentrations were associated with reduced prostate cancer risks in men who reported a high intake of vitamin E, in multivitamin users, and in smokers.     

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.     

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.     

Total antioxidant capacity of the diet is associated with lower risk of ischemic stroke in a large Italian cohort

Experimental studies suggest that oxidative stress and systemic inflammation are involved in the pathogenesis of ischemic stroke. Consuming a diet with a high total antioxidant capacity (TAC) has been related to reduced inflammation and increased circulating antioxidants in cross-sectional and randomized intervention studies. This study investigates the relation between dietary TAC and risk of ischemic and hemorrhagic stroke in 41,620 men and women not previously diagnosed with stroke or myocardial infarction, representing the Italian segment of the European Prospective Investigation into Cancer and Nutrition. Controlling for potential confounders, a diet rich in TAC was associated with a reduction in HR for all types of stroke, but this association was only marginally significant (P-trend = 0.054). When only ischemic stroke cases were considered, data suggest a stronger inverse association with dietary TAC, with HR = 0.41 (95% CI = 0.23-0.74). Regarding single antioxidants, data from subanalyses on stroke types suggest that vitamin C is significantly associated with a decreased risk of ischemic stroke [HR = 0.58 (95% CI = 0.34-0.99)], whereas vitamin E was associated with increased HR of hemorrhagic stroke in the highest tertile of intake [HR = 2.94 (95% CI = 1.13-7.62)]. In conclusion, our findings suggest that antioxidants may play a role in reducing the risk of cerebral infarction but not hemorrhagic stroke. However, a high intake of vitamin E could be positively associated to the risk of brain hemorrhagic events; therefore, more focused investigations about this observation are needed.     

Vitamin E supplementation may transiently increase tuberculosis risk in males who smoke heavily and have high dietary vitamin C intake

Vitamin E and beta-carotene affect the immune function and might influence the predisposition of man to infections. To examine whether vitamin E or beta-carotene supplementation affects tuberculosis risk, we analysed data of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC)Study, a randomised controlled trial which examined the effects of vitamin E (50 mg/d) and beta-carotene (20 mg/d) on lung cancer. The trial was conducted in the general community in Finland in 1985-93; the intervention lasted for 6.1 years (median). The ATBC Study cohort consists of 29,023 males aged 50-69 years, smoking at baseline, with no tuberculosis diagnosis prior to randomisation. Vitamin E supplementation had no overall effect on the incidence of tuberculosis (risk ratio (RR) = 1.18; 95% CI 0.87, 1.59) nor had beta-carotene (RR = 1.07; 95% CI 0.80, 1.45). Nevertheless, dietary vitamin C intake significantly modified the vitamin E effect. Among participants who obtained 90 mg/d or more of vitamin Cin foods (n 13,502), vitamin E supplementation increased tuberculosis risk by 72 (95% CI 4, 185)%. This effect was restricted to participants who smoked heavily. Finally, in participants not supplemented with vitamin E, dietary vitamin C had a negative association with tuberculosis risk so that the adjusted risk was 60 (95% CI 16, 81)% lower in the highest intake quartile compared with the lowest. Our finding that vitamin E seemed to transiently increase the risk of tuberculosis in those who smoked heavily and had high dietary vitamin C intake should increase caution towards vitamin E supplementation for improving the immune system.     

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.