We all remember stories about people getting rickets from lack of vitamin D in the “olden days.” While that is almost unheard of in most developed countries, we are seeing many people with subclinical vitamin D deficiency. Vitamin D deficiency is associated with osteoporosis, increased risk of falls, and possibly fractures. Vitamin D is also believed to be important to the immune and cardiovascular systems, and a factor in breast cancer risk. In 2006, 41% of Americans were vitamin D deficient.
How do you know if you are vitamin D deficient? A simple blood test with your primary care doctor to measure your 25-hydroxyvitamin D (25OHD) level will tell you. Insufficiency is defined as a vitamin D level less than 30 ng/mL (some argue 27, but 30 is the current line in the sand), and a vitamin D level less than 20 is deficient by all standards.
Can my vitamin D level get too high? Though there doesn’t appear to be any toxicity associated with vitamin D supplementation, there are concerns when levels go above 50. It is rare that I see a patient’s level above 50 and I’ve been in private practice for 10 years. Ideally, you want to maintain your vitamin D level between 30 and 50 ng/mL.
So how much vitamin D do you need? This is highly debated but we appear to be settling on a consensus. First, think about getting it through your diet, which will happen only with vitamin D fortified dairy products. The Recommended Dietary Allowance (RDA) of vitamin D for adults through age 70 is 600 IU with the RDA increasing to 800 IU after age 71.
You will need more if you:
- live in a sun deficient state
- are dark skinned
- consistently use sunscreen
- are obese
- don’t absorb well from your gut: inflammatory bowel disease and celiac disease.
What supplements do I need to take to get my vitamin D level above 30? The two commonly available forms of vitamin D supplements are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Studies suggest that vitamin D3 increases vitamin D levels faster than vitamin D2. For this reason I prescribe Vitamin D3 supplements.
Vitamin D3 is available in 400, 800, 1000, 2000, 5000, 10,000, and 50,000 unit capsules. 50,000 IU (1.25 mg) capsules are available as a prescription.
In patients with vitamin D levels less than 20, start with 50,000 international units (IU) of vitamin D3 once a week for six to eight weeks
After that, a maintenance dose of 800 – 2000 IU per day should be taken daily to maintain a vitamin D level above 30 ng/mL.
Three to four months after starting on vitamin D replacement, have your level rechecked to ensure you are on the right track.
The 50,000 IU (1.25mg) strength of vitamin D is prescription only, and may be covered by your insurance, but can be found for as low as $4 for a one-month supply (4 capsules). Lower strengths of vitamin D are available over the counter.