You'd think that with all the milk I drink, all the salmon I eat and all the hours I spend in the sun, the level of vitamin D in my blood would be higher than it is.
Joan Lappe, a vitamin D researcher and professor of medicine at Creighton University, said low D levels aren't surprising. “Study after study shows that many, many people of all ages are low in vitamin D,” she said. “Especially in the latitudes we're at.”
I had called Lappe last week after reading a report from the American Academy of Orthopaedic Surgeons that found 77 percent of trauma patients had deficient or insufficient levels of vitamin D.
Researchers, the academy said, have linked vitamin D deficiency with muscle weakness, bone fractures and the inability of bones to fully heal.
Investigators reviewed the medical records of 1,830 adult patients at a trauma center over a 19-month period. People with vitamin D levels below 20 nanograms per milliliter were categorized in the study as “deficient.” Those with levels between 20 and 32 ng/ml were considered “insufficient.” Levels between 40 and 70 ng/ml, the investigators said, are considered “healthy.”
Lappe uses a slightly different scale for “insufficient” — between 20 and 30 ng/ml. So my reading of 31, taken after our interview, would be either on the high end of “insufficient” or the low end of “satisfactory.” Other researchers say lower readings -- even down to 20 ng/ml -- are adequate.
Whatever. I thought my level surely would be higher. Most mornings and almost every evening, I drink vitamin D-fortified milk, probably 32 ounces or more a day. Depending on the container size, I eat 6 to 8 ounces of D-fortified yogurt every day. Once a week, I eat about a third of a pound of wild salmon, which is naturally high in vitamin D. And I spend a couple of hours per week running outside — more than that when it's warm out. (We get vitamin D from the ultraviolet B rays of the sun when a precursor in our skin is converted into the active form of the vitamin by the liver and kidneys.)
“It's very hard to get enough (vitamin D) from your diet,” Lappe said. And around here, from about mid-October to mid-March, she said, the angle of the sun doesn't allow us to get vitamin D from sunlight.
In November 2010, the National Academy of Science's Institute of Medicine increased its recommended daily allowance of vitamin D from 400 International Units to 600 IU for those up to 70 years old and 800 IU for those 71 and older. Lappe and others at Creighton's Osteoporosis Research Center say 1,000 to 2,000 IU of vitamin D is safe for most people.
So what can you do?
You can take vitamin D and calcium supplements. Vitamin D, Lappe said, facilitates calcium absorption. Without it, the body can't absorb the calcium it takes in, so it takes calcium from bones, increasing the risk of fractures and osteoporosis. Lappe said people don't need to go to the expense of a 25-hydroxy vitamin D test, which I took.
To make it easy, Lappe recommends 1,000 milligrams of calcium per day and 1,000 IU of vitamin D per day. Almost any kind of calcium can be absorbed, she said, but it should be taken with food. And she said more and more scientists say that vitamin D3 is the best form of D.
I'm not a big pill-taker, but Lappe said vitamin D supplements are inexpensive, small and easy to take: “It's not like you're swallowing a horse pill or something.”
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