Written By Scott Braden
For the last three years, vitamin D has received more than its share of attention from the nation’s healthcare professionals.
According to WebMD senior medical writer Daniel J. DeNoon in his December 17, 2009, article, “The Truth About Vitamin D,” for the online health resource, what turned the spotlight on the nutrient was “a 2007 study showing that people taking normal vitamin D supplements were 7 percent less likely to die than those who didn’t take the daily supplements.”
DeNoon followed that dramatic statement by pointing to a 2008 study that found when “women with low vitamin D levels get breast cancer, they have a much higher chance of dying from their cancer than women with normal vitamin D levels.”
The findings got people talking, and medical professionals reacting, especially since many Americans, compared with people in other parts of the world, have insufficient blood levels of the important vitamin.
For example, the latest global tallies of vitamin D insufficiency show that it is less than 1 percent in Southeast Asia, while it is a surprising 29.3 percent in the United States.
And according to Hampstead internist Deogracias Faustino, M.D., there is no better time than now for physicians to act.
“The reason for that is, number one, the population is getting older,” said Faustino. “As we age, our vitamin D begins to be lower. So, we need to check our [levels]. Number two, the technology to check for vitamin D in the serum is more accurate. We can do that accurately now, adjust the dose, and prescribe medication for the patient. It’s common practice to check for vitamin D in a normal blood test.”
But what are the facts and myths surrounding this “miracle” vitamin? Is vitamin D too good to be true? Is its reputation all hype and no substance?
Myth or Fact: Vitamin D is a vitamin.
“You’ll be surprised,” said Faustino. “Vitamin D is classified as a steroid hormone. You would think it’s a vitamin, but it’s also a hormone.”
“Vitamin D is a fat-soluble hormone,” said Amy Michael, a certified diabetes educator and dietician who works for Carroll Hospital Center. “That means that fat must be present for vitamin D to be absorbed in the intestine.”
“When vitamin D is in your body it is called 1.25 dihydroxy vitamin D,” said Faustino. “It starts when your skin is exposed to ultraviolet light, and then is manufactured into 7 dehydrocholesterol by reacting with cholesterol. Next, it is absorbed by the gastrointestinal tract and enters into the bloodstream through the liver. It is then mixed with calcium to help with the bones and then expelled through the kidney. Vitamin D has a half life in the body of about two to three weeks.”
Myth or Fact: Everyone can synthesize vitamin D efficiently.
“Vitamin D can be somewhat difficult to measure,” said Michael. Recently, Three National Health and Nutrition Examination Survey (NHANES) studies examined levels of the nutrient in the United States’ population over time and found that the amount of vitamin D had decreased from the second to the third study.
“I believe that’s where a great deal of the concern about vitamin D originated,” said Michael. “We know that the populations that specifically need vitamin D are infants who are breast fed. They need vitamin D supplementation because human breast milk does not give them the vitamin D that they need. And because adequate vitamin D is so vital for bone growth and development, it is recommended that this specific population receive supplementation.”
According to Michael, the following groups may be unable to synthesize vitamin D efficiently:
- Infants who are breast fed.
- Americans who are 50 years old or older. (As we age, the skin is less able to synthesize vitamin D efficiently and the kidney’s ability to produce vitamin D is also diminished.)
- People with limited sun exposure (for example, people in northern latitudes and women who are covered from head to toe because of religious beliefs).
- People with dark skin (African-Americans are at risk for vitamin D deficiency).
- Individuals with fat malabsorption (Crohn’s disease, cystic fibrosis, and certain forms of liver disease).
- Obese individuals or those who have undergone gastric bypass surgery.
“The normal level [percentage] of vitamin D in your body is about 20 to 30 milligrams (mg) in your blood serum,” said Faustino. “If you are below 15 mg , you should be treated for vitamin D deficiency. Severe low vitamin D in adults could lead to significant bone mineral loss, bone pain, muscle weakness, and soft bones called osteomalacia. Low vitamin D could also lead to osteoporosis. Vitamin D deficiency is also related to malnutrition, inflammatory bowel disease, pancreatic insufficiencies, and kidney disease.”
