Nutrition and Immunity Flashcards
Adipokines
Energy balance
Ideal BMI: 19-24
25-35kcal/kg
Obese adipose tissue secretes adipokines that contribute to low-level systemic inflammation
Mediate inflammation and insulin resistance
Cytokines increase T-lymphocyte production, which may contribute to risk of autoimmunity and cancer risk in morbidly obese
Obesity and Immune Effects
Immune system cells do not function normally with overweight or elevated cholesterol/triglyceride levels
Positive associations between overweight and cancers of the breast, endometrium, kidney, colon, prostate, and others
Overweight increases risk of cancer recurrence and decreases survival
Protein and Immune Function
Need enough protein for adequate number of amino acids to help immune system increase its numbers
AA make Ab and other components
Protein Energy Malnutrition (PEM)
Marasmas and cachexia- prolonged starvation with decreased calorie/protein intake
Muscle wasting
Emaciated
Kwashiorkor- inadequate consumption of protein; higher intake of carbohydrates
Edema
Hypoalbuminemia
Marasmic Kwashiorkor
Wasting, edema, stunted growth
PEM Effects
Lymphoid and thymus atrophy
Depressed cutaneous response, even with moderate deficiencies
Reduction in mature T lymphocytes
Reduced antibody-producing cells and reduced immunoglobulin (while serum antibody response is preserved, antibody affinity is reduced)
Reduced phagocytosis
Increase in number of bacteria adhering to respiratory cells – risk of respiratory infection
Arginine and Glutamine
Arginine and Glutamine: non-essential amino acids
conditionally essential
Consuming adequate amounts of daily protein consistent with individual needs will assure production of adequate amounts of arginine and glutamine
Synthesized in body under normal conditions, and are essential in critically ill because the body uses them so much and need more intake in order to obtain the optimal levels
In a healthy state, most people can obtain these levels through diet alone, but when critically ill these aren’t always available to the level they need
Arginine
Mechanism in critically ill patients
Increases T cell number and release
T lymphocyte proliferation
Considered appropriate for surgical patients
“Immuno-specialized” enteral formulas is controversial for some patients
In trauma and sepsis, arginine is used to release NO, which contributes to inflammation.
Ammonia controversy: how body detoxifies it and excretes it
Glutamine
Mechanism
Lymphocytes, macrophages, and neutrophils use glutamine
Glutamine appears to enhance antimicrobial activity in neutrophils
Cell proliferation
Antigen presentation
Cytokine production
Helps to prevent atrophy of the gastrointestinal tract smooth muscle for a patient on enteral feeding, cancer, or not consuming a lot of calories
Antioxidants
Vitamin A (Beta carotene)
Vitamin C (Ascorbic acid)
Vitamin E
Selenium
What do they do?
Disarm free radicals: Free Radical Scavengers
Ensure lymphocytes can divide and reproduce
Ensure neutrophils and macrophages can engulf and kill bacteria
Free Radical Scavengers
Free radical scavengers: donate electrons when and then become oxidized and aren’t harmful to body; it is a matter of balance because if over oxidation then can be a problem
Too many free radicals: contribute to inflammation and course to chronic disease; antioxidants through diet can be supportive
Free Radical Cycle
A chemically reactive O2 free radical attacks fatty acid, DNA protein, or cholesterol molecules, which form other free radicals
This initiates a rapid, destructive chain reaction
The result is disabling injury to lipids of cell membranes and cellular proteins, damage to DNA, or oxidation of cholesterol. These changes may initiate steps leading to diseases such as heart disease, cancer, macular degeneration, and others
Antioxidants, such as vitamin E, stop the chain reaction by changing the nature of the free radical
Dietary Reference Intake Recommendations
Vitamin A: 700-900 mcg/day
Vitamin C: 75-90 mg/day; add another 35 mg if a smoker
Vitamin E 15 mg/day
Selenium 55 mcg/day
Vitamin A Mechanism
Beta carotene: known antioxidant
High blood levels of carotenoids reduce risk of several chronic diseases
cell growth regulation
induction of enzymes
Visual pigment
Cell differentiation
Gene regulation
Used in innate immune system for NKC, macrophages, and neutrophils to function properly
Adaptive: plays a role in development of T helper cells and B cells
Someone who has celiac or Chrohn’s disease (GI not completely intact) need increased vitamin A and E because not absorbed as well (fat soluble)
Vitamin A Deficiency
Impairs regeneration of mucosal barriers Epithelial function (differentiation and production)
Decreases function of neutrophils, macrophages, and NK cells
Diminishes antibody-mediated responses
Increases susceptibility to bacterial, viral, and parasitic infections
Vitamin A Sources, Functions, Deficiency, and Toxicity
Fortified milk, carrots, sweet potatoes, spinach, beef liver, bok choy, and apricots
Chief Functions; vision, maintainence of cornea, epithelial cells, mucous membranes, skin, bone, and tooth growth, regulation of gene expression, reproduction, and immunity
Deficiency: night blindness, impaired bone growth and decayed teeth, keratin lumps on the skin, impaired immunity
Toxicity: increased activity of bone dismantling cells causing reduced bone density and pain, liver abnormalities, birth defects