v itamin d monica durham rahmina mutlib. v itamin d vitamin d is a fat soluble vitamin synthesized...
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VITAMIN DMonica Durham
Rahmina Mutlib
VITAMIN D
Vitamin D is a fat soluble vitamin Synthesized by the body after exposure to
UV rays or obtained from food sources It is biologically inactive By increasing calcium absorption, vitamin D
helps to form and maintain strong bones
FUNCTIONS
Cell differentiation inhibits proliferation and stimulates the normal
differentiation of cells Immunity
The inactive form of vitamin D aids in the formation of active vitamin D which enhances immunity and inhibits the development of autoimmune disease.
FUNCTIONS
Calcium balance With decreased dietary calcium, PTH is secreted
and causes increased production of calcitriol, a hormone
Calcitriol restores normal calcium levels by increased absorption of dietary calcium, increased mobilization of calcium from bone, and increased reabsorption from kidneys
FUNCTIONS
Heart disease Renin, important in regulation of blood pressure
and heart health, is associated with vitamin D levels
Maintaining normal phosphorus levels Bone cannot be properly mineralized without
phosphorus
ABSORPTION, DISTRIBUTION, METABOLISM
Absorption Vitamin D is absorbed from the small intestine as
bile salt Distribution
Stored in adipose tissue Metabolism
Transported to the liver, then kidneys, where it is activated
EXCRETION
Excreted in bile Metabolized to water soluble metabolites and
then excreted in urine as well
SOURCES Fortified foods
Milk, cheese, yogurt, orange juice Ready to eat cereals Sun exposure
Rays from the sun trigger synthesis in the skin Factors
Season Altitude Time of day Cloud cover (eg. Smog) Sunscreen
DEFICIENCY
During vitamin D deficiency, calcium absorption cannot be increased to meet body's needs
Therefore, calcium is taken from bones to maintain normal serum levels
RISK FACTORS Higher melanin content (darker skin) Breast-fed infants Elderly Body covering/use of sunscreen Fat malabsorption syndrome Obesity Inadequate dietary intake Increased excretion Genetic susceptibility
DISEASES
Rickets/Osteomalacia caused by lack of vitamin
D, calcium, or phosphate, which leads to softening and weakening of the bones
VITAMIN D VS. AUTISM
An increased prevalence of autism over the last years corresponds with increasing medical advice to avoid the sun, advice that has probably lowered vitamin D levels and would greatly lower activated vitamin D (calcitriol) levels in developing brains.
Autism is common in areas of impaired UVB penetration such as urban areas, areas with high air pollution, and areas of high precipitation.
Autism is more common in dark-skinned persons with vitamin D deficiency
One study showed children with vitamin D deficient rickets have several autistic markers that apparently disappear with high-dose vitamin D treatment.
VITAMIN D VS. HEART DISEASE
Vitamin D deficiency was evident among individuals with high blood pressure
There was a 62 % higher risk of a cardiovascular event in participants with low levels of vitamin D compared to those with higher levels
Participants with high blood pressure and low vitamin D levels had two times the risk of cardiovascular disease
TOXICITY
Toxic level: 40,000 IU/day for 1-4 month old; 50,000 IU/day for adults for several months
Symptoms Nausea, vomiting, poor appetite, constipation,
weakness, weight loss Increased blood levels of calcium result in mental
confusion Heart rhythm abnormalities
RECOMMENDATIONS
Age Group Recommended
Pediatrics/adolescents 200-400 IU
19-50 200 IU
51-70 400 IU
71+ 600 IU
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