WHERE CAN VITAMIN D BE FOUND?
Very few foods in nature contain Vitamin D. Fatty fish such as salmon, tuna, and mackerel as well as fish liver oils are among the best sources.Minute amounts of Vitamin D are found in liver, cheese, and egg yolk. Here, Vitamin D is primarily in the form of Vitamin D3 and its metabolite 25(OH)D3. However, certain mushrooms provide Vitamin D2 in variable amounts.
Ready-to-eat breakfast cereals are fortified with Vitamin D, as are some brands of orange juice, yogurt, margarine and other food products.
Nude at Noon
In today’s day and age, most people meet at least some of their Vitamin D needs through exposure to sunlight. Season, time of day, length of day, cloud cover, smog, skin melanin content and sunscreen are among the factors that affect UV radiation exposure and Vitamin D synthesis.
Complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60%. UVB radiation does not penetrate glass; so exposure to sunshine indoors through a window does not produce Vitamin D. Sunscreens with a sun protection factor (SPF) of 8 or more appear to block Vitamin D-producing UV rays. It has been suggested by some Vitamin D researchers that approximately 5–30 minutes of sun exposure between 10AM and 3PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient Vitamin D synthesis. Individuals with limited sun exposure need to include good sources of Vitamin D in their diet or take a supplement to achieve recommended levels of intake.
DIETARY VITAMIN D SUPPLEMENTS
In vitamin d supplements and fortified foods, It is available in two forms, D2 (Ergocalciferol) and D3 (Cholecalciferol).Chemically, they differ only in their side-chain structure. The two forms have traditionally been regarded as equivalent based on their ability to cure rickets and, indeed, most steps involved in the metabolism and actions of Vitamin D2 and Vitamin D3 are identical. Both forms (as well as Vitamin D in foods and from cutaneous synthesis) effectively raise serum 25(OH)D levels.
VITAMIN D DEFICIENCY
Vitamin D deficiency is fairly common. It can occur when usual intake is lower than recommended levels over time, exposure to sunlight is limited, the kidneys cannot convert 25(OH)D to its active form, or absorption of Vitamin D from the digestive tract is inadequate. Vitamin D-deficient diets are associated with milk allergy, lactose intolerance, ovo-vegetarianism, and veganism. Rickets and osteomalacia are the classical Vitamin D deficiency diseases. The fortification of milk with Vitamin D beginning in the 1930s has made rickets a rare disease in the United States, although it is still reported periodically, particularly among African American infants and children.
In adults, Vitamin D deficiency can lead to osteomalacia, resulting in weak bones. Symptoms of bone pain and muscle weakness can indicate inadequate Vitamin D levels, but such symptoms can be subtle and go undetected in the initial stages.