Dec. 7, 2009 -- Healthy levels of vitamin D may help patients with a certain type of non-Hodgkin's lymphoma live longer.

Researchers at the Mayo Clinic have discovered that patients with diffuse large B-cell lymphoma (DLBCL) and low vitamin D levels are two times more likely to die from the cancer than patients with optimal levels. Deficient vitamin D levels also increased the chances of cancer progression.

"These are some of the strongest findings yet between vitamin D and cancer outcome," Matthew Drake, MD, PhD, an endocrinologist at Mayo Clinic in Rochester, Minn., says in a news release. "While these findings are very provocative, they are preliminary and need to be validated in other studies. However, they raise the issue of whether vitamin D supplementation might aid in treatment for this malignancy."

Non-Hodgkin's lymphoma is a cancer of the white blood cells. DLBCL is the most common type of non-Hodgkin's lymphoma. The fast-growing cancer usually occurs in adults.

The new findings are based on a study of 374 patients who were newly diagnosed with DLBCL. Blood testing showed that half of them had a vitamin D deficiency. Vitamin D deficiency was defined in this study as less than 25 nanogram/milliliter of total vitamin D in the blood.

Those with deficient vitamin D levels were 1.5 times more likely to have the cancer progress, and had a twofold increase in the risk for dying.

The findings add credence to the growing body of evidence that suggests vitamin D plays an important role in cancer risk and survival. But the American diet usually doesn't provide enough vitamin D. Few foods and drinks naturally contain the vitamin, although some, such as milk, cereals, and certain brands of orange juice, are fortified with it.

The body's greatest supply of vitamin D comes from the sun. The body makes vitamin D after direct exposure to the sun's UV rays. One cause of vitamin D deficiency is limited exposure to sunlight.

"The exact roles that vitamin D might play in the initiation or progression of cancer is unknown, but we do know that the vitamin plays a role in regulation of cell growth and death, among other processes important in limiting cancer," Drake says.

The study team will present their results this week at the 51st annual meeting of the American Society of Hematology in New Orleans.