Guidelines for blood levels of vitamin D from the National Institutes of Health (NIH) are as follows ( 7):

Other foods are fortified with vitamin D, such as some breakfast cereals, yoghurt drinks and fat-based spreads. If you’re choosing a vitamin D supplement, be sure to find one that contains D3 (cholecalciferol), as it may be more effective at raising your blood levels of vitamin D ( 7). summary You also absorb vitamin D from foods you eat. Natural sources of vitamin D include fish liver oils and fatty fish ( 7).READ NEXT: Best pre-workout supplements The best vitamin D supplements to buy 1. BetterYou Dlux 1000 Vitamin D Oral Spray: Best vitamin D oral spray

The warning signs for vitamin D deficiency aren't always obvious. Read more about the symptoms of vitamin D deficiency.If you’re taking supplements, how much you need to take will depend on your individual requirements. A doctor can advise you on this. How much vitamin D is too much? In these cases, you may need to rely on your diet (or supplements) for vitamin D and on vitamin D that’s stored in body fat. Babies and children are at risk, as well as pregnant and breastfeeding women, and middle-aged adults. This new NHS advice, for the general public to take daily vitamin D supplements, is endorsed, for example, by The British Nutrition Foundation, The Nutrition Society, and the Royal Osteoporosis Society.