Vitamin D Reduces Risk of Melanoma and Other Skin Cancer: Study

Vitamin D supplementation could help reduce cancer risk. Shutterstock

Interest in the sunshine vitamin exploded during the COVID-19 pandemic because of its immunity-boosting effects. A new study found that regularly taking vitamin D supplements is linked to a significant reduction in melanoma risk.

Researchers also discovered that people who regularly took vitamin D supplements also had reduced risk of other kinds of skin cancer.

The new study was conducted under the North-Savo Skin Cancer Program in Finland and included 498 adult patients estimated to have an increased skin cancer risk for:

• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma

Serum calcidiol levels, a measure of vitamin D in the blood, were analyzed in about half of the patients and were found to correspond to the patients’ self-reported intake of vitamin D supplements.

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A key finding was that among regular vitamin D users, there were lower percentages of participants with a history of past or present melanoma—only 18 percent compared to 32 percent in those who didn’t take vitamin D supplements.

When researchers looked at other types of skin cancer, just 62 percent of regular supplement users had a history of the disease, compared to nearly 75 percent of non-users.

“Regular use of vitamin D associates with fewer melanoma cases, when compared to non-use, but the causality between them is obscure,” the study authors wrote.

Dr. Adam Starr, an oncologist at Staten Island University Hospital, part of Northwell Health in New York, told The Epoch Times that there are several possible reasons vitamin D could have an anti-melanoma effect.

“[Reasons could include] modulation of the immune system and [vitamin D’s] antioxidant effects,” he said. “Additionally, the relationship between vitamin D metabolism and sunlight exposure, plus melanoma and sunlight exposure may have some interplay.”

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Research shows that vitamin D also reduces inflammation associated with increased cancer risk, has antitumor properties, and even improves the effectiveness of some anticancer therapies.

Vitamin D is known to help our bodies absorb and retain calcium and phosphorus, which are crucial for healthy bones. Many organs and tissues have receptors for vitamin D, suggesting that this nutrient plays important roles beyond bone health.

Sun Exposure, Necessary for Vitamin D, Also Cancer Risk

Vitamin D is both a vitamin found in food and a hormone our bodies produce when exposed to sunlight.

While exposing our skin to sunlight is among the best ways to get vitamin D, natural ultraviolet light is also a risk factor for melanomas and nonmelanoma skin cancer.

Periodic sun exposure and being sunburned during childhood and adolescence are also associated with increased melanoma risk, especially for fair-skinned people with blond or red hair. Treatment for melanoma is limited to surgical removal, as the condition has a low response rate to chemotherapy.

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However, about 35 percent of U.S. adults are vitamin D deficient, and the American Osteopathic Association blames sunscreen use (used by many to prevent skin cancer) as the culprit.

“People are spending less time outside and, when they do go out, they’re typically wearing sunscreen, which essentially nullifies the body’s ability to produce vitamin D,” Dr. Kim Pfotenhauer, a board-certified osteopathic family physician and assistant professor at Touro University, said in a statement.

The solution is moderation; spend five to 30 minutes in mid-day sun twice per week, depending on your geographic location and skin pigmentation (lighter skin makes more vitamin D than darker skin). Pfotenhauer said it’s important to forget the sunscreen during these sessions because SPF 15 or higher can decrease vitamin D production by up to 99 percent.

“You don’t need to go sunbathing at the beach to get the benefits,” Pfotenhauer said. “A simple walk with arms and legs exposed is enough for most people.”

Vitamin D Supplementation Upper Limit for Healthy People

When taking vitamin D supplements, there’s an optimal daily dose, and taking more than that could adversely affect our health.

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Starr cautioned that vitamin D requirements depend on a person’s baseline vitamin D level and whether they have a malabsorption condition.

“Therefore, the amount one should take if they want to supplement should be discussed with their physician,” he said.

For healthy adults with normal absorption, the National Institutes of Health recommends a maximum of 4,000 international units (IU) per day for adults 19 years and older.

The amount of supplementation that’s too much is still unclear, but there’s evidence that taking 60,000 IU per day for several months could be toxic.

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The main risk of too much vitamin D is a condition called hypercalcemia (too much calcium in the blood), which can lead to various neurological symptoms.

“[Symptoms of hypercalcemia include] confusion, fatigue, coma, as well as bone pain, weakness, stomach pain, nausea, constipation, increased urination, kidney problems, among many others,” Starr said.

Vitamin D Could Protect Against Other Cancers

Regarding the Finnish study, Starr said it’s interesting but still insufficient evidence to recommend taking vitamin D to prevent melanoma because that study had too many confounding factors.

“For example, patients who take vitamin D might also be more likely to wear sunscreen, and that might be what actually accounts for the difference,” he said. “The authors did a statistical analysis to try to eliminate these biases, but the history of these kinds of studies [shows] that a clinical trial, or a forward-looking prospective study, is really needed to definitively say that vitamin D might lower the risk of melanoma.”

But this is only one of many studies in recent years that finds an association between vitamin D levels and cancer risk.

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Research published in 2018 that looked at data from about 13,000 people found that not taking enough vitamin D could increase our risk of colorectal cancer by up to 31 percent.

Another study found that prostate cancer cells responded to vitamin D with decreases in proliferation, invasiveness, and metastasis (spreading in the body).

Not all the research showed a prevention benefit, but scientists still observed a potentially life-saving effect. A recent meta-analysis of randomized controlled trials concluded that vitamin D supplementation significantly reduced total cancer mortality, although it failed to reduce total cancer incidence.

Harvard Health recommends that healthy-weight people at risk for developing cancer because of lifestyle or family history of cancer take daily vitamin D supplements starting at about age 50.