Can a healthy diet prevent cataracts?
Cataracts are a leading cause of blindness in the world today.
While the exact cause of cataracts is unknown, experts believe that oxidative stress damages certain enzymes and proteins in the eye's natural lens, which causes the lens to become cloudy.
And though some research has produced conflicting results, eating a healthy diet rich in antioxidants and certain vitamins has been shown in several studies to be associated with a reduced risk of cataracts or their progression.
Diet, oxidative stress and cataracts
Oxidative stress occurs when there is an imbalance between damaging free radicals roaming the body and the antioxidants that keep them in check. Free radicals are atoms or groups of atoms (molecules) that are highly reactive with other atoms and molecules because they have unpaired electrons.
In the body, a free radical usually is an oxygen molecule that self-stabilizes by taking an electron from another molecule, which in turn tries to take an electron from another molecule, and so on.
Free radicals damage the body by stealing electrons from the normally healthy cells of organs and other tissues. This process of stealing electrons from healthy cells is called oxidation.
In the eye, oxidation affects proteins and fats in the lens to the extent that the lens becomes damaged and cloudy, creating a cataract. Preventing free radical damage with healthy foods, particularly those containing antioxidants, may help slow down this process.
Free radicals that damage our eyes and the rest of the body may originate from eating unhealthy foods, exposure to pollution or chemicals, smoking and ultraviolet radiation.
Some free radicals occur from normal daily metabolism, which means even people who don't have these risk factors need antioxidants found in healthy foods.
Healthy foods and cataract prevention
People who consistently follow a healthy diet that includes colorful fruits, vegetables and whole grains may show a decreased risk of cataracts.
Antioxidant vitamins and phytochemicals found in fruits and vegetables that may reduce the risk of cataracts include vitamins A, C and E, lutein and zeaxanthin.
Researchers in Sweden published the results of a study of the association between all antioxidants in the diet and age-related cataract. More than 30,000 women age 49 and older completed a dietary questionnaire and were observed for age-related cataract development for an average period of 7.7 years. The study authors found that women whose diet contained the highest total antioxidant capacity (TAC) were significantly less likely to develop cataracts, compared with those whose diets were low in antioxidants. The main contributors to dietary TAC in the study population were fruit and vegetables (44.3 percent), whole grains (17.0 percent) and coffee (15.1 percent).
Researchers in Australia found a diet high in carbohydrates may increase cataract risk. Evaluation of the eating habits of more than 1,600 adults revealed that individuals in the top 25 percent for total carbohydrate intake had more than three times the risk for cataracts than those in the lowest 25 percent for carbohydrate intake.
A large study of adult women in the United States found that eating foods rich in a variety of vitamins and minerals may help delay the development of cataracts. In an earlier study published in the same journal, the same researchers found diets rich in and are moderately associated with decreased prevalence of cataracts in older women.
A 10-year study of more than 2,400 older adults in Australia found that higher intakes of or the combined intake of multiple antioxidants reduced the risk of cataracts in this population.
A large study of female health professionals in the United States found that higher dietary intakes of lutein and zeaxanthin were associated with significantly decreased risk of cataract.
However, other studies have failed to show an association between nutritional supplements and reduced risk of cataracts.
In two long-term Age-Related Eye Disease studies (AREDS and AREDS2) sponsored by the National Eye Institute, neither study found use of daily multivitamin supplements containing vitamin C, vitamin E and zinc (with or without beta-carotene, lutein and zeaxanthin, and omega-3 fatty acids) prevented or slowed the progression of cataracts.
And while all nutrients associated with cataract prevention in studies can be found in eye vitamins and vision supplements, many experts believe these substances should be acquired from a healthy diet rather than from nutritional supplements.
But if your diet lacks key nutrients because you're not eating enough fruits and vegetables, it's wise to consider taking one or more daily nutritional supplements to make sure you are getting all the nutrients you need for optimum eye health.
Prior to embarking on a regimen of eye vitamins and other nutritional supplements, consult your eye doctor. In some cases, taking too much of a specific vitamin or nutrient could be harmful to your health.
Shape up your diet for good vision
Five to nine servings of fruits and vegetables per day
At least three servings of 100 percent whole grains daily
At least two servings of fish per week
The total calories consumed should be just enough to keep you at a healthy weight, based on your individual activity level and metabolism.
Dark green and colorful fruits and vegetables are great sources of eye-friendly antioxidants. They also contain folic acid and calcium — important nutrients which also may help reduce the risk of cataracts and should be included in a healthy diet.
To maintain a healthy diet, it is equally important to avoid fried foods, processed foods and sugary snacks and soft drinks — all of which appear to be associated with an increased risk of cataracts, as well as obesity and other health problems.
Reducing sodium in your diet also is a good idea, as researchers at the University of Sydney (Australia) have found evidence that high salt intake may increase your risk for cataracts.
Giving up greasy fast food, chips, sugary snacks and soft drinks may not be easy. But it's worth it. Once you get used to eating delicious fruits and vegetables, fresh fish and other healthy foods, you won't miss junk foods. And your reward just might be both a healthy body and a lifetime of good vision.
Shield your eyes from UV
When taking steps to reduce your risk of cataracts, it's important to know that dietary modifications alone aren't enough.
It's also important to shield your eyes from the primary source of harmful UV radiation: the sun.
In addition to wearing a wide-brimmed hat that shades your eyes from direct sunlight, consider these UV-protective eyewear choices:
Polarized sunglasses provide 100 percent UV protection and are available in a wide variety of colors and shades.
Transitions-brand lenses and other photochromic lenses are clear indoors, darken automatically in sunlight, and provide 100 percent UV protection at all times.
UV-blocking contact lenses
Many soft contact lenses provide at least partial protection against UV rays entering the back of your eyes. But UV-blocking contacts should be considered only supplemental defense against UV rays because they protect only the area of your eye covered by the lens. They don't protect the conjunctiva, sclera, or the eyelids from UV damage like sunglasses or photochromic lenses do.
For the best choices in frame styles for UV-protective eyewear, ask your optician for guidance.