Abstract
Purpose:
To systematically review the evidence currently available on the effects of lutein supplementation on serum lutein and macular pigment and investigate the concept of retinal nonresponse.
Methods:
Three databases were searched systematically to identify human studies in English language, published up to February 2012. Studies were selected using pre-specified criteria. Of 77 potential articles identified, 24 articles met the selection criteria. Meta-analysis and meta-regression techniques were used to quantitatively pool results and investigate the association between study characteristics and mean changes in serum lutein and macular pigment (MP).
Results:
Intervention studies using lutein only and combined lutein supplements were included. Daily dosage ranged from 2.4mg to 30mg lutein and duration of the supplementation period varied from 35 to 365 days. The review included 19 open label studies, 12 placebo-controlled and 10 randomised, placebo-controlled studies. All studies reported an increase in mean serum lutein and all but two reported an increase in MP levels. There was strong heterogeneity amongst studies. Dosage was found to be a significant influence in the increase of serum lutein levels in healthy volunteers. For each increase of 10mg of lutein, there was an increase of 0.02µmol-1 (95% CI 0.003, 0.04) P<0.05 in the change in serum lutein levels. In patients, studies longer in duration of supplementation by 100 days, had increases in the change in serum lutein of 0.005µmol-1 (0.006, 0.006) P<0.05 and increases in the change in MP levels of 0.0003AU (0.00005, 0.0006) P<0.05. The concept of retinal non-response is poorly defined within the published literature. There was no difference found between responders and nonresponders in relation to age, gender, smoker status, iris colour and BMI.
Conclusions:
The results indicate that taking a lutein only or combined lutein supplement are likely to increase serum levels of lutein and MP levels in both healthy individuals and patients with ocular pathologies. This paper highlights a need for further supplementation trials, a uniform definition of nonresponse and standardised method for measurement of macular pigment which will allow direct comparison of results.
Keywords: 587 macular pigment