Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women.
BACKGROUND: Diets high in fruits and vegetables have been shown to be associated with a lower risk of lung cancer. beta-carotene was hypothesized to be largely responsible for the apparent protective effect, but this hypothesis was not supported by clinical trials. METHODS: We examined the association between lung cancer risk and fruit and vegetable consumption in 77,283 women in the Nurses' Health Study and 47,778 men in the Health Professionals' Follow-up Study. Diet was assessed with the use of a food-frequency questionnaire that included 15 fruits and 23 vegetables. We used logistic regression models to estimate relative risks (RRs) of lung cancer within each cohort. All statistical tests were two-sided. RESULTS: We documented 519 lung cancer cases among the women and 274 among the men. Total fruit and vegetable consumption was associated with a modestly lower risk of lung cancer among the women but not among the men. The RR for the highest versus lowest quintile of intake was 0.79 (95% confidence interval [CI] = 0.59-1.06) among the women and 1.12 (95% CI = 0.74-1.69) among the men after adjustment for smoking status, quantity of cigarettes smoked per day, time since quitting smoking, and age at initiation of smoking. However, total fruit and vegetable consumption was associated with a lower risk of lung cancer among never smokers in the combined cohorts, although the reduction was not statistically significant (RR = 0.63; 95% CI = 0.35-1.12 in the highest tertile). CONCLUSION: Higher fruit and vegetable intakes were associated with lower risks of lung cancer in women but not in men. It is possible that the inverse association among the women remained confounded by unmeasured smoking characteristics, although fruits and vegetables were protective in both men and women who never smoked.
J Natl Cancer Inst. 2000 Nov 15;92(22):1812-23
Cruciferous vegetables and cancer risk in a network of case-control studies.
BACKGROUND: Cruciferous vegetables have been suggested to protect against various cancers, though the issue is open to discussion. To further understand their role, we analyzed data from a network of case-control studies conducted in Italy and Switzerland. PATIENTS AND METHODS: The studies included a total of 1468 cancers of the oral cavity/pharynx, 505 of the esophagus, 230 of the stomach, 2,390 of the colorectum, 185 of the liver, 326 of the pancreas, 852 of the larynx, 3,034 of the breast, 367 of the endometrium, 1031 of the ovary, 1,294 of the prostate, 767 of the kidney, and 11,492 controls. All cancers were incident, histologically confirmed; controls were subjects admitted to the same network of hospitals as cases for a wide spectrum of acute nonneoplastic conditions. RESULTS: The multivariate odds ratio (OR) for consumption of cruciferous vegetables at least once a week as compared with no/occasional consumption was significantly reduced for cancer of the oral cavity/pharynx (OR=0.83), esophagus (OR=0.72), colorectum (OR=0.83), breast (OR=0.83), and kidney (OR=0.68). The OR was below unity, but not significant, for stomach (OR=0.90), liver (OR=0.72), pancreatic (OR=0.90), laryngeal (OR=0.84), endometrial (OR=0.93), ovarian (OR=0.91), and prostate (OR=0.87) cancer. CONCLUSION: This large series of studies provides additional evidence of a favorable effect of cruciferous vegetables on several common cancers.
Ann Oncol. 2012 Aug;23(8):2198-203
Cruciferous vegetable consumption is associated with a reduced risk of total and cardiovascular disease mortality.
