Dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study

Nitrate and nitrite are precursors of endogenously formed N‐nitroso compounds (NOC), known animal carcinogens. Nitrosation reactions forming NOCs can be inhibited by vitamin C and other antioxidants. We prospectively investigated the association between dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study, a cohort of 73,118 women ages 40–70 residing in Shanghai. We evaluated effect modification by factors that affect endogenous formation of NOCs: vitamin C (at or above/below median) and red meat intake (at or above/below median). Nitrate, nitrite and other dietary intakes were estimated from a 77‐item food frequency questionnaire administered at baseline. Over a mean of 11 years of follow‐up, we identified 619 colorectal cancer cases (n = 383, colon; n = 236, rectum). Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard regression. Overall, nitrate intake was not associated with colorectal cancer risk (HR = 1.08; 95% CI: 0.73–1.59). However, among women with vitamin C intake below the median (83.9 mg day^?1) and hence higher potential exposure to NOCs, risk of colorectal cancer increased with increasing quintiles of nitrate intake (highest vs. lowest quintile HR = 2.45; 95% CI: 1.15–5.18; p trend = 0.02). There was no association among women with higher vitamin C intake. We found no association between nitrite intake and risk of colorectal cancer overall or by intake level of vitamin C. Our findings suggest that high dietary nitrate intake among subgroups expected to have higher exposure to endogenously formed NOCs increases risk of colorectal cancer.     

Effect of two years' supplementation with natural antioxidants on vitamin and trace element status biomarkers: preliminary data of the SU.VI.MAX study.

The "SUpplementation en VItamines et Minéraux AntioXidants" (SU.VI.MAX) study is a randomized double-blind, placebo controlled, primary-prevention trial designed to test the efficacy of a daily supplementation with antioxidant vitamins (vitamin C, 120 mg; vitamin E, 30 mg; and beta-carotene, 6 mg) and minerals (selenium, 100 microg; and zinc, 20 mg) at nutritional doses (one to three times the daily recommended dietary allowances), in reducing the frequency of cancers and cardiovascular diseases. The study involves 12,735 eligible subjects (women aged 35-60 years, men aged 45-60 years) included in 1994 in France. They will be followed up for 8 years. The targeted population is the general population. The aim of this specific analysis is to assess the effect of 2 years of supplementation on biochemical indicators of vitamin and trace element on a subsample of 1000 subjects. The mean (+/- standard deviation) concentrations of plasma beta-carotene, alpha-tocopherol, vitamin C, selenium and zinc among participants who were randomly assigned to receive a daily supplementation with beta-carotene, vitamin E, vitamin C, selenium and zinc for 2 years were significantly higher than those who were assigned to receive placebo. Specifically, the mean concentrations among men in the intervention group were 0.86 +/- 0.70 micromol/L for beta-carotene, 35.3 +/- 9.3 micromol/L for alpha-tocopherol, 11.5 +/- 4.7 microg/ mL for vitamin C, 1.65 +/- 0.33 micromol/L for selenium, and 16.2 +/- 3.9 micromol/L for zinc. The mean concentrations among women in the intervention were 1.25 +/- 0.90 micromol/L for beta-carotene, 34.9 +/- 8.4 micromol/L for alpha-tocopherol, 12.6 +/- 4.0 microg/mL for vitamin C, 1.68 +/- 0.37 micromol/L for selenium, and 15.3 +/- 3.9 micromol/L for zinc. The values observed for beta-carotene and vitamin E in the supplementation group after 2 years of intervention are those that have been associated with the lowest risk of cancer in observational studies. They are definitely lower than concentrations reported in intervention studies showing an apparent negative effect of high levels of beta-carotene supplementation on the lung cancer incidence rate in high-risk subjects (initial level multiplied by 12-18). Data from the follow-up will ascertain if any plausible reduction in the incidence rate of cancers may be associated with such amounts of antioxidant agents.     

Associations of energy, fat, calcium, and vitamin D with prostate cancer risk.

