Nutrients for food & electrolyte balance & antioxidant function Flashcards Preview

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Flashcards in Nutrients for food & electrolyte balance & antioxidant function Deck (41):
1

Fluid Facts

-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

2

Where Is The Fluid Located?

-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

3

Fluid Composition: Water

-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

4

External Factors That Influence Water Balance

-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

5

Regulation of Body Water

-↓ 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

6

Water Needs

-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

7

What Should Most People Be Drinking?

-Water!
-Milk

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

8

Dehydration

-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

9

Prevention of Dehydration

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

10

Fluid Composition: Electrolytes

-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-

11

The Function of Electrolytes: Fluid Balance

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

12

The Function of Electrolytes: Fluid Balance (active transport)

-Electrolytes move across membranes to maintain the appropriate electrolyte concentration (& fluid) via active transport (protein carrier & ATP)
-Sodium-potassium pump- 20-40% of REE

13

The Function of Electrolytes: Nerve & Muscle Response

-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

14

Regulation of Electrolytes

-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

15

Sodium

-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)

16

Sodium Sources & Needs

-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

17

Potassium

-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

Potassium Sources

-Abundant in fresh foods & fruits & vegetables
-Lost in processing

19

Hypertension

-↑ 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

Antioxidants: Against Oxidation

-Oxidation: chemical reaction where an atom loses an electron
-Reduction: atom gains an electron

21

Free Radicals: The Bad Guys

-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

Free Radical Damage

-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

Antioxidants: The Good Guys

-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

Vitamin E

-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