Intervention study with a high or low antioxidant capacity diet: effects on circulating beta-carotene.
OBJECTIVE
A cross-sectional observation suggests that total antioxidant capacity (TAC) of the diet positively affects plasma concentrations of beta-carotene independent of beta-carotene intake. This study was carried out to investigate the effect of two dietary strategies, designed to be comparable in fruits, vegetables, fibre, alcohol and beta-carotene intake but substantially different in their TAC, on changes in antioxidant intake and antioxidant status, and in particular in circulating beta-carotene concentrations.


METHODS
A randomized cross-over intervention trial involving 33 healthy participants and consisting of two 14-day dietary periods (high TAC diet, HT; low TAC diet, LT) with a 14-day washout in between was conducted.


RESULTS
Energy, macronutrient, dietary fibre, alcohol and beta-carotene intake was not significantly different between LT and HT, whereas intake of other carotenoids and dietary TAC was significantly higher in the HT than in the LT (P<0.001). Circulating carotenoids (with the exception of alpha-carotene, which followed an inverse trend) and alpha-tocopherol decreased significantly during the LT and increased during the HT period. Among these, beta-carotene almost doubled its concentration in plasma after the HT diet.


CONCLUSIONS
The increase in circulating beta-carotene along with the increase in dietary TAC suggests that plasma beta-carotene could be a marker of TAC intake rather than of beta-carotene intake itself. This may explain, in part, why beta-carotene supplementation alone has shown no benefit in chronic disease prevention and adds to a putative beneficial role of high dietary TAC diets, which merits further investigation.
Del Rio
D
D
Human Nutrition Unit, Department of Public Health, University of Parma, Parma, Italy.
Valtueña
S
S
Pellegrini
N
N
Bianchi
M A
MA
Ardigò
D
D
Franzini
L
L
Scazzina
F
F
Monti
L
L
Zavaroni
I
I
Brighenti
F
F
D000428:Alcohol Drinking; D000975:Antioxidants / Q000008:administration & dosage* / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D018592:Cross-Over Studies; D004043:Dietary Fiber / Q000008:administration & dosage; D005260:Female; D016166:Free Radical Scavengers; D005638:Fruit; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000453:epidemiology / Q000517:prevention & control; D008107:Liver Diseases / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D014675:Vegetables; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood; D019207:beta Carotene / Q000008:administration & dosage* / Q000097:blood*
D000975:Antioxidants; D015415:Biomarkers; D004043:Dietary Fiber; D016166:Free Radical Scavengers; D014815:Vitamins; D019207:beta Carotene