If this is the case, could you see effects by simply changing your diet? You can get carotenoids without supplements; vegetables, corn, oranges, and eggs also contain them. But about 20 mg of carotenoids daily are needed to achieve the visual benefits described above, claim the researchers, which can be difficult to pull off even in a health-conscious diet.

“As far as vision goes,” says Billy Hammond of the University of Georgia, “we’re all sort of in a deficient state. We have very low levels of these things within our eye that we once had very high levels of. It is actually pretty challenging these days to have a healthy diet, so supplements likely do have a role to play.”

Other researchers have been experimenting with carotenoid-enhanced eggs instead. The pigment is more “bioavailable” to humans in this form – that is, it’s easier for us to absorb – and also more palatable to consumers who don’t want to take more pills.

Brain improvements

There is also some evidence linking carotenoids with other processes in the body: in motor skills, hearing, immune responses, and cognition.

Nolan published a paper in July indicating that Alzheimer’s patients are highly deficient in their levels of macular pigment, in addition to having worse vision. And a 2013 study by Hammond found that higher macular pigment levels are associated with faster processing speed and better balance (measured by how long you can stand on one foot with both eyes closed).

While these associations do not necessarily mean that supplements can help, a few studies have suggested possible cognitive benefits from taking the pigment. A study Hammond co-authored in September found that macular carotenoid supplements lead to improvements in the brain’s visual processing speed in young people. And other recent research has shown that lutein supplementation leads to improved cognitive skills in older people.

Macular pigment “affects biology profoundly, not just in terms of preventing dementia and macular denegation, but also in how the brain functions overall,” claims Hammond. It’s worth pointing out, however, that most of the studies so far have identified only correlations between the pigments and brain function – the mechanism is not yet clear.

So, while it may be early to say that we should all embrace carotenoid supplements, the accumulating body of research about their benefits suggests that our diet may influence the health of eyes and brain more than we once thought.

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