nutr - micronutrients
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what are micronutrients?
- needed in the diet in small amounts
- not endogenously synthesized at suffient rates to meet requirements
- perform specific biological functions
what happens if micronutrients are withdrawn/ommitted from diet?
results in deficiency
how do you a correct deficiency?
by adding nutrient back into the diet
what is bioavailability?***
what is the most abundant mineral in the body?
calcium = 1150g in a 60kg person
what are vitamins?
- essential organic nutrients required in small amounts (mg or ug)
- many are susceptible to degradation in food
how do vitamins generally function as?
they function as coenzymes
what are vitamers?
different from of a vitamin can have different functions, conversion between forms and form precursors
what are the fat soluble vitamins?
Vitamins A, D, E, K
what are the water soluble vitamins?
Vitamins Bs and C
what are complex B vitamins used in?
- intermediary metabolism
- B1 (thiamin) = coenzyme for pyruvate decarboxylation
- B2 (riboflavin) = coenzyme for FAD, FMN
- B3 (niacin) = coenzyme for NAD, NADP
- B5 (pantothenic acid) = CoA in acetyl CoA
- B6 (pyridoxine) = coenzyme in transamination reactions
how do coenzymes work?
- 1. Enzyme is inactive without coenzyme
- chemical compound cannot bind to enzyme
- chemical reaction cannot take place
- 2. Enzyme is activated by addition of coenzyme
- compound binds to enzyme
- chemical reaction takes place
what are the hormonal functions of vitamins?
Vitamin A (as retinoid acid) = cell differentiation
Vitamin D (as calcitriol) = calcium availability
what are the antioxidant functions of vitamins?
- Vitamins C and E
- e = lipid soluble antioxidant
- imp. in protein lipid membranes in FAs that are being oxidized
what are the 2 nutritional anemias?
- 1. hypochromic microcytic anemia
- 2. megaloblastic or pernicious anemia
what causes hypochromic microcytic anemia?
- iron deficiency
- most common form of anemia
- RBCs are pale, low in color and smaller than normal
- hemoglobin content = ↓
where is hypochromatic microcytic anemia found in?
women and children
what causes megaloblastic or pernicious anemia?
- folate of vitamin B12 deficiency
- really big RBCs that don't mature properly
- don't carry O2 well
- hangs on and won't go away
- B12 deficiency = most likely pernicious
where is megaloblastic or pernicious anemia found in?
what are the different functions of iron?
- to transfer oxygen
- as part of a Heme group in a protein
what is hemoglobin?
transport of oxygen in a protein
what is myoglobin?
- for muscle storage of oxygen
- muscle binds to iron
- short term reservoir of oxygen in muscle
what does heme do?
- transport of electrons through respiratory chain (cytochromes)
- many enzymes such as peroxidase, myeloperoxidase, catalase
what is the iron composed of (structure)?
4 protein units + Fe center
ironically, heme is made of AA but its NOT a protein!!!
whats the difference between hypochromic microcytic anemia and normochromic normocytic cells?
normocytic cells = biconcave disk to maximize surface area for O2
what are signs and symptoms of iron deficiency anemia?
- ↓ work performance
- ↓ childhood development - psychomotor and intellectual
- ↑ lead poisoning susceptibility
- (Pb2+ causes brain damage)
iron deficiency anemia in men and women
- men = Hgb <140g/L
- women = Hgb < 120g/L
what is the prevalence of IDA?
- Developing countries
- 50% of women and children, 25% of men
- Developed countries
- 7-12% of women and children
- 25% of low income infants in Montreal
4-5 billion people are deficient in iron
why are women and children at increased risk of IDA?****
EAR for women = ↑er than for men
how does iron metabolism work?***
- Fe2+ (ferrous iron) = absorbed in the intestinal eithelial cells
- it binds to the protein ferritin
- when iron is bound to a transporter, it is oxidised
what is iron balance?
- iron intake = iron loss
- iron intake : dietary iron and its bioavailability
- amount of iron in storage
- rate of erythrocyte production (RBCs)
- iron loses
assessment of iron storage
what are the sequential changes with development of iron deficiency?
- 1. Depletion of iron stores
- ↓ plasma ferritin
- 2. Changes in iron transport
- ↑ absorption efficiency
- ↑ transferrin iron binding capacity
- ↓ transferrin saturation %
- ↑ transferrin receptors
- 3. Defective erythropoiesis
- ↓ plasma iron↑ free erythrocyte protoporphyrin
- 4. Iron deficiency anemia
- microcytic hypochromatic erythrocytes
- associated behavioural signs
what are the causes of iron deficiency?
- 1. Decreased ↓ dietary iron
- less iron is absorbed
- vegetarian diets lack heme
- 2. Inhibition of absorption
- mineral interaction: calcium, zinc supplements can ↓ iron absorption
- 3. Increased ↑ red cell masspregnancy
- 4. Increased ↑ losseshemolysis
- GI bleeding (occult)
- Heavy menstrual losses
- undiagnosed colon cancer
what are some treatments for IDA?
- change in diet
- taking iron supplement: ferrous sulphate (FeSO4)
- retst hemoglobin = to see if its a secondary deficiency due to heavy bleeding (menstruation), malabsorption
what are some methods to prevent IDA?
- fortify food supply: pasta and grains are already fortified with FeSO4 because of a law
- there are pro/cons
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