2. W h a t i s N u t r i t i o n ?W h a t i s N u t r i t i o n ?
Utilization of foods by living organismsUtilization of foods by living organisms
The process of utilization is biochemicalThe process of utilization is biochemical
Human nutrition has three types:Human nutrition has three types:
– UndernutritionUndernutrition
– Optimal nutritionOptimal nutrition
– OvernutritionOvernutrition
3. N u t r i e n t s a n d D i e tN u t r i e n t s a n d D i e t
Nutrients are the ingredients of foodNutrients are the ingredients of food
needed for normal functioning of the bodyneeded for normal functioning of the body
Nutrients provide energy for various bodyNutrients provide energy for various body
functionsfunctions
Quality (what food items) and quantityQuality (what food items) and quantity
(how much nutrients) are important for(how much nutrients) are important for
maintaining good healthmaintaining good health
4. T y p e s o f N u t r i e n t sT y p e s o f N u t r i e n t s
Two types:Two types:
– MacronutrientsMacronutrients
– MicronutrientsMicronutrients
5. M a c r o n u t r i e n t sM a c r o n u t r i e n t s
Nutrients needed by the body in large amountsNutrients needed by the body in large amounts
are calledare called macronutrientsmacronutrients
Three types of macronutrientsThree types of macronutrients
– ProteinsProteins
– CarbohydratesCarbohydrates
– FatsFats
Macronutrients provide energy and buildingMacronutrients provide energy and building
blocks of proteins, carbohydrates and fatsblocks of proteins, carbohydrates and fats
6. M i c r o n u t r i e n t sM i c r o n u t r i e n t s
Nutrients needed by the body in smallNutrients needed by the body in small
amounts are calledamounts are called micronutrientsmicronutrients
Major types of micronutrientsMajor types of micronutrients
– VitaminsVitamins
– Minerals / trace elementsMinerals / trace elements
Required for maintaining normal health andRequired for maintaining normal health and
preventing various diseasespreventing various diseases
7. N u t r i e n t s f r o m D i e tN u t r i e n t s f r o m D i e t
Proteins, carbohydrates, fatsProteins, carbohydrates, fats
Essential fatty acidsEssential fatty acids
Essential amino acidsEssential amino acids
VitaminsVitamins
MineralsMinerals
Dietary fibersDietary fibers
WaterWater
9. E n e r g y C o n t e n t o f F o o dE n e r g y C o n t e n t o f F o o d
Much of the food we eat is converted toMuch of the food we eat is converted to
ATP and other high-energy compoundsATP and other high-energy compounds
This energy is used for biosyntheticThis energy is used for biosynthetic
pathways, muscle contraction, nervepathways, muscle contraction, nerve
impulse, etc.impulse, etc.
Energy content of food is measured inEnergy content of food is measured in
calories (Kilocalories)calories (Kilocalories) of heat energyof heat energy
released by combustion (burning) of thatreleased by combustion (burning) of that
foodfood
10. Small calorie (cal) is the energy needed to increase 1
gram of water by 1ºC at a pressure of 1 atmosphere.
Large calorie (Cal) is the energy needed to increase 1 kg
of water by 1ºC at a pressure of 1 atmosphere.
Large calorie is also called food calorie and is used as a
unit of food energy.
The energy in large calories (Cal) is equal to the energy in
small kilocalories (kcal):
E(Cal) = E(kcal)
Example
Convert 6 kcal to large calories:
E(Cal) = 6 kcal = 6 Cal
11. E n e r g y E x p e n d i t u reE n e r g y E x p e n d i t u re
Depends on four factors:Depends on four factors:
– Surface area of the body (height and weight)Surface area of the body (height and weight)
The greater the surface area the greater theThe greater the surface area the greater the
heat lossheat loss
– AgeAge
Growth and lean muscle massGrowth and lean muscle mass
Infants have higher basal metabolic rateInfants have higher basal metabolic rate
(rate of energy utilization in resting state)(rate of energy utilization in resting state)
12. – SexSex
Women have lower BMR than menWomen have lower BMR than men
– Activity levelActivity level
Exercise increases energy expenditureExercise increases energy expenditure
13. Recommended Energy IntakeRecommended Energy Intake
Sex Age Weight (Kg) Avg. Energy
Needs (kcal)
Men 23–50 70 2900
Women 23–50 55 2200
Pregnant - - +300
Lactating - - +500
14. Some Definitions
Omnivorous:Omnivorous: eat both meateat both meat
and vegetablesand vegetables
Carnivorous:Carnivorous: eat meat onlyeat meat only
Herbivorous:Herbivorous: eat vegetable,eat vegetable,
grass onlygrass only
15. Vegetarianism - Definitions
Lacto-ovo vegetarian:Lacto-ovo vegetarian: A vegetarian who
consumes eggs (ovo) and milk (lacto)
Lacto vegetarian:Lacto vegetarian: Does not eat eggs, meat,
poultry or fish/seafood of any kind, but does
consume dairy (lacto) products
VeganVegan: A strict vegetarian who does not eat
animal products, meat, fish, poultry, eggs or
dairy
16. Vegetarian diet and disease
(Research results)
-Lower Body Mass Index (BMI) - contain less fat, saturated fat, and
cholesterol
- contain vegetables and fruits high in antioxidants and that contain dietary
fiber and phytochemicals.
