Known as the “sunshine pill” for its supposed ability to mimic the effects of sunshine on health, vitamin D supplements are a billion-dollar industry.
People take vitamin D supplements for a variety of reasons, mental and physical. Some take it if they feel sad, perhaps as the result of the winter blues, for example. Others take it because vitamin D supposedly plays a role in bone health.
But before reaching for the pillbox, you need to know these seven facts about vitamin D supplements and how they work.
What is vitamin D and how does it affect health?
Vitamin D appears to enable the body to absorb calcium and phosphate — both of which are important for bone health and for muscle function. The vitamin influences cell metabolism and growth, as well as overall immune system functioning. Vitamin D is also associated with a healthy gut microbiome.
The United States’ Centers for Disease Control and Prevention recommends mothers who breastfeed their babies supplement their children with vitamin D, and that those who feed their babies infant formula also use formula that contains vitamin D. That is because too little vitamin D is associated with rickets, a condition that is characterized by soft or weak bones.
Beyond bone health, there is evidence that vitamin D plays a role in cancer, too. One study found vitamin D supplementation reduces cancer mortality by 25 percent. The idea is that vitamin D may influence tumor biology, making them less aggressive and less likely to proliferate.
Vitamin D deficiency can result from various problems, like inadequate Sun exposure, digestive problems, and kidney issues. Symptoms may include mood changes, bone loss, fatigue, and muscle, joint, and bone pain.
Does vitamin D affect mental health?
Different experts have different perspectives on this. As Inverse previously reported, Kathleen Holton, associate professor at American University and a nutritional neuroscientist, says low vitamin D can disrupt normal neurotransmission, and that in turn can lead to mental illness.
Others are more cautious about drawing conclusions. Margherita Cantorna, medical microbiologist and immunologist at Pennsylvania State University, tells Inverse that human brain cells have vitamin D receptors, suggesting that vitamin D is important. But there haven’t been sufficient studies in humans to determine what exactly this means for mental health, she says.
Where does vitamin D occur naturally?
Vitamin D is found in certain foods, including oily fish, mushrooms, eggs, and foods that have been artificially supplemented to contain vitamin D, like milk. The body also produces its own vitamin D when exposed to sunlight.
The way it works is that when sunlight touches our skin, we produce of vitamin D through the conversion of cholesterol in our skin cells, according to researchers at Yale University.
Do vitamin D supplements work?