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Faculty of Applied Medical Sciences
Department of Nursing
Nutrition (NUTN 204)
MACRONUTRIENTS
AHMAD A. ALBALAWI
SENIOR SPECIALIST IN NUTRITION
Lecturer
CARBOHYDRATES
Outlines
• Definition and sources
• Simple and complex carbohydrates
(classifications)
• Alternatives of sugar
• Health effects of carbohydrates (fibers,
sugars)
• Recommended intake of carbohydrates
CARBOHYDRATES (CHO)
Definition and sources
•
Carbohydrates provide the majority of calories in
almost all human diets
•
Contain only Carbon, Hydrogen, and Oxygen, hence
the common abbreviation is CHO
•
According to Mozaffarian et al, (2011)
carbohydrates can be found in a variety of food
such as breads, rice, milk, spaghetti and soft drinks
•
The most common forms of carbohydrates are
sugars, fibers and starch (Mozaffarian et al, 2011)
Classification of Carbohydrate
Simple Carbohydrates
Complex Carbohydrates
Monosaccharides
Polysaccharide
Glucose (dextrose)
Starch
Fructose
Glycogen
Galactose
Fiber
Disaccharides
Sucrose
Maltose
Lactose
Simple CHO
Monosaccharides
Fructose (“fruit sugar”)
Found naturally in fruit and honey
Sweetest of all natural sugars
High-fructose corn syrup (HFCS) is commercially
made from the dextrose in cornstarch
Less fructose can be used to sweeten foods so the cost
is less
HFCS is used extensively in soft drinks, fruit drinks,
baked foods, and other products.
Simple CHO
Monosaccharides
Galactose
Does not occur in appreciable amounts in foods
It is significant only as it combines with glucose to
form the disaccharide lactose
Simple CHO
Monosaccharides
Glucose (dextrose)
Sugar of greatest distinction
Circulates through the blood to provide energy for body cells
Component of all disaccharides
Virtually the sole constituent of complex carbohydrates
All digestible carbohydrates are converted to glucose
Sources
Fruit
Vegetables
Honey
Corn syrup
Cornstarch
Simple CHO
Disaccharides
• Disaccharides are composed of two linked
monosaccharides, at least one of which is
glucose.
• Split into their component
monosaccharides before being absorbed.
Simple CHO
Types of Disaccharides
Sucrose
Glucose + Fructose
“sugar” or table sugar
Produced when sucrose from sugarcane and sugar
beets is refined and granulated
Differences among brown, white, confectioner’s, and
turbinado sugars have to do with the degree of
refining
Occurs naturally in some fruits and vegetables
Sweeter than glucose but not as sweet as fructose
Simple CHO
Types of Disaccharides
Maltose
Glucose + Glucose
Not found naturally in foods
Occurs as an intermediate in starch digestion
Simple CHO
Types of Disaccharides
Lactose (“milk sugar”)
Glucose + galactose
Found naturally in milk
Additive in many foods and drugs
Enhances the absorption of calcium
Promotes the growth of intestinal flora that
produce vitamin K
Complex Carbohydrates
• A group name for starch, glycogen, and
fiber; composed of long chains of glucose
molecules.
• Polysaccharide carbohydrates consisting of
many (poly) sugar molecules.
– Not sweet because their molecules are too
large to fit on the tongue’s taste bud receptors
that sense sweetness.
Complex Carbohydrates
Starch the storage form of glucose in plants.
– Plants synthesize glucose through the process
of photosynthesis.
– Glucose not used by the plant for immediate
energy is stored in the seeds, roots, stems, or
tubers in the form of starch composed of
hundreds to thousands of glucose molecules.
– When people eat plant foods, the resulting
digestion reduces starch back to glucose.
Facts about Complex Carbohydrates
1. Glycogen is the storage form of glucose in animals
and humans.
2. Glycogen is the animal (including human) version of
starch: a stored carbohydrate available for energy
as needed.
3. Humans have a limited supply of glycogen stored in
the liver and muscles.
4. Liver glycogen breaks down and releases glucose
into the bloodstream between meals to maintain
normal blood glucose levels and provide fuel for
tissues.
Complex Carbohydrates
• Muscles do not share their supply of
glycogen but use it for their own energy
needs.
• There is virtually no dietary source of
glycogen because any glycogen stored in
animal tissue is quickly converted to lactic
acid at the time of slaughter.
Complex Carbohydrates
Fiber is generally a mixture of non-digestible
polysaccharides that are part of the plant
cell wall or intercellular structure.
– Fibers have important physiologic functions
and provide significant health benefits.