This population-based, case-control study in King County,Washington examined associations of energy, fat, vitamin D, and calcium with risk of prostate cancer in 605 incident cases (ages 40-64 years) identified from the Seattle-Puget Sound Surveillance Epidemiology and End Results registry and 592 controls recruited from the same underlying population using random-digit telephone sampling. Self-administered food frequency questionnaires were used to assess diet over the 3-5-year period before diagnosis or interview date. Total energy was associated with increased risk for both local and regional/distant stage disease. The adjusted odds ratios [95% confidence intervals (CIs)] contrasting highest to lowest quintile of energy intake were 2.15 (95% CI, 1.35-3.43) for local and 1.96 (95% CI, 1.08-3.56) for regional/distant disease. Fat was associated with regional/distant disease only. Adjusted odds ratios comparing the highest to lowest quintiles of percentage energy from total, saturated, and monounsaturated fats were 2.01 (1.03-3.92), 1.82 (0.93-3.56), and 2.00 (1.03-3.87), respectively. For calcium, adjusted odds ratios contrasting the highest to lowest quartiles were 1.07 (0.63-1.84) for local and 2.12 (1.02-4.38) for regional/distant disease. There were no associations of vitamin D, total polyunsaturated fatty acids, or the highly unsaturated, long-chain eicosapentainoic and docosahexaenoic fatty acids with prostate cancer risk. These results suggest that high energy intake is a risk factor for both localized and nonlocalized prostate cancer, whereas dietary fat and calcium increase the risk of regional/distant disease only. These results are consistent with general dietary guidelines to moderate consumption of total energy and fat, and they motivate further research to consider the potential benefits and risks of high calcium intake.     

Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer risk: a prospective cohort study.

Association between breast cancer risk and the intake of vitamins C and E, retinol, beta (beta)-carotene, dietary fibre, vegetables, fruit and potatoes was examined in The Netherlands Cohort Study, for 62,573 women aged 55-69 years. After 4.3 years of follow-up, 650 incident breast cancer cases were identified. After adjusting for traditional risk factors, breast cancer risk was not influenced by the intake of beta-carotene, vitamin E, dietary fibre, supplements with vitamin C, vegetables or potatoes. Fruit consumption showed a non-significant inverse association with breast cancer risk (RR highest/lowest quintile = 0.76, 95% CI 0.54-1.08). A small reduction in risk was also observed with increasing intake of dietary vitamin C (RR highest/lowest quintile = 0.77, 95% CI 0.55-1.08). For retinol, a weak positive association was observed (RR highest/lowest quintile = 1.24, 95% CI 0.83-1.83). Among subjects with a high intake of polyunsaturated fatty acids (PUFAs), both beta-carotene and vitamin C intake showed a non-significant inverse association with breast cancer risk (P-trend = 0.15 and 0.16 respectively). Our findings do not suggest a strong role, if any, for intake of vitamins C and E, beta-carotene, retinol, dietary fibre, vegetables, fruit and potatoes in the aetiology of breast cancer.     

An intervention trial to inhibit the progression of precancerous gastric lesions: compliance, serum micronutrients and S-allyl cysteine levels, and toxicity.

Gastric cancer is the second most frequent cause of death from cancer in the world and the leading cause of death from cancer in China. In September 1995, we launched a randomized multi-intervention trial to inhibit the progression of precancerous gastric lesions in Linqu County, Shandong Province, an area of China with one of the world's highest rates of gastric cancer. Treatment compliance was measured by pill counts and quarterly serum concentrations of vitamin C, vitamin E and S-allyl cysteine. In 1999, toxicity information was collected from each trial participant to evaluate treatment-related side-effects during the trial. Compliance rates were 93% and 92.9% for 39 months of treatment with the vitamins/mineral and garlic preparation, respectively. The means for serum concentrations of vitamins C and E were 7.2 microg/ml and 1695 microg/dl among subjects in the active treatment groups compared with 3.1 microg/ml and 752 microg/dl among subjects in the placebo treatment group, respectively. No significant differences in side-effects were observed between the placebo treatment group and the vitamins/mineral and garlic preparation treatment groups during the 39-month trial period.     

Dietary folate intake, MTHFR genetic polymorphisms, and the risk of endometrial cancer among Chinese women.

