Imagine a substance that may prevent and treat conditions as diverse as cancer, multiple sclerosis (MS), heart disease, osteoporosis and even depression and periodontal disease. What’s more, you can get the healthy stuff for free. Just go outside and sit in the sunshine for about 10 minutes.

This may sound like a quack’s too-good-to-be-true claim, but it’s the remarkable news from a host of scientists about the so-called "sunshine" vitamin -- vitamin D.

According to the National Institutes of Health (NIH), there are several forms of this nutrient. The most important are ergocalciferol (vitamin D2), which is synthesized by plants, and cholecalciferol (vitamin D3), formed in skin exposed to ultraviolet-B (UVB) rays from sunlight.

Although the importance of vitamin D in maintaining normal blood levels of calcium and phosphorus to form and maintain strong bones has been long known, researchers have studied links between vitamin D and other biologic functions over the past few years. And they’ve reached several startling new conclusions.

First, there’s growing evidence that a lack of vitamin D could trigger or contribute to many health problems. Scientists have also documented that low levels of vitamin D appear to be common among all ages of Americans.

Could D fight the Big C?

Cancer is characterized by out-of-control cells, and researchers are looking into how vitamin D might prevent malignancies from starting cancer’s run amok cell growth. For example, in a report published in the medical journal Annals of Epidemiology, scientists at the Moores Cancer Center at the University of California (UC) in San Diego pointed to a host of research that suggests cancer develops when cells lose the ability to stick together in a healthy, normal way. And, they say, the key factor to this initial triggering of cancer could be a lack of vitamin D.

Cedric Garland, DrPH, professor of family and preventive medicine at the UC San Diego School of Medicine, explained that links associating vitamin D with many cancers have been tested and confirmed in over 200 epidemiological studies and more than 2,500 laboratory studies. According to Dr. Garland, with enough vitamin D present, normal cells adhere to one another in tissue. But if there is a lack of vitamin D, cells lose this stick-to-each other quality, as well as their identity as differentiated cells, and become cancerous.

While this remains a theory, several recent clinical studies have shown promising results that vitamin D could help prevent or treat various types of cancer. A case in point: breast cancer. Breast cells have receptors for vitamin D, raising the possibility the nutrient could help keep these cells in a normal, non-malignant state.

Last fall, researchers from the University of Rochester Medical Center announced they’d found about 70% of women being treated for breast cancer had very low levels of vitamin D in their blood. And researchers from Cancer Care Ontario in Toronto recently published a study in the American Journal of Clinical Nutrition showing that women who took at least 400 international units (IU) of vitamin D every day in supplement form slashed their risk of developing breast cancer by almost 25%.

Other research suggests vitamin D supplements may slow the progress of prostate and colon cancer, too.

The autoimmune connection

Insulin-dependent diabetes mellitus (type 1 diabetes), MS and rheumatoid arthritis (RA) are examples of autoimmune diseases. They occur when the body mounts an immune response against its own tissues.

Researchers have long noted that the prevalence of these diseases goes up the farther you are from equator. This raises the possibility that less sun exposure in northern locales leads to a lack of vitamin D that triggers autoimmunity.

On the other hand, increased levels of vitamin D have been linked to decreasing the risk of MS. What’s more, a University of Toronto study found that high doses of vitamin D dramatically cut the relapse rate in people diagnosed with the disease.

More vitamin D news

• Heart health: A study published in the journal Circulation reported that low levels of vitamin D doubled participants' risk of cardiovascular problems when compared to people with higher levels of the vitamin.
• Metabolic syndrome: Several studies have shown adequate vitamin D intake lowers the risk for this pre-diabetic condition.
• Weight loss: University of Minnesota scientists found that overweight people lose more weight on a reduced-calorie diet if their vitamin D levels are increased.
• Bone health: An international research team reported in the British Medical Journal that boosting levels of vitamin D reduces the incidence of fractures in every age group.
• Depression: Cardiology researchers have found people with heart disease who are low on vitamin D are more likely to be depressed than their counterparts with adequate levels of the "sunshine vitamin."
• Oral health: Tufts University scientists have found a connection between low levels of vitamin D and periodontal disease, which is a primary cause of tooth loss, especially in the elderly.
• Pregnancy: A recent Medical University of South Carolina study concluded that pregnant women who took 4,000 IU of vitamin D daily during their second and third trimesters had a reduced risk of compilations including preterm birth and gestational diabetes.

To D or not to D

New research published in the Journal of Clinical Endocrinology and Metabolism found that an amazing 59 percent of Americans tested were vitamin D deficient. And about 25 percent of the study subjects were found to have extremely low levels of vitamin D. What’s more, documented deficiency levels in youngsters prompted the American Academy of Pediatrics to double the vitamin D recommendations for children and adolescents.

So what’s going on here? A contributing factor could be that Americans tend to spend most of their days indoors, with little direct sunshine exposure. We also often wear sunscreen -- which is beneficial because it helps avoid skin cancer and wrinkles but may inadvertently lower vitamin D levels.

Strategies for getting adequate amounts of vitamin D include food sources, supplements and exposing non-sunscreen protected skin to direct sunlight for 10 to 20 minutes several times a week. But talk to your doctor to see if direct sun exposure is a healthy idea for you -- especially if you are at risk for skin cancer -- or if you need supplements.

"The best food sources of vitamin D are found from the flesh of fish like salmon, tuna, mackerel and fish liver oils. Small amounts can also be found in beef liver, cheese and egg yolks," nutrition expert Kate Kennedy, LD, RD, tells Synergy.

"And it’s a good idea to look for products that say ‘fortified with vitamin D’ on labels. Products like margarine, ready to eat cereals, milk, cheese and juices can easily be found fortified with vitamin D."

Can you get too much? Toxicity from vitamin D is rare but Kennedy, who works for DaVita Inc. in Charleston, South Carolina, says it can happen.

"Vitamin D in excess can cause non specific symptoms like headache, nausea, poor appetite, constipation or weakness."

Sherry Baker is a writer from Atlanta, Georgia. She last wrote the M-Factor in your Office. Sherry can be reached at featuredstories@adamcorp.com