Vitamin D deficiency and its role in thyroid disorders

547 points
Vitamin D deficiency and its role in thyroid disorders

Vitamin D is in fashion. It seems like every day another article is published in medical journals or the mainstream press about the dangers of vitamin D deficiency and the benefits of supplementation. In this article, we will discuss the impacts of vitamin D on thyroid physiology and delve into the topic of vitamin D supplementation, specifically as it relates to thyroid disorders.

Vitamin D deficiency and its relationship with autoimmune thyroid disease

Vitamin D deficiency it has been associated with numerous autoimmune diseases in the scientific literature. Vitamin D plays an important role in balancing the Th1 (cell-mediated) and Th2 (humoral) arms of the immune system. It does this by influencing regulatory T cells (Th3), which govern the expression and differentiation of Th1 and Th2 cells.

Vitamin D deficiency is also specifically associated with autoimmune thyroid disease (AITD) and has been shown to benefit autoimmune-mediated thyroid dysfunction.

Vitamin D has another little-known role. It regulates insulin secretion and sensitivity and balances blood sugar. Vitamin D deficiency is associated with insulin resistance. Insulin resistance and dysglycemia negatively affect thyroid physiology in several ways.

Mechanisms that reduce the absorption of vitamin D

Research over the past two decades has identified a variety of mechanisms that reduce the absorption, production, and biological activity of vitamin D in the body.

  • Since vitamin D is absorbed in the small intestine, an inflamed and leaky GI tract, which is extremely common in people with low thyroid function, reduces the absorption of vitamin D.
  • High cortisol levels (caused by stress or medications such as steroids) are associated with lower levels of vitamin D. The synthesis of active vitamin D from sunlight is dependent on cholesterol. Stress hormones are also made from cholesterol. When the body is in an active response to stress, most of the cholesterol is used to make cortisol and not enough is left for vitamin D production.
  • Obesity reduces the biological activity of vitamin D. Obese people have lower serum levels of vitamin D because fat cells absorb it.
  • Not eating enough fat or not digesting it properly reduces the absorption of vitamin D. Vitamin D is a fat-soluble vitamin, which means that it requires fat to be absorbed. People on low-fat diets and people with conditions that prevent fat absorption (such as IBS, IBD, gallbladder or liver disease) are more likely to have low vitamin D levels.
  • A variety of medications reduce the absorption or biological activity of vitamin D. Unfortunately, these include medications that are among the most popular and frequently prescribed, including antacids, replacement hormones, corticosteroids, blood thinners, and blood thinners .
  • Aging reduces the conversion of sunlight into vitamin D.
  • Inflammation of any kind reduces the utilization of vitamin D.

Taking vitamin D supplementation, it’s not that simple

You’ll say, “I’ll just get my vitamin D checked and if it’s low I’ll take supplements.”
If only it were that simple. We now know that certain people with normal serum vitamin D levels still suffer from deficiency symptoms. How is this possible?

In order for circulating vitamin D to perform its functions, it must first activate the vitamin D receptor (VDR). The problem is that many people with autoimmune disease have a genetic polymorphism that affects the expression and activation of the VDR and, therefore, reduces the biological activity of vitamin D. Studies have shown that a significant number of patients with autoimmune Hashimoto’s disease have VDR polymorphisms.

In layman’s terms, here’s what this means: If you have low thyroid function, you may experience a vitamin D deficiency even if your blood vitamin D levels are normal. It also means that if you have a VDR polymorphism, you may need to have higher than normal levels of vitamin D in your blood to avoid the effects of vitamin D deficiency.

And this is where we venture into murky territory.

The question of how high should vitamin d levels be it is very difficult to answer in the case of someone with autoimmune thyroid disease. Studies suggest that the optimal level of vitamin D is 35 ng/mL for the average person. Some researchers have suggested that 50 ng/mL should be the minimum level.

However, most of the evidence does not support that claim.

Higher is not better when it comes to vitamin D

Some recent studies have shown that higher is not better when it comes to vitamin D. A study in the American Journal of Medicine found that, in most people, peak bone density occurs at vitamin D levels between 32 and 40 ng/mL.

When levels exceed 45 ng/mL, bone density begins to decrease. Another study published in European Journal of Epidemiology found that South Indian vitamin D levels above 89 ng/mL were three times more likely to have suffered from heart disease than those with lower levels.

When does vitamin D become toxic?

Recent work by researcher Chris Masterjohn suggests that the deleterious effects of vitamin D toxicity are caused, at least in part, by a corresponding deficiency in vitamins A and K2. According to Masterjohn, the fat-soluble vitamins A, D and K2 work synergistically.

Masterjohn’s hypothesis, which has been confirmed by others, raises the possibility that the higher levels of vitamin D that have been linked to lower bone density and heart disease may be safe if vitamin A and K2 levels are sufficient.

Various disorders affect the absorption of vitamin D

The research is clear that 35 ng/mL is the minimum level for optimal function for healthy people. But people with autoimmune thyroid diseases are not healthy.

They often have gastrointestinal disorders, inflammation, stress, excess weight, VDR polymorphisms, and other factors that affect their production, absorption, and utilization of vitamin D. This suggests that the minimum level of vitamin D for people with AITD it can be significantly higher than for healthy people.

Approach to monitoring vitamin D

A good approach with patients with vitamin D deficiency is to make a cautious attempt to raise his serum levels to a range of 60 to 70 ng/mL. If their symptoms improve to this level, switch them to a maintenance dose while you watch for clinical signs of vitamin D toxicity.

These include kidney stones (also a sign of vitamin K2 deficiency), lack of appetite, nausea, vomiting, thirst, excessive urination, weakness, and nervousness. Also, monitor serum calcium levels, because elevated blood calcium is a sign of vitamin D toxicity and a significant risk factor for cardiovascular disease (especially in the presence of vitamin K2 deficiency).

Calcium levels greater than 11-12 mg/dL (or 2.8-3 mmol/L) are indicative of vitamin D toxicity.

Also, make sure these patients get adequate amounts of vitamin K2 and vitamin A in their diets. Sources of vitamin A include organ meats, cod liver oil, and whole milk and cream from grass-fed cows. Sources of vitamin K2 include fermented foods such as natto, hard cheeses, and kefir, as well as egg yolks and butter from grass-fed cows. Also, a vitamin K2 supplement can be used if patients cannot tolerate fermented foods.

Over time, we can hope that the explosion of research being done on vitamin D will lead to greater clarity on the question of appropriate serum levels of vitamin D for people with autoimmune diseases.

Like it? Share with your friends!

547 points