Nutrients for food & electrolyte balance & antioxidant function Flashcards

1
Q

Fluid Facts

A

-Body fluids comprised of
*Water (solvent)
*Dissolved substances (solutes)
~Electrolytes: sodium, potassium, chloride, phosphorus
-Our bodies contain more water than anything else
-50-70% of body weight is fluid
*95% of blood is fluid
*>70% of muscle is fluid
*25% of bone is fluid
*10-20% of fat is fluid

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2
Q

Where Is The Fluid Located?

A
  • Found in blood, lymph, cells, between cells, tears, GI mucus/saliva, spinal column, joints
  • 2/3 fluid is intracellular
  • 1/3 extracellular
    • Interstitial- between cells or
    • Intravascular- inside blood vessels & lymph
  • ↑ intracellular fluid → cells burst
  • ↓ intracellular fluid → cells collapse
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3
Q

Fluid Composition: Water

A

-Water: the most important nutrient on a daily basis (no reserve), death after 3-4 days without water

Functions:

  1. Dissolves solutes
  2. Transports substances
  3. Blood volume & blood pressure
  4. Lubricant and protection
  5. Regulates body temperature
  6. Chemical reactions
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4
Q

External Factors That Influence Water Balance

A
  • Illness: fever, cough, vomit, diarrhea
  • Injury with blood loss
  • ↑ exercise
  • Variations in temperature, humidity and altitude
  • Pregnancy & breastfeeding
  • Diuretics – alcohol (blocks ADH), medications
    • Caffeine- mild diuretic, 500 mg/d do NOT cause dehydration (4.5 c of coffee/day)
  • High fiber, protein & sodium diet
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5
Q

Regulation of Body Water

A

-↓ body water = increase blood solutes and decrease blood volume and decrease blood pressure
*Due to: vomiting, diarrhea, sweating, low fluid intake
-This signals
*Hypothalamus to trigger sensation of thirst
*GI to absorb more water- constipation
*Hormonal control of urinary losses
~Antidiuretic hormone (ADH): reabsorb water (in response to ↑ solutes)
~Renin-angiotensin-aldosterone system: reabsorb Na and Cl and water (in response to ↓ BV) & vasoconstriction

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6
Q

Water Needs

A
  • Depends on body size, health status, physical activity, environment, diet
  • DRI (beverages & food sources)
    • Men: 3.7 L/day
    • Women: 2.7 L/day
  • Hard to know how much you get in food
  • General guideline: ~ 8 c (~2 L) water daily
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7
Q

What Should Most People Be Drinking?

A
  • Water!
  • Milk

-Exceptions: excessive sweating, vomiting, diarrhea, prolonged activity (exercise >1 hr at 60% maximal effort), physical work in high heat… electrolyte replacement drinks

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8
Q

Dehydration

A
  • Who is at risk? excessive sweating, elderly, babies, diarrhea, excessive heat
  • Measured as % body weight loss (weigh before & after)
    • 1-2% strong thirst sensation, athletic performance can decline
    • 3-5% dry mouth, reduced urine output
    • 6-8% muscle weakness, dizziness, exhaustion, increased body temperature, increased heart rate
    • 9-11% ↓ blood volume & pressure, delirium
    • 20% coma and death
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9
Q

Prevention of Dehydration

A

-Assess your needs, consider what?
-Use water fountains
-Carry water
-Exercise
< 1 hr: water
> 1 hr: CHO & electrolytes
Athletes: Pre-hydrate & Re-hydrate

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10
Q

Fluid Composition: Electrolytes

A
  • Body fluids = water + dissolved solutes
  • Electrolytes: mineral salts separate in solution into ions (carry electrical current)
                  NaCl → Na+ & Cl-
  • Extracellular electrolytes: Na+ & Cl-
  • Intracellular electrolytes: K+ & H2PO4-
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11
Q

The Function of Electrolytes: Fluid Balance

A
  • Electrolytes regulate intra & extracellular fluid balance
    • Cell permeable to water, not electrolytes
    • Osmosis: water moves from a low to a high concentration of solutes
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12
Q

The Function of Electrolytes: Fluid Balance (active transport)

A
  • Electrolytes moveacross membranesto maintain theappropriate electrolyteconcentration (& fluid)via active transport (proteincarrier & ATP)
  • Sodium-potassiumpump- 20-40% of REE
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13
Q