– Dietary fiber carbohydrates and lignin that are
natural and intact components of plants that
cannot be digested by human enzymes.
Alternatives to sugars
• Nutritive:
– polyhydric alcohols (sorbitol, mannitol, xylitol)
• Properties:
– absorbed more slowly than sugars
– converted to fructose
– associated with decreased cariogenicity
• non-nutritive
– saccharin
– aspartame (Nutrasweet)
• aspartic acid + phenylalanine
– acesulfame-K (Sunette /Sweet One)
– cyclamate
– sucralose (Splenda)
Health effects of carbohydrates
(fibers)
• Soluble
– Include gums, pectins, some hemicelluloses, and mucilages
– Sources
•
•
•
•
•
•
•
•
Apples
Barley
Dried peas and beans
Fruits
Vegetables
Oatmeal
Oat bran
Rice hulls
– Lower serum cholesterol levels and improve glucose control
in diabetics
• Insoluble
– Cellulose, many hemicelluloses, and lignins
– Give texture to plant foods
– Sources
•
•
•
•
•
Skin of fruits
Shell of corn kernels
Covering of seeds
Bran (outer layer) of grains
The richest sources of insoluble fiber are wheat bran,
whole grains, dried peas and beans, and vegetables.
– Increase stool weight and thereby promote normal
laxation.
• Sugars:
– Conflict results from many
studies that high consumption of
sugar may or may not increase
risk of diabetes
– However, epidemiological studies
found that there is a link
between increased rate of sugar
in people’s diet and the
possibility of having diabetes in
the future ( University of
California, 2013)
• High intake of cereals, grains, legumes fruits,
starchy vegetables improve weight control and
protective to heart disease, cancer and
diabetes (Vicki Deakin, University of Canberra,
2011)
Brown rice
Notes to Remember!
1. Normally 95% of starch is digested usually
within 1 to 4 hours after eating.
2. Soluble fibers give the feeling of fullness.
3. Insoluble Fibers do not dissolve in H2O.
4. If there are more fibers, more gas and H2O will
be formed in the intestine.
5. Soluble fiber slows the absorption of glucose.
6. Fibers impair the absorption of Zn, Fe, & Ca
Nutritional management
7. Glycemic response is the body’s response to
glucose (from high to normal)
Glycemic response is influenced by many variables
• Amounts of fat and fiber in the food
• Method of preparation
• Amount eaten
Glycaemic Index
•The glycaemic index is the relative measure of
how quickly a food triggers a rise in blood
glucose
•for example, Cornflakes (low fiber, low fat)
have a higher glycemic index than does ice
cream (high fat)
•For diabetics, the glycemic index can help to
fine-tune optimal meal planning
•Also, for those who want to maintain their
body weight have to consider Glycaemic Index
list
GLYCEMIC INDICES OF SELECTED FOODS
High (>60)
Moderate (40–60)
Low (<40)
Glucose
Bran muffin
Apple
Gatorade
Bran Chex
Pear
Potato, baked
Orange juice
PowerBar
Cornflakes
Potato, boiled
Rice cakes
Rice, white
Fruit yogurt, low-fat
Potato, microwaved
Rice, brown
Chickpeas
Jelly beans
Popcorn
Skim milk
Vanilla Wafers
Corn
Lima beans
Metabolism of CHO
•
•
Fructose and galactose are converted to glucose in the liver
Insulin moves glucose out of the bloodstream and into the cells
•
•
Muscle and liver cells store extra glucose as glycogen.
Glucagon raises blood sugar level during hypoglycemic states
and returns it to normal
•
Before exercise eat low to moderate glycemic index foods
•
After exercise take high glycemic index foods.
14. Epinephrine increases glycogenolysis but
decreases insulin; hence hyperglycemia.
15. 1/3 of glycogen reserves in the liver.
16. 2/3 of glycogen is for muscle use.
17. Glycogen storage provides half-day of
energy requirement.
