If you’re living with myeloproliferative neoplasms (MPNs), you may be curious about the role vitamin D plays in disease progression and your overall health. As one myMPNteam member said, “I am experimenting — with the knowledge of my hematologist/oncologist — with vitamin D3 daily supplements after he measured my vitamin D levels.”

Although research is inconclusive as to whether there are any direct connections between vitamin D intake and MPNs, the nutrient may help with your symptoms and your overall health. Conferring with your doctor can help you determine whether increasing your vitamin D intake can be beneficial.

What Is Vitamin D?

Vitamin D is a nutrient that your body needs to make your muscles move, help your nerves send signals, and allow your immune system to fight off bacteria and viruses that can make you sick. Vitamin D is also important so bones can absorb the calcium they need to be strong and healthy.

There are two kinds of vitamin D: vitamin D2 and vitamin D3. Vitamin D2 is mostly found in plants, mushrooms, and yeast. Vitamin D3 can be found in oily fish and is also made in the body during sun exposure. Additionally, vitamin D3 is later converted to 25-hydroxycholecalciferol, which helps turn on and off the genes that allow vitamin D to carry out its function in the body.

According to the Cleveland Clinic, foods that are good sources of vitamin D include:

• Beef liver
• Fortified cereal
• Fish (such as salmon, sardines, herring, swordfish, and cod liver oil)
• Egg yolks
• Fortified milk and orange juice
• Some vegetables such as kale, okra, spinach, white beans, soybeans

Your body breaks vitamin D down into its active form, called 1,25-dihydroxyvitamin D — which is also known as calcitriol. It’s available as a supplement that can be taken daily or weekly. This active form of vitamin D can affect the cells involved in the immune system.

Vitamin D and MPNs — Is There a Link?

Vitamin D is known for its health benefits and its potentially preventative effects on several types of cancer. Additionally, MPNs start in the bone marrow, and the vitamin is known for its role in promoting bone health. As such, it may make you wonder whether there is a link between vitamin D deficiency and the development of myeloproliferative neoplasms.

Among its various functions, vitamin D is also involved in cell differentiation (the process of a cell changing from one type to another). This includes tumor cells. Research shows that vitamin D deficiency is relatively common in people with MPNs and myelodysplastic syndromes. However, the data still isn’t clear on whether this has a direct effect on disease prognosis (outlook).

Vitamin D’s impact on MPNs may also depend on what type you have, as well as other complex genetic factors. For example, a 2020 study that measured people’s serum 25-hydroxyvitamin D levels found that people with MPNs called essential thrombocythemia and polycythemia and who had a certain mutation — called the Janus kinase 2 mutation — were more likely to be deficient in vitamin D, compared to people without the mutation.

More research is needed to determine exactly how vitamin D relates to different kinds of MPNs, but it’s important to check in with your doctor and have a conversation about your vitamin D status.

Should You Take Vitamin D Supplements?

Considering what the research indicates regarding vitamin D and MPNs, you may be wondering if taking vitamin D supplements is right for you. It is certainly reasonable if your vitamin D levels are low. It's important to have a conversation with your oncologist before starting on any supplements, as your physician can best advise you regarding how they may affect your specific case. Monitoring a vitamin D deficiency is only one part of your cancer care, and having open conversations about your concerns is the best way for you and your doctor to be on the same page about your treatment goals.

Additionally, there is a risk that comes along with taking too much vitamin D. The federal Office of Dietary Supplements warns that too much vitamin D can cause nausea and vomiting, muscle weakness, confusion, pain, dehydration, and kidney stones, among other side effects. Vitamin D can also interact with some medications, so don’t start any supplementation plan before speaking with your physician.

Talk With People Who Understand

On myMPNteam, the social network and online support group for people with MPNs and their loved ones, members discuss the chronic nature of the disease. Here, more than 1,500 members from across the world come together to ask questions, offer advice and support, and share stories with others who understand life with myeloproliferative neoplasms.

Have you ever investigated your vitamin D status? Share your experience in the comments below, or start a conversation on myMPNteam.