The Function of Electrolytes: Nerve & Muscle Response

A
  • Nerve conduction
    • Nerve impulse created by a change in the electrical charge across the nerve cell membrane due to an influx of Na resulting in a change in electrolyte concentrations
    • Ca is involved when the nerve impulse reaches its target site
  • Muscle contraction
    • Similar change in electrolyte concentrations but with the addition of calcium allowing muscle fibers to slide and contract
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14
Q

Regulation of Electrolytes

A
  • Blood levels of electrolytes tightly controlled
  • Largely regulated by the kidneys
    • Reabsorb or filter depending on blood levels
    • Reabsorb sodium & chloride as a means to reabsorb water (fluid balance)
    • Salt-sensitive people do not filter as well, retain more water and have increased BV and BP
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15
Q

Sodium

A
  • Principle extracellular cation
  • Functions: fluid balance, nerve transmission, muscle contractions
  • Kidneys regulate levels well
    • filter excess
    • reabsorbed if low BV
    • 30-50% may not filter well
  • When ↑ Na+ intake, thirst signals to dilute with water
  • Toxicity: high blood pressure, fluid accumulation
  • Deficiency: rare, hyponatremia in athletes that replace fluids w/o electrolytes (headache, dizzy, nausea, muscle cramps, coma, death)
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16
Q

Sodium Sources & Needs

A

-Estimated requirement: 200-500 mg
-AI: 1,500 mg/d (19-50 y.o.)
-UL: 2,300 mg/d (1 tsp salt)
-Dietary Guidelines:
↓ sodium to 2,3oo mg and to 51 year old, or any age African American, or have hypertension, DM, kidney disease

  • Average intake: 3,000-6,000 mg daily
  • Sources: salt, processed foods
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17
Q

Potassium

A

-Principle intracellular cation
-Functions: fluid balance, nerve transmission, muscle contraction (heartbeat regulation), help lower BP (suppresses renin-angiotensin system)
-Deficiency: rare not d/t food (diuretics, GI losses, anorexia); irregular heart beats, hypertension
Toxicity: not unless kidney disease, could lead to possible heart attack

18
Q

Potassium Sources

A
  • Abundant in fresh foods & fruits & vegetables

- Lost in processing

19
Q

Hypertension

A
  • ↑ BP → ↑ risk of CVD, stroke, kidney disease
  • Systolic: pressure when heart contracts
  • Diastolic: pressure between contractions
  • Optimal: 140/90 mm Hg
  • ↓ BP: exercise, weight loss, ↓ alcohol, ↓ sodium, ↑ potassium, ↑ F/V & whole grain, DASH diet
20
Q

Antioxidants: Against Oxidation

A
  • Oxidation: chemical reaction where an atom loses an electron
  • Reduction: atom gains an electron
21
Q

Free Radicals: The Bad Guys

A
  • If a stable atom loses an electron during oxidation –> unstable atom now called a free radical
  • Free radicals are very reactive
    • React with other molecules to become stable
    • In the process they can form more free radicals, can lead to a chain reaction
  • Free radicals form from metabolism, pollution, tobacco smoke, sunlight exposure
22
Q

Free Radical Damage

A
  • Free Radicals can damage
    • Unsaturated fatty acids in cell membranes, damaged membranes  change cell functioning & cell death
    • LDL, cell proteins & DNA
  • Associated : cancer, heart disease, diabetes, macular degeneration (leading cause of blindness in older adults)
23
Q

Antioxidants: The Good Guys

A
  • Vitamins A, C, E , beta-carotene & phytochemicals : stabilize free radicals by donating a H or their electrons
  • Minerals: components of antioxidant enzymes that help remove free radicals such as
    • Superoxide dismutase (contains Cu, Zn, Mn) converts free radicals to less damaging molecules (hydrogen peroxide)
    • Catalase (contains Fe) converts hydrogen peroxide to water & oxygen
    • Glutathione peroxidase (contains Se) removes hydrogen peroxide from the body, stops production of free radicals in lipids
24
Q

