As a nation, we are aging – fast. So fast that it is predicted1 that the number of Americans ages 65 and older is projected to nearly double from 52 million in 2018 to 95 million by 2060, and the 65-and-older age group’s share of the total population will rise from 16 percent to 23 percent.
That’s why it’s more important than ever to prioritize vision-protective nutrients and foods. In fact, the American Optometric Association2 has emphasized that consuming food rich in vitamin C can reduce and slow the progression of certain eye conditions and loss of visual acuity. One such nutrient having direct beneficial effects promoting eye health is vitamin C.
About Vitamin C
Vitamin C3 is a busy vitamin. This water-soluble vitamin, which our body does not store, has many functions keeping our body healthy. From promoting healthy capillaries, gums, teeth, cartilage to enhancing the absorption of iron, almost all cells of the body depend on this nutrient also known as ascorbic acid.
Before it was discovered, Vitamin C has an interesting and rich history. Back in the early eighteenth century, seafarers who traveled for months at a time over the ocean knew that fresh vegetables and fruits – especially citrus fruits – could cure scurvy4, which is the deficiency disease of vitamin C.
Today, we now know far more about this vitamin and the vital role it plays in maintaining our body. One part of our body that clearly cannot do without this precious vitamin is our eyes. Vitamin C plays an important role in supporting the health of blood vessels leading to our eyes and is critical for maintaining good eye health.
There are two conditions affecting our eyes in which vitamin C can help reduce at least the progression if not possibly preventing them from occurring. One is age-related macular degeneration (AMD)5 and the other is cataracts6.
Vitamin C and AMD
Linking the benefits of vitamin C to age-related macular degeneration was the landmark Age-Related Eye Disease Study (AREDS)7. AMD is the leading cause of vision loss, affecting more than 10 million Americans which is more than cataracts and glaucoma combined. This incurable eye disease is caused by the deterioration of the central portion of the retina, known as the macula, responsible for focusing central vision in the eye which controls our ability to read, drive a car, and recognize faces or colors.
The AREDS research discovered that people at high risk for the disease who took 500 milligrams a day of vitamin C, along with beta-carotene, vitamin E and zinc supplements, slowed the progression of advanced AMD by about 25 percent and reduced visual acuity loss by 19 percent.
Vitamin C and Cataracts
Cataracts are a leading cause of reduced vision in the U.S. With age, almost everyone will experience cataracts to some degree.
Numerous studies have linked8 vitamin C intake and reduced risk of cataracts. In one study, women taking vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that by delaying the onset of cataracts for 10 years, half of cataract-related surgeries could be avoided.
What is the Recommended Daily Intake for Vitamin C?
The current recommendation from the Dietary Reference Intake9 for vitamin C is that men need 90 mg/day while women require 75 mg/day.
However, people under stress need more vitamin C than the recommended daily allowance. These groups include people who smoke (add 35 mg to the Dietary Reference Intake for men and women), alcoholics, people with diabetes, pregnant (85 mg/day) or breastfeeding women (120 mg/day), older adults, athletes, and people with chronic disease who experience stress from heat, cold, or radiation. The highest safest level or what is known as the Tolerable Upper Intake10 for vitamin C is no more than 2000 mg/day. Any amount higher than that could result in diarrhea, bright yellow urine and could skew the results from a urinalysis test.
Keep in mind that our body does not store vitamin C. Therefore, any amount you may take in a supplement form that the body doesn’t have a use for, will be routed to the kidneys which filter out any unnecessary substances like excess vitamin C to be disposed of in our urine.
Best food sources of vitamin C
The very best way to obtain vitamin C is by eating food sources rich in this nutrient. Fortunately, there are many excellent sources of this vitamin to choose from. It is recommended to eat foods high in vitamin C as opposed to getting them mainly from a supplement. The various components with food along with the vitamin C content has a much better protective effect against AMD and cataract progression than simply taking a supplement by itself.
Vitamin C is found almost exclusively in fruits and vegetables. The best sources of it are listed below:
- All citrus fruits and their juices– oranges, grapefruits, lemons, and limes
- Green and red peppers
- Collard greens
- All berries but especially strawberries
- Kiwi fruit
There is an abundance of evidence linking eating more vegetables and fruits rich in vitamin C with better eye health as you age. Following the Recommended Daily Intake for vitamin C should be sufficient for most people. For those affected by AMD and cataracts, health care providers may recommend supplementation. Talking with a Registered Dietitian on how to incorporate more foods containing vitamin C into their daily diet aiming to protect eye health, is a good start to taking good care of your eyes.
- PRB Fact Sheet – Aging in the United States
- American Optometric Association and vitamin C
- National Institute of Health Office of Dietary Supplements Fact Sheet for Health Professional
- Better Health Channel Information Sheet on Scruvy
- National Eye Institute Fact Sheet on Age-Related Macular Degeneration
- National Eye Institute: At a glance: Cataracts
- National Eye Institute: Age-Related Eye Disease Study (AREDS)
- American Academy of Ophthalmology: Eating Foods High in Vitamin C Cuts Risk of Cataract Progression by a Third. March 23, 2016.
- National Institutes of Health Office of Dietary Supplements – Nutrient Recommendations: Dietary Reference Intakes (DRI)
- Healthfully; What are the Tolerable Upper Intakes of Vitamins? July 8, 2011