Myth or Fact: It is safe to get vitamin D through sunlight.
The experts differ. The American Academy of Dermatology recommends against obtaining vitamin D from unprotected exposure to sunlight. Dr. Faustino agreed: “We have advised people to use sunblock to avoid skin cancer, and this in turn diminishes production of vitamin D.”
But, said Michael, “You can get vitamin D from sunlight.” Basically, ultraviolet rays interact with skin pigmentation to activate the useful form of vitamin D in your body.
“We’re not saying go out and lie in the sun without sunscreen every weekend, but we are recommending some sunlight a couple of times a week.”
Some doctors recommend 10 to 15 minutes of exposure three times a week.
Myth or Fact: You can get vitamin D from pills, a specific diet, and other supplements.
“It’s found naturally in very few foods,” said Michael. “The majority of vitamin D in nature is found in fish: salmon, mackerel, and cod liver oil. We also get vitamin D from such foods as milk and cereal that have been fortified with the nutrient.
“From my standpoint as a dietician, I feel that you should get vitamins and minerals from natural sources. However, there are certainly situations in which vitamin D supplementation may be necessary.
“If you feel that you may be in one of the groups that are at an increased risk for developing vitamin D deficiency, speak with your healthcare provider. Your vitamin D status can be determined by a simple blood test.
“Also, let your doctor know if you are taking supplements. Don’t just let him or her know what is prescribed, give the whole picture. That includes a multivitamin, vitamin D, or a baby aspirin. So, first things first: look at the data and find out where your vitamin D stands. Then, talk to your healthcare provider to determine whether a supplement is needed.
Medical writer DeNoon feels that its better to get the much-needed vitamin D from foods or supplements. He points to salmon, mackerel, and “mushrooms exposed to ultraviolet light to increase vitamin D.” He also recommends tuna canned in water, sardines canned in oil, beef or calf liver, egg yolks, and cheese for small amounts of vitamin D. He said that nearly all milk produced in the U.S. is fortified with vitamin D, as well as “many brands of orange juice, yogurt, margarine, and ready-to-eat breakfast cereals.”
Myth or Fact: Children need vitamin D more than adults.
“Vitamin D is essential for health,” said Michael. “The recommended adequate intakes (AI) for humans from birth to 50 years of age is 5 micrograms (mcg) or approximately 200 international units (IU) . Individuals who are older typically require slightly larger amounts of vitamin D because the body’s ability to synthesize vitamin D efficiently decreases with age.”
The recommended amounts of vitamin D for both men and women are as follows:
- Birth to 50 years – 5 mcg (200 IU)
- 51 to 70 years – 10 mcg (400 IU)
- 71 + years – 15 mcg (600 IU)”
Myth or Fact: You can’t have too much vitamin D.
“Too much vitamin D can cause nausea, vomiting, poor appetite, weakness, weight loss, and constipation,” said Michael. “It can also raise the blood calcium levels, which can cause altered mental status, confusion, and heart rhythm abnormalities. Most toxicity is related to large amounts of supplements. But, because there are no recommended dietary allowances established, what might be too much for one individual may not be too much for another.
But, said Faustino, “It is very rare to have vitamin D toxicity.”
Myth or Fact: Vitamin D fights cancer and other ailments.
Besides promoting bone health, which is what vitamin D is best known for, the nutrient is also believed to “ward off cancer and protect against tuberculosis, diabetes, colds, and the flu,” according to Deborah Kotz in a June 8, 2007 article in U.S. News and World Report. Collecting a wealth of medical studies that were done on vitamin D, Kotz reports that Harvard University researchers believe that the vitamin “might prevent [cancer] tumors from rapidly growing by controlling the expression of certain genes that regulate cell division.”
According to Michael, “There is evidence that vitamin D may be useful in preventing certain types of cancer, although the research is limited.”