Vitamin E

A
  • Fat soluble vitamin- 90% are stored in our adipose tissue, the rest in cell membranes
  • Functions: fat soluble antioxidant that prevents oxidation of
    • Fatty acids & PUFA in cell membranes
    • LDL
    • RBC membranes
    • Lung cells
  • Added to oils and products to reduce rancidity
25
Vitamin E Deficiency & Toxicity
Deficiency: - Rare - Results from diseases causing fat malabsorption - Membrane damage - RBC rupturing resulting in anemia Toxicity: - Uncommon via food - Supplemental doses (400 IU) may ↑ risk of heart failure, stroke and death - Supplements contraindicated with some anticoagulant drugs (aspirin, Coumadin)- interferes with forming prothrombin- ↑ bleeding
26
Vitamin C (Ascorbic Acid)
-Water soluble vitamin, excess is disposed of in the urine (take daily) -Functions *Antioxidant (water-soluble), important in extracellular fluid ~Protects WBC from oxidation enhances immune function, ↓ cold duration if taken regularly at doses ↑ RDA ~Protects lung cells from oxidation ~Regenerates vitamin E *Iron absorption *Collagen formation
27
Vitamin C: Additional Functions
Collagen synthesis | -Connective tissue protein found in skin, teeth, bone, tendons, blood vessels
28
Vitamin C Deficiency & Toxicity
Deficiency: - Scurvy: bleeding gums - Weakened blood vessels * Pinpoint hemorrhages * Bruising - Bone & joint aches - Bone fractures - Poor wound healing Toxicity: unlikely- excreted in urine
29
Vitamin C: RDA
-Men: 90 mg/day -women: 75 mg/day - Smokers require more: RDA + 35 mg/day * Smokers & people around second-hand smoke have lower blood levels - More for wound healing (surgery, burns) but amount not known -UL: 2,000 mg- side effects can occur
30
Vitamin C: In the Diet
- Citrus fruits excellent source - Other fruits & vegetables good source - Unstable and destroyed by oxygen, light, and heat
31
Vitamin E: In The Diet
- Cooking oils - Nuts & seeds - Fortified cereals - Very easily destroyed by heat, light, oxygen -RDA: 15 mg alpha tocopherol/day (22.5 IU)
32
Vitamin A & Beta-Carotene
Vitamin A refers to -Preformed vitamin A: the active form of the vitamin your body will use - Provitamin A carotenoids * Carotenoid: orange, red, yellow plant pigments * Provitamin: inactive form of a vitamin that the body can convert to an active form * Three provitamin A carotnoids: alpha & beta carotene and beta-cryptoxanthin * Lutein, Lycopene, zeaxanthin
33
Beta-Carotene: Provitamin A Carotenoid
- Beta-carotene --> retinal (active vitamin A) in SI - Functions: Provitamin A, fat-soluble antioxidant (LDL, skin, eyes) - Deficiency: none, does not play an essential role in our body - Excess consumption: carotenosis (yellowing of skin), supplements ↑ risk of death
34
Preformed Vitamin A
- Fat soluble vitamin, 90% stored in liver - Three active forms in body: retinol, retinal, retinoic acid - Functions * Fat-soluble antioxidant * Cell differentiation, reproduction and growth * Eyesight- light/dark & color
35
Retinol
- vision - sexual reproduction - bone health - immune function
36
Retinal
- vision - sexual reproduction - bone health - immune function
37
Retinoic acid
- Cell differentiation - bone health - immune function
38
Vitamin A: Deficiency & Toxicity
Deficiency: - Worldwide leading cause of blindness * Night blindness * Color blindness * Xeropthalmia (blindness due to hardening of the cornea , mucus forming cells deteriorate) Toxicity: - Rarely from food - From 5-10 x RDA via supplements: * Liver & bone damage * Teratogenic: causing birth defects & abortion * Increased risk of death
39
Why Deficiency in Developing Countries?
-Africa, South America, India, Asia -Insufficient intake of *Animal *Low-fat/Low-protein/High starch diets ~Need fat for absorption ~Need protein to make retinol-binding protein that transports vitamin ~High starch foods not high in carotenoids
40
Beta-Carotene and Vitamin A in the Diet
- Preformed vitamin A: animal foods (liver), fortified milk | - Provitamin A: plants (orange)
41
Selenium
- Trace mineral - Part of glutathione peroxidase - Helps produce thyroid hormone - Sources: animal foods - Deficiency: rare - Toxicity: not from food