Nutrition and Cataracts

Cataracts are a leading cause of visual impairment among aging Americans and a key quality-of-life issue. Cataract removal is the most common surgical procedure performed in the U.S., accounting for more than 2 million procedures each year.

Experts theorize that if the progression of cataracts could be delayed by 10 years, annual cataract surgeries would decrease by 45 percent. Nutrition is one promising way to prevent or delay the progression of cataracts.

Cataracts

Cataracts develop when the proteins in the lens of the eye are damaged, causing them to become translucent or opaque. There are three major types of cataracts, depending on where they are located in the lens: nuclear, cortical and posterior subcapsular.

Several uncontrollable factors may increase the risk of developing cataracts, including:

• Age
• Family history
• Ethnicity (African Americans have a higher risk of developing and becoming blind from cataracts.)
• Some studies also suggest that women may be at a slightly higher risk than men.

However, research shows we can control several risk factors for cataracts by changing certain behaviors, including:

• Not smoking
• Reducing exposure to sunlight by wearing UVA/UVB protective eyewear and wide-brimmed hats
• Controlling other diseases such as diabetes
• Eating a healthy diet

What Is Nutrition's Link to Cataracts?

Several research studies show that the antioxidant properties of vitamins C and E may protect against the development and progression of cataracts. Early evidence also suggests that the carotenoids lutein (pronounced loo-teen) and zeaxanthin (pronounced zee-uh-zan-thin), which are also antioxidants, may also help protect against cataracts.

Research on antioxidant vitamins

Some recent studies have shown that antioxidants vitamins C and E may decrease the development or progression of cataracts:

• The Nutrition and Vision Project found that higher intakes of vitamin C reduced the risk for cortical and nuclear cataracts. Results also showed that people who used vitamin C and E supplements for more than 10 years decreased the progression of nuclear cataracts.
• A recent analysis of results from a national dietary study (Second National Health and Nutrition Examination Survey) found that higher levels of vitamin C in the diet were associated with a lower risk of cataracts.
• In the Nurses' Health Study, cataract surgery was lower among women who took vitamin C supplements for 10 years or longer.
• The Roche European American Cataract Trial found that taking an antioxidant supplement with vitamins C and E and beta-carotene led to a small decrease in the progression of cataracts in less than three years.
• In the Longitudinal Study of Cataract, taking a vitamin E supplement for at least a year was associated with a reduced risk of nuclear cataracts becoming more severe.
• The five-year follow-up to the Beaver Dam Eye Study showed that people using multivitamins or any supplement containing vitamins C and E had a reduced risk for nuclear and cortical cataracts.

Research - Lutein and Zeaxanthin

Lutein and zeaxanthin are promising nutrients in the fight against cataracts. Lutein and zeaxanthin are the only carotenoids found in the eye. Several recent studies have examined these two nutrients and the risk of developing cataracts:

• The Nurses' Health Study found that people taking high amounts of lutein+zeaxanthin had a reduced need for cataract surgery. On average, people took around 6 milligrams (mg) of lutein+zeaxanthin each day.
• The Health Professional's Follow-Up Study also found that eating foods with high amounts of lutein+zeaxanthin (6.9 mg per day) led to a reduced need for cataract surgery.
• The five-year follow-up to the Beaver Dam Eye Study showed that people with the highest intakes of lutein+zeaxanthin had a significantly lower risk for developing new cataracts than those with the lowest intakes.
• A recent study in England found that people with the highest amount of lutein in their blood, from regularly eating food high in lutein, had the lowest risk for posterior subcapsular cataracts.

What You Need to Know

Given the positive association between nutrition and cataracts, it's probably a good idea to increase the amount of certain antioxidants in your daily diet. Eating five servings of fruits and vegetables each day, as currently recommended by the National Cancer Institute and U.S. Department of Agriculture, can provide more than 100 mg of vitamin C and 5 to 6 mg of carotenoids, including lutein and zeaxanthin. Eating two servings of nuts and seeds can provide 8 to 14 mg of vitamin E. See the tables below for good food sources of these nutrients.

