Lecture 3: Macronutrients

What is the most important nutrient?

waterh

What are the important macronutrients?

• protein

• fat/lipids

• carbohydrates

What are the important micronutrients?

• vitamins

• minerals

What is a complete and balanced diet?

meets all essential nutrient needs and in appropriate ratios

Why may nutrients be increased or decreased compared to current (maintenance) diets?

for therapeutic diets (ex. phosphorus-deficient diet to help slow progression of chronic kidney disease)

What are the sources of essential nutrients?

• protein is a source of essential amino acids

• lipid/fat is a source of essential fatty acids

• carbohydrates are complicated

What is ATP generated from?

• Anaerobic metabolism (i.e. glycolysis) - Carbohydrate

• Aerobic metabolism (i.e. TCA cycle) - Protein, Lipid, Carbohydrates

Not only does the energy density of macronutrients differ, but so does the amount of ____ produced during metabolism (____ increment).

heat

What are the complex structures composed of amino acids connected by peptide bonds?

proteins

What are amino acids?

nitrogen-containing molecules that form proteins

What are the purposes of protein/amino acids?

• Muscle

• Skin & coat health

• Hormones (including GI hormones)

• Enzymes

• Plasma oncotic pressure

• Acid/base balance

• Euglycemia (cats) - Gluconeogenic amino acids

• Energy (aerobic)

What is crude protein?

nitrogen% x 6.25

• does not differentiate amino acids vs non-amino acid nitrogen

• need to confirm that there is a source of essential amino acids

What is the difference between non-amino acid nitrogen and amino acid nitrogen?

non-amino acid nitrogen is from urea and amino acid nitrogen is from animal or plant protein

What is good quality protein?

• Rich in essential amino acids

• Highly digestible & bioavailable

  • Optimizes amino acid utilization

  • Limits protein fermentation in the large intestine

What are the essential amino acids?

• phenylalanine

• methionine

• arginine

• lysine

• taurine for cats

What amino acid is only essential for cats?

taurine

Are “byproducts” a source of protein?

yes, animal-based byproducts are

Can plants be a good source of protein?

• yes, for omnivores

• for carnivores its harder - incomplete in essential amino acids, thus requires careful formulation with complimentary protein source or added amino acids

How can you tell if protein intake is adequate?

• MCS

• serum albumin

• compare the current diet to requirements

What are the protein deficiency syndromes?

• muscle loss

• decreased growth rate

• weight loss

• anemia

• poor hair coat, decreased color

• dilated cardiomyopathy, retinopathy (taurine)

What is the purpose of lipid/fat?

• Energy (aerobic)

• Food energy density - BCS

• Essential fatty acids

• Cell/lipid membranes - Including skin

• Neurologic & retinal development

• Fat soluble vitamin absorption

• Generally, highly palatable (dogs/cats)

What are the 3 types of lipids?

• Triglycerides (animal, seed/grain) - glycerol + 3 fatty acids

• Phospholipids (forage/animal cell wall) - glycerol + fatty acids

• Free fatty acids

How are fatty acids characterized?

by the number of double bonds:

• saturated = 0 double bonds, single bonds only

• unsaturated

  • monounsaturated = 1 double bond

  • polyunsaturated = 2+ double bonds

What type of fatty acid are all essential fatty acids?

polyunsaturated fatty acids (PUFAs)

What are the two types of polyunsaturated fatty acids (PUFAs)?

Omega-6

• 1st double bond at the 6th carbon from the methyl end (CH3)

• Linoleic acid (LA)

• Arachidonic Acid (AA)

Omega-3

• 1st double bond at the 3rd carbon from the methyl end

• Alpha linolenic acid (ALA)

• EPA, DHA

• Anti-inflammatory

How are fatty acids characterized by length?

• Short-chain: aka. volatile fatty acids (VFAs), < 6 carbons, Produced by GI microbes!

• Medium-chain: 6-12 carbons, Coconut oil (source)

• Long-chain: 13-21 carbons, Essential fatty acids are all long-chain

What are the essential fatty acids for dogs?

• linoleic acid

• alpha linolenic acid

• EPA & DHA

What are the essential fatty acids for cats?

• linoleic acid

• arachidonic acid

• alpha linolenic acid

• EPA & DHA

What are lipoproteins?

a vehicle to traffic fats to/from tissue

What are the largest and most lipid-dense of the lipoproteins?

chylomicrons

How are long-chain fatty acids or triglycerides transported from the intestines?

via lymphatics via chylomicrons because they are too large to enter blood and to reduce fat load to the liver

What are the fatty acids in plants?

• leaves - alpha linolenic acid (ALA)

• grain/seed - linoleic acid (LA), ALA

What are the fatty acids in lipids?

• arachidonic acid (AA)

• EPA & DHA (marine only)

What are the sources of lipids?

• Vegetable oils & poultry fat supplies mostly polyunsaturated omega-6 FA

• Mammal fats supply mostly saturated FA

• Fish/marine sources, including algae, supply polyunsaturated omega-3 FA

How can you tell if essential fatty acid intake is adequate?

skin and coat

What are the fatty acid deficiency syndromes?

– Dry skin, dermatitis, dull haircoat

– Decreased neural and retinal function (during development and growth)

– Decreased growth rate

– Weight loss

– Immunodeficiency

How are carbohydrates classified?

– Fiber vs. non-fiber

– By molecular structure, specifically number of monosaccharide units (next slide)

– Complexity

– Solubility

– Fermentability

– Viscosity

How are carbohydrates classified by fiber?

• non-fiber carbs = digestible carbs = starches

• fiber carbs = indigestible carbs = cellulose

What is the carbohydrate classification of starch?

non-fiber polysaccharide

What is the carbohydrate classification of fructooligosaccharides?

oligosaccharide (3-10 monosaccharides)

What is the carbohydrate classification of cellulose?

fiber polysaccharide

What do non-fiber carbohydrates do?

– Energy (aerobic & anaerobic) - Brain & fetus

– Euglycemia

– Lactose

– Glycogen

– Glycoproteins

What do fiber carbohydrates do?

– GI health: Energy for GI microbes, Motility, Stool quality & regularity

– Regulate glucose absorption

– Reduce energy density

– Satiety

– Reduces diet digestibility (in general)

What are some sources of carbohydrates?

• Grains

• Vegetables

• Fruits

• Whole / modified / purified

What is a source of omega 3s?

fish oil

How might fiber be represented on a food label or nutrient analysis?

– Crude fiber (CF): Insoluble, Doesn’t represent TDF

– Total dietary fiber (TDF): A better representation of dietary fiber than CF!

– Neutral detergent fiber (NDF): Large animal

– Acid detergent fiber (ADF): Large animal

How might non-fiber be represented on a food label or nutrient analysis?

Nitrogen-free extract (NFE) % = 100-(%moisture + %CF + %CP + %EE + %Ash)

• CF = crude fiber

• CP = crude protein

• EE = ether extract (fat/lipid)

• Ash = minerals