Benefits
Macular pigment optical density (MPOD)
Lutein builds up in the macula as a yellow pigment. A pooled analysis of 46 studies in healthy adults found that 5 to under 20 mg a day of lutein and zeaxanthin for 3 to 12 months raised macular pigment by about 0.04 units, and 20 mg or more by about 0.11 units; under 5 mg a day showed no clear change. This is a pigment measurement, not a direct test of eyesight, and it covers lutein in general, not FloraGLO alone.
Lutein in the AREDS2 eye study
AREDS2 followed 4,203 people who already had intermediate or one-sided advanced AMD for a median of 5 years. Adding 10 mg lutein and 2 mg zeaxanthin did not significantly reduce progression to advanced AMD in the main analysis (hazard ratio 0.90, P = 0.12). In secondary analyses, progression was lower with lutein and zeaxanthin than with beta-carotene and among people with the lowest dietary lutein intake.
Free (unesterified) lutein form
FloraGLO supplies lutein in its free form rather than as lutein esters, the form found in raw marigold petals. Lutein is fat soluble, so it is usually taken with a meal that contains some fat. No trial cited here compares FloraGLO with ester forms for any eye or health outcome.
Cognitive function in older adults
Lutein is found in brain tissue. In a small 4-month trial in 49 older women (11 took lutein alone), 12 mg a day of lutein improved verbal fluency, while processing speed and mood did not change. In the much larger AREDS2 cognition study (about 3,500 people tested over 5 years), lutein and zeaxanthin had no significant effect on the rate of cognitive decline.
Lutein status in pregnancy
In a randomized trial in 47 pregnant women, 10 mg lutein with 2 mg zeaxanthin a day from the first trimester, added to prenatal vitamins, raised the mothers' macular pigment and the newborns' skin and blood carotenoid levels compared with placebo. Kemin supplied the softgels, but the paper does not name the brand, and infant eye outcomes were exploratory.
Skin response to UV light
In a single trial, a crossover study in 65 healthy adults that tested lutein and a tomato extract, 12 weeks of oral lutein fully blocked the rise of UV-triggered stress genes in skin biopsies when taken in the first treatment period, but had significantly smaller effects when taken in the second. This is a gene-activity measure, not a test of sunburn, and lutein does not replace sunscreen.
Who the AREDS2 findings apply to
The AREDS2 results come from older adults who already had intermediate AMD or advanced AMD in one eye, and they test lutein and zeaxanthin added to the AREDS vitamin and zinc formula. They do not show that lutein prevents AMD in healthy eyes or reverses existing vision loss.
Mechanism of action
Macular pigment formation
Lutein and zeaxanthin, along with meso-zeaxanthin, are the only carotenoids found in the human macula, where they form a dense yellow pigment. This pigment sits in front of the light-sensing cells and is thought to protect them by filtering light and by acting as an antioxidant.
Blue-light filtering
Macular pigment absorbs short-wavelength blue light before it reaches the light-sensing cells of the retina. This filtering is the proposed reason lutein is studied for eye health; it is a mechanism, not proof of a benefit.
Singlet oxygen quenching
Lutein and zeaxanthin can neutralize singlet oxygen and other reactive oxygen species formed when light strikes the retina, an oxygen-rich tissue. This antioxidant role comes from laboratory research and supports, but does not prove, an eye-health effect.
Brain tissue distribution
Lutein is present in human brain tissue, which is the rationale for testing it in cognition trials; the large AREDS2 cognition study, however, found no effect of supplements.
Dose needed to change macular pigment
In a pooled analysis of 46 studies in healthy adults, intakes under 5 mg a day of lutein and zeaxanthin, mostly from diet, did not clearly change macular pigment, while 5 mg a day or more did, with larger rises at 20 mg a day or more.
Clinical trials
Multicenter, double-masked, placebo-controlled phase 3 trial with a factorial design, run from 2006 to 2012. Participants took 10 mg lutein plus 2 mg zeaxanthin, omega-3s, both, or placebo, on top of the AREDS vitamin and zinc formula. (Age-Related Eye Disease Study 2 Research Group 2013, JAMA)
4,203 people aged 50 to 85 at risk of advanced AMD (large drusen in both eyes, or large drusen in one eye and advanced AMD in the other).
The main analysis was not statistically significant: lutein plus zeaxanthin did not reduce progression to advanced AMD compared with placebo (hazard ratio 0.90, 98.7% CI 0.76 to 1.07, P = 0.12). More lung cancers occurred with beta-carotene than without it (2.0% vs 0.9%), mostly in former smokers, so the authors suggested lutein and zeaxanthin as a substitute for beta-carotene.
Exploratory secondary analyses of the same AREDS2 trial. (Chew et al. 2014, JAMA Ophthalmol)
4,203 AREDS2 participants aged 50 to 85.
Comparing anyone given lutein and zeaxanthin with anyone not given it, the hazard ratio for late AMD was 0.90 (95% CI 0.82 to 0.99). Compared directly with beta-carotene, lutein and zeaxanthin had a hazard ratio of 0.82 for late AMD and 0.78 for the neovascular (wet) form. People in the lowest fifth of dietary lutein intake had a hazard ratio of 0.74. These are exploratory results, not the main trial result.
Observational follow-up of the AREDS2 cohort from 2012 to 2018, after all participants were offered the lutein and zeaxanthin formula. (Chew et al. 2022, JAMA Ophthalmol)
3,882 AREDS2 participants (mean baseline age 72).
At 10 years, the odds of lung cancer were higher in people originally assigned beta-carotene (odds ratio 1.82, 95% CI 1.06 to 3.12) but not in those assigned lutein and zeaxanthin (1.15, 95% CI 0.79 to 1.66). Compared directly with beta-carotene, lutein and zeaxanthin had a hazard ratio of 0.85 for late AMD. Because this phase was not randomized, the authors describe these as associations.
Systematic review and meta-analysis of 46 studies of lutein and zeaxanthin from supplements or diet, stratified by daily dose. (Wilson et al. 2021, Adv Nutr)
3,189 adults with healthy eyes (mean age 43).
Macular pigment rose by about 0.04 units (95% CI 0.02 to 0.07) at 5 to under 20 mg a day and about 0.11 units (95% CI 0.06 to 0.16) at 20 mg a day or more over 3 to 12 months. Under 5 mg a day, mostly diet studies, there was no significant change (0.02, 95% CI -0.01 to 0.05).
Meta-analysis of 20 randomized trials of lutein, zeaxanthin and meso-zeaxanthin. (Ma et al. 2016, Nutrients)
938 people with AMD and 826 healthy people.
Supplements raised macular pigment compared with placebo in people with AMD (weighted mean difference 0.07, 95% CI 0.03 to 0.11) and in healthy people (0.09, 95% CI 0.05 to 0.14). Trials that included meso-zeaxanthin showed larger rises, and people with lower starting pigment tended to gain more.
Ancillary study of the AREDS2 randomized trial, with cognitive tests by telephone every 2 years over 5 years. (Chew et al. 2015, JAMA)
3,741 AREDS2 participants consented and 3,501 were tested (mean age 72.7).
Lutein plus zeaxanthin had no statistically significant effect on the yearly change in a composite cognitive score compared with no lutein and zeaxanthin (difference 0.03, 99% CI -0.14 to 0.19, P = 0.66).