As we head into the darker months many people begin to supplement with vitamin D.  In many cases this is a good step in maintaining mood, immune and bone health.  In fact many people don’t realize that every cell in the body has a vitamin D receptor.  Hundreds of genes and their expression are influenced by this important nutrient.  Muscle and cell growth also requires adequate levels of vitamin D.

Up to 70% of our population may be deficient.  This is largely due to diet and lifestyle factors that need to be addressed.  Supplementation alone is not the solution.  Given that deficiency is so common and linked with so many of our chronic, modern diseases its understandable why supplementation has become so popular.

What you didn’t expect about Vitamin D

In recent years high dose supplementation has become commonplace.  What you may not expect is that high levels of vitamin D in the body can be as harmful as low levels. As a fat soluble vitamin we need to consider the consequences of toxicity.  Evidence shows an increase of cardiovascular incidents, kidney stones, headaches, nausea, vomiting, diarrhea, loss of appetite, and even low bone density.

It’s great that more doctors than ever are testing vitamin D levels. However, like many nutrients, vitamin D follows a U-shaped curve, meaning that both low levels and very high levels are associated with negative health outcomes (16).

Deficiency Linked to all the big ones

With an increased risk of heart attack, cancer, diabetes, asthma, and autoimmune disease there is real cause for concern.  Unfortunately, few practitioners are aware of the dangers of vitamin D toxicity.  Many are testing serum vitamin D once and recommending a daily 5,000 or 10,000 IU supplement.  Ongoing monitoring during supplementation along with other interventions is what we need to see.

Testing Vitamin D

Vitamin D status is measured by 25(OH)D in blood. This is the precursor to active vitamin D and is generally considered the most accurate single marker to assess vitamin D status. The laboratory reference range for adequate 25(OH)D is 30 to 74 ng/mL.

But a large body of evidence in the medical literature strongly suggests that optimal vitamin D levels might be lower than these figures. There is little to no evidence showing benefit to 25(OH)D levels above 50 ng/mL

Sunlight has Hormonal Benefits

Sunlight induces relaxation and increases pain tolerance via a natural opiod called beta endorphin.  A 20-year study following 30K subjects found that those individuals avoiding sun exposure were twice as likely to die from all causes.  This is because peptides like substance P and calcitonin gene are stimulated by UV rays reducing oxidative stress, vascular inflammation and hypertension.  Libido is increased and cortisol is lowered by two hormones that also reduce appetite and regulate the immune system.

Exposure to bright light during the day activates neurons in the suprachiasmatic nucleus of the hypothalamus, which sends signals to the pineal gland that regulate melatonin production. Our circadian rhythm is associated with mood, cognition, and metabolic health.

Parathyroid Hormone 

We can use parathyroid hormone (PTH), calcium, and active vitamin D3 as markers for a more complete picture of vitamin D status. Dr. Chris Masterjohn suggests that serum PTH levels above 30 pg/mL may be indicative of biological vitamin D deficiency when 25(OH)D levels are borderline low. Conversely, if 25(OH)D levels are borderline low or even slightly below the laboratory reference range (e.g., 25 to 30 ng/mL), but PTH is less than 30 pg/mL, it is unlikely that vitamin D is deficient. Therefore more vitamin D is not necessarily better.  For optimal calcium and bone health we want to see parathyroid levels suppressed adequately. Ask your doctor to test PTH if you have concerns about bone health.

Conclusion

The functional range for 25(OH)D is between 35 to 60 ng/mL. This is variable though.  For example the optimal range may be a bit lower for those with darker skin pigmentation. Anyone with autoimmune disease may need to tend on the higher end of the range to maximize the immune benefits of vitamin D.

  1. Don’t just supplement Vit D without knowing your level
  • less than 20 ng/mL: Combine with daylight exposure, cod liver oil, and even a vitamin D supplement at this level.
  • 20 to 35 ng/mL: If your parathyroid hormone is less than 30 pg/mL then supplementing is likely unnecessary.
  • 35 to 50 ng/mL: Your current diet and lifestyle is maintaining adequate vitamin D levels.  Continue on course.
  • greater than 50 ng/mL: Reduce your vitamin D supplements.  Ensure you are getting adequate amounts of the other fat-soluble vitamins to protect against toxicity
  1. Test and Retest
    Your diet, lifestyle, or supplements changes can mean that retesting after three to four months makes sense.  We want to see if what we are doing is working or working too well in some cases.
  1. Sunlight is the primary source of vitamin D
    Reap the many benefits of sunlight beyond just subcutaneous production of vitamin D, and reduce your chance of achieving toxic levels. Spend about 15 to 30 minutes, or about half the time it takes your skin to turn pink, in direct sunlight. Sunscreens not only block production of vitamin D, but also all of the other beneficial photoproducts produced in the skin in response to UVB.
  1. Micronutrients from food sources are safer
    Cod liver oil is a good source of vitamins A and D. Pastured butter and dairy can provide adequate vitamin K. Sweet potatoes, bananas, plantains, and avocados all contain significant amounts of potassium. Magnesium is a safe micronutrient to supplement as we can’t get enough from food due to soil depletion.