I’ve read on the Internet that I should take 20mg or more of lutein each day. Is this true?

No. This is simply untrue. There are plenty of websites trying to sell the idea that you should buy their product because it has 15mg, 20mg, or more of lutein! The proper dosage is 10mg per day. The National Eye Institute has completed the largest study on age related eye disease called AREDS 2 and they recommend 10mg. Taking more than this recommended amount may be toxic or harmful to your health.