Educate Your Oncologist: What Vitamin D Level is Normal and Is Normal Good Enough?

Vitamin D acts as a hormone that helps everything from gut function to immune response to bone and joint strength. Adequate (or inadequate) levels affect your muscles, your bones, your nerves, and your immune system. If you feel tired, achy, sick or have low mood regularly – go check your vitamin D levels. This is a simple blood test that your primary care practitioner or oncologist can easily add to your next round of lab work. It is important to know where you’re starting before recommending random doses of a vitamin D supplement. 

Keep in mind that vitamin D is probably not on the top of your doctor’s checklist for monitoring and follow up. Vitamin D deficiency is a modern problem, so unless your doctor is up to date on current research, it’s unlikely that they understand how or why to prioritize it. The standard guidelines for normal vitamin D levels are:

  1. Below 30 nmol/L (12 ng/mL) is too low and might weaken your bones and affect your health
  2. 50 nmol/L (20 ng/mL) or above is adequate for most people for bone and overall health
  3. Above 125 nmol/L (50 ng/mL) is too high and might cause health problems

We can’t rely on nutritional sources for vitamin D and most of what we absorb comes from the sun. If you live in a place that doesn’t get sunlight all year round or you don’t work outside for the majority of your day, it’s unlikely that you’re getting enough vitamin D. We have a lot of environmental hazards working against us (our fruits and vegetables marinating in pesticides is a main one), so we can’t afford to be reactive anymore with health. We need a stronger defense system and vitamin D is a relatively easy intervention that helps our bodies fight off the effects of these environmental hazards.

What’s the difference between normal and optimal vitamin D levels for your body? Normal may be okay for someone who has no health problems AND healthy habits. We’re all aware of the poor health status of the general population and normal is not sufficient for most people who are struggling with chronic health problems because normal doesn’t help you prevent worse health problems, like cancer. That leaves us with optimal – this offers a stronger defense system to be able to decrease risk and reverse illness. The optimal level for vitamin D is closer to 30-50ng/ml (75-125nmol/L). The Endocrine Society believes that a concentration of more than 30 ng/mL (75 nmol/L)  is necessary to maximize the effect of vitamin D on calcium, bone, and muscle metabolism. 

Once you get your vitamin D results, follow up with your doctor about how much you should take to bring your level up to optimal. This may require taking a supplement every day, then re-checking your vitamin D level 2-3 months later to see if it’s working. If your doctor isn’t effectively able to work with you on finding the right dose and monitoring your results, you can start with 1000 units and then increase your dose every 2-3 months until your levels are up to the optimal range and/or you physically feel better. 

Here are a few articles you can send to your doctor to help educate them on vitamin D giving you a health advantage over disease, including cultural applications:

Shedding Light on Vitamin D and Integrative Oncology (2008)

Vitamin D and Cancer: A Uniform Dose is Unlikely to Fit All Patients (2017)

Guidelines for Preventing and Treating Vitamin D Deficiency: A 2023 Update in Poland (2023)

A few things to remember when taking vitamin D:

  1. Vitamin D dissolves in fat, so take it with food for better absorption and tolerance. Because it is stored in fat tissue, it can build up to unsafe levels, so you don’t want to take too high of a dose. This is why starting at a safe dose of 1000 units and getting your levels checked along the way is so important.
  2. Vitamin D3 is the more active form and therefore more effective than other forms, so be sure your supplement specifies this type. 
  3. Find a high quality vitamin D3 without fillers using this link to set up a free Fullscript account and get 20% off on us. D3 is a relatively inexpensive supplement, so go with the best price, but just ensure that the brand isn’t random and adheres to high quality standards.
  4. Depending on your gut health, you may or may not be able to absorb vitamin D pills as well, so consider ways to improve your gut health and consider vitamin D liquid drops or intramuscular injections of vitamin D (which you can find at local wellness clinics, since hospital systems do not offer them) while you work on improving your nutrition.

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The Cancer Team