HEALTH Q&A
Vitamin D toxicity not a big concern at this
level; high doses are sometimes needed
May 8, 2007

QUESTION: I read your column "Vitamin D can come in two types" on the
Vitamin D Council's Web site, in which you said the recommended safe upper
limit for vitamin D was 2,000 IU daily. Just yesterday, my internist
returned from a conference and said my vitamin D level of 27 needs to be
treated with 50,000 IU of vitamin D a week for three months. That's more
than 7,000 IU a day. That seems extremely high, and I'm worried about
vitamin D toxicity. I'm a 68-year-old female. Could you give me an opinion
on this?

ANSWER: Adequate vitamin D is required for proper absorption of calcium. Low
vitamin D levels put you at risk for osteoporosis, bone fractures, and
falls. The vitamin (and hormone) also may play a role in muscle strength and
in preventing autoimmune diseases such as diabetes and rheumatoid arthritis,
as well as some forms of cancer.

Vitamin D deficiency typically results from inadequate sun exposure and poor
dietary or supplemental intake. If this is the case with you, your doctor
has proposed the recommended treatment.

Less commonly, vitamin D deficiency stems from severe malabsorption
syndromes or inflammatory bowel disease. In such cases, even higher doses of
vitamin D or an injectable form may be needed to correct the deficiency.

Your vitamin D level of 27 (nmol/L) indicates a moderate deficiency (less
than 20 would be severe). There's controversy, however, over the laboratory
definition of vitamin D deficiency due to different measuring methods and
other factors.

The goals with these initial high doses are to replenish your vitamin D
stores, push vitamin D up to optimal levels and normalize levels of calcium
and parathyroid hormone. Once that's been done, you could cut back to 1,000
IU of vitamin D-3 daily to
maintain these levels.

At the same time, you want to avoid vitamin D toxicity. Toxicity is
relatively rare and has been reported only in people taking 40,000 IU daily
for weeks or months. That said, it's probably best to avoid doses higher
than 10,000 IU daily (except for
those with malabsorption disorders).

The skin synthesizes vitamin D when exposed to sunlight. Short, regular
exposure can maintain adequate vitamin D levels in southern geographic
areas.

You're more likely to fall short on sun exposure if you live in a northern
latitude with inadequate year-round sunlight (e.g., Seattle, Boston), overdo
the use of sunscreen, keep skin covered by clothes, have darker skin or are
shut in or
institutionalized.

To make up for inadequate sun exposure, you will need to get vitamin D from
foods or supplements. Vitamin D-fortified foods include milk and cereal
products.

Current vitamin D recommendations may be too low. Recent research suggests
that most adults may need at least 800 to 1,000 IU daily.

As I noted in the prior column, vitamin D-3 (cholecalciferol) is more potent
than vitamin D-2 (ergocalciferol). Check the "ingredients" section of
product labels to see which form you're getting.

Richard Harkness is a consultant pharmacist, natural medicinesspecialist and
author of eight books. Write him at 1224 King Henry Drive, Ocean Springs, MS
39564.