Is vitamin C the most important supplement for winter? - Which?

There is one supplement that everyone in the UK should take, and that's vitamin D. Our main source of vitamin D is from sunshine, but in the winter months in the UK, you can't get enough as UV levels are too low, so it's recommended that everyone takes a 10 microgram (400IU) vitamin D supplement daily between October and early March. Vitamin D is important for your immune health and for healthy bones and teeth – and a deficiency means that you can't absorb calcium from food, which can lead to weakened bones or rickets in children. It's found in some food such as oily fish, egg yolks, red meat, liver, mushrooms that have been grown in sunlight, and fortified breakfast cereals or spreads - but it is very difficult to get enough Vitamin D from your diet alone.