Nutrition and vitamins Flashcards
Daily energy loss as heat is about ____kJ ( _____kcal) per kilogram of body weight in a normal adult.
120 kJ, 30 kcal
Daily protein turnover is about ____ g/kg
3 g/kg
What happens in early starvation?
- body tries to maintain blood glucose levels
What happens in later starvation? (6)
- ketone bodies replace glucose (metabolic acidosis)
- muscle protein degradation is inhibited
- decrease in urinary nitrogen excretion
- decrease in hepatic gluconeogenesis
- decrease in plasma insulin, glucagon, glucocorticoids and GH
- increase in brain oxidation of ketone bodies, and decrease in plasma and amino acid concentrations
Biochemical tests for nutritional status (3)
- albumin (t 1/2 about 20 days, but poor index of nutritional status)
- transferrin (t 1/2 about 9 days, depends on iron, but better guide)
- 24h urinary urea excretion (approx. nitrogen excretion, thus catabolic status)
In which situations can we expect vitamin deficiencies? (7)
- in individuals with inadequate dietary intake
- alcoholism
- anorexia nervosa
- parenteral/enteral nutrition
- inadequate absorption
- excess loss
- enhanced utilisation (sepsis, trauma)
4 fat soluble vitamins are?
DEKA
D - calciferol
E - a-tocopherol
K - 2-methyl-1,4-naphthoquinone
A - retinol
Vitamin A (6)
- formed by hydrolysis of beta-carotone in intestinal mucosa, stored in liver
- transported to tissues by alpha globulin retinol binding protein (RBP)
- deficiency is associated with night blindness (nyctalopia), poor bone growth in the skull, anaemia which responds to vitamin A therapy not iron
- lab test for diagnosis is plasma retinol conc.
- treatment is retinyl palmitate
- hypervitaminosis is associated with acute nausea and vomiting, and chronic is fatigue, insomnia, bone pain, desquamation of skin etc.
Vitamin E (3)
- common causes of deficiency are poor intake and fat malabsorption, cystic fibrosis, hypobetalipoproteinemia
- clinical features are increased hemolysis and increased risk of atherosclerosis
- lab test for deficiency is plasma E vitamin level, expressed through vitamin E/LDL cholesterol ratio (3.5-9.5 umol/mmol cholesterol)
Vitamin K (7)
- needed for synthesis of prothrombin and coagulation factors VII, IX and X
- deficiency is associated bleeding and prolonged prothrombin time
- vitamin K can also be given to reverse action of warfarin
- vitamin K is synthesised in the ileum by bacteria so dietary deficiency is unlikely
- deficiency may occur in steatorrhea patients, after some broad-spectrum antibiotics (especially in children)
- over dose is rare and causes haemolytic anaemia
- lab test is indirect; prothrombin time
Water soluble vitamins are (2)
- B complex ( thiamine B1, riboflavin B2, nicotinamide niacin, pyridoxine B6, folate, vitamin B12 complex biotin and pantothenate)
- vitamin C (ascorbate)
Folate and vitamin B12 (5)
- essential for the normal maturation of RBCs
- deficiency causes macrocytosis or megaloblastic anaemia
- folate is absorbed through small intestine, in contrast to most other B vitamins (except B12)
- deficiency is common in malabsorption syndromes, pregnant and lactation
- low maternal uptake is associated with neural tube defects in the fetus
Trace metals (2)
- Zinc (cofactor for certain enzymes, deficiency results in alopecia, dermatitis, diarrhea etc., lab tests include plasma or urinary levels)
- Copper (enzyme cofactor, deficienct may cause arrythmias, neutropenia etc. lab test is plasma copper)
Menke’s disease is an inborn error of _________ transport, resulting in low plasma _______ conc.
copper, copper
Copper is carried on the protein____________, the level of which may be increased due to an acute-phase response, estrogens or pregnancy
caeruloplasmin