Carbohydrates digestion
Recommended Intake of
carbohydrates
• The Recommended Dietary Allowance
(RDA) for carbohydrate is set at 130 g for
both adults and children, the average
minimum amount needed to fuel the brain
• World Health Organization recommends
180g/day to prevent ketosis
• Eat plenty of vegetables 2.5 cups/day
Adequate Intake for Total Fiber
25 g/day for women
38 g/day for men
Functions of CHO (revision)
1. Energy source
2. Spare protein
3. Prevents ketosis (minimum intake of 50 to 100 g of
CHO/day)
Signs of ketosis
– Nausea
– Fatigue
– Loss of appetite
– Ketoacidosis (pH <7.35)
– Dehydration and sodium depletion
4. Glucose is used to make other compounds
PROTEINS
Overview of proteins
• Energy-yielding nutrients composed of
individual building blocks known as amino
acids
• Protein is a component of every living cell
• Bile and urine do not contain protein
Sources
• Animal sources (high quality proteins):
– Meat
– Milk
– Eggs
• Plant sources:
–
–
–
–
Legumes
Breakfast cereals
Bread
Starchy vegetables
• No significant amount of proteins in:
• Fruits, fat
Types of body protein
• Simple proteins:
– Amino acids and their derivatives:
• Albumin (plasma protein): transports free fatty acids and
many drugs
• Insulin (hormone)
• Globulins (myosin)
• Myoglobin (muscle protein)
– Conjugated protein
• Nucleoprotein
– DNA (protein + nucleic acid)
• Glycoprotein
– Mucin (protein + CHO)
• Lipoprotein (Low Density Lipoprotein) : transport fats,
cholesterol, and fat-soluble vitamins; hemoglobin
transports oxygen
Amino acids are involved in
7. Components of numerous body
compounds
a. Opsin, the light-sensitive visual pigment in the
eye
b. Thrombin, a protein necessary for normal
blood clotting
Proteins and health
• Vegetarians and fruitarians may have limiting
nutrients in their diets such as:
– Energy
– Protein
– Vitamins such as:
• Vitamin B12, riboflavin and vitamin D
– Minerals such as:
• Iron
• Calcium
• Zinc
Proteins and health
• Nitrogen (Neutral) Balance occurs when
protein synthesis and protein breakdown
occur at the same rate
Synthesis = Breakdown
•
Protein and health
Positive Nitrogen Balance when protein synthesis
exceeds protein breakdown
Synthesis > Breakdown
Growth
Pregnancy
Recovery from injury
Protein and health
Negative Nitrogen Balance when protein
breakdown exceeds protein synthesis
Breakdown > Synthesis
Starvation
Catabolic phase after injury
How to determine nitrogen balance?
1.
Compare nitrogen intake with nitrogen excretion
over a 24-hour period.
2. To calculate nitrogen intake, protein intake is
measured for a 24-hour period.
1.
The total amount of protein consumed (in grams) is
then divided by 6.25 because protein is 16% nitrogen by
weight.
2. The result is the grams of nitrogen consumed per 24
hours. Nitrogen excretion is ascertained by having a
24-hour urine sample analyzed for the amount (grams)
of urinary urea nitrogen it contains.
3. A coefficient of 4 is added to this number to account
for the estimated daily nitrogen loss in feces, hair,
nails, and skin.
4. Finally the amount of nitrogen consumed is compared
with the total amount of nitrogen excreted to reveal a
positive, negative, or neutral nitrogen balance.
CALCULATING NITROGEN BALANCE
Mary is a 25-year-old woman who was admitted to the hospital with multiple
fractures and traumatic injuries from a car accident. A nutritional intake study
indicated a 24-hour protein intake of 64 g. A 24-hour urinary urea nitrogen
(UUN) collection result was 19.8 g.
Determine nitrogen intake by dividing protein intake by 6.25:
64 ÷ 6.25 = 10.24 g of nitrogen
Determine total nitrogen output by adding a coefficient of 4 to the UUN:
19.8 + 4 = 23.8 g of nitrogen
Calculate nitrogen balance by subtracting nitrogen output from nitrogen
intake:
10.24 - 23.8 = -13.56 g in 24 hours
Interpret the results.
Mary is in a catabolic state.
Protein and health
• Severe burns may require as much as 2.0
g/kg of body weight
• Adequate intake set for infants through the
first 6 months of life is 1.52 g/kg of body
weight
Protein and health
•
Protein eaten in excess of need is not stored;
excess amino acids are converted to fat when
eaten in excess of need, just as carbohydrates
and fat are.
•
Amino acid supplements often provide only
one or few particular amino acids, creating a
disproportion in amounts of amino acids
available.
Classification of Amino Acid
• Essential or Indispensable Amino Acids
Amino acids that cannot be made by the
body; they must be consumed through
food.
• Nonessential or Dispensable Amino Acids are
amino acids the body can make if nitrogen
and other precursors are available.
Classification of
Amino Acid
Essential Amino Acids Nonessential Amino Acids
Histidine
Alanine
Isoleucine
Arginine
Leucine
Asparagine
Lysine
Aspartic acid
Methionine
Cystine (cysteine)
Phenylalanine
Glutamic acid
Threonine
Glutamine
Tryptophan
Glycine
Valine
Proline
Serine
Tyrosine
Intake Recommendations
• Fueling the body
– Protein provides 4 cal/g.
