Exploiting the antioxidant potential of a common vitamin: could vitamin C prevent postmenopausal osteoporosis?

Oxidative stress is thought to play a central role in the pathophysiology of various conditions affecting women's health, including cancer, preeclampsia and osteoporosis. On the back of animal experimentation, we sought to establish whether the oral administration of vitamin C at high doses to postmenopausal women would achieve the plasma antioxidant activity that could prevent osteoporosis.

In our pilot study, we administered vitamin C at a dose of 10 grams daily to eight healthy postmenopausal women over a period of four weeks and measured their serum levels of vitamin C and crosslaps (markers of bone turnover) at baseline and then on a weekly basis.

We found an initial rise in the plasma levels of vitamin C, but these rapidly fell over four weeks and could not be sustained despite continued therapy, presumably due to limited absorption and possibly even augmented excretion. We found no discernable change in the serum levels of crosslaps in association with the consumption of high doses of vitamin C.

Although vitamin C has antioxidant properties, when given orally, even at a high dose, the serum levels required for it to exhibit antioxidant activity cannot be attained. This approach holds no potential for the use of vitamin C in the prevention of osteoporosis, although other routes of administration could overcome this.