More than Sunshine and Healthy Bones – Vitamin D

Vitamin D is one of those health topics that comes up again and again, usually in the context of enjoying some sunshine and keeping our skeleton strong. But there’s much more to know about this critical vitamin. To start with, do you know your body’s vitamin D level (also known as serum 25-OH D)?

Chances are you’re deficient. Scientific and medical experts estimate that at least 3 out of every 4 Americans don’t have enough vitamin D in their bodies. In fact we might even be worse off than that, considering that Dr. John J. Cannell, leader of the nonprofit Vitamin D Council, estimates that at least 95% of Americans are deficient in vitamin D.

Just because everyone is deficient doesn’t mean you shouldn’t worry. In fact, once you learn about the importance of vitamin D’s role in health and longevity, I’m hoping you’ll start working to become one of the few Americans with an adequate vitamin D level.

So, what is vitamin D and why is it so important?

In the blogosphere, there is much discussion and confusion on whether vitamin D3 cholecalciferol is a hormone or a vitamin. Regardless of its characterization, the most important fact to learn is that vitamin D is absolutely critical to your health.

A vitamin is a substance whereby “insufficient amounts in your diet may cause deficiency diseases.” Vitamins are substances your body needs, but can’t produce. Hormones, on the other hand, are chemicals produced by your body that act as critical messengers. They impact many different parts of the body, hence the reason they are given so much attention by doctors. Estrogen, testosterone, insulin and thyroid hormone are a few you may recognize.

Vitamin D is like a vitamin because not having enough of it in our diet definitely causes disease (e.g. rickets, osteoporosis). But, we can’t actually consume enough D3 to meet recommended levels because it’s only found in animal fur and skin. (Plants contain a far more inferior form called ergocalciferol or vitamin D2.) To achieve recommended daily levels, you’d have to consume two servings of sockeye salmon daily or 6-8 glasses of fortified milk--both of which are excessive and would not be recommended for good health for a variety of reasons.

This is what makes vitamin D’s importance so unique. While it meets the definition of a vitamin, it actually acts like a hormone once it’s activated by the kidneys. Vitamin D has many functions in the body, ranging from regulating calcium levels for bone health to managing our expression and production of cytokines, signaling molecules that are critical in healthy immune response. Below are three additional (and underappreciated) reasons why vitamin D is important to your health:

Blood pressure regulation:
Vitamin D reduces the release of the hormone angiotensin II, which increases blood pressure. When released, angiotensin II raises blood pressure by inducing constriction of your arteries (i.e., vasoconstriction) and increasing your sodium and water retention. Vitamin D produces a blood pressure lowering effect by suppressing the gene responsible for renin, the enzyme that converts angiotensin I to angiotensin II, the step that starts the entire process described above. Without adequate vitamin D levels, your body loses an important mechanism for maintaining a healthy blood pressure.

Balanced blood sugar levels:
With the increasing prevalence of type 2 diabetes in America, it’s critical we all pay attention to maintaining balanced blood glucose levels. Vitamin D’s role in blood sugar management is yet to be proven in a clinical study, but animal, in vitro and epidemiological studies point to its ability to lower glucose intolerance and prevent type 1 and type 2 diabetes. The current understanding starts with molecules called vitamin D receptors or VDRs. In the last decade, scientists have learned that humans have VDRs throughout the entire body. They are activated when 1,25(OH)2D, the active form of vitamin D, binds to them. Once activated, VDRs facilitate glucose uptake in insulin-sensitive tissues, thereby lowering blood glucose levels. Also, research shows VDRs and 1-α-hydroxylase, the enzyme responsible for activating vitamin D, are expressed by insulin secreting pancreatic cells which indicates vitamin D has a role in insulin production and secretion. While more research is needed, vitamin D supplementation has been linked to improved insulin sensitivity in individuals with glucose intolerance or type 2 diabetes.

Stronger immunity:
Vitamin D deficiency is associated with increased risk of infection and autoimmunity, a condition in which your body mounts an attack against itself. Adequate vitamin D levels, however, promote a healthy immune response in several ways:

• Vitamin D increases the secretion of antimicrobials, chemicals released to attack pathogens, making the immune attack stronger and more successful. It does this by effecting which genes are expressed in your body.

• There are 500+ vitamin D responsive genes in the body. With adequate vitamin D, these genes can be turned “on or off” as the body desires. T and B cells, immune cells key to antibody creation, can activate vitamin D and VDRs. This activation effectively “turns on” the genes responsible for both helping the immune system produce the right antibodies for a specific pathogen, and promotes rapid replication immune cells, thus promoting a stronger immune attack.

• When the body mounts an attack against pathogens, it often goes into a state of inflammation. Chronic or prolonged inflammation have been linked to many diseases. Through gene expression, vitamin D has been shown to suppress the release of pro-inflammatory cells and improve the release of anti-inflammatory cells--resulting in a shorter immune response and lower risk of chronic inflammation.

These are just a few of the reasons why vitamin D should be a top priority in your life. With this information in mind, I challenge you to boost your vitamin D levels! Here are a few simple ways you can start improving your health with increased vitamin D.

  1. Expose your skin to the sun, without sunscreen, for 10-30 minutes daily. Just before the skin starts to turn pink apply sunscreen or, better yet, cover up.
  2. Eat wild sockeye salmon a couple of times per week. In addition to improving your vitamin D levels, you’ll also be improving your heart health as recommended by the American Heart Association.
  3. Take a high quality vitamin D3 supplement daily, minimum of 600 IUs – more if you have a deficiency. But remember to always speak with your doctor before including supplements in your diet.

References & Additional Resources

  1. Aranow, C. (2011). Vitamin D and the immune system. Journal of Investigative Medicine: The Official Publication of the American Federation for Clinical Research, 59(6), 881–886.

  2. Challem, Jack. (2011, December). The Vitamin D Debate. Retrieved on May 28, 2015 from

  3. Holick, M. F., & Chen, T. C. (2008). Vitamin D deficiency: a worldwide problem with health consequences. The American Journal of Clinical Nutrition, 87(4), 1080S–1086S. Retrieved from

  4. Naeem, Z. (2010). Vitamin D Deficiency- An Ignored Epidemic. International Journal of Health Sciences, 4(1), V–VI. Retrieved from

  5. National Institutes of Health. (2014, November 10). Vitamin D fact sheet for health professionals. Retrieved on May 28, 2015 from

  6. Prietl, B., Treiber, G., Pieber, T. R., & Amrein, K. (2013). Vitamin D and Immune Function. Nutrients, 5(7), 2502-2521. doi:10.3390/nu5072502

  7. Talaei, A., Mohamadi, M., & Adgi, Z. (2013). The effect of vitamin D on insulin resistance in patients with type 2 diabetes. Diabetology & Metabolic Syndrome, 5(1), 8.

  8. Tangpricha, V., Pearce, E. N., Chen, T. C., & Holick, M. F. (2002). Vitamin D insufficiency among free-living healthy young adults. The American Journal of Medicine, 112(8), 659–662.

  9. Vieth, R. (2004). Why Vitamin D is not a hormone, and not a synonym for 1,25-dihydroxy-vitamin D, its analogs or deltanoids. The Journal of Steroid Biochemistry and Molecular Biology, 89-90(1-5), 571–3.

  10. Wang, T.-T., Nestel, F. P., Bourdeau, V., Nagai, Y., Wang, Q., Liao, J., … Hanrahan, J. H. (2004). Cutting edge: 1,25-dihydroxyvitamin D3 is a direct inducer of antimicrobial peptide gene expression. Journal of Immunology (Baltimore, Md.: 1950), 173(5), 2909–2912.