Nutrition for MBBS II

NUTRITION

Department of Biochemistry, KMC, Duwakot

Rajesh Chaudhary 1

Monday, October 12,

2015

You Are What You Eat !

Monday, October 12, 2015

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Rajesh Chaudhary

Questions regarding diet/nutrition?

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1. What do you mean by balanced diet?

2. Why do we need to take a balanced diet?

3. What are the basic components of a balanced

diet?

4. How much food should we take on a daily basis?

5. How much energy do we need on a daily basis?

6. How do we calculate how much energy is required

by a particular person?

7. What are the consequences of unbalanced diet?

Malnutrition, Under-nutrition, Over-nutrition

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Malnutrition: refers to deficiencies, excesses or imbalance of

intake energy, protein and/or other nutrients.

Under-nutrition: is the result of food intake that is continuously

insufficient to meet dietary energy requirements, poor

absorption and/or poor biological use of nutrients consumed.

This usually results in loss of body weight.

Over-nutrition: refers to chronic condition where intake of

food is in excess of dietary energy requirements, resulting in

overweight and/or obesity.


Signs and symptoms of malnutrition

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Loss of fat (adipose tissue)

Breathing difficulties, a higher risk

of respiratory failure

Depression

Higher risk of complications after

surgery

Higher risk of hypothermia -

abnormally low body temperature

The total number of some types of

white blood cells falls;

consequently, the immune system is

weakened, increasing the risk of

infections.

Higher susceptibility to feeling cold


Longer healing times for wounds

Longer recover times from infections

Longer recovery from illnesses

Lower sex drive

Problems with fertility

Reduced muscle mass

Reduced tissue mass

Tiredness, fatigue, or apathy

Irritability

What is double burden of malnutrition? 6

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How do you define a balanced diet and how to plan

a balance diet?

Why is it necessary to have a

balanced diet? 7


Metabolic syndrome

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Essential nutrients obtained from diet

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Basic food groups


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1. Milk group – including diary products

2. Meat group – meat, fish, eggs and

pulses/beans/nuts.

3. Green leafy vegetables – including fruit groups

4. Cereals group – Bread, Rice, Wheat, and Barley.

Classification of nutrients on the basis of their

function


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Nutrients Functions

Carbohydrates Energy production

Fats Protection against infections

Proteins

Vitamins Body building

Minerals

Water Regulation of tissue

functions

Nutrients

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Macronutrients

Carbohydrates

Fats

Proteins

Micronutrients

Minerals

Vitamins


Balanced diet

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We Can Use The Food Pyramid.

Oil and Sugar

Meat, Fish, Nuts Milk, Cheese, Yogurt

Fruit and Vegetables

Bread, Potatoes, Pasta


Factors affecting balanced diet

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Age

Environmental factor (temperature)

Physical activity

Health condition (Disease / healthy)


Energy requirement with age

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Calorific value / Energy density


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1 Calorie: Amount of heat required to raise temperature of 1

gram of water by 1 0C.

Calorific value: The amount of heat generated by burning 1

g of food stuff completely in presence of O2.

1000 calories = 1 kCal = 4.2 kJoule

1 Joule: Amount of energy required to lift 1 kg of water

through 1 meter of height by 1 Newton force.

Dietary Reference Intake (DRI) 17

RDA = EAR + 2SDEAR

Comparison of components of DRI


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Energy Requirement in Human


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1. Energy content of food.

2. How energy is used in the

body.

2.1. Resting Metabolic Rate

2.2. Thermic Effect of Food.

2.3. Physical activity

Respiratory quotient (RQ)

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RQ = 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑎𝑟𝑏𝑜𝑛𝑑𝑖𝑜𝑥𝑖𝑑𝑒 𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑

𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑜𝑥𝑦𝑔𝑒𝑛 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑

More recent technique: isotopically-labelled water (2H2O

18O)

Basal Metabolic Rate (BMR)

Energy expenditure at rest

Controlled condition of thermal neutrality

Measured about 12 hours after meal

Depends on: weight, age and gender


Oxidation of metabolic fuel 21

Energy Yield

(kJ/g)

O2 Consumed

(L/g)

CO2 Produced

(L/g)

RQ Energy

(kJ)/L O2

Carbohydrate 16 0.829 0.829 1.00 20

Protein 17 0.966 0.782 0.81 20

Fat 37 2.016 1.427 0.71 20

Alcohol 29 1.429 0.966 0.66 20

Variation in RQ


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1. In Acidosis: RQ increases.

