L1 Macronutrients Flashcards
Macronutrients
carbs
lipids
proteins
Organic molecules
carbon-containing
Micronutrients
vitamins
minerals (not organic)
Carbohydrates
made of carbon and water
also called sugars or saccharides
grouped by the # of sugars in the molecule
-ose
carb molecule
Groups of carbs
Monosaccharides
Oligosaccharides
Polysaccharides
What are the major roles of carbs?
Energy source
Protein Sparing
Fuel for CNS
Metabolic Primer
Energy source (carbs)
fuel, especially during exercise. Maintains glycogen stores
Protein Sparing (carbs)
adequate intake decreases protein breakdown for fuel as protein is used to make new glucose when glycogen stores are low
also increases load on the kidneys if lacking carbs, since kidneys excrete nitrogen from protein breakdown
Does the body store glucose?
NO
it is the lifeline of the body, it is not stored
Fuel for CNS (carbs)
the brain uses blood glucose exclusively as its fuel
the brain does not have a stored supply of glucose
Metabolic Primer (carbs)
Carbs determine if lipids are completely utilized
decreased carbs means that decreased glycogen reserves, so more lipids are mobilized
increased lipid mobilization (more then can be used) leads to ketone production
Monosaccharides
categorized by number of carbon atoms in ring
also known as simple sugars
glucose, fructose, and galactose are all hexoses
Simple sugars
monosaccharides
disaccharides
Glucose
called dextrose or blood sugar
natural sugar in food (molasses is an example)
major substrate for glycolysis
Produced by digestion of more complex carbs, via gluconeogenesis in liver
Fructose
called fruit sugar or levulose
found in fruits and honey
sweetest of simple sugars
almost all is converted to glucose
Galactose
found most commonly in lactose
less sweet than glucose
liver converts it to glucose
yogurt
Oligosaccharides
Also known as disaccharides or simple sugars
divided into sucrose, lactose, maltose
Sucrose
table sugar
GLUCOSE + FRUCTOSE
most common in diet
Lactose
milk sugar
GLUCOSE + GALACTOSE
least sweet of disaccharides
Maltose
malt sugar
GLUCOSE + GLUCOSE
least common in nature
contained in beer and seeds
Polysaccharides
MANY sugars linked together
two types: animal/plant
has storage and structural functions
Storage polysaccharides
Animals: glycogen
Plants: starch and fiber
Structural polysaccharides
Animals: chitin (bugs)
Plants: cellulose and fiber
Starch
storage form of carbs in plants
most important dietary source of carbs
found in seeds, corn, grains
Fiber
nonstarch polysaccharide
complex carb found in plants
neither digested nor absorbed, resistant to human enzymes
divided into water soluble and water insoluble
zero calories
Water soluble fiber
slows digestion
dissolves in water to form viscous gel and is fermented by microflora in large intestine
Water-insoluble fiber
fills you more
not water-soluble and undergoes limited fermentation
benefits of fiber intake
- reduced risk of developing type 2 diabetes
- improved glycemic status and lipid profiles
- reduced body weight and abdominal adiposity
- decreased risk of and mortality from CVD
- decreased chronic inflammation
- prevention and treatment of constipation
How much fiber is recommended?
25-34 g/day
Glycogen
storage carbohydrate in mammalian muscle and liver
difficult to pack within the body
formed by glucose subunits to form large molecules
condensation forms it
Condensation reactions
building sugars
individual subunits/monosacc covalently bind together via dehydration synthesis or condensation reaction
H atom is removed from monosacc and -OH group is removed from another
water is produced, and glycogen
Fasting blood glucose
70-99 mg/dl
fuel line to cells
Storage of carbs in body
about 375-475 g
majority is muscle glycogen, some is liver glycogen, only 5g is blood glucose
Lipids
long hydrocarbon chains
insoluble in water and soluble in organic solvents
includes oils, fats, waxes
Fat groups
simple
compound
derived
Simple lipids
triglycerides
made of glycerol and fatty acid
more hydrogens then carbs, therefore more energy
main form of fat storage in the body
Saturated fatty acid
no carbon-carbon double bonds
holds as many H atoms as possible
meats, egg yolks, dairy, coconut oils
unsaturated fatty acid
one or more carbon carbon double bonds
divided into monounsaturated and polyunsaturated
Monounsaturated
only 1 double bond along carbon chain
liquid at room temp, solid in fridge
sources are canola, olive, peanut oils
Polyunsaturated fats
more than 2 double bonds
liquid in fridge and room temp
fish, safflower, sunflower oils
What is hydrogenation?
