NEP Ch15 pt 2

body defense systems

include immune system and antioxidant defenses

immune system

protects the body from infection diseases, helps heal wounds, and guards against the development of cancers

nonspecific/innate immune function

specific/acquired immune function

nonspecific/innate immune function

bodys primary defenses

ex: intact skin and healthy mucous membranes

lysozyme (in saliva) destroy bacteria

stomach acid destroy food-borne bacteria

phagocytes engulf bacteria entering the body

inflammatory response (localized swelling, pain, heat and redness)

generalized systemic inflammation produce an acute-phase response (for infections spreading beyond local area, fever, pain, loss of appetite, lethargy, proteins released from liver to provide rapid protection against the microorganism

specific/acquired immune function

directed against antigens (parts of molecule recognized as foreign)

Induce antibodys to destroy invador

memory cells remain in circulation

two main types of immune cells:

B cells and T cells

Active immunity: having the disease or vaccinations (immunizations)

passive immunity: temporary protection, antibodies from another human or example. (ex: antibodies during gestation and breastfeeding gives immunity to baby, antiserum injection such as snakebite)

malfunction can cause chronic inflammation and infection

allergic reactions

autoimmune response

immunodeficiency

malnutrition

how does nutrition affect the immune system

a nourishing diet provides all nutrients immune system needs

single nutrient sublicinical deficiency can cause subtlye abnormalities in immunity

PEM (protein energy malnutrition) and severe deficiencys of several micronutrients result in functional immunodeficiency — protein status esp. important

How PEM impairs immune function

PEM/MN (malnutrition raises risk for infection

infection lowers appetite and often causes vomiting/diarrhea

lowers appetite, vomit, and/or diarrhea cause malnutrition (MN) leading to increased vulnerability to infection

also leads to anergy = lowers ability of the immune system to respond to antigens

overnutrition/obesity in immunity

boh raise incidence and severity of infections

delayed wound healing, poor antibody response to vaccination

chronic inflammatory state may increase asthma, HTN, CVD, DM II among obese individuals

essential fatty acids in immunity

essential fatty acids make signaling molecules for the immune system

essential fatty acids are precursors for signaling molecules: eicosanoids

omega 6 = pro-inflammatory mediators

omega 3 = anti-inflammatory mediators

vitamins and minerals in immune function

vitamin A protects the barrier function of the mucosa

vitamins C and E protect phagocytes from reactive oxygen species

Zn assists immune cell gene expression and protein synthesis

copper deficiency leads to decline in lymphocyte (WBC) proliferation

Fe deficiency and overload both impair immune function

Se deficiency and toxicity impar immune function

phytochemicals in plant based foods can enhance disease resistance

probiotics and prebiotics

antioxidants

compounds that protect cells from the damage caused by oxidation

during metabolic rxns, electrons can be transferred

electron loss during oxidation leaves an unpaired electron = free radical

O molecule that becomes a free radical = reactive oxygen species

antioxidant vitamins donate their electrons

antioxidant minerals function within enzyme systems to convert free radicals to less damaging substances that can be excreted

free radica generation

many metabolic processes including digestion and absorption of food, immune system fighting infections

environmental factors also can generate free radicals: pollution, excess sunlight, toxic substances, tobacco/smoke, asbestos

form within the PL bilayers of cell membranes, damaged lipid molecules are unable to maintain the integrity of the cell membrane

many diseases linked to free radical damage: cancers, heart disease, diabetes, arthritis, cataracts, kidney disease, alzheimer disease, parkinson disease)

antioxidant enzyme systems

break down oxidized fatty acids

make more vitamin antioxidants available to fight free radicals

minerals that fxn as cofactors: selenium, zinc, copper, manganese, iron

superoxide dismutase: converts free radical to less damaging substances, such as H2O2

catalase: removes H2O2 from the body by converting it to water and oxygen

glutathione peroxidase (GPx) also removes H2O2 from body and stops the production of free radicals in lipids

carotenoid sources

red, orange, deep-green veggies (cantalope, carrot, sweet potatoes, apricots, kale, spinach, pumpkin, tomatoes)

flavanoid sources

berrie, black and green tea, chocolate, purple grapes, citrus fruits, olives, soybeans/soy products, flaxseed, whole wheat

phenolic acid sources

coffee beans, fruits (apple, pear, perries, grapes, oranges, prunes, strawberries) potatoes, mustard, oats, soy

selenium

two major forms enter body: selenomethionine (plant derived) and selenocysteine (animal derived)

both formed readily absorbed, 50-90% absorption in diet

no physiological mechanism to control fro absorption, thus a potential for toxicity

largely regulated via excretion

stored primarily bound ot mehtionine and as part of GPx

selenium fxns

glutathione peroxidase - antioxidant system, eliminates peroxides

thioredoxin = antioxidant system

role in thyroid hormone synethsis

others - prevention of colon cancer?

