Many optometrists, such as at Kaster Eye Clinic, are expanding their traditional roles to include other areas that affect eye health, such as nutrition. Research has shown that nutrition can impact the development of cataracts and age-related macular degeneration (AMD), which are the two leading causes of blindness and visual impairment among millions of aging Americans. Nutrition may be particularly important given that currently, treatment options after diagnosis for these eye diseases are limited.

 

Information courtesy of the American Optometric Association, 3/14/11

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Nutrition and Cataracts

On August 23rd, 2010, posted in: Diet & Nutrition by

Cataracts are a leading cause of visual impairment among aging Americans and a key quality of life issue. Cataract extractions are the most common surgical procedure performed in the U.S., accounting for more than two million procedures each year. Experts have theorized that if the progression of cataracts could be delayed by 10 years, the number of cataract surgeries per year would be reduced by 45 percent. Nutrition is one promising means of preventing or delaying 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 types of major cataracts, depending on the location in the lens: nuclear, cortical and posterior subcapsular.

There are several factors that we cannot control that may increase the risk of developing cataracts. These include: age, family history and ethnicity (African Americans have a higher risk for developing and becoming blind from cataracts). Some studies also suggest that women may be at a slightly higher risk than men.

Research also shows that there are several risk factors for cataracts that we can control by changing certain behaviors. These preventive actions include: not smoking, reducing exposure to sunlight by wearing UVA/UVB protective eyewear and wide brimmed hats, controlling other diseases such as diabetes and eating a healthy diet.

Nutrition Link

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 be protective against cataracts.

Research – Antioxidant Vitamins

Some recent studies compared diet and supplement intake of the antioxidant vitamins C and E with the development of cataracts. Many of these studies have shown that these antioxidants may decrease the development or progression of this disease. 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 ten years had decreased 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 lower risk of cataracts.
  • In the Nurses' Health Study, the need for cataract surgery was lower among women who used vitamin C supplements for ten years or longer.
  • The Roche European American Cataract Trial found that an antioxidant supplement with vitamins C and E and beta-carotene lead to a small decrease in the progression of cataracts in less than 3 years.
  • In the Longitudinal Study of Cataract, vitamin E supplement use 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 isk for nuclear and cortical cataracts among people using multivitamins or any supplement containing vitamins C and E.

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 lens. Several recent studies have examined these two nutrients and their relationship to reducing the risk of developing cataracts:

  • The Nurses' Health Study found that high amounts of lutein+zeaxanthin were associated with a reduced need for cataract surgery. On average, people had intakes 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) were correlated with 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, resulting from regular consumption of good food sources of lutein, had the lowest risk for posterior subcapsular cataracts.

What You Need to Know

Given the positive association between nutrition and cataracts, it seems prudent for people to increase the amount of certain antioxidants in their 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 vitamin C and 5 to 6 mg of carotenoids, including lutein and zeaxanthin, given wise choices of fruits and vegetables. Eating two servings of nuts and seeds can provide 8-14 mg vitamin E (11.9-20.8 IU) (see 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, 1-7 mg lutein and zeaxanthin and 8 mg vitamin E (or 12 IU). In the studies mentioned here, the levels associated with benefit 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, multivitamin/mineral and eye health supplements containing these nutrients are available.

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 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, including oranges, grapefruit, strawberries and papaya, as well as green peppers and tomatoes.

Vitamin E is more difficult to obtain from food sources alone since it is found in very small quantities in foods, such as vegetable oils, nuts and seeds. 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 they are also present in lesser amounts 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

 

Information courtesy of the American Optometric Association, 3/14/11

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Age-Related Macular Degeneration (AMD) is an acquired ocular disorder and a leading cause of legal blindness in persons over sixty.1 AMD affects the macula, the central part of the retina, which is responsible for providing clear, sharp vision needed for reading, writing, driving and other visually-demanding activities.

The nature and severity of this condition varies with individual patients, with many experiencing some degree of loss of central vision in one or both eyes. Approximately 90% of patients with AMD have a non-exudative (or dry) form of the disease, which results in the development of dry, atrophic scars in the macular area. Non-exudative AMD patients typically experience slower, more gradual loss of vision. Only 10% of patients develop an exudative (or wet) form, which results in the leaking of fluid beneath the retina, and a greater and more rapid loss of central vision. Effective laser photocoagulation treatment for the disease is limited to small numbers of patients with exudative AMD who are identified early in the disease process.2 Other treatment modalities include photodynamic therapy and surgical transplantation of the macula.

