Antioxidants & Age-Related Eye Disease

Cataracts and age-related macular degeneration (AMD) are the leading causes of visual impairment and acquired blindness in the U.S. These diseases affect millions of aging Americans.

  • AMD is the leading cause of blindness in people over age 55 in the Western world. As the population ages, AMD is expected to triple by 2025.
  • Cataract extractions are the most common surgical procedure performed in the U.S., accounting for more than 2 million procedures a year. Estimates show that if the progression of cataracts could be delayed by 10 years, the number of cataract extraction surgeries per year would be reduced by 45 percent.

Nutrition is one promising means of preventing or delaying the progression of these diseases.

Research on Antioxidants and AMD

The Age-Related Eye Disease Studies (AREDS and AREDS2) are large clinical trials conducted by the National Eye Institute (NEI). These studies tested the effects of a high dose of antioxidant vitamins and minerals on preventing or delaying the progression of AMD and its associated vision loss.

The first AREDS trial showed that antioxidant vitamins and mineral supplements reduce the risk of developing advanced AMD by about 25 percent. In the study, subjects were at high risk for developing the advanced stage of this disease. In the same high-risk group, the supplements also reduced vision loss by 19 percent.

The AREDS2 trial tested whether the vitamin and mineral formulation could be improved by adding lutein, zeaxanthin or omega-3 fatty acids. The second trial found that replacing beta-carotene with a 5-to-1 mixture of lutein and zeaxanthin may reduce the risk of late AMD. Further, beta-carotene has been associated with higher risk of lung cancer in current or former smokers. Lutein and zeaxanthin appear to be safe for smokers and nonsmokers alike.

The doses tested in AREDS and AREDS2 were:

  • 500 milligrams (mg) vitamin C
  • 400 IU vitamin E
  • 15 mg beta-carotene OR 10 mg lutein and 2 mg zeaxanthin
  • 80 mg zinc (25 mg in AREDS2)
  • 2 mg copper (to prevent anemia from high dose of zinc)

According to researchers, this supplement combination is the first treatment to slow the progression of AMD. The NEI concluded that persons older than 55 with signs of intermediate to late vision loss due to AMD should consider taking a supplement such as that used in the AREDS trials. Effective treatment can delay progression from intermediate to advanced AMD.

Research on Antioxidants and Cataracts

Some recent studies have shown that antioxidant vitamins may decrease the development or progression of cataracts. Some of the results are listed below:

  • The Nutrition and Vision Project found that higher intakes of vitamin C led to a reduced risk for cortical and nuclear cataracts. Results also showed that people who used vitamin C and E supplements for more than 10 years had decreased progression of nuclear cataracts.
  • A recent analysis of results from the Second National Health and Nutrition Examination Survey found that higher levels of vitamin C in the diet were associated with lower risk of cataracts.
  • In the Nurses' Health Study, cataract surgery was reduced among women who used 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 leads 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 a reduced risk for nuclear and cortical cataracts among people using multivitamins or any supplement containing vitamins C and E.

What You Need to Know

Given the positive association between nutrition and cataracts and AMD, you might consider increasing the amount of certain antioxidants in your diet.

Eating five servings of certain 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 vitamin C. Eating two servings of nuts and seeds can provide 8-14 mg vitamin E (11.9-20.8 IU). See the following tables 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 vitamin C and 9 mg vitamin E (or 12 IU). However, in the studies referenced here, benefits were associated with intakes considerably higher than the current average intake. If you find it difficult to increase the level of these antioxidants in your diet, consider taking supplements containing these antioxidants.

Nutrient Values Tested

Nutrient

Recommended Dietary Allowance (RDA) 1,2 Levels Associated with Health Benefit Percent of People Getting Less than 100% of RDA 1,2,3,4

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
* The Food and Nutrition Board reported two different RDA values for vitamin E depending on synthetic or natural source.
  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 was 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. Particularly good sources include oranges, grapefruit, strawberries, papaya, green peppers and tomatoes.

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

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 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