If you have lymphoma, you may be curious how vitamin D may impact cancer risk, disease progression, and your overall health. As one MyLymphomaTeam member said, “I found out my vitamin D is mildly low … I hope that doesn't make treatment hard.”

Another member wrote of their own vitamin D levels, noting, “I think vitamin D does have a tendency to cause fatigue and depression when it’s low.”

There is some evidence to suggest a connection between a person’s vitamin D levels and their lymphoma. Additionally, vitamin D offers several health benefits. Consider speaking with your health care provider about your vitamin D levels and whether increasing your intake could 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, swordfish, herring, and cod liver oil)
• Egg yolks
• Fortified milk and orange juice

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

Vitamin D and Lymphoma — Is There a Link?

Vitamin D is known for its health benefits and its potentially preventative effects on several types of cancer, so you may wonder whether there is a link between vitamin D deficiency and the development of lymphoma.

Although the research is still not conclusive, it suggests that there may be some connection. For people with lymphoma, low levels of vitamin D can lead to poorer outcomes, both in terms of disease progression and overall survival.

Moreover, a study from the Wilmot Cancer Institute found that people with follicular lymphoma who had low vitamin D levels before starting treatment were more likely to relapse sooner or die of the disease.

Vitamin D supplementation may even be helpful during lymphoma treatments. A 2018 study looked at people with diffuse large B‐cell lymphoma who were undergoing rituximab‐based treatment. The study found that vitamin D supplementation — which increased participants’ 25-hydroxyvitamin D serum levels — improved health care outcomes.

Should You Take Supplements?

Research suggests that vitamin D deficiency or insufficiency may impact lymphoma outcomes. However, it’s still not known what other impacts vitamin D supplementation may have on people with lymphoma. Without knowing with certainty what those effects may be, many oncologists are wary of making blanket recommendations regarding the vitamin D levels of people with lymphoma.

As one oncologist pointed out, “Ongoing randomized trials are currently addressing key questions, such as the threshold level of vitamin D to define insufficiency, and, most importantly, whether vitamin D supplementation can indeed overcome the inferior prognosis associated with a low vitamin D level at diagnosis of lymphoma.”

It's important to have a conversation with your oncologist before starting on any supplements, as they 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.

Talk With People Who Understand

On MyLymphomaTeam, the social network and online support group for people with lymphoma and their loved ones, members discuss the chronic nature of the disease. Here, more than 8,800 members from across the world come together to ask questions, offer advice and support, and share stories with others who understand life with lymphoma.

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