Folate plays an important role in carcinogenesis. The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR), encoded by the MTHFR gene, is involved in this process. We investigated both the independent and joint effects of dietary folate and other methyl-related nutrients, as well as three polymorphisms of MTHFR (677C>T, 1298A>C, and 1793G>A), on endometrial cancer risk in a population-based case-control study. Between 1997 and 2003, 1,204 newly diagnosed endometrial cancer cases and 1,212 controls were recruited among women between the ages of 30 and 69 years in urban Shanghai, China. Information on dietary intake of folate and other methyl-related nutrients, including vitamin B2 (riboflavin), vitamin B6, vitamin B12, and methionine, was derived from a validated food frequency questionnaire. Genotyping was completed on 1,041 cases and 1,030 controls for MTHFR 677C>T (rs1801133), 1298A>C (rs1801131), and 1793 G>A (rs2274967) [corrected] Haplotype estimation of the three single-nucleotide polymorphisms was performed using PHASE software. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate associations of nutrients, MTHFR genotypes, and haplotypes with endometrial cancer risk. A significant inverse association between dietary folate intake and endometrial cancer risk was observed among all subjects and non-B vitamin supplement users. The greatest reduction in endometrial cancer risk was observed among non-users of supplements in the highest quartile of dietary folate intake (OR, 0.5; 95% CI, 0.4-0.7) as compared with those in the lowest quartile. Dietary intake of folate cofactors (methionine, vitamin B2, vitamin B6, and vitamin B12) was not related to risk of endometrial cancer. No association was observed between endometrial cancer and the MTHFR 677C>T, 1298 A>C, and 1793G>A polymorphisms or derived haplotypes. Among non-users of supplements, however, the 1298C and 1793A alleles were associated with a lower risk of endometrial cancer among women with high dietary folate intake but related to a higher risk among those with low dietary folate intake (P(interaction) = 0.08 and 0.03, respectively). Further analysis showed that the lowest risk (OR, 0.6; 95% CI, 0.4-1.1) was among women with the 1298C allele and the highest intake of both folate and riboflavin (P(interaction) = 0.04). A similar association was observed for the 1793A allele (P(interaction) = 0.03). Our findings suggest that folate intake may decrease the risk of endometrial cancer and modify the effect of MTHFR polymorphisms on risk.     

Diet and breast cancer in Shanghai and Tianjin, China.

Various aspects of adult diet have been linked to breast cancer development. These include intake of fat (risk factor), and intake of fibre, soy protein and vitamins A, C and E (protective factors). Results of previous studies have been inconsistent. We examined the possible associations between breast cancer and various indices of nutrient and food intake in two Chinese populations who are at relatively low risk for breast cancer (one-fifth the rate in US white women). Two case-control studies of breast cancer were conducted in the cities of Shanghai and Tianjin, China. In Shanghai, 534 women aged 20-69 years with histologically confirmed breast cancer were recruited, whereas in Tianjin 300 women aged 20-55 years with histologically confirmed breast cancer were interviewed. All controls were community controls who were individually matched to the cases by sex and age (case-control ratio = 1:1). All interviews were conducted in person. Findings from the two studies were similar, although the diets in Shanghai and Tianjin were different in many respects. Cases and controls were similar in their consumption of soy protein, measured either in absolute levels or as percentages of total protein. Overall, all components of dietary fat (saturated fat, monounsaturated fat, polyunsaturated fat) showed a modest, non-significant association with breast cancer after adjustment for energy intake and other non-dietary risk factors for breast cancer. Intake of crude fibre, carotene and vitamin C, on the other hand, exhibited strong, statistically significant inverse associations with breast cancer risk. The last three indices were highly correlated, rendering it impossible to disentangle their individual effects; they were closely associated with intake of green vegetables in the two study populations. Vitamin E intake was unrelated to breast cancer risk in Shanghai and Tianjin. In the multivariate logistic regression model which included all non-dietary risk factors for breast cancer and energy intake, Shanghai women in the lowest tertile of crude fibre intake and highest tertile of fat intake had a 2.9-fold increased risk for breast cancer relative to those in the highest tertile of crude fibre intake and lowest tertile of fat intake. The comparable relative risk in Tianjin women was 2.4. Our data indicate a strong protective effect against breast cancer development with intake of foods rich in fibre, vitamin C and carotene. Our results are also compatible with dietary fat having a modest, positive effect on breast cancer risk within the range of exposure experienced by women in China.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vitamin supplement use and risk for breast cancer: the Shanghai Breast Cancer Study

