In Ireland, we have limited amount of sunlight and as we continue on into the winter months this will be reduced even further. According to Cashman (2007) vitamin D is an essential vitamin which is synthesised via the sun on the skin when exposed to the sun’s radiation. This vitamin is essential for optimal bone health (calcium absorption) and also plays a very important role in immune function. Apart from the sunlight, vitamin D can be found in dairy products such as eggs but it is very hard to consume enough daily. If you are an athlete the need for vitamin D is even greater. This vitamin is fat soluble, therefore you should consume it with a meal containing fat. Vitamin D stores can accumulate over time and may cause some toxicity issues. IOM (2010) found that 800iu per day was sufficient for the average person, however higher dosages may be needed for athletes. I would highly recommend that you supplement with vitamin D this winter, give your immune system and bones an extra boost during the cold, dark and gloomy winter months.