Well , there is not definite daily allowance currently you should take for lutein as well as other nutrients. however positive effects have been seen at dietary intake levels of 6 mg/day.The only obvious side effect caused by taking excess lutein consumption is your skin will become bronze
The dosage of lutein usually anges from 6 to 10 mg a day. However, you should consult your doctor that how much you should take to keep your eyes healthy. If you already get enough lutein from your diet, then you only need less lutein supplements or don't need them at all.