Objective The influence of vitamin supplements on breast cancer risk is unclear and the interactive effects of dietary and supplemental sources are unknown. This study investigated (1) the association between self-reported vitamin supplement use (multivitamin, A, B, C, and E) and breast cancer and (2) the combined effect of vitamin supplements in relation to dietary vitamin intakes on breast cancer risk. Methods The Shanghai Breast Cancer Study was a population-based case-control study conducted in Shanghai in 1996-1998 (Phase I) and 2002-2004 (Phase II). Participants were aged 25-64 (Phase I) and 20-70 years (Phase II). The analyses included 3,454 incident breast cancer cases and 3,474 controls. Unconditional logistic regression models were used to determine adjusted odds ratios (ORs) for breast cancer risk associated with vitamin supplement use. Results Overall, breast cancer risk was not related to any vitamin supplement intake. However, a 20% reduction in breast cancer risk was observed with vitamin E supplement use among women with low-dietary vitamin E intake (OR = 0.8; 95% confidence interval (CI), 0.6-1.0). A non-significant 20% risk reduction was observed among vitamin B supplement users with low B dietary intake (OR = 0.8; 95% CI, 0.6-1.1). Frequent use of a vitamin B supplement was adversely associated with breast cancer risk among those with high dietary vitamin B intake (OR = 1.4; 95% CI: 0.9-2.1; P for interaction = 0.07). Conclusions This study suggests that vitamins E and B supplements may confer protection against breast cancer among women who have low dietary intake of those vitamins.     

Nivalenol, a main Fusarium toxin in dietary foods from high-risk areas of cancer of esophagus and gastric cardia in China, induced benign and malignant tumors in mice

This is the first report that a Fusarium toxin nivalenol (NIV) naturally existing at high levels in dietary food in high-risk areas of cancer of esophagus and gastric cardia in China induced benign and malignant tumors in mice. The levels of two Fusarium toxins, nivalenol and deoxynivalenol (DON) were quantitated using high performance liquid chromatography (HPLC) in a total of 97 samples of dietary wheat flour, barley and corn collected from families in two areas with high mortality rate of cancer of esophagus and gastric cardia (132/100,000), Linxian, Henan province and Cixiang, Hepei province, China. The mean level of NIV and DON in three dietary foods was 830+/-927 microg/kg (range 584-1,780 microg/kg) and 4,281+/-6,114 microg/kg (range 732-10,980 microg/kg) respectively. The highest mean level of NIV was 1,780+/-1,705 microg/kg found in barley from Linxian, that of DON was 10,980+/-10,139 microg/kg found in corn from Cixiang. NIV was undetectable in 2 samples of rice from USA. The mean levels of NIV in three main dietary foods in those two high-risk areas were estimated at 400 to 800-fold higher than that in the USA, where NIV was undetectable in dietary food, and the mortality rate of esophageal cancer is <5/100,000 in white Caucasians in the USA, (odds ratio was estimated at 17-34, p<0.000005). These data suggest that Linxian and Cixiang peasants who consumed a diet with high NIV had significantly higher risk for developing esophageal cancer than the US residents who consumed food without or with negligible amounts of NIV. Three repeated experiments were performed using Balb/C mice with inter-mittent application of NIV, alternate with 12-Tetradeconoyl-phorbol-13-acetate (TPA) application on skin. Papillomas and carcinomas developed in a total of 23/49 (47%) mice that survived 11-60 weeks of experiments. Among all the tumors, 4 carcinomas in 3 mice were identified. No tumors were found in the 60 control mice applying either TPA or acetone (solvent) only on skin.     

Dietary intake of folate and riboflavin, MTHFR C677T genotype, and colorectal adenoma risk: a Dutch case-control study.