However, the majority of people in the U.S. are not eating five servings of fruits and vegetables and good food sources of vitamin E each day. The average daily diet contains approximately 100 mg of vitamin C, 1 to 7 mg lutein and zeaxanthin, and 8 mg vitamin E. In the studies mentioned here, the consumption levels associated with cataract benefits were considerably higher than the current average intake. If you find it difficult to increase the level of these antioxidants and carotenoids in your diet, consider taking multivitamin/mineral and eye health supplements containing these nutrients.

Nutrient Values Tested

Nutrient	Recommended Dietary Allowance (RDA)1,2	Levels Associated with Health Benefit	Percent of People Getting Less than 100% of RDA1,2,3,4
Vitamin C	90 mg for men 75 mg for women +35 mg for smokers	≥ 250 mg	More than 50% of individuals
Vitamin E*	22 IU (15 mg) natural 33 IU (30 mg) synthetic	≥ 100 IU	More than 90% of individuals
Lutein and Zeaxanthin**	-	6 mg	Average intake per day 1.7 mg

* The Food and Nutrition Board reported two different RDA values for vitamin E depending on synthetic or natural source.
** There is no RDA for lutein, zeaxanthin and beta-carotene. 1. Dietary Reference Intakes for Vitamin C, Vitamin E and Carotenoids. Institute of Medicine, 2000.
2. Dietary Reference Intakes for Vitamin A and Zinc. Institute of Medicine, 2001.
3. Vitamin and mineral data were obtained from CSFII, 1994-1996. Values correspond to all individuals.
4. Carotenoid data was gathered from NHANES III, 1988-1994.

Food Sources

Most fruits and vegetables are excellent sources of vitamin C. Oranges, grapefruit, strawberries, papaya, green peppers and tomatoes are particularly high in vitamin C.

Vitamin E is more difficult to obtain from food sources alone since it is found in very small quantities in foods. Good food sources include vegetable oils (including safflower and corn oil), almonds, pecans, wheat germ and sunflower seeds.

Lutein and zeaxanthin are found together in many food sources. Dark green leafy vegetables are the primary source of lutein and zeaxanthin, but lesser amounts are in other colorful fruits and vegetables, such as broccoli, orange peppers, corn, peas, persimmons and tangerines.

Good Food Sources of Vitamin E (mg/serving)

Food	Amount	Vitamin E
Almonds	1/4 cup	9.3 (13.9 IU)
Sunflower seeds	1/4 cup	5.8 (8.7 IU)
Safflower oil	1 tbsp	4.7 (7.0 IU)
Peanuts	1/4 cup	3.3 (4.9 IU)
Peanut butter	2 tbsp	3.2 (4.8 IU)
Corn oil	1 tbsp	2.8 (4.2 IU)

Source: USDA Nutrient Database for Standard Reference Release 13

Good Food Sources of Vitamin C (mg/serving)

Food	Amount	Vitamin C
Orange juice, fresh squeezed	1 cup	124
Grapefruit juice, fresh squeezed	1 cup	94
Papaya	1/2 medium	94
Cantaloupe	1/4 melon	86
Orange	1 medium	80
Green peppers, raw chopped	1/2 cup	67
Tomato juice	1 cup	44
Strawberries	1/2 cup	43
Broccoli, raw chopped	1/2 cup	41
Grapefruit	1/2 medium	40

Source: USDA Nutrient Database for Standard Reference Release 13

Good Food Sources of Lutein and Zeaxanthin (mg/serving)

Food/Serving (1 cup)	Lutein and Zeaxanthin	Lutein	Zeaxanthin
Kale	20.5 - 26.5*	-	1.1 - 2.2*
Collard greens	15.3	-	5.1
Spinach	3.6 - 12.6*	1.7 - 13.3*	0.5 - 5.9*
Turnip greens	12.1	-	0.4
Broccoli	2.1 - 3.5*	1.4 - 1.6*	-
Corn, yellow	1.4 - 3.0	0.6	0.9
Peas, green	2.3	2.2	-
Orange pepper	-	-	1.7
Persimmons	1.4	-	0.8
Tangerine	0.5	-	0.2

*depending on variety and preparation

Source:

USDA-NCC Carotenoid Database, 1998 USDA Food Nutrient Database for Standard Release 13 Hart and Scott, 1995