Health Effects of Mixed Fruit and Vegetable Concentrates: A Systematic Review of the Clinical Interventions

Abstract

Diets rich in fruits and vegetables (FV) have been associated with a reduced risk of chronic disease, including cardiovascular disease. Unfortunately, public health campaigns to increase FV intake have had limited success. A number of mixed concentrated FV products have been studied, which may help certain individuals improve nutrient status. However, the possible health benefits of FV supplements have not been systematically reviewed. We, therefore, undertook a systematic search of MEDLINE and EMBASE to identify clinical interventions that examined the effect of commercially available concentrated mixed FV supplements on cardiovascular disease risk factors. Twenty-two reports, which used commercially available products, were identified. None of the studies reported any serious adverse effects. Overall, daily consumption of FV supplements significantly increased serum concentrations of the major antioxidant provitamins and vitamins found in plant foods (β-carotene, vitamins C and E) and folate. Functional changes, such as reduced serum homocysteine and markers of protein, lipid, and DNA oxidation, were also reported; in addition, the health advantages on markers of inflammation, immunity, and endothelial function are promising. Limitations of the available studies were related to the diversity of studies conducted with respect to design and study population and the variability in the measured outcomes and assays utilized. While mixed FV supplements may serve as an efficacious complement for individuals who have difficulty achieving their daily FV intake requirement, further research on additional retail preparations is warranted.

Key teaching points:

•	Mixed fruit and vegetable supplements produced from plant foods may serve as an efficacious complement to the habitual diet in individuals who have suboptimal intake or variety of nutrient-dense fruits and vegetables.
•	Current research indicates that fruit and vegetable concentrates significantly increase serum levels of antioxidant provitamins and vitamins (β-carotene, vitamins C and E) and folate and reduce homocysteine and markers of oxidative stress.
•	Mechanistic studies and larger, randomized, placebo-controlled double-blind trials in both healthy and high-risk populations are necessary to better understand the health effects of these supplements.

Key words::

• fruit
• vegetable
• supplement
• concentrate
• antioxidant
• oxidative stress

ACKNOWLEDGMENT

We would like to thank Ms Shahad Abdulnour for helping with data extraction.

Table 1. Description of the Studies Included in the Systematic Review

Table 2. Fruit and Vegetable Composition of the Products

Table 3. Declared Micronutrient Composition of the Supplements

Table 4. The Effects of Supplements on Serum Antioxidant Levels

Table 5. Effects of Capsules on Markers of Oxidative Stress

Table 6. The Impact of Capsules on Serum Folate and Homocysteine Levels

Notes

Support: Amin Esfahani received a travel grant from NSA (Collierville, Tennessee) to attend the 2010 Experimental Biology Meeting. Julia Wong is a recipient of a Canadian Institutes of Health Research Fellowship Award in the area of clinical research.

Presentations: Aspects of this manuscript were presented at the Experimental Biology Meeting (April 24–28, 2010, Anaheim, California).