Vitamin D3 Vitamin D is known as the ‘sunshine vitamin’ because it’s predominantly produced on the skin in the presence of sunlight. Living in the northern hemisphere is a risk factor for deficiency, particularly during the winter months. Such is the concern that the UK Department of Health recommends taking a supplement of 10 ug per day. This is twice the recommended NRV (Nutrient Reference Value) to ensure we all get adequate levels. This is particularly important for at-risk groups such as pregnant and breastfeeding women, the elderly, children up the age of 5 years and those with darker skin tones. However, in the UK it is sensible for everyone to supplement during the winter months (October – March) and to eat a diet rich in Vitamin D foods (such as oily fish).