n u t r i t i o n

N U T R I T I O NN U T R I T I O N N U T R I T I O NN U T R I T I O N

MBC 142 4 Lectures Dr. Usman Ghani

O V E R V I E WO V E R V I E WO V E R V I E WO V E R V I E W

Basic concepts of human nutritionBasic concepts of human nutrition Recommended daily allowances (RDA)Recommended daily allowances (RDA) Energy requirement in humansEnergy requirement in humans Macronutrients (proteins, Macronutrients (proteins,

carbohydrates, lipids, dietary fibers) carbohydrates, lipids, dietary fibers) and micronutrients (vitamins, minerals)and micronutrients (vitamins, minerals)

Nutritional diseasesNutritional diseases Diet and cancerDiet and cancer Dietetic treatment (treatment of disease Dietetic treatment (treatment of disease

by diet)by diet)

W h a t i s N u t r i t i o W h a t i s N u t r i t i o n ?n ?

Utilization of foods by living organismsUtilization of foods by living organismsThe process of utilization is The process of utilization is

biochemicalbiochemicalHuman nutrition has three types:Human nutrition has three types:

– UndernutritionUndernutrition– Optimal nutritionOptimal nutrition– OvernutritionOvernutrition

N u t r i e n t s a n d D i e N u t r i e n t s a n d D i e tt

Nutrients are the ingredients of food Nutrients are the ingredients of food needed for normal functioning of the needed for normal functioning of the body body

Nutrients provide energy for various Nutrients provide energy for various body functionsbody functions

Quality (what food items) and Quality (what food items) and quantity (how much nutrients) are quantity (how much nutrients) are important for maintaining good important for maintaining good health health

T y p e s o f N u t r i e n t T y p e s o f N u t r i e n t ss

Two types:Two types:– MacronutrientsMacronutrients– MicronutrientsMicronutrients

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 sM 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 Nutrients needed by the body in large amounts are called amounts are called macronutrientsmacronutrients

Three types of macronutrientsThree types of macronutrients– ProteinsProteins– CarbohydratesCarbohydrates– FatsFats

Macronutrients provide energy and Macronutrients provide energy and building blocks of proteins, building blocks of proteins, carbohydrates and fatscarbohydrates and fats

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 sM 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 small Nutrients needed by the body in small amounts are called amounts are called micronutrientsmicronutrients

Major types of micronutrientsMajor types of micronutrients– VitaminsVitamins– Minerals / trace elementsMinerals / trace elements

Required for maintaining normal Required for maintaining normal health and preventing various health and preventing various diseasesdiseases

N u t r i e n t s f r o m D i N u t r i e n t s f r o m D i e te t

Proteins, carbohydrates, fatsProteins, carbohydrates, fats Essential fatty acidsEssential fatty acids Essential amino acidsEssential amino acids Vitamins Vitamins MineralsMinerals Dietary fibersDietary fibers WaterWater

Recommended Daily Recommended Daily Allowances (RDA)Allowances (RDA)

RDA are the levels of intake of RDA are the levels of intake of essential nutrients considered by essential nutrients considered by the Food and Nutrition Board, USA, the Food and Nutrition Board, USA, to be enough to meet the nutritional to be enough to meet the nutritional needs of all healthy personsneeds of all healthy persons

RDA varies according to age and sexRDA varies according to age and sex

E n e r g y C o n t e n t o f E n e r g y C o n t e n t o f F o o d F o o d

Much of the food we eat is Much of the food we eat is converted to ATP and other high-converted to ATP and other high-energy compoundsenergy compounds

This energy is used for biosynthetic This energy is used for biosynthetic pathways, muscle contraction, pathways, muscle contraction, nerve impulse, etc.nerve impulse, etc.

