Nutrition Flashcards
What is a nutrient?
A substance found in food that performs one or more specific functions in the body
What are the class of nutrients?
Macronutrients, micronutrients
What are macronutrients?
Carbohydrates, lipids, proteins, water
What qualifies a nutrient as macro?
Required habitually at >1g/day
What are micronutrients?
Vitamins, minerals, and trace elements
What qualifies a nutrient as micro?
Are required in smaller amounts: <1g/day; are essential compounds
What are the three main dietary monosaccharides?
Glucose, fructose, galactose
What are three main dietary disaccharides?
Maltose, sucrose, lactose
How is maltose formed?
Glucose + glucose
How is sucrose formed?
Glucose + fructose
How is lactose formed?
Glucose + galactose
What is a main dietary polysaccharide?
Fibre aka cellulose; is not absorbed by body; important for healthy digestive system and allowing waste to be removed form body through GI tract
What are the functions of carbohydrates in the body?
Energy as sugar and starch for the CNS and for PA; more complex carbohyrdates take longer to break down and provide longer term energy
What is the RQ value of carbohydrates?
1.0
What are classes of lipids?
Simple, compound, derived
What are simple lipids?
Neutral fats, e.g. TGs; waxes e.g. beeswax
What are compound lipids?
Plipids: lecithins, cephalins, lipostilos; glycolipids: gangliosides, cerebrosides; lipoproteins: chylomicrons, VLDL, LDL, HDL
What are derived lipids?
FAs: palmitic, oleic, stearic, linoleic acids; steroids: cholesterol, cortisol, bile acids, vitamin D, oestrogen, progesterone, androgens; hydrocarbons: terpenes
What are functions of lipoproteins?
Are shuttle buses which other lipids (e.g. TGs) bind to and form a complex
What is the difference between saturated and unsaturated lipids?
Saturated have no C=C double bonds, unsaturated has none
How is the number of C and double bonds present in a lipid presented in short form?
E.g. stearic acid is 18:0 = 18 C: 0 double bonds
What is C: double bond ratio for oleic acid?
18:1 (9) = double bond at 9th C
What is C: double bond ratio for linoleic acid?
18:2 (9, 12)
What is C: double bond ratio for alpha-linoleic acid?
18:3 (9, 12, 15)
What are the functions of lipids?
Fuel source; protection of vital organs; cell membrane constituents; precursors of bile, hormones, steroids; fat-soluble vitamin intake; palatability
What is the difference between non-essential and essential amino acids?
Non-essential are “non-essential to diet” aka body can make them; essential are “essential to diet” aka body cannot make them, and must be consumed
What are the non-essential amino acids?
Alanine, arginine, asparagine, aspartate, cystein, glutamate, glutamine, glycine, proline, serine (all AA’s before H + proline and serine)
What are the essential amino acids?
Histidine, leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, tyrosine (all AA’s after G - proline and serine)
Is the balance of amino acids consistent throughout life?
No, balance changes as body develops/ages; histidine is unable to synth’d in infants; arginine is less able to be synth’d in children
Why is water regarded as a macronutrient?
Adult body is 60% H2O; 2/3 water intracellular, 1/3 water extracellular
What is the approximate RDA of water?
2.0-2.8l/day; changes all the time
What are the functions of water?
Nutrient transport; protection; temperature regulation; biochemical reactions; medium for reactions
What are the functions of the micronutrients?
Act as regulators and links in the processes of energy release from food; important cofactors in various chemical reactions, meaning they are important for homeostasis
What are vitamins?
Organic compounds
How many vitamins are there?
13
What are the only vitamins not obtained from the diet/ that are non-essential?
Vitamin D and K: D is synth’d from sunlight; K is synth’s by bacteria in intestine
Why are B vitamins important?
Are important coenzymes in energy metabolism
What are the water-soluble vitamins?
B1 (thiamine); B2 (riboflavin); B3 (niacin); B4 (pyridoxine); B12; biotin; panthothenic acid; folic acid; choline, C (ascorbic acid)
What are the fat-soluble vitamins?
A, D, E (alpha-tocopherol), K
What are minerals?
Inorganic compounds
What are macrominerals?
RDA of >100mg; presence in body >0.01%BW
What are microminerals?
RDS of <100mg; presence in body <0.01%BW
What are examples of macrominerals?
Ca, Mg, Na
What are examples of microminerals?
Cu, I, Zn
What are trace elements?
Inorganic compounds
What is the EAR point in regards to dietary reference values?
50% require more, 50% require less (mean)
What is the RNI point in regards to dietary reference values?
Metabolic needs of 97.5% are met
What is the LRNI point in regards to dietary reference values?
Metabolic needs of only 2.5% are met
What do the EAR, RNI, and LRNI points show about dietary reference values?
Dietary needs can dramatically shift between individuals - small changes can cause drastic changes in how much of the population would have their needs met
What is the safe intake in regards to dietary reference values?
Where EAR, RNI and LRNI all do not occur; avoid deficiency or toxicity risk