BACKGROUND: Asian populations habitually consume a large amount of cruciferous vegetables and other plant-based foods. Few epidemiologic investigations have evaluated the potential health effects of these foods in Asian populations. OBJECTIVE: We aimed to examine the associations of cruciferous vegetables, noncruciferous vegetables, total vegetables, and total fruit intake with risk of all-cause and cause-specific mortality. DESIGN: The analysis included 134,796 Chinese adults who participated in 2 population-based, prospective cohort studies: the Shanghai Women's Health Study and the Shanghai Men's Health Study. Dietary intakes were assessed at baseline through in-person interviews by using validated food-frequency questionnaires. Deaths were ascertained by biennial home visits and linkage with vital statistics registries. RESULTS: We identified 3,442 deaths among women during a mean follow-up of 10.2 y and 1,951 deaths among men during a mean follow-up of 4.6 y. Overall, fruit and vegetable intake was inversely associated with risk of total mortality in both women and men, and a dose-response pattern was particularly evident for cruciferous vegetable intake. The pooled multivariate hazard ratios (95% CIs) for total mortality across increasing quintiles of intake were 1 (reference), 0.91 (0.84, 0.98), 0.88 (0.77, 1.00), 0.85 (0.76, 0.96), and 0.78 (0.71, 0.85) for cruciferous vegetables (P < 0.0001 for trend) and 0.88 (0.79, 0.97), 0.88 (0.79, 0.98), 0.76 (0.62, 0.92), and 0.84 (0.69, 1.00) for total vegetables (P = 0.03 for trend). The inverse associations were primarily related to cardiovascular disease mortality but not to cancer mortality. CONCLUSION: Our findings support recommendations to increase consumption of vegetables, particularly cruciferous vegetables, and fruit to promote cardiovascular health and overall longevity.
Am J Clin Nutr. 2011 Jul;94(1):240-6
Cruciferous indole-3-carbinol inhibits apolipoprotein B secretion in HepG2 cells.
The cardioprotective effect of consuming cruciferous vegetables may be attributed to a number of unique indole-based compounds. We investigated the potential role and mechanism of action of an indole-based compound, indole-3-carbinol (I3C), on apolipoprotein B-100 (apoB) production using HepG2 cells. I3C reduced apoB secretion into the media dose dependently by 56% at 100 micromol/L. Relative to the untreated control cells, no change in the density of the secreted lipoproteins was noted. Significant decreases in cellular lipid synthesis, including triglycerides (TG) and cholesterol esters (CE), were observed in cells treated with I3C, indicating that limited lipid availability is a major factor in the regulation of apoB secretion. The decrease in TG synthesis was associated with significantly decreased diacylglycerol acyltransferase-1 and -2 activity and reduced fatty acid synthase (FASN) gene expression. The decreased CE synthesis was associated with significantly decreased acyl CoA:cholesterol acyltransferase gene expression and activity. The effect on FASN was shown to be mediated by sterol regulatory element binding protein-1, an important transcription factor involved in fatty acid synthesis. Further investigative work revealed that LDL uptake and fatty acid oxidation were not involved in the I3C-mediated reduction of apoB secretion. The results indicate that plant indoles have beneficial effects on lipid synthesis that could contribute to their potential cardioprotective effect.
J Nutr. 2007 Oct;137(10):2185-9
Antiplatelet and antithrombotic activity of indole-3-carbinol in vitro and in vivo.
Indole-3-carbinol, a natural compound found in cruciferous vegetables, is known to have anticancer activity. In the present study, the antiplatelet and antithrombotic activities of indole-3-carbinol were investigated in vitro and in vivo. Indole-3-carbinol significantly inhibited collagen-induced platelet aggregation in human platelet rich plasma (PRP) in a concentration-dependent manner. Indole-3-carbinol significantly inhibited fibrinogen binding to the platelet surface glycoprotein IIb/IIIa (GP IIb/IIIa) receptor by flow cytometric analysis. In addition, the levels of thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) in collagen stimulated PRP were significantly inhibited in a concentration-dependent manner by indole-3-carbinol. Furthermore, indole-3-carbinol dose-dependently suppressed the death of mice with pulmonary thrombosis induced by intravenous injection of collagen and epinephrine. These results suggest that indole-3-carbinol can be a potent antithrombotic agent with antiplatelet activity through the inhibition of GP IIb/IIIa receptor and thromboxane B2 formation.
