Vitamin D is a hot topic currently, with a raft of studies proclaiming its benefits for a variety of serious conditions.
Conversely, other recent studies have been more cautious, questioning its perceived usefulness for treating some illnesses.
Vitamin D is a nutrient that is synthesized in our skin when it is exposed to sunlight, and it is also present in some foods.
Sunlight is the best source of vitamin D, but in the winter months, the National Institutes of Health (NIH) recommend topping up vitamin D levels by eating vitamin D-containing foods each day. These include oily fish, fortified milk, beef liver, egg yolks, mushrooms, and fortified breakfast cereals.
What does vitamin D do?
Scientists know that vitamin D is essential for many aspects of maintaining good health and that deficiency is linked with problems for both physical and mental health.
Perhaps most notably, vitamin D helps to regulate the levels of calcium in our bodies, strengthening our bones and preventing bone-weakening conditions, such as osteoporosis.
Increasingly though, studies are also suggesting that vitamin D might have protective benefits against heart failure, diabetes, cancer, respiratory tract infections, autoimmune disease, and even hair loss.
A surprisingly large number of people have insufficient levels of vitamin D. For instance, according to one study, more than 40 percent of adults in the United States are deficient. Because of its prevalence, it is important to determine what the public health implications of this epidemic might be.
Symptoms of vitamin D deficiency can vary between individuals, but they typically include pain in the joints, muscles, or bones; fatigue; breathing problems; and low mood or seasonal affective disorder (SAD).
Below, we run through a number of intriguing recent studies that investigate associations between vitamin D and an assortment of illnesses.
According to the study results, the higher the levels of vitamin D, the lower the risk of breast cancer.
This relationship remained significant even after the results were adjusted for confounding factors, such as age, body mass index (BMI), intake of calcium supplements, and smoking habits.
Although a link between vitamin D deficiency and colorectal cancer has previously been reported, not all studies have been able to replicate these findings. A new, large-scale study attempted to settle this by drawing on data from three continents, including 5,700 colorectal cancer cases and 7,100 controls.
The resulting Cochrane review, updated in 2015, explains that:
“Observational and circumstantial evidence suggests that there may be a role for vitamin D deficiency in the etiology of chronic painful conditions.” The team scrutinized the findings from a number of studies.
Following the analysis, they concluded that the available scientific evidence is not strong enough to support a connection between vitamin D deficiency and chronic pain.
The authors write, “Based on this evidence, a large beneficial effect of vitamin D across different chronic painful conditions is unlikely. Whether vitamin D can have beneficial effects in specific chronic painful conditions needs further investigation.”
So, as ever, more work will be needed to finally close the lid on this interaction.
We hope this article has enhanced your understanding of the latest scientific thinking around this fascinating chemical. Please remember, however, that over-exposure to sunlight — especially the hot, midday sun — can result in skin damage and increase risk of skin cancer.
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