-breaking double bonds
-process that changes unsaturated oils to more saturated by adding hydrogen
-resulting compound is partially hydrogenated
-some of the double bonds have been reduced to single bonds
Why is hydrogenation performed
-avoid or decrease consumption of saturated fats
-extends the shelf-life of packaged foods
-gives food desired taste and texture
Trans fatty acids
2 hydrogen atoms are on opposite sides of the C-C double bond
hydrogenation, refrying used oil, small amounts naturally are sources of trans fatty acids
What is the problem with hydrogenation?
remaining double bonds after hydrogenation tend to convert from cis to trans
Is consumption of trans fatty acids harmful?
yes
trans fatty acids raise total blood cholesterol levels and LDL and lower HDL
intake of trans fatty acids increases risk of heart disease, stroke, type 2 diabetes
Compound lipids
composed of triglyceride and other chemicals
groups include phospholipids, glycolipids, lipoproteins
Phospholipids
fatty acids and phosphate and nitrogen group
form integral part of plasma membrane bilayer of all eukaryotic cells
responsible for electrochemical gradient
Glycolipids
fatty acids and nitrogen and carbohydrate
found only in outer half of plasma membrane bilayer, with sugar groups exposed on cell surface
Lipoproteins
HDL, LDL, VDL, chlyomicrons
made of protein, triglycerides or phospholipids
formed primarily in the liver
main form of lipid transport in the blood
Derived lipids
derived from simple and compound lipids
Example includes steroids/cholesterol
Cholesterol
-most widely known derived lipid
-obtained both from the diet and synthesized within some cells
-building blocks for all other steroid hormones in the body
Exogenous cholesterol
from diet, found only in animal tissue
egg yolk, red meat, dairy products
Endogenous
liver synthesizes 70% of endogenous cholesterol
.5-2.0 g/day is made by the body, usually sufficient
statins decreases endogenous levels
What do you need cholesterol for?
- building plasma membrane
- precursor in steroid hormone synthesis
- Formation of bile
Role of lipid in body
largest store of energy
cushions and protects vital organs
provides insulation
vitamin carrier of A, D, E, K
Lipid as an energy source
- 80-90% of body’s energy
- 1 g lipid = 9kcal of energy, has more hydrogen
- lipids are concentrated, water-free fuel
Satiety
sensation of fullness between eating episodes that tends to inhibit resumption of eating
Lipid and satiety
fat intake has the least potent action on satiety even though it takes a long time for fat to move through the stomach
protein >carb>fat
Proteins
amino acids linked by peptide bonds, has nitrogen
body has no protein stores, non is used as energy storage
has structural and globular/enzyme types
20 different amino acids
Essential amino acids
must be provided by food because they cannot be synthesized by the body
about 9 amino acids
Nonessential amino acids
can be synthesized by the body
not directly required from food
about 11 amino acids
Complete proteins
foods that contain all the essential amino acids
eggs, milk, meat, fish
Incomplete proteins
foods that lack one or more essential amino acids
grains and legumes
Complementary proteins
combining two incomplete proteins to provide sources of essential amino acids
Protein roles
- amino acids are building blocks of tissue synthesis and repair
- enzymes catalyze every reaction
- form neurotransmitters
- muscle contraction
- plasma proteins
AMDRs
Carbs = 45-65%
Fat = 20-35%
Protein = 10-35%
