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Human Nutrition Unit School of Molecular and Microbial Biosciences University of Sydney
Dear Editor:
The ß-carotene concentrations that we reported (1) are lower than concentrations cited by Watzl and Bub but consistent with those reported by others (2). When the concentrations of ß-carotene are standardized to the LDL cholesterol concentrations, the ratios that are obtained from our data are consistent with those reported by centers as diverse as Spain, the U.K. and Ireland (3). There is much variation in the plasma ß-carotene concentration that is not easily explained by factors such as bioavailability and the presence of "responders" and "nonresponders" (4).
The fruit and vegetable extract that we tested is marketed internationally. In order to meet product labeling laws, the manufacturer acknowledges that some micronutrients are added to restore the levels of micronutrients lost during processing and to ensure uniformity in the final product. These micronutrients are ß-carotene, ascorbic acid, vitamin E and folate.
Previous studies with the same fruit and vegetable extracts did show increases in ß-carotene and a range of other carotenoids including lycopene, lutein/zeaxanthin, and 
- carotene (5,6), reflecting the bioavailability of the endonegous carotenoids. The lack of increase in the concentrations of some carotenoids in our trial could be partly due to the high concentration of lycopene at baseline as well as complex factors that affect bioavailability (4).
It has recently been reported that the fruit and vegetable concentrates similar to those used in our study, are able to blunt the impairment of flow-mediated brachial artery vasoactivity after a high fat meal (7). This response was demonstrated even when the supplementation did not occur with the meal. In contrast, a similar result using this experimental approach required 800 IU of vitamin E and 1000 mg of vitamin C administered with the fatty meal (8). These levels are well beyond those that are found in the fruit and vegetable extract.
Taken together, the data indicate that the endogenous components of the fruit and vegetable extract contribute to improvements in functional outcomes, such as vascular reactivity, and to favorable changes in biomarker concentrations.
Manuscript received 7 August 2003.
LITERATURE CITED
1. Samman, S., Man, J. C., Sivarajah, G., Ahmad, Z. I., Petocz, P. & Caterson, I. D. (2003) Supplementation with a mixed fruit and vegetable concentrate increases plasma antioxidant vitamins and lowers plasma homocysteine in men. J. Nutr. 133:2188-2193.
2. Abbey, M., Noakes, M. & Nesterl, P. J. (1995) Dietary supplementation with orange and carrot juice in cigarette smokers lowers oxidation products in copper-oxidized low-density lipoproteins. J. Am. Diet. Assoc. 95:671-675.[Medline]
3. Wright, J. A., Southon, S., Chopra, M., Meyer-Wenger, A., Moser, U., Granado, F., Olmedilla, B., Corridan, B., Hinninger, I., Roussel, A., van den Berg, H. & Thurnham, D. I. (2002) Comparison of LDL fatty acid and carotenoid concentrations and oxidative resistance of LDL in volunteers from countries with different rates of cardiovascular disease. Br. J. Nutr. 87:21-29.[Medline]
4. van het Hof, K. H., West, C. E., Weststrate, J. A. & Hautvast, J. (2000) Dietary factors that affect the bioavailability of carotenoids. J. Nutr. 130:503-506.
5. Wise, J. A., Morin, R., Sanderson, R. & Blum, K. (1996) Changes in plasma carotenoid, alpha-tocopherol, and lipid peroxide levels in response to supplementation with concentrated fruit and vegetable extracts: a pilot study. Curr. Ther. Res. 57:445-461.
6. Inserra, P. F., Jiang, S., Solkoff, D., Lee, J., Zhang, Z., Xu, M., Hesslink, R., Jr, Wise, J. & Watson, R. R. (1999) Immune function in the elderly smokers and non-smokers improves during supplementation with fruit and vegetable extracts. Intern. Med. 2:3-10.
7. Plotnick, G. D., Corretti, M. C., Vogel, R. A., Hesslink, R., Jr & Wise, J. A. (2003) Effect of supplemental phytonutrients on impairment of the flow-mediated brachial artery vasoactivity after a single high-fat meal. J. Amer. Coll. Cardiol. 41:1744-1749.
8. Plotnick, G. D., Corrett, M. C. & Vogel, R. A. (1997) Effect of antioxidant vitamins on the transient impairment of endothelium-dependent brachial artery vasoactivity following a single high-fat meal. J. Am. Med. Assoc. 278:1682-1686.[Abstract]
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