– It is not the body’s preferred fuel.
– Protein is a source of energy when it is
consumed in excess of need or when calorie
intake from carbohydrates and fat is
inadequate.
Intake Recommendations
• The Recommended Dietary Allowance
(RDA) for protein for a healthy adult is 0.8
g/kg, which is approximately 10% of
recommended total calories.
• RDAs for protein
– Men: 56 g
– Women: 46 g
CALCULATING DAILY PROTEIN ALLOWANCE
John is a 30-year-old man who weighs 184 pounds. What is his daily
protein allowance?
Determine the weight in kilograms by dividing the weight in
pounds by 2.2:
184 ÷ 2.2 = 83.6 kg
Multiply the weight in kilograms by 0.8 g/kg (the RDA for men 19
years of age and older or women 15 years and older)
83.6 × 0.8 = 66.88 g
John should consume 67 g of protein per day.
Metabolism of protein
Metabolism of protein
• Protein digestion:
• Mouth:
– Chewing and crushing foods that are rich in protein
and mix them with saliva to be swallowed
• Stomach:
Protein
Hydrochloric
acid (HCL) +
pepsin smaller
polypeptides
smaller
polypeptides
• Small intestine and pancreas:
pancreatic and
intestinal
proteases
Polypeptides
tripeptides,
dipeptides and
amino acids
Metabolism of protein
• Small intestines:
• Enzymes then on the surface of the small
intestinal cells hydrolyze these peptides to
make it easier to be absorbed by intestinal
cells
Intestinal
tripeptidase and
dipeptidase
Peptides
Amino acids
(absorbed)
LIPIDS/FATS
OUTLINES
• Definitions
• Types of fatty acids
• saturated and unsaturated fatty acids
• Sources
• Essential fatty acids
• Health effects of fats
• Function of fat in human body
• Nutritional management
• Metabolism of fat
Fat and fatty acids
•
Definition:
– Lipids are group of water-insoluble, energy-yielding
organic compounds composed of carbon,
hydrogen, and oxygen atoms.
•
Types of lipids:
– Lipids, commonly referred to as fats, include
a. Triglycerides (fats and oils)
1)
Triglycerides are class of lipids composed of a glycerol
molecule as its backbone with 3 fatty acids attached.
b. Phospholipids (e.g., lecithin)
c. Sterols (e.g., cholesterol)
•
Triglycerides is 98% of the lipids in foods and
are the major storage form of fat in the body.
•
Fatty acids can attach to glycerol molecules in
various ratios and combinations to form a
variety of triglycerides within a single food fat.
•
Fatty acids vary in the length of their carbon
chain and in the degree of unsaturation.
Types of fats, sources and their roles
Triglycerides:
• Structure:
Fatty
• Formed from the
esterification of 3 fatty acid
acids with one glycerol
• The structure and length
of the fatty acid
determines the state of
fat at room temperature
• Sources: found in most of
food
Glycerol
Fatty
acid
Fatty
acid
• Phospholipids
– Example, Lecithin
– Not essential as liver manufactures its own
lecithin
– Functions:
• Constituent in cell membrane
• Component of bile
• Used as an emulsifier in food
• Sterols:
– Example, cholesterol
• Endogenous cholesterol
– made by the liver (approx 1000 mg/day)
– therefore cholesterol is not an essential nutrient
• Exogenous cholesterol
– from the diet
– (approximately 300-400 mg/day)
• plant sterols and stanols:
– Examples, sitosterol and sitestanol
• Sources
– wood pulp, leaves, nuts, vegetable oils
• Actions
– interfere with cholesterol absorption by competing with cholesterol for
uptake into micelles
– has cholesterol-lowering properties
Saturated and unsaturated fatty acids
• saturated fatty acids (SFAs)
– all carbons saturated with single bonds; very
stable; mostly solid fats of animal origin; main
– food sources meat and dairy fat; also in cocoa
butter; coconut oil, palm oil; link to endogenous
cholesterol production
• Unsaturated fat:
– Monounsaturated fatty acids ( MUFAs):
• one double bond; most common oleic acid C18:1n-9
(olive oil); other food sources such as canola, peanut
oils and avocado
– Polyunsaturated fatty acids (PUFAs):
• more than one double bond; least stable; in germ of all
grains; food sources safflower, sunflower, sesame,
soybean oils
• Examples:
– omega-6 polyunsaturated oils: plant oils
– safflower, sunflower, corn, soybean, and
cottonseed oils
– omega-3 polyunsaturated oils
– fish oils (salmon, herring, trout, mackerel, and