Energy content of food is measured Energy content of food is measured in in calories (Kilocalories)calories (Kilocalories) of heat of heat energy released by combustion energy released by combustion (burning) of that food(burning) of that food

One calorie is the heat required One calorie is the heat required to raise the temperature of 1 gm. to raise the temperature of 1 gm. of water by 1of water by 1ooCC

ProteinsProteins 4 kcal/gm 4 kcal/gmCarbohydratesCarbohydrates 4 kcal/gm 4 kcal/gmFatFat 9 kcal/gm 9 kcal/gm

E n e r g y E x p e n d i t u E n e r g y E x p e n d i t u rere

Depends on four factors:Depends on four factors:– Surface area of the body (height and Surface area of the body (height and

weight)weight) The greater the surface area the The greater the surface area the

greater the heat lossgreater the heat loss– AgeAge

Growth and lean muscle massGrowth and lean muscle mass Infants have higher basal metabolic Infants have higher basal metabolic

rate (rate of energy utilization in rate (rate of energy utilization in resting state)resting state)

– SexSexWomen have lower BMR than Women have lower BMR than menmen

– Activity levelActivity levelExercise increases energy Exercise increases energy expenditureexpenditure

Recommended Energy IntakeRecommended Energy IntakeRecommended 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

Some DefinitionsSome Definitions

Omnivorous: Omnivorous: eat both eat both meat and vegetablesmeat and vegetables

Carnivorous: Carnivorous: eat meat eat meat onlyonly

Herbivorous: Herbivorous: eat eat vegetable, grass onlyvegetable, grass only

Vegetarianism - DefinitionsVegetarianism - Definitions

Lacto-Ovo Lacto-Ovo VegetarianVegetarian

Lacto VegetarianLacto VegetarianVeganVegan

Vegetarianism - DefinitionsVegetarianism - 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

Vegetarian and nutrient intake

Lower intake of iron Lower intake of calcium and

vitamin D May develop megaloblastic anemia

because of vitamin B12 deficiencyMost consume enough protein Lower in total dietary fat

Vegetarian diet and disease

(Research results)

Vegetarian diet and disease

(Research results)

Lower Body Mass Index (BMI)Ischemic heart disease lower than non-

vegetarians Lower blood pressureLower cancer rates compared to non-

vegetarians

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

Food PyramidUnited States Department of Agriculture

Center for Nutrition Policy and Promotion

Food PyramidUnited States Department of Agriculture

Center for Nutrition Policy and Promotion

Educational tool for public – established in 1992

Healthy eating guide Size of each section reflects daily

servings recommended Pyramid shape Fats, oils and sweets occupy only a

tiny triangle at the top

OvernutritionOvernutrition

Major cause of many diseases: obesity, diabetes, hypertension, etc.

High morbidity (disease)and mortality

Nutritional Screening/Assessment

It is a nutrition assessment processIdentifies persons who are

malnourishedDone by a physician, nurse, dietitian or

other qualified health-care professional

Identifies individuals who require aggressive nutrition support

Restores or maintains an individual’s nutrition status

Identifies appropriate medical nutrition therapies

Monitors the efficacy of these interventions

Nutritional Importance of Nutritional Importance of ProteinsProteins

Proteins supply amino acids and Proteins supply amino acids and amino nitrogen for the synthesis of amino nitrogen for the synthesis of important nitrogenous compounds important nitrogenous compounds such as purines, pyrimidines and such as purines, pyrimidines and hemeheme

Types of amino acids:Types of amino acids:– Essential (body can’t synthesize)Essential (body can’t synthesize)– Non-essential (body can Non-essential (body can

synthesize)synthesize)

RDA: 0.8 gms/kg body weightWorld Health Organization

10 to 15 % of total calories

Recommended Daily Recommended Daily Protein IntakeProtein Intake

Recommended Daily Protein Recommended Daily Protein IntakeIntake

(mg/Kg body wt.)(mg/Kg body wt.)

Recommended Daily Protein Recommended Daily Protein IntakeIntake

(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

Essential amino acids are not Essential amino acids are not synthesized by the body and must be synthesized by the body and must be supplied in dietsupplied in diet

PVT TIM HALLPVT TIM HALLPPhenylalaninehenylalanine TThreoninehreonine HHistidine*istidine*VValinealine IIsoleucinesoleucineAArginine*rginine*

TTryptophanryptophan MMethionineethionine LLysineysineLLeucineeucine

*Essential only in children*Essential only in children

Essential Amino AcidsEssential Amino AcidsEssential Amino AcidsEssential Amino Acids

Normal Nitrogen BalanceNormal Nitrogen Balance– In a healthy person, the nitrogen In a healthy person, the nitrogen

intake is equal to nitrogen lossintake is equal to nitrogen lossNegative nitrogen balanceNegative nitrogen balance

