Eyewise provides a full 20mg of lutein (pure, free-form) per tablet, making our product one of the strongest available. It also provides bilberry, blackberry and grapeseed, all well known plant polyphenols, as concentrated extracts. Plus the mineral zinc and the B vitamin riboflavin, both of which are known to contribute to the maintenance of normal vision and to the protection of cells from oxidative stress. Lutein is a yellow carotenoid that is not made in the body, and so it has to be obtained from leafy green vegetables in the diet. In plants lutein is produced to help protect the cell contents from damage by sunlight. Our bodies are able to use lutein in the same way as it is deposited in the macula where it filters out the harmful wavelengths in sunlight that can damage the delicate light receptor cells of the macula. Research has shown that eating diets that are low in lutein can result in diminished levels of lutein in the macula. To correct this you should try to include leafy green vegetables in your diet, or failing this it is advisable to take a lutein supplement.