Vitamin D Deficiency

With the flu season here, it’s more important than ever to ensure you are getting enough Vitamin D. As both a nutrient and a hormone, vitamin D helps reduce inflammation, and control processes such as immune function, which may improve the body’s first line of defense against foreign invaders and deter the development of autoimmunity. Researchers have also been studying the immunity –building benefits of vitamin D in prevention and treating of respiratory infections. Research is also showing the importance of vitamin D in protecting against other health problems such as type 1 and type 2 diabetes, hypertension, glucose intolerance and multiple sclerosis.

Vitamin D has multiple roles in the body. It assists in promoting healthy bones and teeth, supports the immune, brain, and nervous system, helps regulate insulin levels, and supports lung function and cardiovascular health. Vitamin D is essential for strong bones because it helps the body use calcium from the diet. In adults, vitamin deficiency D can result in softening of the bones which affects the bone density. Vitamin D deficiency can also present as osteoporosis which affects over 53 million people in the US.

Known as the sunshine vitamin, vitamin D is produced by the body in response to the skin being exposed to sunlight. Vitamin D also occurs naturally in foods such as fish, fish oil, liver oils, egg yolks, beef liver, and fortified diary and grain products. Because some people do not get enough sun exposure or eat enough foods high in vitamin D, a significant number of the population may have a vitamin D deficiency.

There are a number of factors or conditions that predispose you to a vitamin D deficiency. Following a strict vegan diet, limited sun exposure, being homebound, dark skin, obesity, and people with a kidney or digestive tract conditions where vitamin D cannot be absorbed.

Symptoms of vitamin D deficiency include bone or joint pain, muscle cramps, weakness, or mood changes. Some people will not have any symptoms.  But, even without symptoms, too little vitamin D can pose health risks. Low blood levels of vitamin D has been associated with increased risk of cardiovascular disease, cognitive impairment in older adults, severe asthma in children, and even cancer.

The good news is that there is an accurate way to measure the vitamin D in your body. If you have not had a vitamin D blood test, talk to your doctor or healthcare provider and ask if you should be tested. If your vitamin D is low, your physician may recommend taking a vitamin D supplement. Although supplements are available, it is always best to obtain any vitamins and minerals through natural sources, whenever possible.

Guidelines from the Institute of Medicine increased the recommended dietary allowance of vitamin D to 600 international units (IU) for everyone ages 1-70 and raised it to 800 IU for adults older than 70 to optimize bone health. The safe upper limit was raised to 4,000 IU, but doctors may prescribe more to correct a vitamin D deficiency.

Sensible sun exposure on bare skin for 5-10 minutes, 2-3 times per week, allows most people to produce sufficient vitamin D in nice weather.  However, since we live in Michigan, this is not possible in the winter, so we may need to rely on a diet higher in vitamin D and supplements.  As always, talking to your physician or healthcare provider about this, and other concerns is always recommended.


  •, NOURSIH by WebMD, Diet and Weight Management, Vitamin D Deficiency, Reviewed by Christine Mikstas, RD, July 28, 2020.
  • Medical News Today, “What are the Health Benefits of Vitamin D, Written by Megan Ware, RDN, Reviewed by Debra Sullivan, Ph.D, MSN, R.N., November 7, 2019.
  • Costco Connection, Get an A in Vitamin D, January 2023.