Scientists have found yet another reason for people to take a daily supplement of vitamin C. Not only does it help to ward off colds, but the antioxidant vitamin C can improve the blood circulation in people with type 2 diabetes. As a result, vitamin C may prove to be a potent combatant against diabetes-induced vascular disease, which can cause retinopathy, nephropathy and atherosclerosis.
Scientists injected 24 mg of vitamin C per minute for 10 minutes into 10 people with diabetes and ten age-matched, non-diabetic control subjects. Vitamin C increased the circulation in the forearm blood vessels of the subjects with diabetes by 36%. The vitamin C injections did not affect the non-diabetic control subjects.
People with type 2 diabetes may experience circulation problems because they do not produce or release nitric oxide, an enzyme which adds oxygen to the nitrogen in the blood. The proper functioning of endothelial cells, a layer of flat cells lining the interior of the blood vessel, relies on the circulation of nitric oxide. The study, which established that vitamin C improves endothelial cell performance, supports the theory that a lack of nitric oxide is responsible for impaired vascular function.
Doctors involved with the study recommend that people with diabetes ingest 250 mg to 500 mg of vitamin C a day. (H. Ting et al., Journal of Clinical Investigation 97:22-8, Jan. 1996)