Emerging Research

In the last 20 years, eye health research has linked diet and nutrition with a decreased risk of age-related macular degeneration (AMD). A major clinical study of older adults concluded that taking an antioxidant vitamin or mineral supplement significantly reduced the risk of advanced AMD progression in some people. Additionally, today there is significant evidence that vitamin D plays a role in preventing AMD.  

AREDS Made it Clear

The Age-Related Eye Disease Study (AREDS) was a major clinical trial sponsored by the National Eye Institute. It enrolled 3640 subjects, age 55 to 80, and was released in October 2001. This landmark study provided evidence that nutritional intervention in the form of supplements could delay the progression of AMD. The study concluded that taking an antioxidant vitamin or mineral supplement reduced the risk of advanced AMD progression by about 25 percent and showed a 19 percent reduction in visual acuity loss in some of the subjects.

The Case for Lutein and Zeaxanthin

It was not clear in the original AREDS report which vitamin, mineral or combination of nutrients was responsible for reducing the risk of AMD. When the study was planned, the lutein and zeaxanthin carotenoids that constitute the macular pigment were not assessed because they were not commercially available. Since then, several studies have provided growing evidence specific to the beneficial role of lutein and zeaxanthin intake, and their positive effect on eye health and AMD risk reduction. The AREDS Report No. 22 published in 2007 described the relationship between dietary intake of various nutrients and AMD among the AREDS subjects. This report concluded that high dietary intake of lutein and zeaxanthin is associated with a reduction in the risk of geographic atrophy, advanced AMD, and large or extensive intermediate drusen, the waste byproducts of cellular metabolism (activity).

New Study Builds on Long Term Nutrient Benefits

A follow up to the original AREDS trial, AREDS2, began in June 2008. This multi-centered, five-year study builds on a multitude of existing science supporting lutein and zeaxanthin’s role in maintaining healthy eyes. It is the largest human clinical trial to evaluate lutein, zeaxanthin, and omega-3 fatty acids supplementation, and includes 4,000 patients at high risk for AMD. The study is focusing on the protective effects lutein (10 mg/day), zeaxanthin (2 mg/day) , and omega-3 fatty acids (1 g/day) have against AMD, as well as the link between nutrition and macular pigment optical density, cataract development and visual function.

Vitamin D

Vitamin D deficiency has been linked to age-related macular 
degeneration, as well as 17 types of cancer.

Vitamin D is good for our bones and teeth. It aids in preventing rickets, cavities and adult softening of the bones. Yet today there is significant evidence that vitamin D also plays a role in helping to prevent cancer, heart disease, diabetes, and age-related macular degeneration (AMD). Activated Vitamin D, also known as calciferol, is a fat-soluble essential vitamin that helps to prevent skeletal diseases by maintaining normal levels of calcium and phosphorous in the blood. Vitamin D also regulates cells, systems and organs throughout the body. It is the most potent steroid hormone in the human body, and is the only vitamin formed with the help of sunlight.

When ultraviolet B radiation is absorbed by the skin, it triggers the synthesis of vitamin D, which is stored in the liver. Before the Industrial Revolution, more than 90 percent of people living in Europe and North America obtained their supply of vitamin D from this sunlight-driven process. With work and life style changes over the last 100 years, the decrease in UV exposure has led to an increase in vitamin D deficiency. Today, vitamin D deficiency has been linked to 17 types of cancer, cardiovascular disease, diabetes, autism, multiple sclerosis, schizophrenia and even influenza. (1,2,3,4)

You are vulnerable to the lack of sunlight if you live in a northern climate, have black or dark brown skin, work indoors, or are housebound and elderly. Infants also are considered vulnerable. Therefore, it appears that the degree of UV B sunlight exposure you receive based on the latitude in which you live, your race, and working environment (office vs. outdoor worker), can greatly affect your health.

Benefits to Eye and Systemic Health

Age Related Macular Degeneration

A recent study presents evidence that vitamin D may protect against the onset of age-related macular degeneration (AMD). In a study of nearly 8,000 participants, those with early AMD were associated with lower blood levels of vitamin D. However, it must be noted that the authors caution additional studies are needed to confirm these findings. (5)

Vitamin D and Cardiovascular Disease

Cardiovascular disease (CVD) is associated with many eye diseases, including AMD and glaucoma. The etiology of cardiovascular disease is not completely understood. Yet, a recent review summarizes data supporting the hypothesis that insufficient levels of vitamin D may contribute to the worldwide high prevalence of CVD. (Zittermann A, Schleithoff SS, Koerfer R, Putting cardiovascular disease and vitamin D insufficiency into perspective, Br J Nutr. 2005 Oct;94(4):483-92 )

Juvenile Diabetes

The American Academy of Pediatrics (AAP) announced in October 2008 it has doubled the recommended amount of vitamin D for infants, children, and adolescents. The decision to increase daily dosage is an update of the 2003 AAP initiative that sought to combat childhood rickets, but clear evidence suggests a correlation of juvenile diabetes and latitude, with children in Finland having nearly 400 times the rate of juvenile diabetes compared with children living near the equator.

Obesity, Diabetes and the Metabolic Syndrome

Vitamin D deficiency is important to pre-diabetic and diabetic adults, as it lowers insulin resistance, or the ability of cells to utilize excess glucose from the bloodstream. As well, vitamin D acts as an immunosuppressant and improves pancreatic function.

Food Sources and Supplementation

There is no substitute for the sunlight-driven process of vitamin D synthesis. As a point of reference, approximately 10,000 IU of vitamin D3 is produced by one hour of midday summer full-body skin exposure for Caucasians living at southern latitudes. Season, latitude, time of day, cloud cover, smog, and applied sunscreen all affect UV B exposure. Sunscreen with a protection factor of 8 or higher blocks vitamin D synthesis.

It is possible to supplement the diet with biologically inactive vitamin D found in plants and marine life. Vitamin D3 is abundant in cold water fish (i.e. red sockeye salmon, sardines or cod liver oil) along with crucial essential fatty acids. Even less vitamin D (100 IU vitamin D2 per cup) is available from the synthetic source, ergocalciferol, used to fortify milk. The most recent 2005 U.S. Department of Agriculture (USDA) Food Triangle recommends the equivalent of three 8 oz. glasses of milk each day. However, 24 ounces of vitamin D fortified milk supplies only a meager 300 IU of the less potent plant-based and synthetic vitamin D2. There is growing consensus that milk sources are not enough to maintain overall health for Caucasians, let alone African-Americans and populations living further from the equator. (6)

Daily Intake* 

One cup of milk has 100 IU of vitamin D2, which has 70 percent of the effectiveness of natural vitamin D3 found in fish.

The static USDA Recommended Daily Allowance of vitamin D, regardless of race, season or geographic location, presently is:
 
Less than Age 50 200 IU
Age 50 400 IU
50-70 600 IU
70+ 800 IU

References

*At this time, the AOA is unaware of any studies that have examined interactions between specific medications and vitamin D. The AOA also is not aware of any adverse health reports from interactions between specific medications and vitamin D. However, the AOA recommends consulting with a health care professional before beginning any supplementation regiment.