Chapter 1

Nutrients and Recommended Intakes

nutrition def

the net processes of ingestion, digestion, absorption and metabolism of food and the subsequent merging of nutrient materials into tissues

substances found in food that perform >(_) specific bodily functions

don’t eat nutrients, we eat food

46 known essential nutrients

sports nutrition vs general nutrition recommendations

may vary/differ to elevate/maximize athlete performance

6 nutrient categories

carbs

fats

proteins

water

vitamins

minerals

nutrient functions

promotion of growth and development

provision of energy

metabolism regulation

macronutrients

>10g/day

includes carbs, fats, proteins, water

micronutrients

<10g/day; often <1g/day

includes vitamins, minerals, phytonutrients (not essential but important for health)

phytonutrients def

phyto - plant

certain organic parts of plants that may promote health but are nonessential

common classes: carotenoids and polyphenols

many have antioxidant and anti-inflammatory effects

Carbohydrates - what are they, energy sources

molecules built of C, H, and O₂

energy source for: muscles, CNS, energy storage (as glycogen in live and muscle)

Essential for both performance and recovery in sport

4kcal/g

• except fiber = ~2kcal/g

carb function

normal conditions = blood glucose is only fuel for CNS cells

• optimal when blood glucose > 4mmol/L

  • normal is ~5.5mmol/L

after prolonged fasting (~3days), FA create ketone bodies from liver and serve as a blood glucose substitute

hypoglycemia

<3mmol/L

Symptoms: weakness, hunger, dizziness, and shivering

carb types

glucose

fructose

sucrose

glucose polymers (malodextrins)

starch (amylopectin)

main carbs in sports drinks

glucose

glucose polymers/malodextrins

Classes of carbs

monosaccharides

disaccharides

• with mono- = called sugars, simple sugars/carbs

oligosaccharides

polysaccharides

Monosaccharides

basic unit of a carb

3 types:

• glucose/dextrose/grape sugar

  • only carb oxidized in the muscle

• fructose/fruit sugar

  • convert into glucose at liver slowly

• galactose

  • convert into glucose at liver slowly

disaccharides

combo of 2 monosaccharides

types:

• Sucrose

• lactose

• maltose

sucrose

glucose + fructose

most common, 20-25% of intake

lactose

glucose + galactose

maltose

glucose + glucose

oligosaccharides

3-9 monosaccharides combined

most vegetables

polysaccharides definition

>(_) monosaccarides

10-20 = glucose polymers/malodextrins

1000’s = starches, glycogen, fiber

• predominant types of polys-

Polysaccharides: starch/complex carb

2 types:

amylopectin

amylose

Amylopectin

starch/complex carb

highly branched molecule that contains 2,000-200,000 glucose units

rapidly digests and absorbed (due to higher surface area)

Amylose

starch/complex carb

long chain (200-4,000) glucose units twisted in a helical coil

digested more slowly

• harder for enzymes to attach to and break down

glycogen

polysaccharide

storage form of carbs

80-100g stored in liver

300-900 g stored in muscles

fiber

polysaccharide

most common type: cellulose

• other types: gums, hemicellulose, beta-glucans, fructans, pectin

not digested by enzymes in stomach and small intestine

• goes through large intestine primarily unchanged, but can partially degrade and metabolize via a large amount of resident bacteria/microbiota

decreases rate of gastric emptying (food in stomach longer)

influences absorption of many micronutrients

insoluble and soluble

soluble fiber

dissolves well in water (~70% of fiber in diet)

1.5 kcal/g

broken down in large intestine into sugars by enzymes produced by microbiota

• ferments sugars anaerobically to form short-chain FA

  • can be used as an energy source by both bacteria and cells that line LI

    • SCFAs have broad significant health effects

insoluble fiber

water attracting properties that increase bulk, soften stool, and shorten transit time via intestinal tract

commonly used for constipation

~0 kcal/g (due to basically being excreted unchanged in feces

eg. fruit skin

fiber types in diet

dietary fiber

functional fiber

total fiber = dietary fiber + functional fiber

• total intake is most important

dietary fiber

natural non-digestible carbs

Functional Fiber

lab created nondigestible carbs that has beneficial effects

simple carb food sources

fruit (+juices)

sweetened cereals/baked goods

jam

candy

chocolate

most sports drinks

beet/cane sugar

honey

starch food sources

cereal

potatoes

pasta

rice

bread

fiber food sources

whole-grain cereals and breads

oats

dried beans and peas

fruits and vegetabels

lipid def

general name for oils, fats, waxes and related compounds

• oils are liquid and fats are solid at room temp

9 kcal/g

important for light-moderate long duration exercise (ultras)

lipid function

helps absorb 4 essential fat-soluble vitamins: A, D, E, K

carries many aromatic substances and makes food tastier, more attractive, creamier, more appetizing, more energy dense

