Lack of Vitamin D has been associated with eye diseases like uveitis, macular degeneration, and dry eye. Vitamin D deficiency is also linked to cancer, immune disorders, heart disease, high blood pressure, osteoporosis, bone pain, depression, asthma, multiple sclerosis, and even dementia. Shockingly, more than 40% of the US population is Vitamin D deficient. The body manufactures Vitamin D, so why is deficiency wide spread? Indoor living, aging, and many other factors are behind this virtual pandemic. How can you measure your vitamin D levels? How can you get enough? Isn’t fortified milk enough? Should you take a supplement? Which one?
What is Vitamin D?
Vitamin D is an antioxidant that fights free radical damage in the body and reduces inflammation. The good news is that your body produces its own Vitamin D. The bad news: You need sunlight to manufacture it. People in climates with cold, overcast winters rarely get enough sunlight to make sufficient Vitamin D. Getting 20 minutes of exposure while bearing your arms and legs is not reasonable during a cold winter. Darker skinned people need even longer exposure.
Other reasons that we may not get enough vitamin D include: spending most of the time indoors; working and going to school in buildings; using sunscreens and sun proof shirts to fight excess sun exposure; and aging. A senior manufactures this vitamin from sunlight much less efficiently than a 20-year-old.
Foods that Provide Vitamin D
Vitamin D is also available through certain foods. Fatty fish are high in Vitamin D, as well as pumpkin seeds (pepitas), walnuts, sesame seeds and Brazil nuts. Dark leafy greens and avocado contain natural Vitamin D. However, if you have a deficiency, food will probably not be enough.
This vitamin helps you absorb calcium, so most milk is Vitamin D-fortified. However, fortified milk will probably not provide optimum amounts of Vitamin D. Make sure your milk contains Vitamin D3, which is more beneficial than D2.
Optimum Vitamin D Levels
Your doctor can order a simple blood test to check your Vitamin D level. This test is often part of a typical blood screening for a physical examination. The accepted normal range is between 20 and 50 nanograms per milliliter. However, the author of The Vitamin D Solution, Michael Holick, Ph. D., M.D., recommends more: 30 to 100 nanograms per milliliter of blood. Some studies have set the deficiency mark at 50 nanograms.
Vitamin D deficiency in the United States is common. Estimates are forty percent of the population or higher. Certain groups are high-risk: seniors, premenopausal women, Caucasians who stay out of the sun, people with poor eating habits or poor absorption, and people with celiac disease or obesity, bariatric surgery patients, and those with chronic liver or kidney disease. Also, prescription medications for digestive problems can contribute to deficiency. Even young people with no risk factors are showing up as deficient.
What to Supplement and For How Long
If the Vitamin D levels in your blood are not optimal, you can take a supplement. Vitamin D2 is less beneficial and can be overdosed.
Vitamin D3 in liquid form is best. Each drop of Vitamin D3 Liquid by Pure Encapsulations contains 1000 IU. The typical recommendation for adults is 400 – 800 IU daily. For eye conditions such as macular degeneration, we recommend 5,000 IU per day, or as prescribed by your doctor. Vitamin D is fat-soluble, so it may not need to be taken every day. Consult your doctor, who may prescribe a megadose on a weekly or monthly schedule. Or just take 400 – 1000 IU per day until quarterly bloodwork shows optimal levels. Do not stop taking the vitamin just because it is summer — refer to your current bloodwork.
Consequences of Deficiency
What are the consequences of Vitamin D deficiency? Why should you worry about it? A significant body of research has connected deficiency with a multitude of diseases and conditions. The eye conditions include uveitis, macular degeneration, and dry eye. Also, deficiency is linked to cancer, osteoporosis, bone pain, depression, heart disease, high blood pressure, asthma, immune disorders, multiple sclerosis, and dementia.
Deficiency and Inflammation
Researchers have found many of the conditions above are associated with chronic systemic inflammation (SI). In SI, immune-related cells release pro-inflammatory cytokines and the innate immune system is chronically activated. SI leads to food and chemical intolerances, autoimmune diseases and other conditions. Nutritional deficiencies such as low Vitamin D levels can lead to SI, causing or progressing these types of diseases.