Research has now suggested that the development of AMD is linked to a depleted level of macular pigment. This retinal layer efficiently filters out harmful blue wavelengths of light, and also reduces the amount of free radicals, which are compounds found in high concentrations in the macular area and can cause oxidation of cell membranes.3 It is theorized that certain antioxidant compounds reduce the effect that these free radicals have on the macular pigment, and consequently may have an impact on the development of AMD. 4,5,6 These antioxidants have demonstrated their effectiveness in building and maintaining the thickness of the retinal pigment layer, and are known as carotenoids, a family of colored compounds found in fruits and vegetables. Beta-carotene is an example of a carotenoid; altogether we consume and utilize fourteen different carotenoids in our diet. Two other carotenoids were found to have effectivity in the retinal pigment layer. Lutein and zeaxanthin are carotenoids found in many vegetables and fruits; they are found in the highest concentration in dark, leafy green vegetables such as spinach, collard greens, and kale. Studies have shown that a diet high in these materials have some effect on delaying the advancement of AMD. 7,8,9,10 The use of synthetic supplements that contain these carotenoids, along with the vitamins C, E, and zinc, have been proven to be an effective means of limiting the disease in patients with advanced signs and symptoms of AMD.11

The use of antioxidants cannot reverse the damage caused by AMD; however, its use may prevent or slow the progression of AMD in certain patients. If dietary supplementation of antioxidants taken along with Vitamins C, E, and zinc is undertaken, this therapy may be most appropriate for individuals who:

  • Show early evidence of AMD
  • Are over 50 years of age
  • Have family history of AMD
  • Receive insufficient dietary intake of vitamins and minerals

Additional studies and data are needed to further define the nutritional and antioxidant therapies and their relative dosages for the prevention of AMD. Other risk factors, although not thoroughly understood, may include smoking, alcohol intake, excessive sunlight, and elevated total cholesterol levels. Until further study results are available, the American Optometric Association recommends patients reduce their risk of AMD by wearing appropriated sun protection to limit ultraviolet exposure, stopping smoking, moderating any alcohol consumption, maintaining a nutritionally balanced diet, increasing consumption of foods or supplements that contain antioxidants, and seeking periodic optometric retinal examinations.


  1. Prevent Blindness America. Vision problems in the U.S. Schaumburg, IL: Prevent Blindness America 1994.
  2. Cavallerano AA, Cummings JP, Freeman, PB, et al. Optometric Clinical Practice Guideline on Care of the Patient With Age-Related Macular Degeneration. St. Louis: American Optometric Association, 1994.
  3. Van Der Hagen AM, Yolton DR, Karninski MS, Yolton RL. Free Radicals and Antioxidant Supplementation: A Review of Their Roles in Age-Related Macular Degeneration. J Am Optom Assoc 1993; 64:871-878.
  4. Hayes KC. Retinal Degeneration in Monkeys Induced by Deficiencies of Vitamin E or A. Invest Ophthalmol 1974; 13:499-510.
  5. Ham WT, Mueller Ha, Ruffolo JJ et al. Basic Mechanisms Underlying the Production of Photochemical Lesions in the Mammalial Retina. Curr Eye Res. 1984; 3:165-174.
  6. Organisciak DT, Wang HM, Li Z, Tso MO. The Protective Effect of Ascorbate in Retinal Light Damage of Rats. Invest Ophthalmol 1985; 26:1580-1588.
  7. Seddon JM, Ajani UA, Sperduto RD, et al. Dietary Carotenoids, Vitamins A, C, and E and Advanced Age-Related Macular Degeneration. JAMA 1994; 272:1413-1420.
  8. Age-Related Macular Degeneration Study Group. Multicenter Ophthalmic and Nutritional Age-Related Macular Degeneration Study-part 1; design, subjects and procedures. J aM Optom Assoc 1996; 67:12-29.
  9. Age-Related Macular Degeneration Study Group. Multicenter Ophthalmic and Nutritional Age-Related Macular Degeneration Study-part 2; antioxidant intervention and conclusions. J aM Optom Assoc 1996; 67:30-49.
  10. The Eye Disease Case-Control Study Group, Antioxidant Status and Neovascular Age-Related Macular Degeneration. Arch Ophthalmol 1993; 111:104-109.
  11. A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss. Arch Ophthalmol 2001; 119:1417-1436.

 

Information courtesy of the American Optometric Association, 3/14/11

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Cataracts and age-related macular degeneration (AMD) are the leading causes of visual impairment and acquired blindness in the U.S., and are key quality of life issues among millions of aging Americans.

  • Approximately 10 million Americans suffer from early signs of AMD and almost a half million people have significant visual loss from late-stage AMD.

  • Cataract extractions are the most common surgical procedure performed in the U.S., accounting for more than 2 million procedures each year. It has been estimated 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.

Both the severity and irreversibility of cataracts and AMD have generated interest in ways to either prevent or delay their progression. Nutrition is one promising means of protecting the eyes from these diseases.

Nutrition Link

The carotenoids lutein (pronounced loo-teen) and zeaxanthin (pronounced zee-uhzan-thin), which are antioxidants and the only carotenoids located in the eye, may protect against cataracts and AMD.