swordfish)
Unsaturated Fats, the “Good” Fats
• Are soft or liquid at room temperature
– oils and soft margarines
• Prone to rancidity from exposure to light
and O2
– Loss of vitamins A & E
– Antioxidants are added to prolong life
Essential Fatty Acids
•
•
Essential Fatty Acids cannot be synthesized in
the body
Examples:
– Linoleic acid (an n-6 fatty acid)
– Alpha-linolenic acid (an n-3 fatty acid)
•
Health effects:
– Maintaining healthy skin and promoting normal
growth in children
– May reduce risk of cardiovascular disease in adults
Essential Fatty Acids
• Precursors of eicosanoids (group of
hormone- like substances)
– Inflammation and blood clotting
•
•
•
Prostaglandins
Thromboxanes
Leukotrienes
Most effective omega 3 fatty acids
components
eicosapentaenoic acid (EPA)
docosahexaenoic acid (DHA)
omega-3 polyunsaturated fatty acids
found in animal tissues (cold-water fish)
not found in plants
Health effects of unsaturated fat and
essential fatty acids
From n-6 fatty acids
Actions of EPA and DHA in several body systems:
1. Lower high triglyceride levels
2. Anti-arrhythmic
3. Anti-inflammatory
4. Beneficial for the musculoskeletal, GI, and immune
systems
5. Normal blood flow
6. Normal fetal & infant brain development and for normal
brain functioning throughout life (cognition and mood).
7. Normal functioning of retinal rods and cones.
From n-3 fatty acids
1. Lower serum triglyceride levels
2. Reduce BP (blood pressure)
3. Decrease factors involved in blood clotting and
stroke
4. Anti-inflammatory (ulcerative colitis, Crohn’s
disease, and rheumatoid arthritis)
5. May inhibit the development of certain cancers
6. Fish oils prevent arrhythmias and sudden cardiac
death.
Health effects of saturated fat
“Bad” Fats: Saturated Fats
1. Raise LDL-cholesterol; lower HDL-cholesterol
2. More saturated than the oil from which they
are made and often contain trans fats
3. Low Density Lipoprotein (LDL)-Cholesterol
4. Solid at room temperature & stable
5. Highest in meats, dairy products, and tropical
oils (palm kernel and coconut)
6. Raise LDL-cholesterol in the blood
Function of fat
Functions of Fat in the Body
• Vital components of cell membranes
• Cholesterol is a precursor of vitamin D,
steroid hormones, and bile acids
• Provide energy (55% of calorie needs at
rest); 9 cal/g
• Protect vital organs
Functions of Fat in the Body
• Insulate against cold environmental
temperatures
• Facilitate the absorption of fat-soluble
vitamins (ADEK)
• Normal fat reserves can last up to 2 months
during fasting
Nutritional management and
recommendation
• It is recommended to increase the
consumption of unsaturated fatty acids and
reduce the intake of saturated ones
• Recommended intake of unsaturated fatty
acids:
– Consume 2 to 3 oily fish/ week
– Fish oil or capsules
• Less than 7% of total energy comes from
saturated fat
• How to lose weight?
– 1 pound of fat = 3, 500 cal
– To lose 1 pound per week, decrease calorie
intake by 500 cal/day
– It is not recommended to reduce 1, 000 cal/day
– REMEMBER: 3% of the original calories is
needed to make fat from fat; hence, increased
body weight
Metabolism of fat in human body
• Fat digestion:
– Mouth and salivary glands: Some hard fats begin to melt by
salivary lipase
– Stomach: Acid stable lipase hydrolyses one bond to form
diglycerides and fatty acids; churning mixes fat with water and
acid ; gastric lipase hydrolyses some fat
– Small intestine: Bile from gallbladder emulsifies fat;
pancreatic/intestinal lipase hydrolyse fat to monoglycerides and
fatty acids
– Large intestine: Some fat and cholesterol trapped in fibre exit in
faeces
• Fat absorption:
• Small molecules diffuse easily into intestinal
cells
• Larger molecules:
– Fat merge into micelles formed by bile surrounding
monoglycerides and fatty acids and enter intestinal
cells
– fats diffuse into cells and are reassembled into new
triglycerides
– new triglycerides and other lipids are packed with
protein into chylomicrons for transport to the
lymphatic system and then into the blood
• Metabolism:
Dietary fat in
food
Long chain free fatty acids + triglycerides + cholesterol + phospholipids
Triglycerides
Chylomicrons
Lymph
Muscle tissue
Adipose
tissue
Liver
blood
Cells
Storage
Blood
Thank You