selenium food sources

animal products: fish, meats (esp. organ meats), eggs, milk, shellfish

plant products relect amount of Se in soil in which grown

selenium recommendations

RDA: 55 micrograms for adults

DV = 55 ug

selenium deficiency

muscle pain, muscle wasting, cardiomyopathy

keshan disease - cardiomyopathy

keshan-back - subform of keshan with joint deformity in addition to cardiomyopathy

chronic diseases

toxcicity of selenium

UL = 400

hair loss, GI upsets, skin rashes, liver cirrhosis, garlic breath odor, nausua, fatique, nail changes only from supplements

vit C

reduced form = ascorbic acid

oxidized form = dehydroascorbic acid

most animals synthesize vitamin C, but not humates includingin nonhuman primates, guinnea pigs, some birds/fish

absorption in amall intestine vis active transport of ascorbic acid or faciliated diffusion for dehydroascorbic acid

no real storage form btu concentrated in pituitary, adrenal glands, WBC, eyes, and brain

vitamin C

antioxidant activity: regeneration of vit E

nonspecific reducing agent: cofactor for metalloenzymes

collagen synthesis

iron (nonheme) absorption

biosynthesis of other vital cell components: carnitine, norepi and epi, thyroxine, tryptophan into serotonin, cholesterol into bile acids, corticosteroids, aldosterone, tyrosine metabolism

vit C food

citrus, potatoes, dark green veggies

easily lost in processing and cooking

very unstable - in contact with heat, Fe, Cu, O2

vit C reccomendations

RDA male 90; female 75 mg

smoking causes oxidative stress, raises requirement by 35 mg

based on near max vitamin C concentration in neutrophils

vit C deficiency

scruvy

appears after 20-40 days on vitamin C free diet

prevents normal synthesis of collagen, thus changes in connective tissue thru out body

signs and sx: fatigue, pinpoint hemorrhages (petechiae), bleeding in gums and joints, impaired wound healing, bone pain; fractures

scurvy associated with poverty

north americans at risk: drug/EtOh addict, elderly who hate f and v

ppl exposed to cigarette smoke

high intakes of vit C

intake over 100 mg excreted in urine

not enough research about prevention/treatment of colds

toxicity: GI problems like nausea, ab cramps, osmotic diarrhea

UL 2g based on osmotic diarrhea and GI problems

vitamin E

naturally occuring forms: tocopherol and tocotrienol. both have alpha, beta, gamma, delta forms (alpha and gamma are biologically active)

% absorption dnds on total absorption of dietary fat. absorption pattern follows other FSV

transport and storage: LP needed for transport to liver, adipose tissue, and skeletal muscle where stored. associates itself with PL in cell membrane

exreted in urine, bile, and skin

vit E functions

antioxidant function, especially protection of fat oxidaiton

vit E in foods

plant oils, salad dressing, grain meals, nuts and seeds

animal fats have very little

content depends on harvesting process, storage, cooking

vit E reccomendations

RDA 15 mg a-tocopherol (based on amount to prevent hemolysis)

conversion to IUs: .045 mg of synthetic form, 0.67 mg of natural source

vit E deficiency

at risk: smokers (bc oxidative damge), preterm infants (limited stores, ineffective absorb, hemolytic anemia, treated with formulas), low fat diets, fat malabsorption, genetic abnormality in LP synthesis

sx: NS damage, lower immune fxn

dx: measuremet of membrane destruction when RBCs treated with peroxide (RBC hemolysis)

Intakes tend to be low in US diet

avg adult consumes 2/3 of RDA

vit E toxicity

UL = 1000 mg/d or 1500 IU of any form of supplementary a-tocopherol (dont have to worry about dietary)

based on hemorrhagic effects due to interference with vitamin K