One of the best parts of leading a healthy lifestyle is that it doesn't only affect one or two aspects of your health; it makes you healthier overall. Take eating vegetables, which is arguably one of the most important aspects of living healthy.
Vegetables contain many different antioxidants and other disease-fighting compounds that are very difficult to get anywhere else.
Plant chemicals called phytochemicals may reduce inflammation and eliminate carcinogens, while others regulate the rate at which your cells reproduce, get rid of old cells and maintain DNA.
Vegetables are also a primary dietary source of naturally occurring nitrates, which have multiple health benefits, including for your vision health.
Glaucoma is a leading cause of blindness for people over 60. It's estimated that 3 million Americans suffer from it, but only about half of them know it. In the early stages, glaucoma has no symptoms, but it progresses slowly until vision loss becomes noticeable.
At this point, it may be too late, but if glaucoma is caught early your vision loss may be slowed or prevented. Even with treatment, however, about 10 percent of people with glaucoma will still lose their sight.1 Prevention is therefore the best strategy.
Glaucoma is caused by damage to your optic nerve, often due to abnormally high eye pressure. Impaired blood flow is also known to play a role, and this is where eating your veggies come in.
Green leafy vegetables are an excellent source of nitrates, which are converted into nitric oxide in your body. Nitric oxide, in turn, helps to relax and dilate your blood vessels, improving blood flow and lowering blood pressure (high blood pressure is a risk factor for glaucoma).
There's also some evidence that nitric oxide signaling may be involved in maintaining low eye pressure. Adding more nitrate-rich veggies to your diet may therefore be a simple way to lower your risk of glaucoma.
How Much Nitrate Per Day Was Protective?
Leafy greens were the richest source of nitrates in the study participants' diets. Those who ate the most leafy greens were 48 percent less likely to develop "paracentral" glaucoma, which is particularly associated with blood flow.
So how much nitrate appeared to be protective against glaucoma? Those who were on the high end of consumption consumed about 1.5 servings of greens daily, which contain about 240 milligrams (mg) of nitrate.
"The only vegetable that was consistently inversely associated with POAG was kale or collard greens: 1 serving or more per month of kale or collard greens was significantly associated with 55% to 70% reduced odds of POAG [primary open-angle glaucoma]."
This means that many are missing out on the protective effects of green leafy vegetables, and this extends far beyond nitrates. For instance, the carotenoids lutein and zeaxanthin are primarily found in green leafy vegetables, with kale and spinach topping the list of lutein-rich foods.
Other healthy options include Swiss chard, collard greens, broccoli and Brussels sprouts. Lutein and zeaxanthin are both important nutrients for eye health,5 as both of them are found in high concentrations in your macula — the small central part of your retina responsible for detailed central vision.
More specifically, lutein is also found in your macular pigment — known for helping to protect your central vision and aid in blue light absorption — and zeaxanthin is found in your retina. Both have been linked to a lower risk of cataracts and advanced macular degeneration.
While lettuce is typically listed as a healthy leafy green (and a good source of nitrates), there's a growing movement that suggests you should ditch your lettuce in favor of more nutritious options, like microgreens.
It's not that lettuce is bad, per se. It's just that, pound for pound, it doesn't really supply the concentration of nutrients that you could get from microgreens. Microgreens are basically very young vegetables, harvested at about 1 or 2 weeks when they're only a few inches tall.
The greens are snipped off above the root (in contrast to sprouts, in which you consume the whole thing — root, stem, seed and all) and can be enjoyed in place of lettuce or even as a vegetable side dish.
Red cabbage, cilantro, garnet amaranth, and green daikon radish were noted as particularly nutritious microgreens, but you may also want to try basil, broccoli, kale and sunflower microgreens.
They're pricey to buy at specialty markets, so your best bet (for your wallet and for freshness) is to simply grow your own at home.
A diet focused on processed foods (i.e. sugars, grains and unhealthy fats) sets the stage for developing insulin resistance, which in turn is associated with multiple chronic diseases, including glaucoma.
Dark green leafy vegetables are also a good source of magnesium, another nutrient that may play a key role in helping to prevent insulin resistance and diabetes, and therefore may affect your glaucoma risk.
Following my nutrition plan will automatically reduce, or eliminate, excess sugar and grain intake from your diet while helping you increase your vegetable intake and optimize your insulin levels. Aside from eating right, one of the most effective ways to lower your insulin levels is through exercise.
If you're looking for a different way to get more vegetables into your diet, try vegetable juicing. Raw juice can be likened to a "living broth," as it is teeming with micronutrients that many people are lacking. When you drink fresh-made green juice, it is almost like receiving an intravenous infusion of vitamins, minerals, and enzymes because they go straight into your system without having to be broken down.
Push all ingredients through juicer, pour into two glasses, and stir.
Egg yolk is a source of both lutein and zeaxanthin along with healthy fat and protein, and while the total amount of carotenoids is lower than in many vegetables, they're in a highly absorbable, nearly ideal form. According to research,12 adding a couple of eggs to your salad can also increase the carotenoid absorption from the whole meal as much as ninefold.
A second study published in 2009 found those with diets high in omega-3 fats, along with vitamin C, vitamin E, zinc, lutein and zeaxanthin, had a lower risk of macular degeneration.15 In addition to wild-caught Alaskan salmons, sardines and anchovies are other good sources of animal-based omega-3s.
Dr. Mark Tso,16 now of the Wilmer Eye Institute at Johns Hopkins University, but who was my boss when I worked at the University of Illinois Eyebank in the1970s, has demonstrated that astaxanthin easily crosses into the tissues of your eye and exerts its effects safely and with more potency than any of the other carotenoids, without adverse reactions.
Depending on your individual situation, you may want to take an astaxanthin supplement. I recommend starting with 4 milligrams (mg) per day. Krill oil also contains high-quality animal-based omega-3 fat in combination with naturally occurring astaxanthin, albeit at lower levels than what you'll get from an astaxanthin supplement.