Scientists are trying to identify exactly how Vitamin D suppresses excess inflammation.1
Uveitis Linked to Vitamin D Deficiency
Uveitis is swelling of the uvea: the iris, ciliary body and blood vessels that line the back of the eye. This problem has a number of possible causes, including infection, digestive disease, post-eye surgery complications, eye trauma, inflammatory conditions, and autoimmune diseases. Sensitivity to light, blurry vision, floaters, pain, and/or redness are symptoms of uveitis.
A study looked at non-infectious uveitis patients.2 The researchers measured the levels of Vitamin D in the blood, as well as Vitamin D intake and exposure. The subjects who had active uveitis had lower levels of this vitamin in their blood (46 nmol/L) than those with inactive uveitis (64 nmol/L). Compared to the general local population (62 nmol/L), active uveitis patients were also lower. Subjects who supplemented with Vitamin D were less likely to have active uveitis. So were those who had more sun exposure. The researchers concluded that Vitamin D supplements may help prevent uveitis relapse.
Macular Degeneration and D Deficiency
Age Related Macular Degeneration generally strikes seniors. The macula at the center of vision begins to break down. Macular Degeneration causes central vision loss, making it difficult to read, drive, and be self-sufficient.
Inflammation and the build-up of waste in the eye are risk factors for Macular Degeneration. A study treated lab animals with Vitamin D3. They had significantly reduced levels of amyloid beta (also related to Alzheimer’s Disease) and less inflammation. Microphages are cells that help remove waste. The animals had high levels of microphages in the retina, indicating waste clean-up. They also had better vision.3
Dry Eye and Vitamin D
Dry eye symptoms include grittiness, burning, dryness, and irritation. The functioning of the tear film on the eye is complicated. Dry eye syndrome can become serious. A study of 17K adults in Korea controlled for gender, location, health conditions, and exercise. It found an association between low levels of Vitamin D and dry eye syndrome.4. Another study5 also found an association between low Vitamin D and dry eye. It discovered changes in the cornea, including damage to the nerve structures.
While Vitamin D deficiency is common, it is also easy to detect and treat. Be sure to monitor your levels with regular blood tests. Follow your doctor’s instructions for supplementing if you are deficient.
Editor’s Note: The eyes are the 2nd most nutrient-hungry organ in the body — the brain needs the most nutrients. Eyes have high metabolic activity. A diet low in nutrients leads to many eye diseases in seniors. A teenager in the UK developed blindness from optic neuritis by eating a diet of fries and chips. The Standard American Diet has the most calories in the world (about 3,700 per person per day), but is high in fried, processed, high-fat foods and refined carbohydrates. Focus on eating more fruits and vegetables, fatty fish, raw nuts and seeds, and lean, unprocessed meats. Learn more about nutrition for the eyes.
- Yong Zhang, Donald Y. M. Leung, Brittany N. Richers, Yusen Liu, Linda K. Remigio, David W. Riches, And Elena Goleva. Vitamin D Inhibits Monocyte/Macrophage Proinflammatory Cytokine Production by Targeting MAPK Phosphatase-1. The Journal of Immunology, March 1, 2012 DOI: 10.4049/%u200Bjimmunol.1102412 ↩
- Patterns of Vitamin D Levels and Exposures in Active and Inactive Non-Infectious Uveitis Patients. Ophthalmology. By Zelia K. Chiua, Lyndell L. Limbc, Sophie L. Rogers, Anthony J. Hallad. Available online 11 July 2019 ↩
- Researchers: V. Lee, E. Rekhi, et al. Published: Vitamin D rejuvenates aging eyes by reducing inflammation, clearing amyloid beta and improving visual function, Neurobiology of Aging, October, 2012. ↩
- Researchers: S.Y. Yoon, et al. Published: Low Serum 25-Hydroxyvitamin D Levels Are Associated with Dry Eye Syndrome, PLoS One, January, 2016 ↩
- Researchers: R. Shetty, et al. Published: Corneal Dendritic Cell Density Is Associated with Subbasal Nerve Plexus Features, Ocular Surface Disease Index, and Serum Vitamin D in Evaporative Dry Eye Disease, BioMed Research International, February, 2016 ↩