Lecture 15 Macronutrients Metabolism Overview I+II Flashcards
What are macronutrients
Class of chemical compounds that humans consume in large quantities and provide the majority of our energy ( carbs,lipids,protein)
Macronutrients that do not provide energy (water, fiber)
Balancing 3 macronutrients percentages
AMDR- Carbs 45-65%
AMDR- Fat 20-35%
AMDR- Protein 10-35%
AMDR - acceptable macronutrient distribution range
What are carbohydrates
One of three macronutrients
Important source of energy for all cells
Only energy source for red blood cells
Composed of carbon, hydrogen, oxygen
Glucose most abundant
Monosaccharides
Disaccharides
Monosaccharide: One molecule ( Glucose, fructose, and galactose
Disaccharides: two molecule (lactose, maltose, sucrose)
Galactose+ glucose =
Lactose
Glucose+ glucose =
Maltose
Glucose + Fructose =
Sucrose
What are complex carbohydrates
Oligosaccharides contains 3 to 10 monosaccharides
Startch, glycogen, most fibers
Startch, glycogen, fiber functions
Startch = storage form of glucose in plants ; food sources include grains, legumes and tubers
Glycogen = storage form of glucose in animals ; stored in liver and muscles
Fiber = forms the support structures of leaves, stems and plants
Fiber
Digestion and absorption
Sources
Most fibers are not digested and absorbed by our bodies
Soluble fibres can be digested by bacteria in our colon
Source: whole grains, vegetables, nuts and seeds, fruits.
Importance of carbohydrates in the diet
Carbohydrates spare protein and prevent ketoacidosis
Fiber helps us stay healthy - promote bowel health, reduces risk of diverticulosis, reduce risk of colon cancer
How much carbohydrate should we consume in a day
130grams a day
Range o 45 to 65% of daily calories
Consuming to much carbohydrates
High in simple sugars can cause tooth decay, increase LDL, decrease HDL, contribute to obesity
Fructose may increase hepatic de novo lipogenesis, may increase visceral adiposity,
Too little carbohydrates
Intake for women and men, where to get fiber from
14g of fiber for every 1000 kcal per day( 25g/day for women and 38g/day for men)
Best to get fiber from food
What is enriched and fortified food
Enriched : nutrients that were lost during processing have been added back so the food meets a specific standard
Fortified: have nutrients added that did not originally exist in the food
Anatomy of grain
Bran - rich in fibre and vitamins
Endosperm = rich in carbs and protein
Germ - rich in unsaturated fats and vitamins
Nutritive sweeteners vs non nutritive ( alternative) sweeteners
Nutritive sweeteners - sucrose, fructose, honey, brown sugar, contains 4 kcal per gram. Slow absorbing sugar alcohols
Non nutritive (Alternatives) sweeteners - provide little or no energy, safe for adults, children and people with diabetes
What about alternative sweeteners
Acceptable daily intake
50mg/kg body weight for aspartame
5mg/kg body weight for sucralose
What are lipids
Diverse group of molecules that are insoluble in water
What are the three types of lipids found in foods and in body cells and tissues
Triglycerides
Phospholipids
Sterols
What are triglycerides
Three fatty acid molecules
One glycerol molecule
Fatty acids are classified by :
Carbon chain length - How many C
Saturation Level - how many double bonds
Shape - straight and rigid or bent and kinked
Triglyceride carbon chain length
Short - (<6), medium - (6,12), or long chain FAs (14+)
Carboxyl end (COOH): alpha-carbon (Alpha-first)
Methyl end (CH3): omega carbon
Determines method of lipid digestion, absorption, metabolism and use
Saturation of triglyceride
Saturated fatty acids have hydrogen atoms surrounding every carbon in the chain
Monounsaturated fatty acids lack two hydrogen atoms
Polyunsaturated fatty acids (PUFA) have more than one double bond
Triglyceride shape
Saturated fatty acids pack tightly together and are solid at room temp
Unsaturated fatty acids do not pack tightly together and are more often liquid at room temp
Hydrogen atoms at the unsaturated part can be arranged in different positions
Cis: same side of carbon chain
Trans: opposite sides of the chain
Triglyceride hydrogenation
Hydrogenation: hydrogen atoms are added to unsaturated fatty acids
Create trans fatty acids
Reduce oxidation; resist rancidity
Triglyceride fatty acids (EFAs)
Essential fatty acids
- cannot be made by or body and must be obtained in the diet
- linoleum acids ( omega 6 fatty acids), found in vegetable and nut oils
- alpha-linolenic acid ( Omega-3fatty acid), found in vegetables, soy, flaxseeds, and flaxseed oil, soybeans and soybean oil
Phospholipids consist of the following
Glycerol backbone, two fatty acids, phosphate
Hydrophobic end, which is their lipid “tail” and a hydrophilic end, which is their phosphate “head”
Transport substances in and out of the cell
Phospholipids in the liver are called _____ (combined with bile salts and electrolytes)
Lecithins
AIDS in digestion of fat
Sterols
Found in both
Contain multiple
Foods….
