The MPOD value measures the amount of lutein and zeaxanthin in the brain.
The higher the value, the greater the amount of lutein and zeaxanthin in the brain crucial in filtering blue-light harmful to the eyes.
In the intervention group, both their blood serum lutein level and MPOD were significantly higher than that of the placebo group by the end of the study.
The study, conducted by researchers from Josai University and Health Sciences University of Hokkaido, was published in Nutrients.
A total of 59 subjects between 20 and 69 years old took part in the randomised, double-blind, and placebo-controlled trial that took place in Sep 2018 to Jan 2019.
The intervention group took two lutein capsules provided by Japanese ingredient supplier firm Omnica once per day.
By the 8th week, the intervention group had twice as much serum lutein as compared to the placebo.
The trend continued until the end of the study, where the intervention group’s serum lutein level was 0.751 ± 0.473 µmol/L, while that of the placebo was 0.391 ± 0.175 µmol/L.
This was also a statistically significant result, with the p-value lower than 0.001.
The higher serum lutein level in the intervention group was also associated with a higher MPOD value.
The intervention group started off with a lower baseline MPOD value at 0.498 ± 0.185, while that of the placebo was higher at 0.522 ± 0.145.
By the end of the study, the MPOD of the intervention group went up to 0.545 ± 0.173, while the placebo group remained at 0.523 ± 0.159.
“The significantly improved MPOD at week 16 suggested that lutein administration increased the serum level and subsequent accumulation in the macular area of the retina,” the researchers said, adding that the research did not receive any external funding.
Better contrast sensitivity
Lutein supplementation also improved contrast sensitivity.
This means that one is able to distinguish patterns that have no clear contours and those that have a few differences in shading.
In real life settings, contrast sensitivity is important as it measures how well one could view the headlight of an opposing car at night.
The researchers believe that the intervention group had better contrast sensitivity as lutein can inhibit the decrease in visual function caused by a glare from light.
“This study demonstrated significant improvements in contrast and glare sensitivities in the lutein group at week 16.
“Macular pigment filters blue light in front of photoreceptors, thereby attenuating the effects of colour aberration and light scattering and enhancing visual function,” the researchers concluded.
Clinical Effects of Dietary Supplementation of Lutein with High Bio-Accessibility on Macular Pigment Optical Density and Contrast Sensitivity: A Randomized Double-Blind Placebo-Controlled Parallel-Group Comparison Trial
Authors: Naomichi Machida, et al