We investigated the associations between dietary intake of folate and vitamin B2, MTHFR C677T genotype, and colorectal adenomas in a Dutch case-control study. Data of cases with at least one histologically confirmed colorectal adenoma (n = 768) and controls with no history of any type of colorectal polyp (n = 709) were included. Dietary intake was assessed using a food-frequency questionnaire. Multivariable models included age and, if appropriate, dietary folate and calcium intake. The adjusted odds ratio (OR) and 95% confidence interval (CI) for the highest compared with the lowest sex-specific tertile of intake were 1.32 (95% CI, 1.01-1.73) for folate and 0.51 (95% CI, 0.36-0.73) for vitamin B2. Folate seemed to be a risk factor, especially when vitamin B2 intake was low; vitamin B2 was inversely associated with adenomas, especially with relatively high folate intake. No association was observed between MTHFR C677T genotype and colorectal adenomas. The inverse association between vitamin B2 intake and colorectal adenoma risk seemed to be more pronounced among those with the MTHFR TT genotype. We conclude that this study does not provide evidence for a decreased colorectal adenoma risk for subjects with high dietary intake of folate. It suggests, however, an inverse association between vitamin B2 and colorectal adenomas, which may be more relevant for those with the MTHFR TT genotype.     

Determinants of plasma ascorbic acid in a healthy male population.

The antioxidant properties of vitamin C may be involved in the prevention of cancer. The correlation between dietary vitamin C intake as estimated by a dietary questionnaire and plasma ascorbic acid (AA) was examined in 68 nonsmoking male volunteers aged 30-59 years. Determinants of plasma AA as well as interrelationships between various antioxidants in plasma were also explored. The determinants of plasma AA were examined by a multiple regression model containing dietary vitamin C, calories, body weight, and amount of beverages consumed. Higher vitamin C intake (P < 0.0002) increased plasma AA, while greater body weight (P < 0.005) decreased plasma AA. A significant correlation (r = 0.43; P < 0.0003) between vitamin C intake and plasma AA was observed. There was a negative correlation between plasma AA and plasma uric acid (r = -0.32; P < 0.007) and positive associations between plasma beta-carotene and plasma alpha-tocopherol (r = 0.39; P < 0.001) and between plasma beta-carotene and plasma glutathione peroxidase (r = 0.32; P < 0.008). Vitamin C supplement users had higher plasma AA compared to nonusers. The relationship between plasma AA and vitamin C intake appears to be curvilinear with the non-supplement users at the linear part of the curve and the supplement users at the plateau. Plasma AA is an appropriate biomarker, in our subjects, of dietary vitamin C except for people consuming large amounts of this vitamin either in their diet or in supplemental form.     

Dairy, calcium, and vitamin D intake and postmenopausal breast cancer risk in the Cancer Prevention Study II Nutrition Cohort.

BACKGROUND: Calcium, vitamin D, and dairy products are highly correlated factors, each with potential roles in breast carcinogenesis. Few prospective studies have examined these relationships in postmenopausal women.METHODS: Participants in the Cancer Prevention Study II Nutrition Cohort completed a detailed questionnaire on diet, vitamin and mineral supplement use, medical history, and lifestyle in 1992 to 1993. After exclusion of women with a history of cancer and incomplete dietary data, 68,567 postmenopausal women remained for analysis. During follow-up through August 31, 2001, we identified 2,855 incident cases of breast cancer. Multivariate-adjusted rate ratios (RR) were calculated using Cox proportional hazards models.RESULTS: Women with the highest intake of dietary calcium (>1,250 mg/d) were at a lower risk of breast cancer than those reporting < or =500 mg/d [RR, 0.80; 95% confidence interval (95% CI), 0.67-0.95; P(trend) = 0.02]; however, neither use of supplemental calcium nor vitamin D intake was associated with risk. Consumption starting at two or more servings of dairy products per day was likewise inversely associated with risk (RR, 0.81; 95% CI, 0.69-0.95; P(trend) = 0.002, compared with <0.5 servings/d). The associations were slightly stronger in women with estrogen receptor-positive tumors comparing highest to lowest intake: dietary calcium (RR, 0.67; 95% CI, 0.51-0.88; P(trend) = 0.004); dairy products (RR, 0.73; 95% CI, 0.57-0.93; P(trend) = 0.0003), and dietary vitamin D (RR, 0.74; 95% CI, 0.59-0.93; P(trend) = 0.006).CONCLUSIONS: Our results support the hypothesis that dietary calcium and/or some other components in dairy products may modestly reduce risk of postmenopausal breast cancer. The stronger inverse associations among estrogen receptor-positive tumors deserve further study.     

