The Effects of Lutein-Containing Supplement Intake on Glycation Inhibition Among Diabetic Patients with Cataracts

Abstract

Glycation is known as an important factor inducing human diseases, including diabetic complications. As oxidative stress contributes to procedures of glycation, antioxidants may inhibit glycation and delay the progression of diabetic complications. Our previous investigation of human aqueous humor after the intake of a lutein-containing supplement demonstrated increases in antioxidative activities and decreases in peroxidative products. This study enrolled 25 patients with diabetes (DM group) and 100 age-matched controls. Aqueous humor samples were collected during cataract surgery before and after 6 weeks of oral intake of the lutein-containing antioxidant supplement, Ocuvite + Lutein^®. The carboxymethyl-lysine level (CML) was measured as an indicator of glycation. Levels of superoxide dismutase activities (SOD) and total hydroperoxide (TH) were measured as indicators of oxidation. Changes after intake and the differences between age-matched controls and the DM group were evaluated. CML decreased after intake among the DM group, while there were no changes among the age-matched controls. SOD was significantly lower and TH was significantly higher in the DM group as compared to the age-matched controls, both before and after intake. In line with the decreases in glycation, the intake of lutein-containing antioxidant supplements may inhibit diabetic complications in diabetic patients.

Keywords: advanced glycation end products; antioxidant; aqueous humor; diabetes; glycation; lutein; senile cataract.

Figure 1

Changes in CML levels of the DM group after 6 weeks of lutein-containing supplement intake. (a) Among males in the DM group, CML levels in the post-intake samples were significantly lower compared to those observed in the pre-intake samples (p = 0.0192, analyzed with paired t-test). Although the same tendency was found among females in the DM group, this did not reach statistically significant levels. There were no significant differences between the genders for either the pre-intake or post-intake samples (analyzed with t-test). (b) There was a significant correlation between the CML levels in the pre-intake samples and those in the post-intake samples among males (analyzed with regression analysis). Although the same correlation was not shown among females, the CML level values for females are located on the right portion of the graph below the regression line, which indicates decreases in the CML levels after the intake. * p = 0.0192.

Figure 2

Changes in SOD levels of the DM group after 6 weeks of lutein-containing supplement intake. (a) There were no significant differences between the SOD levels in the pre-intake and post-intake samples (analyzed with paired t-test) in either males or females (analyzed with t-test). (b) There was no correlation between the SOD levels in the pre-intake samples and the post-intake samples among both genders (analyzed with regression analysis).

Figure 3

Changes in TH levels of the DM group after 6 weeks of lutein-containing supplement intake. (a) There were no significant differences between the TH levels in the pre-intake and post-intake samples (analyzed with paired t-test) in either males or females (analyzed with t-test). (b) There was no correlation between the TH levels in the pre-intake samples and post-intake samples among both genders (analyzed with regression analysis).

Figure 4

Changes in the CML levels of the age-matched controls after 6 weeks of lutein-containing supplement intake. (a) In the age-matched controls, there were no significant differences between the CML levels in the pre-intake and post-intake samples (analyzed with paired t-test) in either males or females. (b) There was a significant correlation between the CML levels in the pre-intake samples and post-intake samples among both genders (analyzed with regression analysis). There were no significant differences between the genders for either the pre-intake or post-intake samples (analyzed with t-test).

Figure 5

Comparisons between the DM and the age-matched controls for the changes in the CML levels. There were no significant differences in the CML levels, in either the pre-intake or post-intake samples in both genders (analyzed with t-test). * p < 0.05.

Figure 6

Comparisons between the DM and aged groups for the changes in the SOD levels. The SOD levels were significantly lower in the DM group among both genders, in both the pre-intake and post-intake samples (analyzed with t-test). * p < 0.05. ** p < 0.01.

Figure 7

Comparisons between the DM and aged groups for changes in the TH levels. TH levels were significantly higher among males in both the pre-intake and post-intake samples while they were only higher in the post-intake samples among females (analyzed with t-test). * p < 0.05. ** p < 0.01.