Effect of zinc supplementation on vitamin status of middle-aged and older European adults: the ZENITH study.
OBJECTIVE
To assess the effects of zinc supplementation on vitamin status in middle-aged and older volunteers.


METHODS
Three hundred and eighty-seven healthy middle-aged (55-70 years) and older (70-85 years) men and women, randomly allocated to three groups to receive 15 or 30 mg Zn/day or placebo for 6 months. Dietary intake was assessed by means of a validated 4-day recall record. Fasting blood samples were simultaneously analysed for levels of plasma retinol and alpha-tocopherol by high-performance liquid chromatography. Erythrocyte folates were measured by a competitive immunoassay with direct chemiluminescence detection on an automatized immunoanalyser. Biochemical measurements were performed at baseline and after 3 and 6 months of zinc supplementation.


RESULTS
Plasma vitamin A levels were significantly increased proportionally with zinc dose and period of treatment, particularly at 6 months (for 15 mg Zn/day, P<0.05; for 30 mg Zn/day, P<0.0001); no significant changes were observed in the placebo group. There was no effect of zinc supplementation on vitamin E/cholesterol ratio and erythrocyte folates.


CONCLUSIONS
Our results show that a long-term zinc supplementation increases plasma vitamin A levels in middle-aged and older people of similar characteristics to those involved in this study. Moreover, supplementation influences serum zinc levels but does not affect erythrocyte zinc concentration and both plasma vitamin E and erythrocyte folate status.
Intorre
F
F
Human Nutrition Unit, National Institute for Research on Food and Nutrition, Via Ardeatina 546, Rome, Italy. intorre@inran.it
Polito
A
A
Andriollo-Sanchez
M
M
Azzini
E
E
Raguzzini
A
A
Toti
E
E
Zaccaria
M
M
Catasta
G
G
Meunier
N
N
Ducros
V
V
O'Connor
J M
JM
Coudray
C
C
Roussel
A M
AM
Maiani
G
G
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004032:Diet; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000378:metabolism; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009749:Nutrition Surveys; D009752:Nutritional Status; D014131:Trace Elements / Q000008:administration & dosage*; D014801:Vitamin A / Q000097:blood; D014810:Vitamin E / Q000097:blood; D015032:Zinc / Q000008:administration & dosage* / Q000097:blood*
D014131:Trace Elements; D014801:Vitamin A; D014810:Vitamin E; D005492:Folic Acid; D015032:Zinc