The 6-a-day study: effects of fruit and vegetables on markers of oxidative stress and antioxidative defense in healthy nonsmokers.
BACKGROUND
Fruit and vegetables contain both nutritive and nonnutritive factors that might contribute to redox (antioxidant and prooxidant) actions.


OBJECTIVE
We investigated the relative influence of nutritive and nonnutritive factors in fruit and vegetables on oxidative damage and enzymatic defense.


METHODS
A 25-d intervention study with complete control of dietary intake was performed in 43 healthy male and female nonsmokers who were randomly assigned to 1 of 3 groups. In addition to a basic diet devoid of fruit and vegetables, the fruit and vegetables (Fruveg) group received 600 g fruit and vegetables/d; the placebo group received a placebo pill, and the supplement group received a vitamin pill designed to contain vitamins and minerals corresponding to those in 600 g fruit and vegetables. Biomarkers of oxidative damage to protein and lipids and of antioxidant nutrients and defense enzymes were determined before and during intervention.


RESULTS
Plasma lipid oxidation lag times increased during intervention in the Fruveg and supplement groups, and the increase was significantly higher in the former. Plasma protein carbonyl formation at lysine residues also increased in both of these groups. Glutathione peroxidase activity increased in the Fruveg group only. Other markers of oxidative damage, oxidative capacity, or antioxidant defense were largely unaffected by the intervention.


CONCLUSIONS
Fruit and vegetables increase erythrocyte glutathione peroxidase activity and resistance of plasma lipoproteins to oxidation more efficiently than do the vitamins and minerals that fruit and vegetables are known to contain. Plasma protein carbonyl formation at lysine residues increases because of the vitamins and minerals in fruit and vegetables.
Dragsted
Lars O
LO
Danish Institute for Food and Veterinary Research, Søborg, Denmark. lod@fdir.dk
Pedersen
Anette
A
Hermetter
Albin
A
Basu
Samar
S
Hansen
Max
M
Haren
Gitte R
GR
Kall
Morten
M
Breinholt
Vibeke
V
Castenmiller
Jacqueline J M
JJ
Stagsted
Jan
J
Jakobsen
Jette
J
Skibsted
Leif
L
Rasmussen
Salka E
SE
Loft
Steffen
S
Sandström
Brittmarie
B
D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D004032:Diet; D004790:Enzyme Induction; D005260:Female; D005638:Fruit; D006801:Humans; D008297:Male; D008903:Minerals / Q000008:administration & dosage*; D018384:Oxidative Stress; D014675:Vegetables; D014815:Vitamins / Q000008:administration & dosage* / Q000097:blood
D000975:Antioxidants; D008903:Minerals; D014815:Vitamins