Lutein and zeaxanthin are part of the carotenoid family. Although they are different compounds, both are in the xanthophylls category of carotenoids, and some methods of measuring nutrients do not separate the two, so they are often reported in a single combined amount.

Lutein and zeaxanthin are found mainly in dark green leafy vegetables, including spinach, Brussels sprouts or broccoli. Studies suggest that consuming foods high in those nutrients may help protect the eye against age-related macular degeneration and cataracts. Studies involving supplements, however, have shown limited success. The compounds absorb blue light, which researchers believe may help protect the sensitive tissues in the eye from light-induced cell damage.

Carotenoids are best absorbed with fat in a meal, 3 to 5 grams of fat appear to be sufficient. Chopping, pureeing or cooking vegetables in oil helps to increase the bioavailability of lutein and zeaxanthin.

There is currently no recommended daily allowance for lutein or zeaxanthin, but preventive effects have been seen at intakes of higher than 6 mg per day. No known toxicities have been reported.

— Markian Hawryluk, The Bulletin

Good sources of lutein and zeaxanthin:

Spinach (cooked, 1 cup): 29.8 mg

Kale (cooked, 1 cup): 25.6 mg

Turnip greens (cooked, 1 cup): 19.5 mg

Peas (cooked, 1 cup): 3.8 mg

Brussels sprouts (cooked, 1 cup): 2 mg

Sources: Linus Pauling Institute, American Optometric Association