House Calls / Dr. Michael Schwartz

Vitamins and nutritional supplements are becoming increasingly popular. Pharmacies, vitamin shops and Internet companies sell these products to consumers who are captivated by their potential benefits.

Some manufacturers assert their supplements can prevent diseases while others suggest that they can extend lifespan.

While eating a well-balanced diet will provide many of the daily vitamins we need, we are now learning that adding certain daily supplements may actually play an important role in health and prevention of disease.

One nutritional supplement that is getting a great deal of publicity is Vitamin D.

More Information
Fact box

It may be surprising to learn that Vitamin D is not really a vitamin at all.

It is actually a hormone. Hormones are chemicals that are produced by our bodies to assist cells and organs to do their jobs and keep our bodies functioning properly.

Vitamin D is produced when ultraviolet sunlight hits our skin and converts cholesterol into a specific active form of this steroid hormone.

Many Americans are deficient in this "vitamin" and do not know it.

Fortunately, a Vitamin D level can easily be determined by your doctor during a routine blood test.

Those in the Northern Hemisphere are especially susceptible to Vitamin D deficiency due to the lack of sunshine.

However, only 10 to 15 minutes of direct sunlight daily can supply our bodies with an adequate amount of Vitamin D.

Unfortunately, Vitamin D is only synthesized from UVB radiation in these areas between April and early autumn.

Vitamin D can also be acquired by eating certain foods including dairy products such as milk, cheese, butter and certain types of fish (including salmon and tuna) or by eating or drinking food or liquids fortified with Vitamin D (such as orange juice and yogurt).

For years, it has been widely accepted that Vitamin D (along with calcium) minimized the risk of developing osteoporosis (bone loss). Over the past few years, there have been indications that Vitamin D also possesses many additional health benefits.

Potential benefits of Vitamin D include:


Higher levels of Vitamin D have been associated with an across the board decrease in mortality. Many believe that Vitamin D may affect the chromosomes (genes) in our cells allowing them to replicate and survive longer.

Cancer prevention

Vitamin D is believed to decrease abnormal cell development and along with its anti-inflammatory effects, it is thought to reduce the risk of certain types of malignancies.

Decreased risk of heart disease and stroke

Patients with low levels of Vitamin D in some cases were twice as likely to suffer a heart attack or stroke. It is believed that Vitamin D deficiency can play a role in blood pressure, inflammation of arteries and the risk of diabetes.


Vitamin D may play a role in regulating testosterone. In men, it appears that Vitamin D deficiency affects sperm development; in women, it appears to change the ratio of estrogen and progesterone.

Weight loss

Vitamin D appears to affect leptin levels. Leptin is a hormone which sends signals to the brain telling us we are full. A deficiency of leptin can lead to overeating and weight gain.

Psychiatric health

Low levels of Vitamin D have been linked to depression.

Immune system

Vitamin D appears to increase the level of cathelicidin in our blood.

Cathelicidin is a substance which promotes immune system function.

Other potential benefits:

Vitamin D deficiency during pregnancy may affect a child's language skills.

Higher levels may decrease the risk of developing multiple sclerosis.

Higher levels may increase energy and a feeling of well being.

Vitamin D is not a panacea for all medical conditions. As a matter of fact, too much Vitamin D can cause adverse effects including irregular heartbeats, confusion and weakness.

Currently, physicians and researchers are conducting clinical trials to determine the beneficial (or detrimental) affects of Vitamin D.

Many of these potential beneficial effects will be proved or disproved by future research.

Until then, always consult your physician about the proper dose of Vitamin D that is right for you.

Dr. Michael Schwartz is board certified in internal medicine with a private practice in Darien. Visit his website at