The role of antioxidant micronutrients in the prevention of diabetic complications.

Bonnefont-Rousselot D.

Laboratoire de Biochimie Metabolique et Clinique (EA 3617), Faculte de
Pharmacie, Paris, France.

Diabetes mellitus is associated with an increased production of
reactive oxygen species and a reduction in antioxidant defenses. This
leads to oxidative stress, which is partly responsible for diabetic
complications. Tight glycemic control is the most effective way of
preventing or decreasing these complications. Nevertheless, antioxidant
micronutrients can be proposed as adjunctive therapy in patients with
diabetes. Indeed, some minerals and vitamins are able to indirectly
participate in the reduction of oxidative stress in diabetic patients
by improving glycemic control and/or are able to exert antioxidant
activity. This article reviews the use of minerals (vanadium, chromium,
magnesium, zinc, selenium, copper) and vitamins or cofactors
(tocopherol [vitamin E], ascorbic acid [vitamin C], ubidecarenone
[ubiquinone; coenzyme Q], nicotinamide, riboflavin, thioctic acid
[lipoic acid], flavonoids) in diabetes, with a particular focus on the
prevention of diabetic complications. Results show that dietary
supplementation with micronutrients may be a complement to classical
therapies for preventing and treating diabetic complications.
Supplementation is expected to be more effective when a deficiency in
these micronutrients exists. Nevertheless, many clinical studies have
reported beneficial effects in individuals without deficiencies,
although several of these studies were short term and had small sample
sizes. However, a randomized, double-blind, placebo-controlled,
multicenter trial showed that thioctic acid at an oral dosage of 800
mg/day for 4 months significantly improved cardiac autonomic neuropathy
in type 2 diabetic patients. Above all, individuals with diabetes
should be educated about the importance of consuming adequate amounts
of vitamins and minerals from natural food sources, within the
constraints of recommended sugar and carbohydrate intake.