– When nitrogen loss is more than When nitrogen loss is more than intakeintake

Positive nitrogen balancePositive nitrogen balance– When nitrogen intake is more than When nitrogen intake is more than

lossloss

N i t r o g e n B a l a n N i t r o g e n B a l a n c ec e

Protein-Energy Protein-Energy MalnutritionMalnutrition

Malnutrition:Malnutrition:– Condition/disease caused by Condition/disease caused by

not eating enough food or not not eating enough food or not eating a balanced dieteating a balanced diet

Malnutrition due to inadequate Malnutrition due to inadequate intake of proteins or energyintake of proteins or energy

Two conditions:Two conditions:– MarasmusMarasmus– KwashiorkorKwashiorkor

Marasmus:Marasmus:– Inadequate intake of both Inadequate intake of both

proteins and energy (calories)proteins and energy (calories)– Occurs in growing children Occurs in growing children

under 5 yearunder 5 year– Usually found in poor Usually found in poor

population suffering from food population suffering from food shortageshortage

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

KwashiorkorKwashiorkor– Inadequate intake of proteins with Inadequate intake of proteins with

adequate energy intakeadequate energy intake Clinical featuresClinical features

– Edema (swelling of body)Edema (swelling of body) – Dry, weak – Dry, weak hairhair

– DiarrheaDiarrhea –– Dermatitis Dermatitis– Weak immune systemWeak immune system – Retarded – Retarded

growthgrowth– Sensitive to developing infectionSensitive to developing infection

Excess Protein-Energy Excess Protein-Energy IntakeIntake

Can lead to obesity, diabetes, Can lead to obesity, diabetes, hypertension, coronary heart hypertension, coronary heart disease, etc.disease, etc.

C a r b o h y d r a t e sC a r b o h y d r a t e sC 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 Their major role in diet is energy productionproduction

Excess carbohydrates are converted Excess carbohydrates are converted to glycogen (in liver) and to glycogen (in liver) and triacylglycerols (fat) for storage in triacylglycerols (fat) for storage in adipose tissueadipose tissue

Carbohydrate intolerancesCarbohydrate intolerances– Diabetes mellitusDiabetes mellitus– Lactase insufficiencyLactase insufficiency

CarbohydratesCarbohydrates

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

Carbohydrates in FoodCarbohydrates 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

CarbohydratesCarbohydratesProtein-sparing effect

Dietary protein requirement and CHO diet are related to each other

If CHO intake is less than 130 g/day:–more protein is metabolized–more gluconeogenesis

CarbohydratesCarbohydratesCHO 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)

Fats in the DietFats in the DietFats 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 Triacyglycerols (fats) are used as energy

sourcesource Supply essential fatty acids that cannot be Supply essential fatty acids that cannot be

synthesized by the body (linoleic and linolenic synthesized by the body (linoleic and linolenic acids)acids)

Phospholipids are essential for membrane Phospholipids are essential for membrane functionfunction

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)

Fats in the dietFats in the diet

Contribute to the satiety (satisfactions) of a meal

Contribute to taste and smell of foodsMay stimulate appetiteSlow gastric emptyingExcessiveExcessive fat intake fat intake can causecan cause

– atherosclerosisatherosclerosis/heart disease/heart disease

Dietary FatFrom animals and plantsDietary 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

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

Recommendations for Saturated Fat

World Health Organization–Lower Limit: 0% of total calories

–Upper Limit: 10% of total calories

Essential Fatty AcidsEssential 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

Essential Fatty AcidsEssential Fatty Acids

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)

Omega-3 Fatty AcidsOmega-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–Modulator of ω-6 fatty acid metabolism

Recommendations for Omega-3 Fatty Acid Intake

American Heart Association Guidelines

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 -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

Mediterranean DietMediterranean Diet Seasonal food More vegetables and fruits Less red meats Olive oil – a major fat source Rich in:

– monounsaturated fatty acids (olive oil)– Omega-3 fatty acids (fish, nuts)

Low in saturated fat Reduces total serum cholesterol and LDL

Trans Fatty AcidsTrans 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 oilsFound in baked food: cookies, cakes,

deep-fried foods

D i e t a r y F i b e rD i e t a r y F i b e rD 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 The component of food that cannot be broken down by human digestive enzymesbroken down by human 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 Decreases absorption of dietary fat and

cholesterolcholesterol– Delays gastric emptyingDelays gastric emptying– Generates sensation of fullnessGenerates sensation of fullness

