Lec 39 Metabolic adaptations to nutritional interventions

highlighted info

recommended dietary allowance

the average daily dietary nutrient intake level sufficient to meet the nutritional requirement of nearly all (97%) of healthy individuals in a particular life stage and gender group

adequate intake

the recommended average daily intake level based on observed or experimentally determined approximations or estimates on nutrient intake by a group of apparently healthy people that are assumed to be adequate

used when RDA can’t be determined, research regarding these are a bit murky

estimated average requirement

avg daily nutrient intake level estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group. 50% of people

Not used as much

Upper limit, not much for macros

average macro distribution ranges (AMDR)

carbs: 45-65% of energy

protein: 10-35% of energy

fats: 20-35% of energy

estimated energy requirements

The average dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height, and level of physical activity, consistent with good health

130g/d

RDA of carbohydrates

based on average amt of glucose used by brain

38g/d for men, 25g/d for women

AI for fiber

17g/d for men, 12g/d for women

AI for fats

1.6g/d for men, 1.1 g/d for men

AI for Omega 3 polyunsaturated fatty acid (alpha-linolenic acid)

0.8g per kg of body weight

RDA of protein

body composition

divided into fat mass (FM) and fat free mass/lean body mass (FFM/LBM)

fat free mass (FFM)

makes up 75% of normal body weight

contains all the body’s protein and water content

ongoing homeostatic drive to preserve this

fat mass

makes up about 25% of body composition

• women need 22-25% for repro functioning

• below 15% affects performance in atheletes

• men can tolerate 3-4% body fat

stress response

activation of this will block the body’s adaptive responses and allow protein to be used for fuel

impaired immunity and increased risk of infection

(think older pts in long term facilities/w chronic disease)

10% loss of LBM leads to:

decreased healing, weakness, thin skin

20% loss of LBM leads to:

spontaneous wounds and pressure sores

30% loss of LBM leads to:

death (usually pneumonia)

40% loss of LBM leads to:

ebb phase and flow phase

2 phases of metabolic stress

critical illness, sepsis, trauma, burns, surgery

examples of metabolic stress

ebb phase of metabolic stress

Occurs immediately following injury (Hypovolemia, Decreased basal metabolic rate, Reduced cardiac output, Hypothermia, Lactic acidosis, Shock, Tissue hypoxia)

Lasts for approximately 24–48 hours

flow phase of metabolic stress

Follows fluid resuscitation & restoration of O2 transport

Mobilization of body energy stores (For recovery and repair, replacement of lost/damaged tissue)

Activation of innate immune system

May be subdivided:

• Initial catabolic phase: ~3–10 days, tissue breakdown

• Anabolic phase: tissue reformation, weeks*

glucagon

Promotes gluconeogenesis, AA uptake, ureagenesis, & protein catabolism

↑ ratio of glucagon to insulin

cortisol

Enhances skeletal muscle catabolism: Branched chain AA’s (BCAAs) are oxidized from muscle as a source of energy for muscle, {glucose alanine cycle and muscle glutamine synthesis}

↑ hepatic use of AA’s for gluconeogenesis, glycogenolysis, and acute-phase protein synthesis

gluconeogenesis

first metabolic change after trauma

burn pts

require high energy, high protein nutrition therapy

• Adequate calories = basal energy expenditure x 1.3-1.4

• Protein adequate for positive nitrogen balance (1.5 – 2 g/kg for adults 2.5–4.0 g/kg/day for burned children; 20-25% of energy)

• Early enteral nutrition with high-carb formulas

• High-carb diets promote wound healing and impart a protein-sparing effect

• Very low-fat diets (<15% of total calories)

starvation

the metabolic response to critical illness/injury is very different from:

circulating insulin levels

in starvation, lipid is mobilized and metabolized to supply other tissues. this is largely dependent on a decrease in:

classic ketogenic diet

4:1 ratio of fat to combined protein and carbs

used to primarily treat refractory epilepsy in kids

low carb diet

AAFP defines this as: a diet that restricts carb intake to 20-60g/day, typically <20% of caloric intake

endurance athletes

Increase muscle glycogen stores

Improvements in performance varies

• Exercise taper + normal mixed diet followed by high CHO diet + low intensity and short duration physical activity prior to endurance event

• 1-2 days of inactivity + high CHO diet prior to endurance event

pre-op feeding strategy

Decreases insulin resistance (following surgery)

Decreases inflammatory response to surgery

atkins diet

high fat, low carb

<20g carb daily, gradual increase to 50g carb daily

zone diet

macronutrient balance

40:30:30 carb:protein:fat ratio

weight watchers diet

reduce calories

24-32 points at 50kcal/point

Ornish diet

low fat

vegetarian diet, 10% kcal fat

cardiac

for most diets, weight loss predicts the amount of improvement in several _______ risk factors