Low intake of calcium, folate, nicotinic acid, vitamin E, retinol, beta-carotene and high intake of pantothenic acid, biotin and riboflavin are significantly associated with increased genome instability--results from a dietary intake and micronucleus index survey in South Australia

The aim of this study was to determine the association between dietary intake, determined using a food frequency questionnaire, and genome damage in lymphocytes measured using the micronucleus (MN) assay. The study, performed on 190 healthy individuals (mean age 47.8 years, 46% males), also examined whether a supplementation with beta-carotene, vitamins C and E along with zinc (ACEZn), in a randomized trial for 6 months, improves genome stability. Multivariate analysis of baseline data showed that (1) the highest tertile of intake of vitamin E, retinol, folic acid, nicotinic acid (preformed) and calcium is associated with significant reductions in MN frequency, i.e. -28, -31, -33, -46 and -49%, respectively (P < 0.005) relative to the lowest tertile of intake and (2) the highest tertile of intake of riboflavin, pantothenic acid and biotin was associated with significant increases in MN frequency, i.e. +36% (P = 0.054), +51% (P = 0.021), and +65% (P = 0.001), respectively, relative to the lowest tertile of intake. Mid-tertile beta-carotene intake was associated with an 18% reduction in MN frequency (P = 0.038); however, the highest tertile of intake (>6400 microg/day) resulted in an 18% increment in MN frequency. Supplementation with ACEZn significantly reduced the MN index by 13% (P = 0.038). The study also showed interactive additive effects such as the protective effect of increased calcium intake (-46%) and the exacerbating effect of riboflavin (+42%) on increased genome damage caused by low folate intake. The results from this study illustrate the strong impact of a wide variety of micronutrients and their interactions on genome health, depending on the level of intake.     

The effects of vitamin C and vitamin E on oxidative DNA damage: results from a randomized controlled trial.

Oxidative DNA damage may be important in mutagenic, carcinogenic, and aging processes. Although it is plausible that antioxidant vitamins may reduce oxidative DNA damage, evidence from human studies has been sparse and inconsistent. We determined the short-term effects of vitamin C (500 mg/day) and vitamin E (400 IU d-alpha-tocopheryl acetate/day) supplements on oxidative DNA damage in a double-masked, placebo-controlled, 2x2 factorial trial in 184 nonsmoking adults. Mean duration of supplementation was 2 months. Oxidative DNA damage was measured by 24-h urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG). At baseline, urinary 8-OHdG (mean +/- SE; ng/mg creatinine) was associated with race (15.6 +/- 0.8 in African Americans versus 20.3 +/- 1.2 in Caucasians, P = 0.001), prior antioxidant supplement use (18.6 +/- 0.8 in users versus 13.8 +/- 1.5 in non-users, P = 0.007), and regular exercise (19.2 +/- 1.1 in exercisers versus 16.6 +/- 0.9 in non-exercisers, P = 0.04). Fruit and vegetable intake and serum ascorbic acid were inversely associated with urinary 8-OHdG (P-trend = 0.02 and 0.016, respectively). The benefits of fruit and vegetable intake became evident with the consumption being at least three servings/day. At the end of supplementation, change from baseline in urinary 8-OHdG (mean +/- SE; ng/mg creatinine) was -0.6 +/- 1.4 (P = 0.61), 0.6 +/- 1.1 (P = 0.59), 0.5 +/- 1.0 (P = 0.61), and 1.6 +/- 1.4 (P = 0.27) in the placebo, vitamin C alone, vitamin E alone, and combined vitamins C and E groups, respectively. In overall and subgroup analyses, there was no significant main effect or interaction effect of the supplements on urinary 8-OHdG. In conclusion, supplementation of diet with vitamin C (500 mg/day) and vitamin E (400 IU d-alpha-tocopheryl acetate/day) had no significant main effect or interaction effect on oxidative DNA damage as measured by urinary 8-OHdG in nonsmoking adults. However, several aspects of a healthy lifestyle were associated with lower oxidative DNA damage.     