Two Types of Dietary FiberMost 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

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

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

Sources of Insoluble FiberSources of Insoluble Fiber

Cellulose: Whole-wheat flour, bran, vegetables

Hemicellulose: Bran, whole grainsLignin: Mature vegetables, wheat,

fruits and edible seeds, such as flaxseeds and strawberries

Sources of Soluble FibersSources of Soluble Fibers

Gums: Oats, legumes, guar, barley

Pectin: Apples, citrus fruits, strawberries, carrots

Benefits of FiberBenefits of Fiber

Lowers serum LDL levelsPromotes feelings of fullnessSlows gastric emptying, long-term

glucose control in patients with diabetes mellitus

Reduces energy consumption by displacing calorie-dense fats

Protects against colon cancer

Nutrition and cancerNutrition and cancer

Nutritional problems in cancer Cachexia

– Weakness, loss of appetite, metabolic/hormonal abnormalities, weight loss

Change in taste, lack of energy, feeling of fullness, nausea, vomiting

Tumors produce substances that cause loss of appetite

Nutritional problems due to cancer treatment Radiation therapy:

– Causes dry mouth, gum destruction, change in taste, difficulty in swallowing, malabsorption of nutrients, GIT damage

Chemotherapy:– Severe side effects

Surgery:– Limited swallowing/digestion of food– Limited absorption of nutrients

Nutritional needs of cancer patients– The diet must supply all nutrients– Energy and protein needs are increased by

20%– 3000 to 4000 calories– 100 to 200 g of proteins in the diet:

To prevent tissue breakdown/weight loss

Dietetic Treatment (Diet Therapy)

Treatment or control of diseases by therapeutic diet (modified diet)

Purpose:– Maintain/improve nutritional status– Maintain, increase or decrease body

weight– Rest certain organs or whole body– Adjust the diet so that the body can handle

it in a disease

How diet is modified?How diet is modified?

Basic diet becomes therapeutic when:– Calories, fiber, some nutrients, food

types are increased or decreased– Diet is modified to become soft or liquid– Certain foods are eliminated

Some examples of therapeutic dietsSome examples of therapeutic diets

Consistency– Mechanical, tube feeding, high fiber,

liquidCarbohydrates

– Diabetic diet, Low-calorie diet– Ketogenic diet– Lactose-free diet

Some examples of therapeutic dietsSome examples of therapeutic diets

Fat– Restricted fat diet– Low cholesterol diet

Proteins– Restricted protein diet– Gluten-free diet– Restricted phenylalanine diet (for PKU)– Restricted purine diet (for gout)– High protein diet

Diet therapy of diabetes mellitus

Calories– Calorie intake should be the same for

diabetics compared to non-diabetics– Adjustment in calories by modifying food

contentsProteins

– 15 to 20% calories from proteins– RDA: 1 to 1.5 gm/kg

Carbohydrates– CHO content is the same as for normal diet– More complex CHOs + high fiber– Use of nutritive / non-nutritive sweeteners

Fats– 20 to 30% calories from fat– Low fat, lean meats, polyunsaturated fats,

low cholesterol

Complex CHOs and fiber:– Improve glycemic control in diabetics– Lower serum cholesterol, triglycerides– Promote weight loss

50 g or more fiberUpto 60% complex CHO intake

Diet therapy of renal diseases

Calories– Protein restricted diet– Adequate calories are provided in the

diet from other sources (fats, CHO) to avoid protein degradation in muscle

Proteins– RDA for renal patients: 0.5 to 1.5 gm/kg– Normal amount of proteins is provided if

kidney function is normal– Restricted protein diet for patients with

reduced kidney function to avoid retention of protein met. products

– Protein content is increased to compensate for high albumin loss in urine

Electrolytes– Restricted sodium (500 mg/day) to avoid

edema in hypertensive patients– Restricted potassium (1.5 gm/day)

Retained in kidney failure patients

Fluids– Restricted in patients with kidney failure– A balance of urinary input and output is

maintained

Diet therapy of hyperlipidemia and

cardiovascular disease

Diet therapy of hyperlipidemia and

cardiovascular disease

Saturated fat, cholesterol restricted dietMore polyunsaturated fatsDiet should meet RDA for proteins, CHOsSodium restricted diet to prevent:

– Hypertension– Congestive heart failure

Sodium intake: 250 to 2000 mg/day

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