Bloomington / Normal, IL

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What You Need to Know About Vitamin D


By Lauren Chan, ISU Dietetic Intern, and Mary Kay Holloway RDN, LDN at the Community Canc

Vitamin D is one of the many vitamins that are important for our health. What do you know about vitamin D? Vitamin D is used in the body’s every day functions, from bone health to building a strong immune system. Vitamin D is also tied to prevention of chronic diseases such as cancer and heart disease. While vitamin D is essential to a healthy lifestyle, many Americans have unhealthy, low levels and do not know it, while others supplement without knowing their number. In either case, the important thing is that you know your number.

The Vitamin D Council, a nonprofit group in California, researches health and vitamin D. Researchers at the Vitamin D Council believe vitamin D levels that are too low or too high can negatively affect health. The Council states that best health is seen with levels in a “target range” of 40 to 60 ng/mL, and over 50 percent of the risk of breast, colon, and kidney cancers can be reduced when vitamin D levels are in this range. Other health improvements may include decreased diabetes and hypertension rates. The first step towards getting to the target range is to know your vitamin D number.

Individuals below the target range are deficient. Those whose number exceeds 100 may be at risk of vitamin D toxicity, especially if they continue to supplement with high doses of vitamin D. Multiple factors including sun exposure, supplements, and diet affect vitamin D levels.

Sunlight increases vitamin D creation in the body, so limited sun exposure can cause deficiency. Individuals who are pregnant or who eat little vitamin D-rich foods are also at deficiency risk. Vitamin D rich foods include fish, egg yolks, and milk. After testing at a deficient level, a supplement or increased safe sun exposure are two ways to increase your level. Healthy sun exposure varies based on skin color, geographical location, and season. In central Illinois, the summer months are when your skin makes vitamin D. However, we must be careful not to sun burn, as burning can damage skin and limit vitamin D formation. Individuals within the target range may also need a supplement or additional sunlight to maintain healthy levels, but without knowing your number, it is difficult to know how much or how little you need to supplement.

A simple blood test will identify if you meet the target range of 40 to 60 ng/mL. Doctors test for many lab values at check-ups, but it is not a standard to test for vitamin D at this time. You may have to ask for this test at your next physical. If you want to test your vitamin D in the comfort of your own home, testing kits are available online at

Knowing your Vitamin D level can help you avoid deficiency or toxicity and reach the target range. Take the first step and get tested today. For more information, talk with your healthcare provider and visit

The Community Cancer Center offers a variety of free supportive and educational programs to help patients and families cope with cancer and its effects. For more information, go to