1Vitamin D is a fat-soluble vitamin obtained from food. It is also a hormone made in the skin when exposed to the sun’s UV light and warmth. The vitamin D in our blood is a combination of the two.

2Vitamin D is needed for the formation of bones and teeth in particular and for our calcium and phosphorus metabolism.

3Vitamin D deficiency increases the risk of common cold and other respiratory infections. Osteomalacia, the softening of the bones due to defective bone mineralization, is a classic sign of vitamin D deficiency. Osteomalacia is known as rickets in children.

4Sunlight and its UVB rays are the main source of vitamin D. In Finland, the best time for sunlight exposure and vitamin D production is from 11 am to 3 pm. In the North, winter sun does not provide enough UVB radiation for vitamin production. This is because the angle of the sunlight is not right between late September and early March. Vitamin D produced by the skin in the summer sun or during a winter sun holiday lasts for about 2 months.

5The most important dietary sources of vitamin D include fish, such as salmon, pike-perch and white fish, and dairy products, margarines and low-fat spreads fortified with vitamin D.

6Vitamin D has two main forms: D3 or cholecalciferol from animal sources and D2 or ergocalciferol from plants.

7Vitamin D is measured in micrograms (µg) and in International Units (IU); 10 µg = 400 IU.

8National studies indicate that at least 40 percent of Finns suffer from vitamin D deficiency, particularly in winter. According to the National FINDIET 2007 Survey, Finns do not get enough vitamin D and it is difficult to obtain sufficient amounts from diet alone.  

9People with darker skin need much longer sunlight exposure to produce the same amount of vitamin D as light-skinned people.

10Vitamin D is a fat-soluble vitamin stored in the body. Vitamin D is toxic in excess. The recommended maximum daily intake for adults is 50 µg. The recommended safe daily intake level for children is 25 µg. Vitamin D poisoning requires very large doses (exceeding 1.2 mg/day = 50,000 IU/day) and is fairly rare.