Original Article

European Journal of Clinical Nutrition (2007) 61, 69–76. doi:10.1038/sj.ejcn.1602485; published online 12 July 2006

The total antioxidant capacity of the diet is an independent predictor of plasma bold italic beta-carotene

Guarantor: F Brighenti.

Contributors: SV participated in the study design and the collection of clinical data, performed the statistical analysis and was the primary writer of the paper, but received input from all the other authors. DDR contributed to the preparation of the paper, to laboratory analysis and to the study design. NP provided expert advice and was involved in paper editing and data interpretation. DA and LF participated in subjects' recruitment and management, in the collection and interpretation of clinical data and in the discussion of the paper. PMP and SS were involved in laboratory analysis and quality control. PR carried out the analysis of plasma beta-carotene and provided expert advice on data interpretation. DDR, NP, SS and FB were responsible for the collection, completeness and interpretation of dietary data. IZ was responsible for ethical approval and subjects' recruitment. IZ and FB were responsible for the study concept and design and for securing the funding. None of the authors had any conflicts of interest in connection with this study.

S Valtueña1,2, D Del Rio1, N Pellegrini1, D Ardigò2, L Franzini2, S Salvatore1, P M Piatti3, P Riso4, I Zavaroni2 and F Brighenti1

  1. 1Department of Public Health, University of Parma, Parma, Italy
  2. 2Department of Internal Medicine and Biomedical Sciences, University of Parma, Parma, Italy
  3. 3Cardiovascular and Metabolic Rehabilitation Unit, IRCCS H San Raffaele, Milan, Italy
  4. 4Department of Food Sciences and Microbiology, University of Milan, Milan, Italy

Correspondence: Dr S Valtueña, Department of Internal Medicine and Biomedical Sciences, University of Parma, Via Gramsci 14, Parma 43100, Italy. E-mail: valtuena@libero.it

Received 26 December 2005; Revised 23 May 2006; Accepted 29 May 2006; Published online 12 July 2006.

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Abstract

Objective:

 

To investigate the contribution of the total antioxidant capacity (TAC) of the diet to plasma concentrations of beta-carotene.

Design:

 

Cross-sectional study.

Setting:

 

Department of Public Health and Department of Internal Medicine and Biomedical Sciences, University of Parma.

Subjects:

 

A total of 247 apparently healthy adult men (n=140) and women (n=107).

Methods:

 

A medical history, a physical exam including height, weight, waist circumference and blood pressure measurements, a fasting blood draw, an oral glucose tolerance test and a 3-day food record.

Results:

 

We observe a negative trend across quartiles of plasma beta-carotene for most biological variables clustering in the insulin resistance syndrome, as well as for traditional and new risk factors for type II diabetes and cardiovascular disease (CVD), including C-reactive protein and italic gamma-glutamyltranspeptidase (P<0.05). Regarding dietary characteristics, energy-adjusted intake of fat, fiber, fruits, vegetables, beta-carotene, vitamin C, vitamin E and dietary TAC significantly increased with increasing plasma beta-carotene (P<0.05), whereas alcohol intake decreased (P=0.013). Adjusted geometric means (95% confidence interval) of plasma beta-carotene significantly increased across quartiles of dietary TAC, even when single dietary antioxidants were considered in the model (QI=0.087 mg/dl (0.073–0.102); QII=0.087 mg/dl (0.075–0.103); QIII=0.114 mg/dl (0.098–0.132) and QIV=0.110 mg/dl (0.093–0.130); P for linear trend=0.026). When the population was divided on the basis of alcohol consumption, this trend was also observed in subjects drinking <20 g alcohol/day (P=0.034), but not in those with higher alcohol intake (P=0.448).

Conclusions:

 

Dietary TAC is an independent predictor of plasma beta-carotene, especially in moderate alcohol drinkers. This may explain, at least in part, the inverse relationship observed between plasma beta-carotene and risk of chronic diseases associated to high levels of oxidative stress (i.e., diabetes and CVD), as well as the failure of beta-carotene supplements alone in reducing such risk.

Sponsorship:

 

Supported by the European Community IST-2001–33204 'Healthy Market', the Italian Ministry of University and Research COFIN 2001 and the National Research Council CU01.00923.CT26 research projects.

Keywords:

beta-carotene, antioxidants, diet, oxidative stress, insulin resistance, alcohol drinking

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