This essential vitamin is known as the ‘sunshine vitamin’ as the skin is able to produce vitamin D naturally in response to exposure from natural sunlight. It is also found in parts of your diet and critical to bone and muscle health. It also plays a part in regulating a healthy immune system and so it is critically important we maintain this at the correct levels. The British Heart Foundation recommends taking a daily supplement of Vitamin D at 400iu or 10 micrograms especially in the autumn and winter months.