Musculoskeletal pain is the key warning sign of vitamin D deficiency

The tricky part about these symptoms is that they tend to be “not quite as obvious” in adults, according to the Cleveland Clinic.

That’s why the NHS recommends taking a vitamin D supplement during the less sunny months in the UK – between October and early March.

Adults, and children over the age of one year, need 10 micrograms of vitamin D daily.

International Units (IU) are also used for measuring vitamin D content, which brings the number you’re looking for to 400 IU.