While several studies have shown only moderate effects in reducing the incidence of cataracts with lutein and zeaxanthin, the most reliable studies — mainly those from India, where cataracts are a common problem — have shown significant benefits.

For example, one study found that people with the highest blood levels of lutein and zeaxanthin had a 41 percent lower risk of developing cataracts, compared to those with the lowest levels of these carotenoids.

Similar benefits were found in the Women’s Health Initiative’s Carotenoids in the Age-Related Eye Disease Study.

These two carotenoids are available as a combined supplement, but usually come as a dry powder in a capsule.

Both are exclusively oil-soluble and cannot be dissolved in water. This means that you can get the best absorption by mixing the supplement with extra virgin olive oil or coconut oil.

Another high-absorption mechanism is created when lutein and zeaxanthin are mixed with

phospholipids.

This is why lutein absorption from chicken eggs is so much better than from spinach and other vegetables known to have high lutein levels — because egg yolks are high in phospholipids.

Most studies have shown a reduction in cataracts with a dose from 6 to 20 mg a day.

Personally, I take 20 mg a day to protect my lenses and retinas.

The highest lutein levels are found in:

• Parsley

• Spinach

• Yellow corn

• Red peppers

• Egg yolks

• Lettuce

• Leeks

• Kale

• Basil

Only a few foods, such as corn chips and red peppers, have high zeaxanthin levels.