- have lower blood cholesterol levels
- are less likely to develop heart disease
- have lower weight
- are less likely to have high blood pressure
- have lower rates of cancer
17. Dietary guidelines – more about RDA
Recommended Dietary Allowance (RDA)
– Developed during the 1940’s
– Prevention of vitamin and mineral deficiencies
– Revised every 5 year
Dietary goals
– Goals for healthy diet
– Health promotion and disease prevention
19. Overnutrition
Major cause of many diseases: obesity,
diabetes, hypertension, etc.
High morbidity (disease)
and mortality
20. Nutritional Importance of ProteinsNutritional Importance of Proteins
Proteins supply amino acids and aminoProteins supply amino acids and amino
nitrogen for the synthesis of importantnitrogen for the synthesis of important
nitrogenous compounds such as purines,nitrogenous compounds such as purines,
pyrimidines and hemepyrimidines and heme
Types of amino acids:Types of amino acids:
– Essential (body can’t synthesize)Essential (body can’t synthesize)
– Non-essential (body can synthesize)Non-essential (body can synthesize)
21. RDA: 0.8 gms/kg body weight
World Health Organization
10 to 15 % of total calories
Recommended Daily Protein IntakeRecommended Daily Protein Intake
22. Recommended Daily Protein IntakeRecommended Daily Protein Intake
(mg/Kg body wt.)(mg/Kg body wt.)
Infants (4–6 months)Infants (4–6 months)
– 11001100
Children(10–12 year)Children(10–12 year)
– 10001000
Adult (Men and Women)Adult (Men and Women)
– 800800
PregnancyPregnancy
– Additional 200Additional 200
LactationLactation
– Additional 300Additional 300
23. Essential amino acids are not synthesized byEssential amino acids are not synthesized by
the body and must be supplied in dietthe body and must be supplied in diet
PVT TIM HALLPVT TIM HALL
PPhenylalaninehenylalanine TThreoninehreonine HHistidine*istidine*
VValinealine IIsoleucinesoleucine AArginine*rginine*
TTryptophanryptophan MMethionineethionine LLysineysine
LLeucineeucine
*Essential only in children*Essential only in children
Essential Amino AcidsEssential Amino Acids
24. Normal Nitrogen BalanceNormal Nitrogen Balance
– In a healthy person, the nitrogen intake isIn a healthy person, the nitrogen intake is
equal to nitrogen lossequal to nitrogen loss
Negative nitrogen balanceNegative nitrogen balance
– When nitrogen loss is more than intakeWhen nitrogen loss is more than intake
Positive nitrogen balancePositive nitrogen balance
– When nitrogen intake is more than lossWhen nitrogen intake is more than loss
N i t r o g e n B a l a n c eN i t r o g e n B a l a n c e
25. Protein-Energy MalnutritionProtein-Energy Malnutrition
Malnutrition:Malnutrition:
– Condition/disease caused by not eatingCondition/disease caused by not eating
enough food or not eating a balanced dietenough food or not eating a balanced diet
Malnutrition due to inadequate intake ofMalnutrition due to inadequate intake of
proteins or energyproteins or energy
Two conditions:Two conditions:
– MarasmusMarasmus
– KwashiorkorKwashiorkor
26. Marasmus:Marasmus:
– Inadequate intake of both proteins andInadequate intake of both proteins and
energy (calories)energy (calories)
– Occurs in growing children under 5 yearOccurs in growing children under 5 year
– Usually found in poor populationUsually found in poor population
suffering from food shortagesuffering from food shortage
27. Clinical FeaturesClinical Features
– Thin appearanceThin appearance
– Weight lossWeight loss
– Small for his/her ageSmall for his/her age
– Poor physical/mental developmentPoor physical/mental development
– Weak immune systemWeak immune system
– Sensitive to developing infectionSensitive to developing infection
28. KwashiorkorKwashiorkor
– Inadequate intake of proteins with adequateInadequate intake of proteins with adequate
energy intakeenergy intake
Clinical featuresClinical features
– Edema (swelling of body)Edema (swelling of body) – Dry, weak hair– Dry, weak hair
– DiarrheaDiarrhea –– DermatitisDermatitis
– Weak immune systemWeak immune system – Retarded growth– Retarded growth
– Sensitive to developing infectionSensitive to developing infection
29. Excess Protein-Energy IntakeExcess Protein-Energy Intake
Can lead to obesity, diabetes, hypertension,Can lead to obesity, diabetes, hypertension,
coronary heart disease, etc.coronary heart disease, etc.
