Vitamin D is one of the fat-soluble vitamins and is also called the sunshine vitamin, as the body manufactures it when exposed to ultraviolet rays of the sun, and sunlight is the most important factor in the manufacture of vitamin D in the body through the skin. Dr. Olesya Savelyeva revealed that rapid fatigue and brittle nails indicate a lack of vitamin D in the body. She pointed out that vitamin D contributes to many important processes taking place in the body, and is responsible for mood stability and good health. She explained: “Vitamin D is an essential fat-soluble secosteroid…