Vitamin D is crucial to the overall health of the body, as it helps to keep muscles, bones and teeth healthy, said the NHS. The vitamin is needed to regulate the amount of calcium and phosphate in the body. A lack of vitamin D can lead to serious complications, including osteomalacia, rickets, or some deformities. You could be at risk of a vitamin D deficiency if you are constantly feeling tired, it’s been revealed. Between the months of April and September, the best time to spend outside is between 11am and 3pm. Express