Nutritional factors in relation to endometrial cancer: a report from a population-based case-control study in Shanghai, China

We evaluated the role of dietary nutrients in the etiology of endometrial cancer in a population-based case-control study of 1,204 newly diagnosed endometrial cancer cases and 1,212 age frequency-matched controls. Information on usual dietary habits was collected during an in-person interview using a validated, quantitative food frequency questionnaire. Logistic regression analysis was conducted to evaluate the association of nutrients with endometrial cancer risk using an energy density method (e.g., nutrient intake/1,000 kilocalories of intake). Higher energy intake was associated with increased risk, which was attributable to animal source energy and a high proportion of energy from protein and fat. Odds ratios comparing highest versus lowest quintiles of intake were elevated for intake of animal protein (Odds ratio (OR) = 2.0, 95% confidential interval: 1.5-2.7) and fat (OR = 1.5, 1.2-2.0), but reduced for plant sources of these nutrients (OR = 0.7, 0.5-0.9 for protein and OR = 0.6, 0.5-0.8 for fat). Further analysis showed that saturated and monounsaturated fat intake was associated with elevated risk, while polyunsaturated fat intake was unrelated to risk. Dietary retinol, beta-carotene, vitamin C, vitamin E, fiber, and vitamin supplements were inversely associated with risk. No significant association was observed for dietary vitamin B1 or vitamin B2. Our findings suggest that associations of dietary macronutrients with endometrial cancer risk may depend on their sources, with intake of animal origin nutrients being related to higher risk and intake of plant origin nutrients related to lower risk. Dietary fiber, retinol, beta-carotene, vitamin C, vitamin E, and vitamin supplementation may decrease the risk of endometrial cancer.     

Dietary fiber, beta-carotene and breast cancer: results from a case-control study

To study the association between dietary fiber, beta-carotene and breast cancer, the average daily intake of these dietary components was compared among 133 incident breast cancer cases and 238 population controls. Average daily intake of cereal products, fruit and vegetables was also studied. A statistically significant lower energy-adjusted intake of dietary fiber was observed in cases than in controls (mean +/- SD: 25.4 +/- 6.7 g vs. 27.7 +/- 7.4 g, 95% confidence interval (CI) of the age-adjusted difference = -3.8, -0.8). Intake of beta-carotene was similar for cases and controls. The multivariate adjusted odds ratio (OR) of breast cancer among women in the highest quartile of intake of cereal products, as compared to those in the lowest quartile, was 0.42 (95% CI = 0.19-0.92) and the trend was statistically significant (p = 0.03). The corresponding OR for intake of dietary fiber was 0.55 (95% CI = 0.26-1.17) but the trend was not significant. The OR for the highest quartile of intake of beta-carotene, fruit, vegetables, and all vegetable products combined was less than unity, but there was no significant inverse trend. These results suggest that a high intake of cereal products, especially those rich in fiber, may be inversely related to incidence of breast cancer.     

Dietary intake of calcium, fiber and other micronutrients in relation to colorectal cancer risk: Results from the Shanghai Women's Health Study

We evaluated the associations of dietary intake of calcium, fiber and vitamins with colorectal cancer risk in a population-based prospective cohort study conducted among Chinese women in Shanghai. Subjects were recruited in urban Shanghai from March 1997 to May 2000. All subjects were interviewed in-person to obtain information on demographic and lifestyle factors and anthropometric measurement was conducted. Usual dietary intake, using a validated food frequency questionnaire was assessed at the baseline survey. After following a total of 73,314 women for a median of 5.74 years, 283 incident colorectal cancer cases were recorded. Excluding the first 2 years of follow-up, a high intake of calcium was associated with a decreased risk of colorectal cancer. Comparing the highest quintile of nutrients intake to the lowest, the adjusted relative risk for colorectal cancer was 0.6 (p value for trend = 0.023) for calcium. No apparent associations were found for fiber, total vitamin A, carotene, vitamins B1, B2, B3, C and E with colorectal cancer risk. Our results suggest that calcium may be protective against colorectal cancer development even at a lower consumption level compared to Western populations.     

Dietary factors and risk of colon cancer in Shanghai, China.

