M5S3: VITAMINS Flashcards
What is a vitamin
-substance essential for maintenance of normal metabolic functions but not made in body and therefore must be provided from outside source (exceptions to this rule are vitamins D and K)
-participate in diverse array of metabolic pathways
-initial knowledge of vitamins came from study of disease states
Ex. Scurvy (vitamin c deficiency) led to discovery of vitamin C
-more recent interest has been growing in using vitamins in prevention and treatment of diseases
+refer to goodnote images
Classifications of vitamins
-2 main categories
Water-soluble
-vitamin C and eleven vitamins in B group are water-soluble
Fat-soluble
-vitamins A, D, E, K
Are vitamins considered drugs
-when person obtains vitamin from healthy diet, vitamins in food not drugs
-vitamins consumed as tablet in chemically pure form they are drugs
Vitamin as supplement situation use
Need for increased nutrition
-may occur during period of growth, hard physical work, pregnancy, chest feeding, menstruation or stress.
-may occur from hyperthyroidism (overactive thyroid), fever, tissue wasting disorder or long-term immobilization
Absorption disturbances
-disturbances in GI absorption can be due to prolonged diarrhea, surgery involving absorption area of intestine or liver disease, individual taking antibiotics that alter intestinal bacteria (as vitamin K and biotin (one of the B vitamins) require synthesis of intestinal bacteria into usable forms within body
Inadequate nutritional intake
-from consuming inadequate diet for reasons like poverty and/or geography (area of famine), individuals with substance use disorder who have inadequate food intake and individuals on restricted diets for disease management or otherwise
The 2 approaches to vitamin therapy
Nutritional approach
-individual selects a diet aimed at supplying the recommended dietary allowance (RDA) for each vitamin, or a multivitamin preparation that supplies the RDA of each vitamin
Megavitamin approach
-ingest vitamins in excess of RDA
-assuming vitamins in ways that few consequences
-excess of some water vitamins is rapidly excreted in urine, so assumed water-soluble vitamins were safe, irrespective of magnitude of dose
-more recent studies have shown that overdosing of vitamin B (pyridoxine) can cause nerve injury
-in addition, clear that taking high doses of fat soluble vitamins A, D, and E can accumulate in body fat and can cause severe toxic effects
Overview of vitamins
5 main vitamins: A, D, E, B12, C
* K not discussed as not typically taken as dietary supplement
Note: therapeutic uses and toxicities of some vitamins are focus of ongoing research (ex. Vitamin D and A). As such, RDAs for vitamins constantly being revised as new information as acquired
Vitamin A
-fat-soluble vitamin
Food sources of vitamin A
-found only in animal products like liver, milk, fat, egg yolk
-other compounds like carotene found in carrots, are pro-vitamin A, as have to be converted to vitamin A in the body
Functions of vitamin A
-required for growth and development, for normal structure of mucous membranes and epithelial cells and as constituent of complex molecule in rods of eye, called rhodospsin, required for night vision
Therapeutic use
-administered in periods of increased requirement like infancy, pregnancy and lactation
-derivatives used in treatment of acne and some other skin diseases including psoriasis and skin cancer
Deficiency
-delayed growth and development, night blindness and drying of surface of eye, changes in cells lining in bronchioles in lungs which enhance opportunity for respiratory infections, and dry, thick and horny skin
Excess intake
-result in dry itchy skin, vomiting, headache and enlarged liver and spleen
What are retinoids? Why they only available by prescription?
-vitamin A derivatives
-specifically oral forms and associated with number of serious adverse effects, including damage to unborn child, depression, diabetes and liver disease
-for these reasons, use of retinoids must be monitored
Vitamin D
-fat-soluble nutrient
Food source
-found in meat, fish, mushrooms
-in several countries, milk is fortified with vitamin D
Function of vitamin D
-increases absorption of calcium and phosphate from intestine, which needed for new bone formation and bone health
-involved in regulation of blood calcium level and in removal of calcium from older bone
Therapeutic uses
-prevention of osteoporosis (with calcium)
Deficiency
-result in decreased absorption of calcium and phosphate from the intensive and therefore decrease blood calcium levels
-lead to removal of calcium from bone in attempt to maintain blood calcium levels
-as result, defective bone growth occurs in infants and children leading to boweleggedness or rickets
-rickets also occur in adults
Excess intake
-result in elevated calcium levels in blood
-deposited in several tissues, including kidney, heart, lungs, blood vessels and skin
-during pregnancy, fetus also suffered from high blood calcium levels, which worry if individual with kidney or heart disease
-cause excess removal of calcium from bone and fatigue, nausea, vomiting, diarrhea, impaired kidney function
Vitamin E
Food sources
-number of naturally occurring tocopherois that present in vegetable oils and some green leafy veggies
Function
-essential for biochemical reactions including role as antioxidant and protecting cells in cardiovascular system and other tissues from the damaging effects of free radicals
Therapeutic uses
-treatment of premature babies with an uncommon type of hemolytic anemia (disorder where red blood cells are destroyed faster than the body can make them). Effect may be dye to Antioxidant effect of vitamin E
Deficiency
-in adult Canadians rare as tocopherols are so preventable in our diets
-mat occur in conditions of a malabsorption syndrome (chrons disease)
Excess intake
-inhibit platelet aggregation and contribute to anticoagulant effect of warfarin
Vitamin B12 and folic acid
-vitamin B12 aka cobalamin is water soluble vitamin
Folate (naturally occurring) or folic acid (synthetic) is vitamin B12 and found in many foods
Food source
-vitamin B12 found in meats and dairy
Folate in all food groups however fresh green vegetables, liver and yeast especially high
Function
-they work together to synthesis red blood cells
Therapeutic use
-absorption of vitamin B12 decrease with age so some elders may take
-RDA for folic acid increases in pregnant women to help prevent deficiencies that may lead to neural tube defects (spina bifida) in unborn child
-recommended that any women anticipating pregnancy should began taking prenatal vitamins before pregnant
Deficiency
-alcohol misuse or malabsorption syndromes lead to deficiency in both
-if vitamin B12 cannot be absorbed from intestine, a concision known as pernicious anemia occurs as decrease in production of red blood cells occur
-certain drugs (ex. Oral contraceptives, some anticonvulsants, and folate antagonists used in cancer chemotherapy) may result in folate deficiency
Excess intake
-no sufficient toxic effects with B12
-folic acid generally considered non-toxic when taken as supplement
-can be mask undiagnosed pernicious anemia, leading to delay in treatment
-in addition, since antifolate medications now used in cancer chemotherapy, further research regarding safety of folic acid supplements in patients is required
Vitamin C
Source
-fruits and veggies
Function
-contributes to framework that holds cells together
-required for formation of bone and teeth, function as antioxidant and helps absorb iron
Therapeutic use
-prevention and treat,ent of scurry
-prevent cold
-supplementation for very fit pension working in army like conditions
-can be helpful in preventing cancer if combined with other proven anticancer drugs
Deficiency
-results in scurry with symptoms weakness, bruising, anemia, loss teeth, bleeding gums
Excessive intake
-diarrhea, formation of kidney stones and rebound scurry( as high dosage of vitamin C on continuing basis increase vitamin C metabolism so when individuals suddenly stop high doses, rebound scurvy may appear
