The Study
Bioavailability of Lutein from Marigold Flowers (Free vs. Ester Forms): A Randomised Cross-Over Study to Assess Serum Response and Visual Contrast Threshold in Adults
This study gave people lutein pills and measured what happened in their blood and eyes. It shows that lutein pills raise lutein levels in the blood — that’s a solid finding. But it doesn’t prove the pills make your eyesight better, only that higher lutein levels are linked to slightly better vision in some tests.
Analysis score
Maximum 45 for a randomized controlled trial.
Where the score came from
Scientists gave people lutein pills for two months to see if it helps their eyes work better, and if it matters whether the lutein is in a natural or processed form.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 545 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though lutein levels went up a lot, people didn't see better — meaning just having more lutein in blood doesn't automatically improve vision in healthy adults within two months.
- 2After 15 days, lutein in blood doubled (2.4x) no matter the form.
- 3Zeaxanthin also rose (1.7x) even though the pill had little of it.
- 4After two months, eyesight didn't get better, even though blood lutein stayed high.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nutrients
Year
2024
Authors
Begoña Olmedilla-Alonso, Fernando Granado-Lorencio, Julio Castro-Feito, Carmen Herrero-Barbudo, Inmaculada Blanco-Navarro, Rocío Estévez-Santiago
Related Content
Claims (6)
The chemical structure of nutrients in supplements determines how much of the nutrient the body can absorb and use.
Higher levels of lutein in the blood are linked to better ability to see contrast in bright light, especially when details are fine, in healthy adults, but this link does not always appear after taking lutein supplements and changes depending on age.
Taking lutein supplements for two months raises lutein levels in the blood but does not improve how well healthy adults see differences in contrast between light and dark.
Taking 6 milligrams of lutein from marigold extract daily for 15 days raises the level of zeaxanthin in the blood by about 1.7 times in healthy adults, even though the supplement contains very little zeaxanthin.
When healthy adults take 6 mg of lutein daily for up to two months, the amount of lutein that enters the bloodstream is the same whether it comes from free lutein or lutein ester supplements.
Taking 6 mg of lutein from marigold extract daily for 15 days raises lutein levels in the blood by about 2.4 times in healthy adults aged 20–65, whether the lutein is free or bound, and these higher levels stay elevated for at least two months.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.