Colon cancer incidence rates have risen sharply in Shanghai, China, since the early 1970s, and diet may have contributed to the rising incidence. To clarify the role of dietary factors for colon cancer in Shanghai, we analyzed data from a population-based case-control study of 931 cases (462 males and 469 females) and 1552 controls (851 males and 701 females) ages 30-74 years in Shanghai, China, from 1990-1993. Subjects were interviewed in person for a detailed history of dietary practices and food preferences by using a food-frequency questionnaire. Colon cancer risk was estimated by odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, total energy, and other confounding factors. Risk for the highest versus the lowest quartile of intake was elevated for red meat (OR, 1.5; 95% CI, 1.0-2.1 for men and OR, 1.5; 95% CI, 1.0-2.2 for women), fish (OR, 1.7; 95% CI, 1.2-2.4 for men and OR, 1.2; 95% CI, 0.8-1.7 for women), and eggs (OR, 1.4; 95% CI, 1.0-1.9 for men and OR, 1.3; 95% CI, 0.9-1.9 for women), but was reduced for fresh fruit (OR, 0.7; 95% CI, 0.5-1.0 for men and OR, 0.6, 0.4-0.9 for women). High intake of preserved foods, whether animal or plant source, was associated with an excess risk of colon cancer (OR, 2.0; 95% CI, 1.5-2.9 for men and OR, 2.7; 95% CI, 1.9-3.8 for women). For dietary nutrients, risk generally declined with greater consumption of fiber and micronutrients common in fruit and vegetables, including vitamin C, carotene, and vitamin E. Intake of macronutrients in general was not significantly related to risk. Our findings suggest that diets high in fruit and antioxidant vitamins that are common in plant foods reduce the risk of colon cancer, whereas diets high in red meat, eggs, and preserved foods increase the risk.     

Vitamin intake and liver cancer risk: a report from two cohort studies in china

Correspondence to: Xiao-Ou Shu, MD, PhD, Vanderbilt Epidemiology Center, 2525 West End Ave, Ste 600 (IMPH), Nashville, TN 37203-1738 (e-mail: xiao-ou.shu@vanderbilt.edu) and Yong-Bing Xiang, MD, MSc, Shanghai Cancer Institute, No. 25, Lane 2200, Xie Tu Road, Shanghai 200032, People's Republic of China (e-mail: ybxiang@shsci.org).Background Epidemiologic studies on the relationship between vitamin intake and liver cancer risk are sparse and inconsistent. Methods We evaluated vitamin intake from diet and supplements and risk of liver cancer in 132 837 women and men from China who were recruited into the Shanghai Women's Health Study from 1997 to 2000 or the Shanghai Men's Health Study from 2002 to 2006. In-person interviews, using a validated food-frequency questionnaire, were conducted to collect data on dietary habits. Follow-up consisted of in-person surveys and record linkage. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazard models with adjustment for potential confounders to compare liver cancer risk among participants with high vs low vitamin intake. All statistical tests were two-sided. Results After excluding the first 2 years of follow-up, 267 participants (including 118 women and 149 men) developed liver cancer during an average of 10.9 (Shanghai Women's Health Study) or 5.5 (Shanghai Men's Health Study) years of follow-up. Dietary vitamin E intake was inversely associated with liver cancer risk (P (trend) = .01), as was vitamin E supplement use (hazard ratio = 0.52, 95% confidence interval = 0.30 to 0.90). This association was consistent among participants with and without self-reported liver disease or a family history of liver cancer. Vitamin C and multivitamin use was associated with increased risk among participants with self-reported liver disease or family history of liver cancer, whereas intake of vitamin C and other vitamins from dietary sources was unrelated to liver cancer risk. Conclusions Vitamin E intake, either from diet or supplements, may reduce the risk of liver cancer.     

Vitamin A supplementation and plasma retinol levels: a randomized trial among women

Although dietary intake of vitamin A has little, if any, overall effect on blood retinol in generally well-nourished populations, subgroups may exist that would be responsive to supplementation. The hypothesis that vitamin A supplementation increases blood retinol in apparently well-fed individuals with lower than usual blood levels was tested in female health workers, with relatively low blood retinol values, who were randomly assigned to receive vitamin A (10,000 IU daily) or placebo. After 4 weeks the mean change in plasma retinol was -0.4 micrograms/dl for the group receiving placebo and +4.1 micrograms/dl (an increase of 9% over base-line values) for the group receiving vitamin A (P = .02). The results were similar when the base-line retinol level and several other covariates were considered. Thirteen women who had initially received placebo were then switched to vitamin A for 4 weeks. These women experienced a mean increase of 5.3 micrograms/dl in plasma retinol (P = .04). Responses to vitamin A supplementation tend to be greater among women with lower previous total vitamin A intake, as assessed by questionnaire [Spearman rank correlation coefficient (r) = 0.50; P = .01].