SOMETHING NEW ABOUT VITAMIN D

SOMETHING NEW ABOUT VITAMIN D

Khoa Noi tong hop

BS Nguyen Anh Tuan

• Vitamin D is a fat-soluble vitamin that was isolated in 1930 and named calciferol.

• Vitamin D is actually a hormone precursor which can be manufactured by the body.

• Vitamin D have a significant clinical role because of their interrelationship with calcium homeostasis and bone metabolism.

Two form of vit D

• D2 (ergocalciferol) : is synthesized from plants.

• D3 (cholecalciferol) : form in the skin when it exposed to direct sunlight.

• D2,D3 not active in the body.It must be metabolized by the liver and kidney into an active form called Calcitriol and it promotes absortion of calcium and phophorus from intestine.

Used of vit D

• Vitamin D is used for preventing and treating rickets, weak bones (osteoporosis), bone pain (osteomalacia), preventing fractures in people at risk for osteoporosis, prevention low calcium and bone loss in people with kidney failure.

Used of vit D (cont.)

• Vit D is also used for condition of the heart and blood vessels, including high blood pressure and high cholesterol.

• For diabetes, obesity, muscle weakness, multiple slerosis, rheumatoid arthritis, chronic obstructive pulmonary disease, asthma, brochitis, premenstrual syndrome(PMS), and tooth and gum disease.

Used of vit D (cont.)

• It is also used for boosting the immune system, preventing autoimmune diseases, and preventing cancer ( such as breast, colon, skin ,pancreas and prostate cancer)

In heart and blood vessels

• Vit D deficiency was associated with lower serum calcium, systolic and diastolic blood pressure, lower HDL cholesterol.

• Low levels of vitamin D may play role in the development of high blood pressure in those with kidney disease.

• vitamin D may help prevent or treat high blood pressure.

In heart and blood vessels (cont.)

• people with low levels of vitamin D have a greater risk of developing heart disease, including heart attack, stroke, and heart failure.

• Low levels of vitamin D may increase the risk of calcium build up in the arteries created atherosclerosis and can lead to a heart attack or stroke.

Vit D and influenza

• Vit D insufficiency was associated with increased risk of influenza and supplementation of vit D reduce the incidence of influenza.

• Vit D was found to protect against influenza A, but not against the less comon influenza B.

Vit D and influenza ( cont.)

• Vit D can stimulate the production of cathelicidin antimicrobial peptides ( AMP) and defensins, and inhibit cytokine response to viral infection.

• Both mechanisms are extremely helpful in the prevention of influenza and infectious diseases.

Mechanism of action

• AMP rapidly damage the lipoprotein membranes of microbial targets, including envelope viruses such as influenza.

• Vit D control both innate immunity and adaptive immunity.

• T cell ( killer cell ) must have vit D for activation . Sufficient intake vit D , the T cell will not be able to react.

Cancer

• Getting enough vitamin D may lower risk of certain cancers, especially of the colon, breast, prostate, skin, and pancreas .

• Studies indicate that vitamin D may have anti-cancer effects .

DiabetesDiabetes

• People who have lower levels of vitamin D are more likely to develop type 2 diabetes than people who have higher levels of vitamin D.

• vitamin D deficiency increases the risk for type 1 diabetes in children. (CDC)

Multiple Sclerosis (MS)

• Women who take at least 400 IU of vitamin D daily lower their risk of developing MS. And higher levels of vitamin D in the blood seem to be associated with a lower risk of developing MS in white men and women.

Obesity

• Studies have found that people who have lower levels of vitamin D are more likely to be obese compared to people with higher levels of vitamin D.

Overall mortality

• Studies (from the National Health and Nutrition Examination Survey) suggest that people with lower levels of vitamin D have a higher risk of dying from any cause compared to those with higher levels of vitamin D.

• The American Academy of Pediatrics (AAP-2008) recommends 400 IU of vitamin D daily for breastfed infants until they are weaned and drinking at least 1 liter of whole milk or formula fortified with vitamin D. The AAP also recommends that children and teens who drink less than 1 liter of milk a day take 400 IU of vitamin D.

• The recommended adequate intake of vitamin D to prevent deficiency in normal infants and young children is 400 Int. Units/day.

• Human milk typically contains less than 25 Int. Units of vitamin D per liter unless the mother receives vitamin D supplementation in high doses (eg, 2000 Int. Units per day).

Vit D supplementation (400 IU/day) is recommended for each of the following groups

• All breast-fed infants; supplementation should start in the first week of life. Supplements should be continued until the infant is ingesting at least 400 IU of vit D daily through formula, milk, or other food sources.

• All nonbreast-fed infants who are ingesting less than 1000 mL of vit D fortified formula or milk per day.

• Children and adolescents who do not ingest at least 400 IU of vit D daily (eg, 1000 mL of vitamin D fortified milk per day), do not get regular sunlight exposure, and do not take a multivitamin supplement that contains at least 400 IU of vit D.

• In a cross-section study ( involved 205 men and 432 women aged 18-85 ) in HCM City, the prevalence of vit D insufficiency in men was 20%, lower than woman 46%.

• Vit D insufficiency is common even in tropical region, woman had a greater risk of vit D insufficiency than man.

• For infants (birth to 12 months) the tolerable Upper Limit, (maximum amount that can be tolerated without harm) is set at 1000 IU. 40,000 IU in infants has produced toxicity within 1 month.The U.S. Dietary Reference Intake Tolerable Upper Intake Level (upper limit) of vitamin D for children and adults is set at 50 micrograms/day (2,000 IU).

Vitamin D Excess

• Taking very high daily doses 50 or more times the recommended daily allowance (RDA)—over several months can cause toxicity and a high calcium level in the blood (hypercalcemia)

Vitamin D Excess

• Early symptoms are loss of appetite, nausea, and vomiting, followed by excessive thirst, weakness, nervousness, and high blood pressure. Because the calcium level is high, calcium may be deposited throughout the body, particularly in the kidneys, blood vessels, lungs, and heart. The kidneys may be permanently damaged and malfunction, resulting in kidney failure.

Vitamin D Excess

Diagnosed when blood tests detect a high calcium level in a person who takes high doses of vit D. The diagnosis is confirmed by measuring the level of vit D in the blood (25-hydroxy-vitamin D).Treatment consists of the following:

• Stopping vit D supplements.• Following a low-calcium diet.• Taking drugs (such as corticosteroids or

bisphosphonates) to suppress the release of calcium from the bones.

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