You've probably heard about the immunity benefits of Vitamin C - but it's time to move one letter down the alphabet. It turns out that Vitamin D may be the more critical vitamin when it comes to fighting off colds and flus.

An important vitamin that also promotes anti-aging, the ‘sunshine vitamin’ is a nutrient generated by the body through exposure to the rays of the sun.  "Vitamin D plays a role in many important functions of the body.

Most American’s are suffering from dangerously low levels of this key vitamin and we do not realize it." says Sara Kinninger, D.C., former Chiropractic Director of Chiro One Wellness Center of Schaumburg West.  

According to the Journal of Clinical Endocrinology and Metabolism, “Abnormal levels of Vitamin D are associated with a whole spectrum of diseases including cancer, osteoporosis, and diabetes, as well as cardiovascular and autoimmune disorders.” (Kremer et al. March 2010). “The best way to know if your vitamin D level is normal is to have a blood test. That way you know if supplementation with vitamin D is necessary for your overall health and well being.” 

How can I get vitamin D? 

The best form of vitamin D comes from natural sunlight. A good rule of thumb is that unless you are getting 30 minutes of summer sunlight exposure on large parts of your body every day, you will almost certainly be deficient in vitamin D. Many people live in a climate where during most of the year we have very little sun exposure. That is when supplementation becomes even more important. When supplementing, always choose vitamin D3 cholecalciferol, not vitamin D2 ergocalciferol which the body has to convert to vitamin D. Vitamin D3 is sold in either a liquid form (where it is suspended in a substance like olive oil) or in pill form. Both are effective forms of supplementation. Some foods in the American diet contain small amounts of vitamin D. 

These foods include: 

• Fatty fish such as salmon and tuna 

• Beef liver, egg yolks and some mushrooms.  

Although some foods contain Vitamin D, humans cannot get adequate amounts through our diet. We are genetically designed to get Vitamin D from sun exposure so the best way to ensure you are getting enough Vitamin D is to be exposed to sunlight and to supplement daily. 

Am I getting enough vitamin D? 

The amount of Vitamin D required depends on your age. Average daily recommended amounts for different ages are listed below in International Units (IU): Children from birth to 1: 500 IU Children ages 1-3: 1500 IU Children ages 4-8: 2000 IU Children ages 9 and up: 3000 IU Adults ages 18 and over: 3500 IU 

How does vitamin D affect health? 

In addition to reducing the risk of bone loss and fractures as people get older, some studies suggest that vitamin D may protect against cancers of the colon, prostate, and breast. Vitamin D is important in maintaining strong teeth, proper parathyroid function, and enhancing the body’s immune system. In fact, when taken properly, Vitamin D is more effective than the flu vaccine in helping to prevent the flu. Vitamin D is also being studied for its possible role in the prevention and treatment of low-back and joint pain, bronchitis, colds, diabetes, hypertension, glucose intolerance, multiple sclerosis and other conditions.  

What precautions do I need to take with vitamin D? 

When amounts of vitamin D in the blood become too high, it can lead to toxicity—nausea, vomiting, poor appetite, constipation, weakness and weight loss. In addition, by raising blood levels of calcium, too much Vitamin D can cause confusion, disorientation and problems with heart rhythm. Excess Vitamin D can also damage the kidneys. Be aware that higher levels of vitamin D in the blood have also been linked to higher rates of pancreatic cancer. At this time, more studies are needed to assess the connection between Vitamin D and cancer. 

Although uncommon, vitamin D toxicity can occur and happens from the overuse of supplements. A simple blood test will confirm your body’s level of Vitamin D. Excessive sun exposure doesn't cause Vitamin D poisoning because the body limits the amount of this vitamin it produces. Like most dietary supplements, Vitamin D may interact or interfere with other medicines or supplements, most notably: steroid usage, some weight loss medications, seizure medications and cholesterol lowering statins. Tell your health care providers about any dietary supplements and medicines you take.