Depression, tiredness and weak muscles can all be signs of vitamin D deficiency, research finds.
The vitamin is also thought to play a role in regulating serotonin, a neurotransmitter important for mood.
One study has linked vitamin D deficiency to a 75 percent higher risk of depression.
Other signs of vitamin D deficiency include headaches and poor sleep.
Vitamin D deficiency is still common around the world.
The main function of vitamin D in the body is to help it absorb calcium.
Vitamin D deficiency is linked to rickets in children.
Rickets is a disease that affects bone development, causing them to be painful and soft.
In adults, vitamin D deficiency can contribute to the risk of bone fractures and osteoporosis.
Elderly people, in particular, may benefit from vitamin D and calcium supplementation to reduce the risk of fracture.
The current guidelines for the amount of vitamin D required in the body vary.
Professor Sylvia Christakos, the study’s first author, said:
“Recommendations based on earlier studies using a number of different tests for vitamin D levels persist and, not surprisingly, current guidelines vary.
For example, it is not clear that the most optimal levels for vitamin D are the same for Caucasians, blacks or Asians alike.
More laboratories are now implementing improved tests and efforts are being made to standardize results from different laboratories.”
The current recommendations by the National Academy of Medicine are 600 IU per day for adults.
Foods that are rich in vitamin D include oily fish and eggs, but most people get their vitamin D from the action of sunlight on the skin.
That is why levels are typically lower in the body through the winter months in more northern climes.
The study was published in the journal Metabolism (Christakos et al., 2019).