Vitamin D or the sunshine vitamin has received worldwide attention and its deficiency is of wide spread concern. Bones are the pillars of the human body. Vitamin D affects bone health, so new guidelines of recommended intake based on scientific research are constantly formed.
Role of Vitamin D
• Building and strengthening of bones is the primary function of Vitamin D. Proper absorption and metabolism of calcium and phosphorus is crucial for the formation and maintenance of the skeletal system. Vitamin D promotes absorption of these minerals from the ingested food in the gut, re-absorption from the kidneys and maintains a steady flow in the blood. Normal mineralization and demineralization of the bone takes place with adequate levels of the vitamin.
• Studies suggest that fractures can be prevented by Vitamin D supplementation. It also helps build muscle strength. However, moderate doses of Vitamin D taken on a regular basis protects against falls and fractures. More research on why high single doses of the vitamin are not safe is required.
• Studies link Vitamin D deficiency to the incidence of heart diseases. There seems to be a higher risk of heart failure, cardiac arrests and cardiovascular disease with lower levels of the vitamin. Evidence suggests the important role of the vitamin in controlling blood pressure and preventing artery damage.
• In colder countries with less exposure to sunlight there are higher incidences of Vitamin D deficiency. Lower levels of Vitamin D increases the risk of cancer and multiple sclerosis. Some claims seem to be still in their infancy and require more research data for valid conclusions.
Sources of Vitamin D
Vitamin D is a nutrient supplied through the diet and also a hormone synthesized in the body. Very few foods contain the vitamin naturally. The best dietary sources are the fortified foods and supplements (Vitamin D and health, Harvard School of Public Health).
Vitamin D is derived from exposure to sun. It is present in the skin in an inactive form. On exposure to the ultraviolet rays of the sun it undergoes hydroxylations to convert into an active form called Calcitriol or 1, 25 – dihydroxycholecalciferol. People living in the tropics are better exposed to sunlight, thus adequate amounts of the vitamin are formed. Those living far away from the equator have less sunlight and have inadequate amounts. Sunscreens, cold climates or smog also increase the risk of deficiency. Lifestyle changes, less outdoor work, full clothing and protection from sun rays to avoid risk of skin cancer have substantially contributed to Vitamin D deficiency. Top 5 foods that contain Vitamin D –
1. Fish: Different types of fish contain sufficiently higher amounts of Vitamin D. Herring, Mackerel, Tuna, Salmon and Sardines are rich sources with herring providing the highest amounts. Raw, uncooked and fatty cuts of fish are better than cooked and lean cuts.
2. Cod liver oil: Supplying more than a 1000 I.U. of Vitamin D in a tablespoon of oil, cod liver oil has been the most popular choice for ages.
3. Fortified foods: With a lot of research suggesting the importance of Vitamin D and its limited supply due to less or no exposure to sunshine, additional amounts have been added to different foods. Breakfast cereals and dairy products are fortified with this essential vitamin. Soy products like tofu and soy milk are also fortified. Before purchasing check on the labels for the correct nutritional information.
4. Eggs: Eggs are a good source supplying about 9g% of the vitamin.
5. Mushrooms: Mushrooms are another good source of Vitamin D with about 7g.
Oysters, whole milk, salami, cheese and caviar are the other food that supply good amounts of Vitamin D, but are high fat food with high cholesterol content.
Some resort to Vitamin D supplementation to correct very low levels. It is always advisable to follow recommendations of health care providers before starting or stopping any form of supplementation.