Influence of beta carotene, vitamin E, and vitamin C on endogenous antioxidant defenses in erythrocytes.

OBJECTIVE

To evaluate the in vivo radical scavenger activity of vitamin E, vitamin C, and beta carotene on erythrocyte membranes.

DESIGN

A prospective, open trial without placebo.

SETTING

Department of Clinical Pharmacy.

PATIENTS

Ten healthy volunteers being supplemented with beta carotene, vitamin E, and vitamin C.

MEASUREMENTS

Erythrocytes were incubated in water bath with 2,2' azobis (2 amidinopropane) hydrochloride (AAPH). AAPH decomposes spontaneously at 37 degrees C to generate free radicals inducing membrane cellular damage and hemolysis. The absorbance was measured at 405 nm at 0, 30, and 60 min, and then every 20 minutes for four hours. The time for 50 percent of maximal hemolysis (T50%), which expresses the radical scavenger activity of erythrocytes, was determined.

RESULTS

The physiologic T50% value determined in 52 healthy volunteers is 117 +/- 12 min. Patients receiving these supplements have a higher value of T50% (143.2 +/- 11.6 min at 30 d and 145.7 +/- 10.5 min at 60 d) than the physiologic value (p < 0.001).

CONCLUSIONS

These data suggest that vitamin C, vitamin E, and beta carotene stimulate the radical scavenger activity of erythrocyte membranes after 30 days.