Nutrition Flashcards
What is the caloric requirement for an average healthy adult male (70kg)?
25 kcalories/kg/day
1500-1700 calories/day
What is the protein requirement for an average healthy adult male (70kg)?
1 g/kg/day
How many calories does fat provide per gram?
9 calories/g
How many calories does protein provide per gram?
4 calories/g
How many calories do carbohydrates provide per gram?
4 calories/g
How many calories does dextrose provide per gram?
3.4 calories/g
What percentage of calories should come from protein for an average healthy adult male?
20% of calories, with 20% being essential amino acids
What percentage of calories should come from fat for an average healthy adult male?
30% of calories
What percentage of calories should come from carbohydrates for an average healthy adult male?
50% of calories
How does trauma, sepsis, or stress affect caloric requirements?
Increases kcal requirement by 20-40%; 30 calories/kg/day; protein 1.5-2 g/kg/day
How much does pregnancy increase caloric requirements?
300 kcal/day
How much does lactation increase caloric requirements?
500 kcal/day
What is the protein requirement for obese patients?
2.5 g/kg/day with 20 calories/kg/day
hypocaloric high protein
How does the basal metabolic rate change with fever?
Increases by 10% for each degree above 38°C
Much of energy expenditure is used for heat production
What is the caloric requirement for burn patients with 2nd degree burns and at least 20% TBSA?
25 calories/kg/day + 30 kcal X percentage burned
What is the protein requirement for burn patients?
1.5-2 g/kg/day + 3 g/day X percent burned
What is the maximum caloric intake for burn patients?
Don’t exceed 3000 kcal/day
How is adjusted body weight calculated for caloric needs in overweight patients?
Adjusted body weight = (actual body weight - ideal body weight) X (0.25) + ideal body weight
What is the ideal body weight formula for men?
106 + 6 lb for every inch above 5 ft
What is the ideal body weight formula for women?
100 + 5 lb for every inch above 5 ft
What does the Harris-Benedict equation calculate?
Basal energy expenditure based on weight, height, age, and gender
What is the maximum glucose given in central line TPN?
3 g/kg/hour
What is PPN and its caloric composition?
Fat based, about 50% of calories from fat, use 5% dextrose in PPN
(TPN glucose based)
PPN: no evidence it improves outcomes; may impair immune responsiveness
What is the primary nutrient for colonocytes?
Short chain fatty acids
In patients with diversion (colostomy) they may get diversion colitis in rectal pouch; tx short chain fatty acid enema
Glutamine
Non-essential amino acid, can become conditionally essential in stressed states. Arginine too.
Most common AA in blood and tissue. 75% in mm. Also made in muscle
Necessary for nucleotide synthesis
Majority of fuel for enterocyte; also proliferating lymphocytes
Primary fuel for neoplastic cells
MC AA released from muscle in catabolism, alanine #2
Used in gluconeogenesis as an energy source
Enhances immune function by inhibiting small bowel mucosal breakdown and prevents translocation
Releases NH4 in kidney, so helps nitrogen excretion Urea cycle
Bone marrow transplant have decreased infection when supplemented with glutamine
What is the best indicator of pre-operative nutritional status?
Albumin
Low albumin < 3.0: strong risk factor for morbidity and mortality after surgery
What is the half-life of albumin?
21 days
What is the half-life of transferrin?
8 days
What is the half-life of prealbumin?
2 days
What is the normal protein level range?
6-8.5 g/dL
What is the albumin level range?
3.5-5.5 g/dL
What is the prealbumin level range?
15-35 mg/dL
What are acute indicators of nutritional status?
1 prealbumin, retinal binding protein, transferrin
Nitrogen balance
Nitrogen balance - 1 g of nitrogen contains 6.25 g of protein
Total protein for a health 70 kg male synthesized is 250g/day
N in – N out = N balances
(protein/6.25) – (24 hour urine nitrogen + 4) = Nitrogen balance
Positive = anabolism. Negative = Catabolism
In order to prevent negative nitrogen balance, 1 g of nitrogen should be provided for every 150 k/cal
Liver
- Responsible for AA production and breakdown
- Majority of protein breakdown from skeletal muscle is #1 glutamine, and alanine
- Urea production Is used to get rid of ammonia NH3, from AA breakdown
What is the primary NH3 donor in the urea cycle?
Glutamine
reaction occurs in the liver and urea is removed by the kidney; this accounts for 90% of nitrogen loss
What are essential fatty acids?
Essential fatty acids
- Linolenic (Omega 3), linoleic (omega 6)
- Unsaturated fatty acid
- Plays a role in cell membrane synthesis and inflammation.
- Needed for prostaglandin synthesis (long chain fatty acid).
Omega 3 - Linolenic
- Polyunsaturated fatty acids
- Humans do not synthesize unsaturated fatty acids
- Anti-inflammatory, anti-thrombotic, anti-atherosclerotic effects protect against heart disease
Omega 6 – linoleic
- Same as above but is proinflammatory
- Protects against heart disease
Carbohydrate metabolism
Glucose and galactose absorbed by secondary active transport (Na gradient by ATPase) and released into portal vein
Fructose - by facilitated diffusion and release into portal vein
Enterocyte can only absorb monosaccharides
Sucrose - fructose and glucose
Lactose - galactose and glucose
Maltose - glucose and glucose
Protein digestion
Begins with stomach pepsin, then trypsin, chymotrypsin, and carboxypeptidase
Broken down to AA, dipeptides, and tripeptides
Absorbed by secondary active transport; released as free AA into portal vein
AA are taken up by cells under influence of
AA are taken up by cells under influence of insulin