It’s estimated that as many as one billion people globally are vitamin D deficient. That’s a staggering number — especially when you consider all of the functions of the body that rely on this essential nutrient in order to function properly. While we can’t cover all of these functions here, we have highlighted a few that are well-known along with a couple that aren’t.

Vitamin D is a powerful vitamin that our bodies make from exposure to the sun. (Did you know that vitamin D is one of only two vitamins that your body can produce on its own? The other one is vitamin K.) As little as fifteen minutes of exposure several times a week is enough sun but, as you know, living in Wisconsin can make even that challenging to do on a year-round basis. The next best bet would be to get plenty of vitamin D-rich foods into your diet regularly. There are not a lot of foods that naturally contain vitamin D, but good sources are fatty fish such as salmon, trout, tuna, and mackerel. Fish liver oils are also a good source of the vitamin. Egg yolks, beef liver, and some dairy products offer some vitamin D, as well. There are also cereals and other packaged foods available that have been fortified with vitamin D. While fortified foods might not always be the best option, fortunately, there are some great vitamin D supplement choices available in several different forms. You can find it in drops, capsules, and supplements suitable for kids (and BIG kids) who can’t swallow pills.   

Infection and Immunity

Undoubtedly, we have all heard many times about how important vitamin D is for the immune system. Chances are, if you get sick easily and often, you are probably deficient. Vitamin D has been shown to protect against infections of all kinds. Particularly, protection from respiratory infection has been linked to vitamin D along with less severe symptoms if you do get a respiratory infection. The science behind why vitamin D helps immunity is rather, well, “science-y” and may not be too exciting to read. But the gist is that a component of our immune systems are T-cells. You may have heard of them; they are also often referred to as “killer T-cells”. They are the cells capable of regulating or suppressing invaders to our systems such as viruses or bacteria. In fact, regarding the immune system, one study on vitamin D and the immune system plainly states, “Deficiency in vitamin D is associated with increased autoimmunity and an increased susceptibility to infection.” |5| |7| |8|

Heart Health

It goes without saying that taking care of our heart should be a main health priority. There are many ways to go about taking good care of the ‘ol ticker. Some of the ways are very well-known and probably even common sense. You know—eat right, exercise, and all that. But what hasn’t been talked about a lot is the role vitamin D plays in heart health. In fact, low serum vitamin D levels are a huge commonality amongst people diagnosed with a myriad of cardiovascular diseases. This has shown up in several heart-related studies. Last year, an article appeared in European Heart Journal with the conclusion made up of two simple sentences: “Vitamin D deficiency can increase the risk of CVD (cardiovascular disease). Burden of CVD could be reduced by population-wide correction of low vitamin D status.” So, it would appear that a relatively easy way to give yourself some protection against these major health concerns would be to know your vitamin D level and do what is needed to get and keep it within a healthy range. The medical field has long-acknowledged the correlation between heart health and vitamin D, but the reason why vitamin D is a key player in heart health has not been clearly understood. There was an interesting study done in 2018 that offers some insight. It’s a lot to include here, but if you’re interested in reading more about it, the article can be found here. [2] |9|

Athletic Performance

Did you know that adequate vitamin D levels are essential for muscles to work properly? This includes the expansion and contraction of muscles along with the recovery and associated inflammation that comes after challenging the muscles. Some inflammation is inevitable as the muscles are worked. Tiny tears can occur in the muscle tissue but, as the body repairs these tears, muscle growth occurs. Some of you may even do this on purpose on a regular basis using weights! A healthy immune system will kick in and calm the inflammation down and even help release body chemicals that grow and restore the muscle tissue. Vitamin D plays a big role in this restorative process. Suboptimal vitamin D levels in athletes has been linked with stress fractures, muscle weakness, and poor athletic performance due to the inability of the muscles to function properly. In addition, athletes (or those who remain active for fun or for their health), may experience prolonged muscle recovery after exercise due to low vitamin D levels. |4|

Decreased Bioavailability in Obesity  

With all these health benefits of vitamin D, we want to be sure to get the most out of the vitamin D we consume, whether it be from our diet or from supplements. You probably already know to take it with food since our bodies don’t assimilate it well without food, particularly fats. But did you know that obesity also affects how well a body can absorb vitamin D? It has been shown that obesity actually prevents our bodies from properly absorbing vitamin D. That, paired with the strain of obesity on the heart and joints, is plenty of motivation to maintain a healthy weight. |1|

Hopefully, you now have a better understanding of how crucial it is to get enough vitamin D year-round. If you’re not sure how to determine if you’re getting enough vitamin D, or you are interested in starting on a high quality supplement for you or your family, you are welcome to stop in at any of our locations any time to discuss your particular concerns with one of our knowledgeable staff members.


  1. Decreased bioavailability of vitamin D in obesity – PubMed (
  2. Vitamin D Deficiency and Supplementation and Relation to Cardiovascular Health – American Journal of Cardiology (
  3. Cannell, J.J., B.W. Hollis, M.B. Sorenson, T.N. Taft, and J.J. Anderson (2009). Athletic performance and vitamin D. Med. Sci. Sports Exerc. 41:1102-1110.
  4. [Current Topics on Vitamin D. The effects of vitamin D on the immune system] – PubMed (
  5. Nair R, Maseeh A. Vitamin D: The “sunshine” vitamin. J Pharmacol Pharmacother. 2012 Apr;3(2):118-26.
  6. The impact of vitamin D on regulatory T cells – PubMed (
  7. Vitamin D and the immune system – PubMed (
  8. Non-linear Mendelian randomization analyses support a role for vitamin D deficiency in cardiovascular disease risk | European Heart Journal | Oxford Academic (

The information provided here is for educational purposes only. None of the research or evidence presented here is intended as a substitute for consulting an appropriate healthcare professional. These statements have not been evaluated by the Food and Drug Administration. The products offered here are not intended to diagnose, treat, cure, or prevent any disease. If you believe that you may have a disease condition, please consult your healthcare practitioner before using this or any other dietary supplement.