30. C a r b o h y d r a t e sC a r b o h y d r a t e s
Their major role in diet is energy productionTheir major role in diet is energy production
Excess carbohydrates are converted toExcess carbohydrates are converted to
glycogen (in liver) and triacylglycerols (fat) forglycogen (in liver) and triacylglycerols (fat) for
storage in adipose tissuestorage in adipose tissue
Carbohydrate intolerancesCarbohydrate intolerances
– Diabetes mellitusDiabetes mellitus
– Lactase insufficiencyLactase insufficiency
31. Carbohydrates
Provide 4 kcals/gram
Major energy supply to the cells
RDA: 130 grams/day for adults and children
World Health Organization
– Lower limit: 55% of total calories
– Upper limit: 75% of total calories
32. Carbohydrates in Food
Added
– table sugar (sucrose)
– honey, high fructose
corn syrup, fruit juice
concentrate, etc.
Naturally occurring
– fruit (fructose)
– milk (lactose)
Refined grains
– white breads, rice, pasta
– cereals, crackers
Whole grains
– whole wheat breads and
pasta; brown and wild rice
– whole oats
– cereals, crackers and baked
goods made with “100%
whole wheat flour”
Simple Carbohydrates Complex Carbohydrates
34. Carbohydrates
CHO have protein-sparing effect:
–inhibit gluconeogenesis from amino
acids
–amino acids are used for repair and
maintenance of tissue protein
–not for gluconeogenesis
Protein-sparing (protein-saving)
35. Fats in the DietFats in the Diet
Concentrated source of energy – 9 kcals/gramConcentrated source of energy – 9 kcals/gram
Triacyglycerols (fats) are used as energy sourceTriacyglycerols (fats) are used as energy source
Supply essential fatty acids that cannot beSupply essential fatty acids that cannot be
synthesized by the body (linoleic and linolenic acids)synthesized by the body (linoleic and linolenic acids)
Phospholipids are essential for membrane functionPhospholipids are essential for membrane function
Help in the absorption of fat-soluble vitaminsHelp in the absorption of fat-soluble vitamins
Source of fat-soluble vitamins (A, D, E and K)Source of fat-soluble vitamins (A, D, E and K)
36. Fats in the diet
Contribute to the satiety (satisfactions) of a meal
Contribute to taste and smell of foods
May stimulate appetite
Slow gastric emptying
Excessive fat intake can causeExcessive fat intake can cause
– atherosclerosis/heart diseaseatherosclerosis/heart disease
37. Dietary Fat
From animals and plants
Animal fats
– Usually high melting point
– Solid (hard) at room temperature
Plant fats (oils)
– Usually low melting point
– Liquid at room temperature
38. Recommendations for Total Fat
World Health Organization
– Lower limit: 15% of total calories
– Upper limit: 30% of total calories
National Cancer Institute
– 30% or less of total calories
39. Recommendations for Saturated Fat
World Health Organization
–Lower Limit: 0% of total calories
–Upper Limit: 10% of total calories
40. Essential Fatty Acids
Two essential fatty acids:
– α-linolenic acid (ω-3 fatty acid)
– linoleic acid (ω-6 fatty acid)
Deficiency causes: scaly skin, dermatitis, reduced growth
(most common in infants)
Deficiency very rare
ω-3 and ω-6 fatty acids used to make eicosanoids which
appear to have cardioprotective effects
– decreased blood clotting
– decreased blood pressure
41. Food Sources of α-Linolenic Acid
Vegetable Oils
– Soybean oil
– Flaxseed oil
Fish oils
– Especially from fatty fish
– Provide a mixture of eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA)
42. Omega-3 Fatty Acids
EPA and DHA primarily found in cold-water
ocean fish such as: albacore, mackerel, salmon,
sardines, tuna, whitefish
Play an important role as:
–Structural membrane lipids
43. Recommendations for Omega-3 Fatty Acid Intake
American Heart Association Guidelines
Population
Patients without coronary
heart disease (CHD)
Patients with CHD
Patients who need to lower
triglycerides (fats)
