There’s no reason to believe that teenagers in the UK would be any different. They get less sun exposure than many parts of the US and have a low intake of oily fish, the primary dietary source of vitamin D. This is yet more evidence that children, teenagers and adults need more vitamin D than is delivered by diet or most RDA based multivitamins. They also need to get outdoors. The classic archetype of a teenager who wakes up late and spends all day indoors is a major part of the reason for this widespread deficiency. I recommend everyone achieve 30mcg a day (the RDA is only 5mcg). 15mcg a day can be achieved by eating oily fish three times a week, plus half a dozen eggs and 15 minutes of sun exposure a day. That leaves 15mcg, which is the level I would recommend any decent multivitamin should contain. If you’d like to find out more about nutrition for children read Optimum Nutrition for Your Child. Also read my Special Report on Vitamin D.