Vitamin D and your health: Breaking old rules, raising new hopes Flashcards
(33 cards)
how many vitamins are there
Vitamin D is one of the 13 vitamins discovered in the early 20th century by doctors studying nutritional deficiency diseases.
what is a vitamin
organics( carbon containing) chemicals ,hat must be obtained from dietary sources because they are not produced by the body’s tissues.
How much vitamin is required
Vitamins play a crucial role in our body’s metabolism, but only tiny amounts are needed to fill that role.
Which vitamin is soluble in fat
Vitamin D,Although vitamin D is firmly enshrined as one of the four fat-soluble vitamins, it is not technically a vitamin.
Vit d debunks
But it breaks the other rules for vitamins because it’s produced in the human body,
Nature of Vit D
it’s absent from all natural foods except fish and egg yolks, and even when it’s obtained from foods, it must be transformed by the body before it can do any good.
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what’s a stroke
“A stroke occurs when blood flow to part of the brain is disrupted, depriving it of oxygen and crucial nutrients.”
Vit D life cycle
The natural type is produced in the skin from a universally present form of cholesterol, 7-dehydrocholesterol.
. Sunlight is the key: Its ultraviolet B (UVB) energy converts the precursor to vitamin D3
dietary supplements are manufactured by exposing a plant sterol to ultraviolet energy, thus producing vitamin D2.
Because their function is almost identical, D2 and D3 are lumped together under the name vitamin D — but neither will function until the body works its magic (see figure).
The sun’s energy turns a chemical in your skin into vitamin D3, which is carried to your liver and then your kidneys to transform it to active vitamin D.
is used for diagnosis,
although 25(OH)D
although 25(OH)D can’t function until it travels to
kidney.
25(OH)D , There it acquires a final pair of oxygen and hydrogen molecules to become
1,25 dihydroxy vitamin D;
scientists know this active form of the vitamin,1,25 dihydroxy vitamin D;
1,25(OH)2D, or calcitriol,
Vitamin D’s best-known role is to keep bones healthy by increasing
the intestinal absorption of calcium.
Without enough vitamin D, the body can only absorb
Without enough vitamin D, the body can only absorb 10% to 15% of dietary calcium,but 30% to 40% absorption is the rule when vitamin reserves are normal
A lack of vitamin D in children and adults
rickets; causes osteomalacia.,Both bone diseases are now rare in the United States, but another is on the rise — osteoporosis, the “thin bone” disease that leads to fractures and spinal deformities.
Other Vit D uses
body’s tissues contain vitamin D receptors, proteins that bind to vitamin D.
the receptors capture vitamin D, enabling efficient calcium absorption
prostate to the heart, blood vessels, muscles, and endocrine glands. And work in progress suggests that good things happen when vitamin D binds to these receptors. The main requirement is to have enough vitamin D, but many Americans don’t.
Vitamin D deficiencies were rare when
most men rolled up their sleeves to work in sunny fields, Because pigmentation can reduce vitamin D production in the skin by over 90%, nonwhite populations are at particular risk.
Deficiencies are also common in patients with
Deficiencies are also common in patients with intestinal disorders that limit absorption of fat and those with kidney or liver diseases that reduce the conversion of vitamin D to its active form, calcitriol (1,25(OH)2D
standards vary, most experts agree that levels of
25(OH)D below 20 ng/ml (nanograms per milliliter) reflect clear-cut vitamin D inadequacy, while levels between 20 and 30 ng/ml are borderline.
Sunlight contains two forms of radiant energy,
unlight contains two forms of radiant energy, ultraviolet A (UVA) and ultraviolet B (UVB). UVB provides the energy your skin needs to make vitamin D, but that energy can burn the skin and increase the cell damage that leads to cancer. UVA also contributes to skin damage and premature aging.
blood calcium is critical for
neuromuscular and cardiac function, the body does not allow levels to fall. Instead, it pours out parathyroid hormone, which mobilizes calcium from bone., Blood calcium levels remain normal, so your heart and nerves keep working nicely. But your bones bear the brunt: As bone calcium density falls, bones become weak and fracture-prone.
Dosage
others a combination of D and varying doses of calcium; and some administer 400 international units (IU) of vitamin D a day, others up to 800 IU a day.