Recommendation
Fatty fish twice a week
Include oils and foods rich in
α-linolenic acid (flaxseed,
canola and soybean oils;
flaxseed and walnuts)
---------
1 gm of EPA+DHA per day
from fatty fish
EPA+DHA supplements
---------
2 to 4 grams of EPA+DHA
per day provided as capsules
under a physician’s care
44. Trans Fatty Acids
Unsaturated fatty acids, behaving more like
saturated fatty acids in the body
–increase serum LDL (but not HDL)
–risk of CVD
Not found in plants (animals only)
Formed during the hydrogenation of liquid
vegetable oils
Found in baked food: cookies, cakes, deep-
fried foods
45. D i e t a r y F i b e rD i e t a r y F i b e r
The component of food that cannot be broken down byThe component of food that cannot be broken down by
human digestive enzymeshuman digestive enzymes
Dietary fiber provides little energyDietary fiber provides little energy
FunctionsFunctions
– Reduces constipationReduces constipation
– Increases bowel movementIncreases bowel movement
– Reduces exposure of gut to carcinogensReduces exposure of gut to carcinogens
– Decreases absorption of dietary fat and cholesterolDecreases absorption of dietary fat and cholesterol
– Delays gastric emptyingDelays gastric emptying
– Generates sensation of fullnessGenerates sensation of fullness
46. Two Types of Dietary Fiber
Most high fiber foods are a combination of insoluble and soluble dietary fibers
Insoluble Fiber
–tough, fibrous structures of fruits,
vegetables and grains
–indigestible food components that do not
dissolve in water
–usually passes though the body unchanged
47. Two Types of Dietary Fiber
Most high fiber foods are a combination of insoluble and soluble dietary fibers
Soluble Fiber
–indigestible food components that readily
dissolve in water
–gel-like or gummy in nature
–tend to be broken down by bacteria in the
colon
48. Recommendation for Dietary Fiber
World Health Organization
– More than 25 grams per day
Recommended Dietary Allowance (adults)
– Men: 38 grams per day
– Women: 25 grams per day
49. Sources of Insoluble Fiber
Cellulose: Whole-wheat flour, bran, vegetables
Hemicellulose: Bran, whole grains
Lignin: Mature vegetables, wheat, fruits and
edible seeds, such as flaxseeds and
strawberries
51. Benefits of Fiber
Lowers serum LDL levels
Promotes feelings of fullness
Slows gastric emptying, long-term glucose
control in patients with diabetes mellitus
Reduces energy consumption by displacing
calorie-dense fats
Protects against colon cancer
Editor's Notes
Key T, Davey G Prevalence of obesity is low in people who do not eat meat. Br Med J 313:816-817, 1996.
Key T et al Mortality in vegetarians and nonvegetarians: Detailed findings from a collaborative analysis of 5 prospective studies Am J Clin Nutr 70:516S-524S, 1999.
Messina MJ, Messina VL The Dietitian’s Guide to Vegetarian Diets, Gaithersburg, MD:Aspen Publishers; 1996.
Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets, Am J Diet Assoc 103:748-765, 2003.
Dietary Reference Intakes – September 2002
http://books.nap.edu/html/dri_macronutrients/reportbrief.pdf
Dietary Reference Intakes – September 2002
http://books.nap.edu/html/dri_macronutrients/reportbrief.pdf
Dietary Reference Intakes – September 2002
http://books.nap.edu/html/dri_macronutrients/reportbrief.pdf
Dietary Guidelines – 2000 http://www.health.gov/dietaryguidelines/dgac/pdf/2kdiet.pdf
World Health Organization – April 2003
http://www.who.int/mediacentre/releases/2003/pr32/en/
National Cancer Institute
Therapeutic Lifestyle Change (TLC) Diet of the National Cholesterol Education Program – May 2001
http://www.nhlbi.nih.gov/guidelines/cholesterol/index.htm
Dietary Reference Intakes – September 2002
http://books.nap.edu/html/dri_macronutrients/reportbrief.pdf
Position of the American Dietetic Association: Health implications of dietary fiber. JADA 201(7):993-1000, 2002.