 Dark green leafy vegetables are packed with a brain antioxidant called lutein. And so increasing our greens intake could be an important public health strategy for reducing the risk of visual or cognitive impairment. Lutein is the dominant dietary pigment in the retina of the eye as well as the brain, and so not surprisingly that macular pigment, the concentration of lutein in the center of your eye called the macula, was found to be significantly correlated with levels in the brain, which may explain the link between how much of these greens nutrients you can see in the back of the eye and cognitive function. The neuro-protection is assumed to be because lutein is such a powerful antioxidant, but it also has anti-inflammatory properties. This relationship between lutein and another greens nutrient called zeaxanthin and visual and cognitive health throughout the lifespan is compelling, but that was based on observational studies where you observed that higher lutein levels in brain function seem to go together, but you don't know if it's cause and effect until you put it to the test. Could lutein and zeaxanthin be supplemented as part of a lifestyle intervention to both improve brain function and reduce the probability of slipping into dementia? The reason everyone's so excited about the possibility is because of the hopeful data from eye health studies that have convinced many ophthalmologists to start recommending people start increasing their lutein and zeaxanthin intake to prevent and treat macular degeneration, a leading cause of age-related vision loss. You don't have to take pills, though, adding as little as 60 grams of spinach a day for a month. That's like one-fifth of a 10-ounce package of frozen spinach can significantly boost macular pigment in most people. And it's not just good for treating diseased eyes or randomized placebo-controlled study found that these greens goodies can improve visual processing speed in young, healthy people. That's like when you're trying to hit a fastball and your body has to start reacting before you even consciously register it, with real-world benefits outside the major leagues, improving, for example, visual driving performance. OK, but what about cognition? A randomized double-blind, placebo-controlled trial of adults average age 73, given the equivalent of about a half cup of days of cooked kale, or a full cup of cooked spinach, and got significant improvements in cognitive function compared to those randomized to the placebo. Maven working young adults, too, average age 21. Daily supplementation with the same amount of lutein and zeaxanthin not only increased their macular pigment, but resulted in significant improvements in brain function, spatial memory, reasoning ability, and complex attention. After they ever tried putting whole foods to the test, it's hard to get Americans to eat greens every day, but not so hard to get them to eat guacamole. This study tested the effects of the intake of avocado on cognition in a six-month randomized controlled trial. What was the control? One avocado a day or a potato or a cup of chickpeas. And those in the avocado group had a significant improvement in cognitive function. But to the avocado board's chagrin, so did the tater and chickpea group. That's the problem with having healthy placebos. Maybe they should have used iceberg lettuce or something. What about the impact on cognition of those who really need it, Alzheimer's disease patients? Their vision got better, that's good, but no significant changes in cognitive function. Now it's possible that eating whole foods like dark green leafies might have worked better than just the pigments in pill form. Yes, oxidation and inflammation appear to be key to both Alzheimer's and macular degeneration, but neither disease seems particularly amenable to late-stage treatments. That's why prevention is the key. Reducing oxidation and inflammation in the earliest stages may be our most promising approach.