Thursday, April 30, 2015

Vitamin D, structure, food sources, deficiency, toxicity

Fat soluble vitamins:
They are dissolved in fat and reserved in the body almost a month. They are storage in the fatty tissues as well as the liver. Vitamin A, D, E, and K are the fat-soluble vitamin. They are absorbed in the GI tract with the help of fatThey are eliminated much more slowly than water-soluble vitamins.



Vitamin D:

Vitamin D is a fat-soluble vitamin essential for human. It plays a critical role in the use of calcium and phosphorus. It is important for immunity and cell growth. For strong bone and teeth development. It is much essential for a child.

Food sources of Vitamin D:

Vitamin D is made in our skin on the expose of sunlight. About 80-90% vitamin D can be synthesized under the skin by sunlight. Exposure of the hands, face, arms, and legs to sunlight two to three times a week for about one-fourth of the time it would take to develop a mild sunburn will cause the skin to produce enough vitamin D. Besides this some animals food sources can provide vitamin D includes:



  •     Eggs
  •     Fortified fat spreads
  •     Fortified breakfast cereals
  •     Fatty fish such as herring
  •     Some powdered milk
  •     Oily fishes like Sardines and tuna salmon.
  •     Some mushrooms
  •     Cod liver oil

Structure of vitamin D:



Vitamin D deficiency:

Taking an inadequate amount of vitamin D may cause some diseases. Rickets and osteomalacia are the classical vitamin D deficiency diseases mostly in children.
Rickets, a disease characterized by a failure of bone tissue to properly mineralize, resulting in soft bones and skeletal deformities.
Osteomalacia causes muscle and bone weakness and osteoporosis causes loss of bone mass largely in adults.

RDA (Recommended dietary allowance):

Recommended dietary allowance for vitamin D appears as micrograms of cholecalciferol (vitaminD3).
           20mcg cholecalciferol = 800 international unit.(IU)
   For Infants,
                   0 - 12 months: 400 IU (10 micrograms (mcg) per day)
   For Children,
         1 - 8years: 600 IU (15 mcg/day)
   For adults,
        Adults over 70 years: 800 IU (20 mcg/day)
        Pregnancy and breast-feeding: 600 IU (15 mcg/day)

What happens if you take too much vitamin D?

Your body doesn't make too much vitamin D from sun exposure, but always remember to cover up or protect your skin if you are out in the sun for long periods or use sunscreen.
Taking too many vitamin D supplements over a long period of time can cause more calcium to be absorbed than can be excreted. The excess calcium can be deposited in and damage the kidneys. Excessive intake of vitamin D can also encourage calcium to be removed from bones, which can soften and weaken them. 

Risk factors of vitamin D:

It is essential to maintain vitamin D status for many people who consume vitamin D-fortified foods and, arguably, being exposed to some sunlight. Some groups need extra vitamin D in the form of supplements or fortified foods.
Breastfed infants:
Human milk provides only <25 IU/L to 78 IU/L of vitamin D. So All breastfed infants should have 400 IU per day. It must be recall that a mother should have a good vitamin D status, otherwise infants may suffer from some deficiency like rickets.
Older adults:
Vitamin D efficiency is decreased with the increase of age. For older people, the skin cannot synthesize vitamin D as efficiently, they are likely to spend more time indoors, and they may have inadequate intakes of the vitamin.
People with Dark skin:
Those who have darkly pigmented skin cannot synthesize vitamin D than the light pigmented skin. So they have to take extra vitamin D in their diet.
Covered or protective skin:
Those who wear or covered all of their skin with clothes and use sunscreen, they may block the synthesis of vitamin D from sunlight.
People with inflammatory bowel disease and other conditions causing fat malabsorption:
Fat malabsorption is associated with a variety of medical conditions, including some forms of liver disease, cystic fibrosis, celiac disease, and Crohn's disease, as well as ulcerative colitis when the terminal ileum is inflamed. Fat malabsorption symptoms, inflammatory bowel disease, and obesity can prevent vitamin D absorption.








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