LOWELL -- It can prevent cancer! It can prevent diabetes! It will wipe away your depression!
In the last year, vitamin D has been touted as some kind of miracle pill, preventing or curing what ails you. Consumers may be compelled to head to local pharmacies to snatch its bottles off shelves.
Not so fast, warn nutritional-science professors at UMass Lowell. The "good news" needs to be taken with a grain of salt and a heavy dose of caution, they said.
"There is just not enough evidence that the general population should be supplementing with vitamin D," said Eugene Rogers, chairman of the Department of Clinical Laboratory and Nutritional Sciences at UMass Lowell. "Vitamin D is more complex than any other vitamin."
Vitamin D has been proven to be essential, along with calcium, for bone health. It is produced by the human body by the skin and can also be found in cold-water fish such as salmon, in mushrooms, egg yolks and in foods that have been fortified with the vitamin like milk, cereals and bread.
"They are quietly adding it to the food supply the same way niacin and folate were added," said UML nutritional-sciences professor Garry Handelman.
He said most people can obtain their required daily intake of the vitamin by spending about 20 minutes in the sun with their arms and face exposed, as long as they are not slathered in sunscreen.
Rogers said the sudden interest in vitamin D and vitamin D deficiency can be attributed to advances in technology that now allow for an easy blood test to determine a patient's vitamin D levels. Many doctors are ordering the test as part of routine blood work.
He added there are many questions regarding what level should be considered adequate and at what level there is considered a deficiency.
The National Center for Health Statistics says more than one-third of Americans are vitamin D deficient, and other research suggests that figure could be as high as 50 percent.
"What we are seeing is nothing new, it is just that doctors are now testing for it," Rogers said. "I don't believe humans have been deficient in vitamin D for 5,000 years."
He added if that were the case, there would have been some evolutionary changes to make up for the natural deficiency.
Rogers' conclusion was upheld by a report released by the Institute of Medicine in late 2010 challenging the notion that the majority of Americans are vitamin D deficient.
In the lab in UML's Weed Hall, Rogers, along with colleagues and students, are researching more accurate ways of determining the vitamin D level in blood through the use of a liquid-chromatography mass spectrometer. The machine has the ability to analyze and fragment specimens at the molecular level.
"We will find the truth," Rogers said.
"Or it will find is," Handelman added.
Recent studies have tied low blood levels of the vitamin to nearly every chronic disease: heart disease, high blood pressure, diabetes, depression, arthritis and cancer.
Rogers said questions abound on those findings because they were based solely on observational, not clinical, data.
"There needs to be clinical trials done to determine the effectiveness of vitamin D, but I am not sure who would fund that," he said. "Right now, we just don't have enough information to make any definitive statements other than to say it is good for bone health."
Handelman cautioned against putting too much stock in observational studies, pointing to a clinical trial he was involved with that studied the effect of beta carotene in cancer prevention. Observational studies concluded it could be a factor in preventing cancer, but when scientists administered doses to smokers, the result was those who were given the beta carotene ended up with a higher instance of cancer than those who did not.
A clinical trial appears to be on the horizon. Researchers at Brigham and Women's Hospital are recruiting 20,000 men and women nationwide to participate in a study investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) reduces the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses.
In its 2010 report, the Institute of Medicine released recommendations regarding the amount of vitamin D most Americans should consume: 600 international units per day for people aged 1 to 70 and 800 IU for those 71 and older.
The IOM study concluded evidence of vitamin D's ability to cut the risk of chronic disease is inconclusive, therefore recommending supplementation for bone health only.
"There is still a lot of research that should be done," said Dr. Eric Huang, of Merrimack Family Medicine in Chelmsford. "But it is important for bone and joint health, especially in elderly patients. If someone over the age of 70 breaks their hip, their mortality rate in the following two years is 80 percent."
Huang added if a patient's blood test shows a vitamin D deficiency "we fill up their tank up with 50,000 IU weekly for two months."
Because vitamin D is fat-soluble, meaning it is stored in the body's tissues and liver, rather than excreted in the urine, there is a threat of toxicity.
"But, you would have to take a whole bottle to reach toxic levels," said Huang.
Handelman and Rogers, however, said they fear some people may self-dose or not follow their physician's instructions and could inadvertently poison themselves.
"The bottom line is people should consult their doctors if they are considering taking a vitamin D supplement and follow their instructions," Rogers said.