Many of us know that Vitamin D is important for our health, but how can we determine whether we need more of it—and if so, how much? Moreover, what should we do if supplementation doesn’t work? In this article, I will unpack why we need Vitamin D, how to measure and consume it, and why some of us might not respond to Vitamin D supplements.   

Vitamin D is a fat-soluble nutrient that has an active role in many health functions—most notably, bone strength. Vitamin D can also reduce the risk of heart disease, high blood pressure, Type-2 diabetes, respiratory infections, depression, dementia, cancer, and many auto-immune diseases such as Multiple Sclerosis, Lupus, Hashimoto’s, and Rheumatoid Arthritis.  

The simplest method of vitamin D consumption is through the sun’s ultraviolet (UV) rays. When UV light hits our skin, a process called photo-biomodulation activates vitamin D, so it can begin to perform its many functions. The problem is there are many variables that determine how much vitamin D the body can produce during sun exposure. Some of these factors include our age, skin color, where we live, the time of year, length of exposure, amount of skin covering, and type of sunscreens. Vitamin D can also be obtained to a lesser degree from foods like fatty fish, beef liver, egg yolks, and mushrooms.  

Vitamin D levels can also be influenced by inadequate vitamin A and magnesium intake (which many of us are deficient in), as well as gut, liver, and kidney function. Another overlooked factor that can cause low vitamin D levels is a genetic defect in how the body activates or hydroxylates Vitamin D in the liver and kidneys. We can measure this with blood tests by looking at the 25, OH Vitamin D3 levels and the 1.25 OH Calcitriol levels. This will determine whether the body can activate Vitamin D both in the liver and kidneys.   

When looking at these lab values to assess vitamin D levels, medical physicians will often consider “normal” ranges to be between 30-100 ng/ml. However, when evaluated through the lens of a functional medicine provider—with the goal to maintain bone, heart, brain and immune health—we want both the 25, OH Vitamin D3 and the 1.25 OH Calcitriol to be in a range of 60-100ng/ml, with Calcitriol equal to or greater than the 25-OH D3 level.   

When we find a person deficient in Vitamin D, this usually means they will need to supplement with Vitamin D3 for the rest of their life. I often hear from patients that once their Vitamin D is within a normal range, they are told not to supplement anymore, but this often causes them to become deficient again.  

So, what is the long-term dose a person needs to take to maintain optimal Vitamin D levels? This will often require frequent and consistent testing to see how the body is absorbing and activating vitamin D. Everyone’s need for Vitamin D3 is different, so the answer is not one-size-fits-all. Some might find it difficult to keep their Vitamin D at optimal levels due to genetic variants, medications, vitamin A or magnesium deficiencies, and infections such as Epstein Barr, Cytomegalovirus, or Lyme’s Disease.   

When supplementing with Vitamin D3, it’s also important to take it along with Vitamins K2. This is not to be confused with K1, the clotting vitamin. Vitamin K2 works with Vitamin D3 in both the absorption and distribution of calcium. While Vitamin D3 aids with absorbing calcium into the body, Vitamin K2 controls where calcium is deposited to make sure it enters bones, not the arteries, kidneys, or other soft tissues.  

Vitamin D is one of the most important nutrients for optimal health, and while most of us are deficient in vitamin D, achieving the ideal levels will differ for everyone. Testing for vitamin D frequently and working with a functional medicine practitioner to reach the correct levels is a powerful way to prevent or manage chronic illness.   

Dr. Laura Korman, DC, is a functional medicine practitioner, chiropractor, and nutritional counselor. She is also the owner of Korman Relief and Wellness Center, located at 16954 Toledo Blade Blvd., Port Charlotte. For more information and to schedule an appointment, call 941-629-6700 or visit https://www.drlaurakorman.com/