Found in both plant and animal foods and produced in body
Contain multiple rings of carbon atoms
Primarily found in fatty part of animal products
Cholesterol (Exogenous vs endogenous)
The Importance of fats in the diet
Fats are a major fuel source at rest: 9kcal/g, 30-70% of our daily energy, primary fuel source for the heart
Important for energy storage
Essential fatty acids
Fat-soluble vitamins
How much fat is acceptable
Acceptable macronutrient distribution range for fat : 20-35% of calories
Active people may need more energy from carbs and can reduce their fat intake to 20-25% of total calories
Minimize saturated and trans fatty acid intake
Ratio of linoleic: alpha-linolenic acid
5:1 to 10:1 ratio of linoleic: alpha -Linolenic acid
What are proteins
Large, complex molecules found in cells of all living things
- synthesis controlled by genetic material (DNA)
-contain carbon, hydrogen, oxygen, nitrogen
-made from a combination of amino acids
Amino acids are connected by ….
Peptide bonds, di-tri-oligo-poly-peptides
Amino acids
Essential amino acids
Nonessential amino acids
Transamination
Nine essential amino acids:
- cannot be produced in sufficient quantities to meet physiological needs
- must be obtained from food
Non essential amino acids
- can be synthesized in sufficient quantities
Transamination
- transfer amine group from an essential amino acid to a different acid group and R group
- used to make nonessential amino acid
What is phenylketonuria (PKU)
Condition where the body cannot metabolize phenylalanine and it can build up toxic levels if consumed in significant quantities in diet
How are proteins made?
Protein turnover
Existing proteins are degraded to provide the building blocks blocks for new proteins
Amino acids pool includes amino acids from food and cellular breakdown
Dietary protein
Maximal effective protein dose in young health individuals is??
What are BCAA
20g
Branched chain amino acids may be able to enhance muscle protein synthesis by activating mTOR
What are some complementary food combinations
Rice and lentils
Peanut butter and bread
Tofu and broccoli
Sesame seeds with mixed bean salad
Functions of protein in the body
Cell growth, repair, maintenance
Enzymes and hormones
Fluid and electrolyte balance
Acid-base balance
Immune system
Energy source
Nutrien transport and storage
Neurotransmitter synthesis
Positive nitrogen balance
Negative nitrogen balance
In nitrogen balance
+ = body is retaining or adding protein: growth pregnancy or recovery from illness or a protein deficiency
- = body is losing protein : starvation of very low energy diets, severe illness, infections, high fever, burns
In nitrogen balance
How much protein should you consume a day
0.8g per kg body weight per day
ADMR for energy from protein is 10-35%
What are some adverse effects of to much protein
Greater than 2g/kg body weight
Increase bone loss
Increase kidney disease in people who may be more suspceptible
May Linked to increased risk of CHD
What are some benefits to vegetarians diet
Reduced risk for obesity/type 2 diabetes
Lower Bp
Reduce risk of heart disease
Fewer digestive problems
Reduced risk of some cancers
Vegetarian diets cons
Can be low in some nutrients
Special attention to vitamins D, B12, Riboflavin, zinc and iron (vegans)
