Daily supplementation of cholecalciferol, also known as vitamin D3, can reduce the risk of fatal cancer by nearly 40 percent.
The link between vitamin D and cancer has captivated experts’ mind for years.
People in areas that receive higher amounts of sunshine and so high amounts of vitamin D have lower rates of death from many types of cancer.
Animal studies show that vitamin D slows the progression of cancer cells, but clinical studies on humans couldn’t give a certain answer until now.
The Vitamin D and Omega-3 Trial (VITAL) examined whether higher serum 25-hydroxyvitamin D (vitamin D levels in the blood) has any connection with reducing the risk of lethal cancers.
They found that daily intakes of 2,000 IU of vitamin D3 were associated with a 17 percent reduced risk in cancer.
But, an examination of participants with a normal BMI (body mass index) showed a risk reduction of 38 percent in these individuals.
This means that factors related to obesity such as excess body fat could lower the beneficial effect of vitamin D supplements.
Obesity has also been shown to damage the immune system, including destruction of natural killer cell function and long-term inflammation.
Dr Paulette Chandler, the study’s first author, said:
“These findings suggest that vitamin D may reduce the risk of developing advanced cancers.
Vitamin D is a supplement that’s readily available, cheap and has been used and studied for decades.
Our findings, especially the strong risk reduction seen in individuals with normal weight, provide new information about the relationship between vitamin D and advanced cancer.”
The five years VITAL research involved 25,871 adults who had no cancer at the start of the trial.
The study wanted to see the possible reduction in cancer death by a combination or individual effects of omega-3 and vitamin D supplementations.
Participants were put into four groups:
- 2,000 IU vitamin D plus 1 g fish oil per day,
- vitamin D plus placebo,
- omega-3 plus placebo,
- and the fourth group received only placebos instead of vitamin D with fish oil.
The discovery that BMI influences the role of vitamin D has also been suggested in previous studies.
Moreover, inflammation due to obesity would reduced vitamin D effectiveness by changes in vitamin D receptor function or vitamin D response.
Cancer patients have been found to be low in vitamin D with research suggesting that the deficiency rate is 72 percent among these sufferers.
More evidence also confirms that the higher someone’s body fat the bigger the risk of developing cancers.
Dr Chandler said:
“Our findings, along with results from previous studies, support the ongoing evaluation of vitamin D supplementation for preventing metastatic cancer—a connection that is biologically plausible.
Additional studies focusing on cancer patients and investigating the role of BMI are warranted.”
The study was published in the journal JAMA Network Open (Chandler et al., 2020).