Lipid Classes

simple lipids

compound lipids

derived lipids

simple lipids

neutral fats → eg triacylglycerol

waxes → eg beeswax

compound lipids

phospholipids → lecithins, cephalins, lipositols

glycolipids → cerebrosides, gangliosides

lipoproteins → chylomicrons, very low-density lipoproteins, LDL, HDL

derived lipids

fatty acids → palmitic acid, oleic acid, stearic acid, linoleic acid

steroids → cholesterol, ergosterol, cortisol, bile acids, vitamin D, estrogens, progesterone, androgens

hydrocarbons → terpenes

Triglycerides

main storage form of fat

most abundant form of fat in diet

if excess carbs or fat are consumed in diet = stored as triglycerides in adipose tissue

cholesterol

lipid found in cell membranes and helps build/maintain membranes

transported in blood plasma

commonly found in the liver where it is produced

found in diet - little consumed (~300 mg/d)

Bile

cholesterol makes bile

stored in the gallbladder and hlep sdigest fats

important for:

• metabolizing fat-soluble viatmins

• major precursor to vitamin D synthesis and various steroid hormones (testosterone, estrogen, cortisol)

lipid functions

stored primarily in subcutaneous adipose tissue

• mobilized and transported to organs for use when needed

• muscles have a direct store of fat (intramuscular triglycerides)

Protects vital organs (heart, liver, spleen, kidneys, brain, spinal cord) against trauma

• ~2-4% of total fat is stored around organs

transport carriers for fat-soluble vitamins and carotenoids

Lipids: fuel

only some can be used

FA, intramuscular triglycerides, circulating plasma triglycerides (chylomicrons and VLDLs)

• HDL, LDL, IDL have little role in energy production

ketone bodies (acetoacetate, beta-hydroxybutyrate)

glycerol can convert into glucose via gluconeogensis in the liver and then oxidizes

amino acids

building blocks of all proteins

20 different types

• 11 are created naturally in the body = nonessential

  • 9 essential - need to get form our diet

complete proteins

contain all essential AA

high quality PRO

incomplete PRO

low-quality PRO

deficient in >(_)1AA

• can’t support life and growth

peptide

many types of AA binding from peptide bonds

most are polypeptides (+300AA)

Amino Acid functions

central roles in metabolism of many organs and tissues

precursors and regulators of synthesis

• for important metabolic mediators and compounds with regulatory biological activity

  • neurotransmitters, hormones, DNA, RNA

PRO - energy use

not used for energy → unless carb stores are depleted in starvation periods

4 kcal/g

• highest satiety and thermic effect of feeding all macronutrients

After digestion, absorption and metabolism = ~3kcal/g

Total calories coming from protein on nutrition label = not true

Protein functions

provides structure to all cells in the body

integral part of cell membrane, cytoplasm, and organelles

muscle, skin, and hair = largely composed of pro

• defieicney = structures break down = decreased muscle mass, loss of skin elasticity, thinning hair

many are enzymes:

• increase metabolic reactions rate

some are transporters or receptors for hormones (insulin, glucagon, thyroid-stimulating hormone)

Protein intake

recommended = 0.8-1.2 g/kg

western world = ~80-100 g/day (more than recommendations)

• not associated with negative health effects

Protein quality

degree protein contributes to daily requirements

method = PDCAAS

• protein digestibility corrected AA scores

  • ranking is determined by comparing AA profile of a specific food protein against a standard AA profile

• Max score of 1 = after digestion it provides 100% or more indispensable AA required per unit of protein

  • lowest score = 0

water overview

cannot survive w/out it

adult body is ~60% water by weight

• ⅔ is intracellular water

• ⅓ is extracellular fluid

  • includes plasma, lymph, cerebrospinal fluid, interstitial fluid, urine, fluid inside joints and eyes.

water function

transport nutrients in solution

• O2 and CO2/waste products

• helps remove waste products through urine

protection → lubrication, cleansing, cushioning

regulate body temperature → sweating

participates in biochemical reactions and provides medium in which reactions take place

Water intake

adults average: 2-2.8 L/day (68-95 fl oz)

• general rule = 1mL/kcal

• 1-1.5 is from fluid; rest from foods

athletes training and competing in hot conditions may need >15 L/day

alcohol

aka ethanol

7 kcal/g

not essential in our diet

most coverts to fat

may have health benefits when ingested in moderation

• excess impairs brain function

binge drinking slows recovery processes after exercise

vitamins/minerals/trace elements def and function

essential compounds = have many biological functions

regulators and links in processes of energy release from food

important in:

• cofactors in various chemical reactions

• maintaining homeostasis

absence (3-4wks) from diet in adequate amounts = disease states

many minerals are also essential nutrients (zinc, calcium, iron)

vitamins

organic compounds

13 known - important functions in most metabolic processes in the body

types:

• fat = A, D, E, K

• water = C, 8B’s

must be obtained in diet expect D (sunlight) and K (intestine bacteria)

minerals

inorganic compounds

divides in macro- and micro - minerals/trace elements

• macro = daily intake of >100 mg or presence in body is >0.01% of BW

• micro/trace = required daily intake of <100mg or presence in body is <0.01% of BW

Carotenoid Sources

red, orange, yellow pigments

alpha-carotene: carrots

beta-carotene: orange and yellow vegetables, leafy green vegetables

beta-cryptoxanthin: citrus, peaches, apricots

lutein: leafy greens

lycopene: tomatoes, pink grapefruit, watermelon, guava

zeaxathin - green vegetables, eggs, citrus

Polyphenol Sources

nonflavonoids:

• ellagic acid - stawberries, blueberries, raspberries

• coumarins - bell peppers, bok choy, cereal grains, broccoli

flavonoids:

• anthocyanins - red fruits

• catechins - tea, wine

• flavanones - citrues

• flavones - fruits and vegetables

• flavonols - fruits, vegetables, tea, wine

• isoflavones - soy beans

conditionally essential nutrients

nutrients under normal circumstance are not essential but can become essential under certain conditions

deficiency can be due to a defect int he synthesis of a certain nutrient or temparily an increase need for that nutrient (surgery or pregnancy)

must be supplied exogenously to specific populations taht do not syntehsize them in adequate amounts

Dietary Reference Intake

framework fro a set of 5 current recommendations

• recommended dietary allowance

• estimated average requirement

• adequate intake

• tolerable upper intake level

• acceptable macronutrient distribution range

RDA

recommended dietary allowance

intended as a goal for daily intake

recommendations depend on age, sex, and if a female is pregnant or lactating

based on median heights and weights of a population

stress, disease, injuries, and total energy expenditure influence the needs for certain nutrients

EAR

estimated average requirement

amount of a nutrient that is deemed sufficient to meet the needs of the average person in a certain age and sex group

• a chosen individual has a 50% chance of meeting their requirements at the desired intake level

adequate intake

set when lacking data to set an EAR/RDA

used as a goal intake level based on observed or experimentally determined estimate for groups of healthy populations

TUL

tolerable upper limit

max amount of nutrient intake that is unlikely to cause serious health risks for the greatest amount of individuals in a group

not intended to reach intake level

need came from increased fortified foods with nutrients and supplements that would cause high intakes of some nutrients

AMDR

acceptable macronutrient distribution

range of intake for a dietary macronutrient that at the lower end provides adequate intake of essential nutrients and below the upper limit that limits risk of chronic diseases and allows sufficient intake of other macronutrients

food labels

reference values to determine RDAs are age and sex specific

food labels must be the same for men and women as well as children and adults

• thus RDA values had to be condense into an acceptable recommendation for all groups

DV

daily values

based on 2 sets of references: reference daily intake, and daily reference value

on food labels all values are listed as DV but can be either DRV or RDI

%DV = %RDI/DRV available in 1 serving

RDI

reference daily intake

makes up most DVs

gives a set of dietary references for essential vitamins and minerals

DRV

daily reference value

standard for proteins and dietary components that have no RDA or other standard

cholesterol, fat, carb, fiber, sodium, potassium

Analyzing Dietary Intake

Useful for several reasons:

• average intake in a group of athletes can be studied and the data used with biochemical or anthropometric data

• used with a medical report or to explain incidence/prevalence of health problems

• educational purpose → efficacy of nutritional advice or intervention programs can be investigated

• several methods have been created to measure dietary intake → each has pros/cons

nutrition in sports

amount, composition, and timing of food intake can profoundly affect sports performance

good diet will not make an average athlete become elite; a poor diet will prevent an elite athlete from achieving their performance potential

well being, performance, and recovery from sports are enhanced by good nutrition

valuable role in optimizing physical and mental performance and maintaining overall health of a long season

fatigue contributors

carb depletion

dehydration

pros of good nutrition

increases endurance

delays physical and mental fatigue

speeds recovery

perform harder training

avoid illness

decrease risk/accelerate recovery from injury

maintain mental concentration

sleep better

maintain proper BW/body comp