Fat soluble vitamins- Focus on Vitamin D

what % of vitamin D is absorbed?

80% of vitamin D consumed is incorporated into micelles -Absorbed in the small intestine and transported via chylomicrons -Fat malabsorption impairs vitamin D absortption

What is the Al for vitamin D for adults under age 51?

-5 ug (microgram)/d (200 IU/d)

How does vitamin D helps with calcium absorption?

-At the kidney, active vitamin D acts with PTH (parathyroid hormone) to increase calcium retention so less is lost in the urine. -At the bone, active vitamin D acts with PTH to increase bone breakdown, releasing calcium into the blood. -At the intestine, active vitamin D increases the absorption of calcium from the diet. ALL OF THIS FUNCTIONS RESULT ON A RISE IN BLOOD CALCIUM IN THE BODY.

In adults, vitamin D deficiency can result in what?

Osteomalacia

What affects can oversupplementation of vitamin D have in the body?

-high blood and urine calcium concentrations -depositing of calcium in blood vessels and kidneys -cardiovascular damage and possibly death

In children, vitamin D deficiency can result in what?

Rickets

what foods are rich with vitamin D?

1. Salmon

How much vitamin D supplementation do infants need?

5 ug (200 IU)/d until weaned to fortified infant formula

Is there an RDA for vitamin D?

Do to variation in sunlight exposrue, no RDA set

Where does Vitamin come from?

-Prohormone -Derived from cholesterol -Synthesis from sun exposure -Activated by enzymes in liver and kidneys

What are the consequences of deficiency of vitamin D?

-Rickets -Osteomalacia

How how does the sun activate vitamin D?

-Sunlight converts provitamin D3 to previtamin D3 in skin. -Previtamin D3 converted to vitamin D3 and released into bloodstream.

What affect does vitamin D deficiency have on calcium levels?

-When vitamin D is deficient, dietary calcium cannot be absorbed efficiently and there can be improper bone mineralization and abnormalities in bone structure.

What is the role of vitamin D in the body?

Bone health, normal functioning of the parathyroid gland and regulation of the immune system. Vitamin D helps calcium to be absorbed, without it, calcium cannot be used in the body.

Can vitamin D be toxic at high levels?

Yes, so there are strict limitations on the categories of foods that can be vitamin D-fortified.

Describe vitamin D synthesis and Activation

1. When ultraviolet light strikes the skin, 7-dehydrocholesterol, which is made from cholesterol in the body, is converted to vitamin D3 (cholecalciferol). 2. Vitamin D consumed in foods, fortified foods, an supplements, and that synthesized in the skin, ravels in the blood to the liver. 3. In the liver, enzymes add a hydroxyl group (OH) to carbon number 25 to form 25-hydroxy vitamin D3. 4. In the kidneys, enzymes add a hydroxyl group (OH) to carbon number 1, forming active vitamin D (1,25-dihydroxy vitamin D3 which is active vitamin D. 5. Vitamin D travels in the blood for biological functions.

What is the Al for older adults?

10-15 ug/d (400-600 IU/d)