Vitamin D (D3)

What role does vitamin D play in eye or vision?

As of this writing very little research has been done on the direct connection of vitamin D and the eye. Vitamin D plays a critical role in almost everything the body does and chances are good that it is critical for the eye as well. It is a multitasker and supports a healthy immune system, strong bones, and mood maintenance and appears to protect against most cancers. While it’s called a “vitamin,” it’s actually a hormone the body makes from cholesterol. 

One known effect of Vitamin D is inflammation. It calms and reduces inflammatory processes within the body. Inflammation has been linked to chronic red eyes, dry eye, blepharitis, and Age-related Macular Degeneration (ARMD). So there you go… there is at least one indirect link for the eye and this critical vitamin.  It may help reduce chronic red eye, dry eye, non-infectious blepharitis and ARMD.

How much Vitamin D?  Blood levels of Vitamin D should be at least 20-30 ng/ml  preferably 35- 45 ng/ml but it is estimated that over 70% of US citizens fall well below these levels.  It is difficult to obtain Vitamin D in the foods we eat (cod liver oil is a natural source, but too much cod liver oil can cause vitamin A overdose) . About the only “food” that naturally contains high levels of Vitamin D is Shiitake (pronounced she-taw-kee) mushrooms. So unless you get a lot of sunlight, about the only other way to boost levels is to take a vitmin D3 supplement (vitamin D is added to most milk but at low levels and some question absorption amounts).  Look for supplements that provide vitamin D3 (choleciferol), the form better used by the body than the more common vitamin D2 (ergocalciferol). Recommended maintance dosages are between 1000 IU and 2000 IU daily.

Too much Vitamin D? That question is still being researched. For some individuals, symptoms such as hypercalcemia can start as low as 5000-6000 IU daily.  Most researchers agree 1000-4000 IU daily  is safe with a 2000 IU supplement being a good average daily intake. For specifice “treatment” or prevention efforts, higher daily dosages may be required.

Cedric Garland, DrPH, professor of family and preventive medicine at the UCSD Moores Cancer Center, stated as follows:

“We found that daily intakes of vitamin D by adults in the range of 4000-8000 IU are needed to maintain blood levels of vitamin D metabolites in the range needed to reduce by about half the risk of several diseases — breast cancer, colon cancer, multiple sclerosis, and type 1 diabetes.”

Naturopathic physicians often use short-term, high dosages of up to 20,000 IU daily for up to 6 weeks (sometimes longer) for therapeutic purposes, with no apparent adverse side effects. It would be advisable when using these higher dosages, to do so only under a doctor’s supervision.