Phytother Res. 2008 Jan;22(1):58-64
Plasma vitamin C level, fruit and vegetable consumption, and the risk of new-onset type 2 diabetes mellitus: the European prospective investigation of cancer-- Norfolk prospective study.
BACKGROUND: Epidemiologic studies suggest that greater consumption of fruit and vegetables may decrease the risk of diabetes mellitus, but the evidence is limited and inconclusive. Plasma vitamin C level is a good biomarker of fruit and vegetable intake, but, to our knowledge, no prospective studies have examined its association with diabetes risk. This study aims to examine whether fruit and vegetable intake and plasma vitamin C level are associated with the risk of incident type II diabetes. METHODS: We administered a semiquantitative food frequency questionnaire to men and women from a population-based prospective cohort (European Prospective Investigation of Cancer-Norfolk) study who were aged 40 to 75 years at baseline (1993-1997) when plasma vitamin C level was determined and habitual intake of fruit and vegetables was assessed. During 12 years of follow-up between February 1993 and the end of December 2005, 735 clinically incident cases of diabetes were identified among 21,831 healthy individuals. We report the odds ratios of diabetes associated with sex-specific quintiles of fruit and vegetable intake and of plasma vitamin C levels. RESULTS: A strong inverse association was found between plasma vitamin C level and diabetes risk. The odds ratio of diabetes in the top quintile of plasma vitamin C was 0.38 (95% confidence interval, 0.28-0.52) in a model adjusted for demographic, lifestyle, and anthropometric variables. In a similarly adjusted model, the odds ratio of diabetes in the top quintile of fruit and vegetable consumption was 0.78 (95% confidence interval, 0.60-1.00). CONCLUSIONS: Higher plasma vitamin C level and, to a lesser degree, fruit and vegetable intake were associated with a substantially decreased risk of diabetes. Our findings highlight a potentially important public health message on the benefits of a diet rich in fruit and vegetables for the prevention of diabetes.
Arch Intern Med. 2008 Jul 28;168(14):1493-9
Serum and dietary potassium and risk of incident type 2 diabetes mellitus: The Atherosclerosis Risk in Communities (ARIC) study.
BACKGROUND: Serum potassium levels affect insulin secretion by pancreatic β-cells, and hypokalemia associated with diuretic use has been associated with dysglycemia. We hypothesized that adults with lower serum potassium levels and lower dietary potassium intake are at higher risk for incident diabetes mellitus (DM), independent of diuretic use. METHODS: We analyzed data from 12,209 participants from the Atherosclerosis Risk in Communities (ARIC) Study, an ongoing prospective cohort study, beginning in 1986, with 9 years of in-person follow-up and 17 years of telephone follow-up. Using multivariate Cox proportional hazard models, we estimated the hazard ratio (HR) of incident DM associated with baseline serum potassium levels. RESULTS: During 9 years of in-person follow-up, 1475 participants developed incident DM. In multivariate analyses, we found an inverse association between serum potassium and risk of incident DM. Compared with those with a high-normal serum potassium level (5.0-5.5 mEq/L), adults with serum potassium levels lower than 4.0 mEq/L, 4.0 to lower than 4.5 mEq/L, and 4.5 to lower than 5.0 mEq/L had an adjusted HR (95% confidence interval [CI]) of incident DM of 1.64 (95% CI, 1.29-2.08), 1.64 (95% CI, 1.34-2.01), and 1.39 (95% CI, 1.14-1.71), respectively. An increased risk persisted during an additional 8 years of telephone follow-up based on self-report with HRs of 1.2 to 1.3 for those with a serum potassium level lower than 5.0 mEq/L. Dietary potassium intake was significantly associated with risk of incident DM in unadjusted models but not in multivariate models. CONCLUSIONS: Serum potassium level is an independent predictor of incident DM in this cohort. Further study is needed to determine if modification of serum potassium could reduce the subsequent risk of DM.
Arch Intern Med. 2010 Oct 25;170(19):1745-51