and Health Fruits & Vegetables

The scientific evidence for the health benefits of fruit and vegetable consumption continues to expand. The extensive literature characterizing the phytochemicals and other bioactive components in fruits and vegetables reflect advances in science and technology that have made it possible to identify how these agents might affect biological processes using more accurate and sophisticated endpoints.

This review provides an overview of recent studies related to fruit and vegetable consumption and health, with an emphasis on investigations of whole food sources. The goal of the review is to evaluate a potential independent effect of collective intake of fruits or vegetables or a combination of both. Individual fruits and vegetables are highlighted only if they emerged as statistically significant in analysis. Data for the review is based on peer-reviewed articles between January, 2002 and August, 2006, and included only human studies. The topics in this review are those for which the scientific literature is relatively small. In 2005, the World Health Organization published reviews on Dietary intake of fruits and vegetables and management of body weight and on Dietary intake of fruits and vegetables and risk of diabetes and cardiovascular diseases The World Cancer Research Fund is reviewing the literature on diet and cancer, including fruits and vegetables, which will be published in 2007.

A variety of studies have been conducted to examine the relationship between fruit and vegetable intake, health promotion and disease prevention. Studies conducted in the past 5 years add to earlier work suggesting that fruits and vegetables appear to have health-promoting properties. Many of the studies reported during this time have focused on investigating mechanisms and understanding the bioactive compounds in these foods. The majority of evidence linking fruit and vegetable intake to health continues to be observational and data is often conflicting.

Review of the literature on pulmonary health suggests a plausible positive relationship with fruit and vegetable intake. For Chronic Obstructive Pulmonary Disease (COPD), the evidence is suggestive of a positive relationship, based on a few human studies. The literature on asthma, both in children and adults is relatively small, but growing, and the preliminary results indicate a ‘watching’ status for potential relationships. Although studies have controlled for potential confounders, the studies and their results are subject to inconsistencies.

The literature on fruit and vegetable intake and bone health continues to grow, and results of recent studies suggest a plausible positive relationship, especially mechanistic studies. However, there are very few clinical trials to confirm cause and effect.

The variety of processes associated with aging and amplified in neurodegenerative diseases of aging are complex and not completely understood. Available data on aging and cognition warrant continued ‘watching’, and data related to fruit and vegetable intake and neurodegenerative diseases indicate a plausible relationship, suggesting the potential of fruits and vegetables to modulate some of these processes. Extensive work remains to be done.

Available data relating fruit and vegetable intake to cataracts and eye health is primarily observational. However, the results of these few human studies are suggestive of a moderate effect. Further study is clearly warranted, especially clinical intervention trials.

There are possible mechanisms for a protective effect of fruits and vegetables related to inflammatory and oxidative processes associated with onset of arthritis. Results of studies suggest the relationship between fruit and vegetable intake and improvement in risk or prognosis of arthritis is plausible. However, not all antioxidants found in fruits and vegetables or total intake emerge consistently as protective. Much more work is needed in this area.

While there have been no recent intervention or prospective trials on fruit and vegetable consumption and diverticulosis, a high fiber diet that that includes ample quantities of both remains an important aspect of therapy, based on a convincing relationship shown by the literature.

Finally, in the area of birth defects, the majority of data shows a convincing protective effect of folate from supplements and not from natural folate intake. However, a number of studies demonstrate the importance of fruit and vegetable intake on plasma folate levels suggesting their potential contribution to reducing birth defects.

There is clearly a need for controlled, clinical intervention trials in order to confirm that consumption of fruits and vegetables promotes health and reduces risk of disease. Accurate assessment of dietary intake remains difficult, and cost-efficient methods to estimate intake more precisely are needed. Consistent use of appropriate endpoints and methodologies will also help to clarify potential relationship. More mechanistic studies will enable characterization of the components and processes that mediate protective effects in humans.