Saturday, October 29, 2011

Take Vitamin D Year Round

Most of you have heard that lots of people are low in vitamin D. 
But many people who take vitamin D stop their vitamin D supplement during the summer.
They think they don't need it then.
I recommend that you take vitamin D year round.

Sure you make some vitamin D when you expose your skin to the sun’s rays. But sunscreen reduces vitamin D production in the skin. And those with darker skin need 3-5 times the amount of time in the sun to make vitamin D compared to a person with light skin.

Worried about getting too much vitamin D? Well you can’t get too much vitamin D from sun exposure. 

Even people who live in sunny regions like Arizona  and Hawaii commonly have low levels of vitamin D in their blood. 

And very few foods contain much vitamin D. Even foods fortified with vitamin D do not provide enough vitamin D for most people.

You may know that Vitamin D year round is important for bone strength and bone health. Vitamin D is also important to maintain normal levels of calcium and phosphorus levels in the blood. And adequate levels of vitamin D help prevent falls and improve balance.

But did you know that vitamin D may also be important for cancer prevention and optimal function of the immune system? Vitamin D acts more like a hormone than a vitamin D. It has multiple effects on tissues throughout the body.

People with vitamin D deficiency may have muscle achiness that gets better with vitamin D supplementation. A recent study showed improvement in insulin secretion with vitamin D.

There is  need for more randomized controlled clinical trials with vitamin D.
A large NIH trial is being conducted to examine the effects of 2000 units of vitamin D daily on cancer and heart disease risk. Prescription fish oil is also being studied in this trial.

The test used to measure vitamin D levels is the serum 25 hydroxy-vitamin D.  I usually aim for a level of at least 35 but below 60 ng/ml. This is consistent with the recent Endocrine Society guidelines.

The Endocrine Society recommends measuring vitamin D levels in those at increased risk of vitamin D deficiency. Those at increased risk for vitamin D deficiency include people who are overweight, or above 50 years of age or those who get little sun exposure. 
I have found that about 80% of adults I test are either low or borderline low in vitamin D.
This includes those not considered to be at increased risk.

Of course, our practice is in northern Ohio! Not too often sunny here and recently very rainy.

A standard multivitamin supplement only contains 400 units of vitamin D3. For those with a low vitamin D level, supplementation with 4000 to 6000 units daily of dietary supplement vitamin D is usually needed. Some doctors prescribe a supplement of 50,000 units weekly of vitamin D2. All supplements obtained without a prescription contain vitamin D3.

It is important to continue to supplement with vitamin D once the blood level is normal. If the vitamin D supplement is stopped, the level will drop again. Your body needs a continuous supply of this vitamin.

2000 units of vitamin D daily are needed by most people to maintain an adequate level. A higher daily dose of Vitamin D year round may be needed in those who are overweight or obese.

For those with vitamin D deficiency, I periodically check blood levels. 
Yes it is possible to get too much vitamin D. For most people, 10,000 units a day is the upper safe limit.  
But remember that dietary supplements like vitamin D are not regulated like prescription drugs. 
You may be getting more or less than you think in each supplement. There have been reports of vitamin D overdose  with dietary supplements. So you should be monitored if you are taking more than 2000 units a day.

And don't think you’ll be fine in the summer months without a supplement.
Most people need to take vitamin D year round.



  1. A wonderful post!

    I have found that towards the end of the summer I run numbers like a pre-diabetic or even entirely normal simply by using diet and exercise and no medication. Every year it is the same.

    I usually would take my two thousand IU of vitamin D in the winter but I would still go back to some awful numbers and require insulin. I have since tried increasing my Vitamin D supplementation greatly by taking 30,000IU. I have not noticed any adverse effects, and I have seen some improvement in the blood sugar. I will be checking my vitamin D serum level this week to see where they are at.

  2. Interesting. Thanks for sharing this with us.