Effects of simultaneous zinc and vitamin A supplementation on serum lipoproteins, apoproteins A-1and B and glycemia in patients with type I diabetes

Zinc (Zn) is an essential trace element found in a wide spectrum of metalloenzymes,. It participates in many metabolic processes, including normal metabolism of vitamin A. On the other hand, vitamin A affects zinc absorption and utilization. Recent investigation has shown that vitamin A plays a role in the secretion of insulin by the pancreas. There is evidence that the metabolism of zinc and vitamin A is altered in type 1 diabetes mellitus (DM). The objective of the present study was to investigate the effects of simultaneous zinc and vitamin A supplementation on serum lipoproteins, apoproteins A-I and B and glycemic status in patient with type I DM.

Fifty-two 7-20 year-old patients with at least 2 years of DM history, not suffering from any other metabolic disease, and not taking any medicine, but under insulin treatment, participated in a 12-week randomized double-blind clinical trial. They were divided,, after matching for sex, age and DM duration, into 2 groups: a Zn- and vitamin A-supplemented group (10 mg Zn-sulfate syrup per day and half of a 25000-IU vitamin A tablet every other day) and a control group (taking a zinc and vitamin A placebo). Forty-eight patients completed the study. Nutrients intakes were estimated using a 24-hour recall and analyzed by Food Processor III. The serum contents of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), triglyceride (TG), apoproteins B and A-I, fasting blood sugar (FBS), insulin, and glycosylated hemoglobin (HbA1c) were determined at the beginning and at the end of the trial. The independent sample t-test was used for comparisons between the two groups and the paired sample t-test was used to compare the differences between different time points in each group. A P-value £ 0.05 was considered significant.

The final mean serum TC, TG, LDL-c, HDL-c, FBS, insulin, HbA1c and apoprotein B values were not significantly different between the 2 groups.As compared to the control value, only the apoprotein AI level significantly increased in the experimental group (p<0.0001).

It seems that simultaneous zinc and vitamin A supplementation may increase the serum ApoA-I level, which can reduce the atherogenic risk factor in patients with type 1 DM.