Dietary vitamin D is available in foods such as oily fish, cod liver oil, red meat, fortified cereals, fortified spreads and egg yolks.
In the UK, milk is not fortified with vitamin D, so dairy products contain only small amounts of vitamin D.
The NHS says risk factors include a lack of sunlight exposure, darker skin, being housebound, malabsorption, and being pregnant or breastfeeding.
Symptoms can include muscle aches and weakness, waddling gait, chronic widespread pain or bone pain in lower back, pelvis and foot.
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