Lutein is not known to cause any negative side effects in relation to the eyes, according to WebMD. To the contrary, lutein is often used as a supplement to prevent age related macular degeneration, improve vision in elderly patients with cataracts and provide eye allergy relief.
Lutein taken in recommended dosage is generally considered safe states WebMD. Lutein occurs naturally in many foods. One cup of cooked kale contains 44 milligrams of lutein, one cup of spinach contains 26 milligrams and one cup of broccoli contains 3 milligrams. Certain doses of lutein have been studied and supported by scientific research. Evidence suggests that people who consume 6.9 to 11.7 milligrams of lutein daily through diet have the lowest risk of developing cataracts and age-related macular degeneration. People who already have age-related macular degeneration should take 10 milligrams of lutein per day through supplements.