What Is the Best Form of Vitamin D?

Hi, I'm Dr. Marie Starling.

At The Healing Center, we help people like you reach their full potential.

I specialize in adjunctive care for internal disorders, autoimmune conditions, IBS, thyroid symptoms, diabetes, and other complex health issues.


By Jessica Yoches, CNTP, MNT and Dr. Starling DC, DCCN

Spring is here, which means longer days of sunshine and increased access to the UVB rays that activate the body’s own Vitamin D production in your skin. This is critical for optimum immune function, especially if you have Hashimoto’s, MS, Celiac disease, Lupus, or another autoimmune condition.

However, around 50% of the nation is deficient in this crucial nutrient for these reasons:

  • Insufficient exposure to sunlight without sunscreen (even an SPF 8 sunscreen can block UVB rays by 100%)
  • Low fat diets and diets low in foods with Vitamin D
  • Poor functioning digestive system, liver, gallbladder, kidneys, or pancreas
  • Obesity
  • Darker Skin
  • Living at Northern Latitudes, such as in Colorado, where the Earth’s atmosphere blocks almost all the UVB rays; from November to March all rays are blocked, making supplemental Vitamin D imperative.
  • Medications such as steroids and antacids that block its absorption
  • Vitamin D absorption is a complicated process that relies on many factors

Vitamin D Absorption and Micellization and Fat

Because it is fat-soluble, Vitamin D must be consumed in the presence of healthy fats and with a proper functioning gallbladder, digestive tract, and pancreas; a low fat diet fails to support absorption, as does impaired organ function. Ideal Vitamin D levels in your blood are 80-100 ng/ml.

When supplementation is needed, the form of Vitamin D really matters; for example, the powder form of Vitamin D is the least bioavailable.

What is the best form? Either Vitamin D in an oil or fat base, or the micellized form, which includes a fat, are the two best sources.

Micellization is a process that mimics the body’s break down of fat into tiny, water-soluble structures that can reach the absorptive cells of the digestive tract. These structures are called micelles.

The digestive tract is lined with a water solution, so Vitamin D must be emulsified and made water soluble to enter the mucosal absorptive cells.

This is why the micellized form of Vitamin D3 is optimal because it is already emulsified and readily bioavailable. It can normalize absorption for those with malabsorption issues.

For a lot of patients we see at The Healing Center with autoimmune conditions or leaky gut, taking bioavailable Vitamin D is extremely important through the healing process while the body cannot convert D into a usable form.

Micellized Vitamin D has significantly better absorption rates than either standard or emulsified forms1.

What is Vitamin D and why is it important?

Vitamin D is an essential nutrient that is not actually a vitamin, but a hormone that every cell in the body relies on for peak function.

  • Vitamin D plays an integral role in bone health and in cancer, autoimmune, and heart disease prevention.
  • A deficiency of this essential nutrient not only impairs the immune and cardiovascular systems, but also mood, asthma, neurological imbalances, blood pressure, and other issues.
  • Your body can produce its own Vitamin D via UVB rays from the sun – just 15 to 20 minutes with skin exposure between 10am and 2pm is sufficient.
  • Pink skin means that you have produced 10,000 IUs of Vitamin D in the skin.
  • It also means time to cover up; overexposure to the sun leads to skin cancer, so make sure to cover up after 20 minutes or if the skin is pink.

Natural food sources of Vitamin D

Animal sources are best as they are in the D3 form which is bioavailable and better than plant based sources that are in D2 form and must be converted to D3. These include:

  • Wild caught salmon and mackerel, fatty fish like sardines and shrimp
  • Eggs
  • Mushrooms
  • Halibut and Cod liver oils
  • Liver (organ meat)
  • Butter – grass-fed


Blood Testing

It is best to test your whole family for Vitamin D, especially if anyone is autoimmune. Testing in the spring lets you know if your winter levels are too low and what your supplementation levels should be. Testing in the fall shows you if you are getting enough summer exposure. If you supplementing with Vitamin D, you should always test at least one time per year.

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