The "sunshine vitamin" may assist in recovery from a number of cancers, according to a new paper published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.
The researchers found higher levels of vitamin D are linked to better survival rates for breast, colorectal and prostate cancers. The researchers also say the vitamin may play a critical in recovery for patients with leukemia, melanoma and Merkel cell carcinoma.
Their analysis is based on 25 prior studies that examine the links between vitamin D levels and cancer survival rates. The data reviewed for the paper accounts for more than 17,000 cancer patients. The study found cancer patients with a 10 nmol/L increase in vitamin D levels in their blood had a 4 percent higher survival rate than those with lower levels.
Vitamin D is essential to the body's absorption of calcium and phosphorus -- two minerals needed to maintain bone health. However, the researchers say it also binds to a protein called vitamin D receptors, which are present in all cells in the body, meaning that it's critical to a cell's normal life cycle.
The body produces vitamin D with exposure to sunlight and it's also absorbed from foods such as fish, milk and eggs.
The recommended dose for vitamin D varies depending on an individual's health. The Institute of Medicine suggests people 70 years or younger consume at least 600 IU of vitamin D each day, while people over age 70 get 800 IU. Experts say no one should exceed a daily vitamin D dose of 4000 IU.
But some researchers claim the benefits of vitamin D supplements are overrated, and taking the recommended dose has little to do with good health. A study published in Lancet Diabetes & Endocrinology in January analyzed 40 studies on vitamin D levels and chronic health conditions, such as heart disease, stroke, bone weakness and cancer. The researchers failed to find a substantial correlation.
The authors of this new study say it remains unclear how much vitamin D would be needed to help cancer patients. "In addition to the effective dose, other issues such as intervention time, the intervention methods, and potential side effects need to be considered in clinical trials," they write. "Well-designed, randomized clinical trials are warranted to answer these questions."