I don't know where you are looking at. But there are number of studies and metanalysis which shows the benefits of fruits & vegetables in diseases.
And it is not just fiber and vitamins, there are number compounds which are yet to be discovered in fruits and vegetables which is very now established and which can prevent diseases. The thousand of phytochemicals discovered recently is a good example. And who knows we might discover a few hundreds more in the next 10 years.
Here is a few studies that I just saw.All recent studies and there are a lot more.
Fruit and vegetable consumption and stroke: meta-analysis of cohort studies.
He FJ, Nowson CA, MacGregor GA.
Lancet. 2006 Jan 28;367(9507):320-6.
Abstract
BACKGROUND: Increased consumption of fruit and vegetables has been shown to be associated with a reduced risk of stroke in most epidemiological studies, although the extent of the association is uncertain. We quantitatively assessed the relation between fruit and vegetable intake and incidence of stroke in a meta-analysis of cohort studies. METHODS: We searched MEDLINE, EMBASE, the Cochrane Library, and bibliographies of retrieved articles. Studies were included if they reported relative risks and corresponding 95% CIs of stroke with respect to frequency of fruit and vegetable intake. FINDINGS: Eight studies, consisting of nine independent cohorts, met the inclusion criteria. These groups included 257,551 individuals (4917 stroke events) with an average follow-up of 13 years. Compared with individuals who had less than three servings of fruit and vegetables per day, the pooled relative risk of stroke was 0.89 (95% CI 0.83-0.97) for those with three to five servings per day, and 0.74 (0.69-0.79) for those with more than five servings per day. Subgroup analyses showed that fruit and vegetables had a significant protective effect on both ischaemic and haemorrhagic stroke. INTERPRETATION: Increased fruit and vegetable intake in the range commonly consumed is associated with a reduced risk of stroke. Our results provide strong support for the recommendations to consume more than five servings of fruit and vegetables per day, which is likely to cause a major reduction in strokes.
Intakes of fruits, vegetables, vitamins A, C, and E, and carotenoids and risk of renal cell cancer.
Lee JE, Giovannucci E, Smith-Warner SA, Spiegelman D, Willett WC, Curhan GC.
Cancer Epidemiol Biomarkers Prev. 2006 Dec;15(12):2445-52.
Abstract
BACKGROUND: Fruits and vegetables rich in antioxidants have been proposed to reduce the risk of renal cell cancer. However, few prospective studies have examined the intakes of fruits, vegetables, and antioxidant vitamins in relation to the risk of renal cell cancer. METHODS: We prospectively examined the associations between the intakes of fruits, vegetables, vitamins A, C, and E, and carotenoids and risk of renal cell cancer in women and men. We followed 88,759 women in the Nurses' Health Study from 1980 to 2000, and 47,828 men in the Health Professionals Follow-up Study from 1986 to 2000. We assessed dietary intake every 2 to 4 years using a validated semiquantitative food frequency questionnaire. The Cox proportional hazards model was used to estimate study-specific multivariate relative risks (RR), which were pooled using a random effects model. RESULTS: A total of 248 (132 women and 116 men) incident renal cell cancer cases were ascertained during 2,316,525 person-years of follow-up. The consumption of fruits and vegetables was associated with a decreased risk of renal cell cancer in men (multivariate RR, 0.45; 95% CI, 0.25-0.81, for >or=6 servings of fruit and vegetable intake/d versus <3 servings/d; P test for trend = 0.02), but not in women (multivariate RR, 1.17; 95% CI, 0.66-2.07, for the same contrast; P test for trend = 0.25; P test for between-studies heterogeneity = 0.02). Intakes of vitamins A and C from food and carotenoids were inversely associated with the risk of renal cell cancer in men only, but we cannot exclude the possibility that this was due to other factors in fruit and vegetables. No clear association was observed for vitamin E in women or men. CONCLUSIONS: Fruit and vegetable consumption may reduce the risk of renal cell cancer in men.
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.
Arch Intern Med. 2008 Jul 28;168(14):1493-9.
Abstract
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 2 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.
