Vitamin D is known as the sunshine vitamin. Well, I certainly haven’t got a lick of vitamin D from the sun this winter, especially not during the holidays when a blast of arctic air swooped down, plunging temperatures to minus ridiculous. Seriously, it was 40 below in Norfolk, NE, where I work as a Nurse Practitioner in an ER, and as a functional medicine practitioner at a diabetes wellness clinic. Forget about worrying about your blood sugar when it’s that cold. Your only concern is praying that the electricity doesn’t go out and you don’t freeze to death. 

Most people in the U.S. should take a vitamin D3 supplement. Dietary sources are few and far between: fatty fish like salmon, cod liver oil, egg yolks, mushrooms, and beef liver. Not only that, the winter sun in all but the extreme south of the U.S. is too weak for our bodies to synthesize vitamin D3. 

How do you know if you need to take a supplement? The first step is to take a comprehensive lab test, which I can order and evaluate for you. 

Why Should You Care About Vitamin D? 

You may already know that vitamin D affects bone health and immune function. In addition, it also plays a critical role in: 

  • Muscle contraction
  • Cellular health
  • Cardiovascular health
  • Mood and mental wellness
  • Inflammation control
  • Hormone regulation
  • Fetal development

There’s one more function of vitamin D you should be aware of if you’re trying to manage blood sugar levels: controlling insulin resistance. 

Vitamin D & Insulin Resistance: What’s The Connection?

Insulin resistance is where the body’s cells become less responsive to the blood-sugar-controlling hormone insulin. Insulin resistance is a key player in developing type 2 diabetes and, as research suggests, Alzheimer’s, which some health experts are now referring to as type 3 diabetes. 

So how can adequate vitamin D levels make you more sensitive to insulin, meaning your body needs less of the hormone to enter the cells and regulate blood sugar? 

For starters, let’s learn some basic facts about vitamin D. Once in the body, vitamin D undergoes metabolic processes to become an active hormone known as calcitriol. This active form plays a crucial role in various physiological functions, including calcium absorption, bone health, immune system modulation, and, as recent research suggests, insulin sensitivity.

A 2020 study says, “It has been found that vitamin D mediated increase in insulin sensitivity occurs via binding of calcitriol to vitamin D receptor, induction of Insulin Receptor substrate expression [140], and the activation of peroxisome proliferator-activated receptor delta.”

Are your eyes glazing over?  The important takeaway is that vitamin D directly affects insulin levels.

Insulin Resistance: A Growing Concern

Insulin, produced by the pancreas, is essential for regulating blood sugar levels. It facilitates glucose uptake by cells, providing them with the necessary energy. Insulin resistance disrupts this process, leading to elevated blood sugar levels and, over time, the development of type 2 diabetes. 

Vitamin D and Insulin Sensitivity: How Does It Work?

Vitamin D impacts pancreatic beta cells that are responsible for insulin production. Vitamin D receptors have been identified in these cells, indicating a direct link between vitamin D and insulin secretion. But that’s not the only way vitamin D may enhance insulin sensitivity. There are also vitamin D receptor sites in muscle and fat tissue. By improving the efficiency of insulin in these tissues, vitamin D may contribute to better glucose uptake and utilization.

According to the World Journal of Diabetes, vitamin D deficiency can be detrimental to insulin synthesis and secretion. In some human observational trials, there is an inverse correlation between vitamin D and insulin insensitivity, pre-diabetic states, and dysglycemia. In other words, low vitamin D levels have been found to be associated with blood sugar problems. On the flip side, The Journal of Biomedicine and Biotechnology says that vitamin D plays a role in glucose homeostasis by improving insulin sensitivity in target cells, such as the liver, skeletal muscle, and adipose (fat) tissue. It also enhances and improves beta-cell function. 

Some researchers believe that vitamin D may regulate gene expression in insulin signaling. Additionally, vitamin D is known to have anti-inflammatory properties, and chronic inflammation is closely linked to insulin resistance. By mitigating inflammation, vitamin D contributes to improved insulin sensitivity.

Vitamin K2: The Co-Factor For Vitamin D3

If you’re going to buy a vitamin D supplement, don’t go for a cheap brand. Like anything, you get what you pay for. Many vitamin D supplements lack the co-factor, Vitamin K2, also known as menaquinone. Co-factors help the body assimilate (uptake) certain nutrients. Magnesium is a co-factor for hundreds of processes in the body. Taking a vitamin D supplement that doesn’t have vitamin k2 is like keeping your gas tank full but having no motor oil. 

Vitamin K2 is involved in activating proteins, including osteocalcin and matrix Gla-protein (MGP). I know, boring stuff. However, these proteins play roles in calcium metabolism and distribution. Proper calcium metabolism is crucial for maintaining insulin sensitivity. Abnormal calcium deposition has been linked to insulin resistance, and vitamin K2’s role in directing calcium to the appropriate tissues may contribute to metabolic health.

Osteocalcin is produced by osteoblasts in bones, and when it’s activated, it may directly improve insulin sensitivity. In addition, Vitamin K2 has anti-inflammatory properties, and chronic inflammation is associated with insulin resistance. By reducing inflammation, vitamin K2 contributes to better insulin sensitivity.

Let me leave you with one more crucial role of Vitamin K2: preventing the inappropriate calcification of blood vessels. Proper vascular health is crucial for metabolic function, and vitamin K2’s involvement in preventing your arteries from calcifying (hardening) will improve insulin sensitivity. 

How To Purchase a High-Quality Vitamin D Supplement

If your skin hasn’t seen the light of day in months, you definitely should purchase a vitamin D3 supplement (with K2 co-factor). I’m not one for pushing supplements on people. Before you purchase a supplement, I recommend knowing what your baseline levels are. 

Contact me here to learn more about my functional medicine services, where I get to the root causes of your health concerns rather than chase symptoms. 

Until next time, 

Jenna Witt, NP

Fundamental Wellness of Nebraska, Founder