This is an archived article that was published on sltrib.com in 2011, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.
Misty Fowler is like a lot of Utahns: she doesn't drink much milk, slathers on the sunscreen when she's outside and, until a year ago, didn't consistently take vitamins which is partly why she has one more thing in common with residents of the Beehive state.
Fowler's levels of vitamin D are too low, which she discovered during an annual visit to her doctor.
"I had never heard of anybody being told they were deficient before," said Fowler, 33, a software developer and who lives in Sugar House.
But the fact is, many Utahns don't have enough vitamin D in their systems to keep them healthy. Researchers at the Heart Institute at Intermountain Medical Center recently reviewed medical records of 41,000 people and found only one-third had sufficient levels of vitamin D.
And that's cause for concern. Victoria J. Drake, a research associate at the Linus Pauling Institute at Oregon State University, says vitamin D known as the sunshine vitamin because our skin makes it when exposed to ultraviolet-B rays acts as a hormone in the body, regulating calcium and keeping bones healthy.
There's no consensus on what else vitamin D may do, but various studies have tied inadequate amounts to such health issues as depression, diabetes, hypertension, muscle soreness, autoimmune diseases, upper respiratory tract infections, heart failure, stroke and some cancers.
It's particularly critical for elderly adults, whose bodies have a harder time making vitamin D naturally and who are often home bound. This also is the group most prone to weak muscles and osteoporosis. Other vulnerable groups include breast-fed infants, people with limited sun exposure, people with darker skin and those who are obese or have undergone gastric bypass surgery, according to the Office of Dietary Supplements at the National Institutes of Health.
And given the apparent connection between vitamin D and muscle strength, it is important for athletes also to be vigilant of their vitamin D status, said Kary Woodruff, a dietician in sports medicine at The Orthopedic Speciality Hospital (TOSH) in Murray.
How much is enough? • Researchers are still trying to figure out the optimum level of vitamin D a person needs to get its overall protective effect. The Institute of Medicine (IOM) says blood levels between 20 nanograms and 50 nanograms per milliliter are adequate for bone and overall health. Some researchers and experts, including Woodruff, put the lower cut-off point at 30 nanograms, and some even say it should be at least 50.
"There is a lot of confusion about what is deficient and what amount is sufficient," said Christine Stencel, Institute spokeswoman.
Adding to confusion is the fact that testing labs don't all use the same cut points, she said. For example, the IOM pegs blood levels below 12 nanograms as deficient, but local lab ARUP identifies values below 20 as deficient and values less than 30 as insufficient.
Likewise, there are conflicting recommendations about much vitamin D is needed to keep blood levels up. The current recommended dietary allowance of vitamin D is 600 International Units (IUs) from ages 1 to 70, and 800 IUs at ages 71 and older.
"These numbers are set trying to take into account everybody, and everybody is so different from each other that when it comes to dealing with the issue of risk, you have to be conservative," Stencel said.
However, many experts suggest higher doses. The Pauling Institute, for example, recommends generally healthy adults take 2,000 IUs per day, Drake said. The maximum tolerable daily limit is 4,000 IUs, according to the IOM, but if you are deficient a physician may prescribe therapeutic doses of 50,000 IUs for short periods to get levels boosted.
How to get it • There are three ways to get vitamin D: from certain foods, in supplements and through exposure to sunshine.
"We know it seems to be best absorbed from the sun, and then probably from natural foods and thirdly from supplements," Woodruff said.
Fatty fish such as wild salmon, mackerel and tuna fish provide the most IUs of vitamin D per food serving. In fact, 19th century moms who gave their children a spoonful of cod liver oil as a preventative against rickets knew what they were doing. A tablespoon of cod liver oil packs 1,360 IUs of vitamin D, according to the U.S. Department of Agriculture.
Since the 1930s, the U.S. has fortified milk and several other dairy products with vitamin D, sparring millions of children from having to gag down cod liver oil; other food products grains, cereal, bread and orange juice also are now enriched with vitamin D.
But nutritionists say it's impossible to get enough of the vitamin from food alone. A glass of milk has 100 IUs, which means you'd have to drink six glasses a day to meet the minimum recommendation.
Some experts say five to 15 minutes in the sun depending on your skin type, skin cancer concerns, age and geographic location two to three times a week will adequately boost vitamin D levels. Your limbs should be exposed but unprotected as sunscreen blocks the rays that generate vitamin D production. In general, a 10-minute sunbath generates 10,000 IUs of vitamin D.
Concerns about skin cancer make many experts reluctant to recommend sunbaths as a way to get your dose. But it is the most natural way to get a lot of vitamin D fast. And Utah's northern location, seasonal weather and pollution all may reduce vitamin D available via sunlight.
That's why supplements of vitamin D3, the form best absorbed by the body, are necessary, particularly in the winter from November to March, for many Utahns.
"For people who want to supplement above and beyond the daily allowance, I always recommend they get their blood levels checked," Woodruff said.
Initially, Fowler didn't follow her doctor's recommendation that she take a supplement of 1,000 IUs of vitamin D daily. Then she learned she was still deficient at a second annual check up.
"Since then I've been taking it every day," she said.
What you need
The current daily recommendation of vitamin D from the Institute of Medicine:
Infants • 400 IUs
Children and adolescents • 600 IUs
Adults 14-70 • 600 IUs
Adults 71+ • 800 IUs
Pregnant and breastfeeding women • 600 IUs