Vitamin D deficiency can cause tiredness, bone pain and mood changes, and a daily supplement is recommended for most people in the UK from October to March, according to health experts.
Dr Henrik Premasundaram, a GP and health screener at HCA Healthcare UK, said the body cannot get enough vitamin D from diet alone, and sunlight is the main source. "But with vitamin D you simply can't, because the main production is from the sun," he said. "Vitamin D is essential for healthy bones, muscles, and normal immune function, and if you're deficient, it can lead to things like tiredness, and in really low cases it can affect your mood."
Why sunlight is not enough in winter
Bridget Benelam, a nutrition scientist from the British Nutrition Foundation (BNF), explained that in the UK from October to March the sunlight is not strong enough to make vitamin D, and the body relies on stores built up during the summer and on dietary sources.
She said deficiency does not always cause obvious symptoms straight away, but low levels over time can lead to bone pain, muscle weakness and an increased risk of falls in older adults. In children, severe deficiency can result in rickets, while in adults it can cause osteomalacia, a condition that leads to soft, weak bones.
Supplements advised for all ages
Benelam said the Government recommends a daily 10 microgram vitamin D supplement for everyone aged over five years from October to March. The NHS also recommends supplements for babies and young children, with suitable amounts depending on whether babies are breastfed or bottle fed, and on the age of the child.
People with darker skin, those who cover their skin for religious or cultural reasons, and those who do not get outside regularly are at higher risk of vitamin D deficiency, so it is recommended that they take a supplement all-year round.
The latest National Diet and Nutrition Survey results show nearly one-in-five adults (18%) are vitamin D deficient. Benelam said BNF surveys suggest only around half of people are aware of the recommendation to take a supplement during autumn and winter.
Premasundaram said taking a supplement can make a noticeable difference. "Yes, definitely," he stressed. "It can even help with moods, and help people feel more energetic. I take vitamin D regularly, and I feel a lot better – I feel less tired."