Research – Lutein and Zeaxanthin and AMD

One of the first large studies on carotenoids is the Eye Disease Case Control Study, in which diet was compared to the risk for developing AMD. Results found a significantly lower risk for developing the eye disease in people with high amounts of lutein+zeaxanthin in their blood. Also, those people eating a diet with the most lutein+zeaxanthin (as much as 5.8 milligrams (mg) per day) had a significantly lower risk for AMD than those whose diet contained the least amount (as low as 1.2 mg per day). Dietary studies confirmed the association between frequent consumption of spinach or collard greens, particularly good sources of lutein and zeaxanthin, and lower AMD risk.

Similar results were found in a recent analysis of a national dietary study called the Third National Health and Nutrition Examination Survey or NHANES III. This analysis also showed that consuming 6 mg per day of lutein+zeaxanthin was associated with reduced risk for developing AMD.

Research – Lutein and Zeaxanthin and Cataracts

Lutein and zeaxanthin intake and its relationship to risk of cataracts has been examined in four recent observational or epidemiological studies:

  • The Nurses' Health Study found that consuming high amounts of lutein+zeaxanthin reduced the need for cataract surgery. Intake among this group was approximately 6 mg per day.

  • The Health Professional's Follow-Up Study also found that high amounts of lutein+zeaxanthin (6.9 mg per day) lowered the need for cataract surgery.

  • The five-year follow-up to the Beaver Dam Eye Study showed that people who got the most lutein+zeaxanthin had a much lower risk for developing new cataracts than people had the least amounts.

  • A study of 372 men and women aged 66-75 in England found that the risk for specific type of cataracts was the lowest in people with the highest amount of lutein in their blood.

What You Need To Know

Given the positive association between lutein and zeaxanthin and age-related eye disease, it seems prudent for people to obtain higher amounts of these nutrients from their 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 about 5 to 6 mg of carotenoids, including lutein and zeaxanthin, given wise choices of fruits and vegetables (see table 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 each day. The average intake of lutein and zeaxanthin is approximately 2 mg per day. The studies referenced here suggest an intake of 6 mg or more per day to decrease the risk of developing AMD and cataracts. If you find it difficult to increase the amount of these carotenoids in your diet, multivitamin/mineral and eye health supplements containing lutein and zeaxanthin are available.

Food Sources

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

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
HHN-1550B/0502

 

Information courtesy of the American Optometric Association, 3/14/11

read more

Cataracts and age-related macular degeneration (AMD) are the leading causes of visual impairment and acquired blindness in the U.S., and are key quality of life issues among millions of aging Americans.

  • Approximately 10 million Americans suffer from early signs of AMD and almost a half million people have significant visual loss from late-stage AMD.

  • Cataract extractions are the most common surgical procedure performed in the U.S., accounting for more than 2 million procedures a year. It has been estimated 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.

Both the severity and irreversibility of cataracts and AMD have generated interest in ways to either prevent or delay their progression. Nutrition is one promising means of protecting the eyes from these diseases.

Research – Antioxidants and AMD

The Age-Related Eye Disease Study from the National Eye Institute (NEI) is the first large clinical trial to test the effect of a high dose antioxidant vitamin combination plus zinc on preventing or delaying the progression of AMD and its associated vision loss.

The antioxidant vitamins and zinc supplement reduced the risk of developing advanced AMD by about 25 percent in the study subjects who 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 doses tested were:

  • 500 milligrams (mg) vitamin C
  • 400 IU vitamin E
  • 15 mg beta-carotene
  • 80 mg zinc
  • 2 mg copper (to prevent anemia from high dose zinc)

According to researchers, this supplement combination is the first effective 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 this trial. Effective treatment can delay progression to advanced AMD in about 300,000 people who are at high risk.

Research – Antioxidants and Cataracts

Some recent studies compared dietary and supplemental intake of antioxidant vitamins with development of cataracts. Many of these studies have shown that antioxidant vitamins may decrease the development or progression of this disease. 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 ten years had decreased 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 lower risk of cataracts.

  • In the Nurses' Health Study, the need for cataract surgery was lower among women who used vitamin C supplements for ten years or longer.

  • The Roche European American Cataract Trial found that an antioxidant supplement with vitamins C and E and beta-carotene lead to a small decrease in the progression of cataracts in less than 3 years.

  • In the Longitudinal Study of Cataract, vitamin E supplement use 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, it seems prudent for people to increase the amount of certain antioxidants in the 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 vitamin C, given wise choices of fruits and vegetables. Eating two servings of nuts and seeds can provide 8-14 mg vitamin E (11.9-20.8 IU) (see 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). In the studies referenced here, levels associated with a benefit were considerably higher than the current average intake. If you find it difficult to increase the level of these antioxidants in your diet, multivitamin/mineral and eye health supplements containing these antioxidants are available.

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, including oranges, grapefruit, strawberries and papaya, as well as green peppers and tomatoes.

Vitamin E is more difficult to obtain from food sources alone since it is found in very small quantities in foods, such as vegetable oils, nuts and seeds. Good food sources include 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

 

Information courtesy of the American Optometric Association, 3/14/11

read more