2. In alkalosis: RQ decreases.

3. In febrile conditions: RQ increases.

4. In diabetes mellitus: RQ falls, but increases after insulin therapy.

5. In starvation: RQ falls.

Factors affecting RQ


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1. Role of diet

1.1. For Carbohydrate: 1, Fat: 0.7, Protein: 0.8, Mixed

diet: 0.85

2. Effect of interconversion in body

3. Muscular exercise

3.1 Light Vs Strenuous exercise

Energy balance: Over & Under

Nutrition 24

Body Mass Index (BMI) = 𝑤𝑒𝑖𝑔ℎ𝑡 (𝑖𝑛 𝐾𝑔)

ℎ𝑒𝑖𝑔ℎ𝑡2

Energy requirement are measured by the amount of energy

expenditure.

Direct method: amount of heat produced

Indirect method: amount of O2 consumed

Reference: Center for Disease Control

Normal BMR Range


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For adult men: 34-37 kCal/square meter/hour.

For women: 30-35 kCal/Sq.m/hour

Normal BMR range

BMR for adult is fixed at 24kcal/kg body wt/day

Measuring BMR

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Let oxygen consumed in 6 minutes be “y” liters

1 liter of O2 = 4.8 kilocalorie

Heat produced in 6 minutes = 4.8×y

Similarly, in 24 hours = y×4.8×10×24 kilocalories.

Body surface area A = W0.425×H0.725×71.84

A = area in sq. cm

H = height in cm

W = weight in Kg

BMR for

Men: 34-37 kCal/sq.meter/hr

Women: 30-35 kCal/sq.meter/hr

Instrument: Benedict-Roth basal

metabolism apparatus


Energy requirements increase with activity

Sedentary: 1.1-1.2×BMR

Vigorous work: 6-8×BMR

Calculate the BMR of the following

patient


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A male aged 35-years, height: 170 cm and weight

= 70 kg, consumed an average of 1.2 liters of O2

in 6-minute period. He has body surface area of

1.8 sq. meter.

What might be his BMR?

Calculating BMR by Read’s formula

BMR = 0.75(PR+0.74×PP)-72

Pathological variations in BMR


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1. Fever

2. Disease

3. Perforation of an eardrum.

4. Endocrine diseases

4.1. Hyperthyroidism

4.2. Hypothyroidism

Factors affecting BMR


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1. Age

2. Sex

3. Climate temperature

4. Exercise / Activity

5. Fever

6. Thyroid hormones

7. Barometric pressure

8. Racial variation

9. Body surface area

10. State of nutrition

11. Drugs

12. Pregnancy

What is the importance of BMR?


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Body weight affects BMR

Decrease in BMR with increase in age

BMR ∝1

𝐴𝑔𝑒

BMR men vs. women

Energy requirements increase with activity

Sedentary vs. Rigorous activity



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Environmental temperature

Winter season/cooler temperature increase in BMR

Fever

12% increase in BMR per degree centigrade rise in temp.

Thyroid hormone

Raised BMR in “hyperthyroidism”

Lower BMR in “hypothyroidism”


Specific Dynamic Action (SDA)

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What is SDA of foods?

100 calories of white sugar SDA 7%

100 calories of butter/oil SDA 12%

100 calories of protein SDA 30%

Increasing

order!


1. What is SDA?

2. Is there any difference between SDA, thermogenic effect

of food, and diet-induced thermogenesis ?

Contributing factors to SDA 33

Three proximate principles of diet:

carbohydrate, fat and protein.

Proximate principles of diet


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Dietary carbohydrates


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Why is it said that carbohydrates is not

essential for our body but still we have to

consume it on daily basis?

RDA for carbohydrate: 130 g/day.

What do you mean by glycemic index?

What are the foods with higher, medium

and lower glycemic index?

Role of Carbohydrates in diet


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1. Requirement of carbohydrates in diet

Normally: 55-65% of total food calories should come from carbohydrate.

A moderately active man requires 3000 calories /day.

Should take about 450 grams of carbohydrates daily.

NOTE: Poor section of Nepal/India gets 85% of caloric value from carbohydrate alone.

2. Undue restriction of dietary carbohydrate influence both fat and protein metabolism adversely, even if the caloric intake in adequate – ketogenesis is increased and ketosis may develop.

Role of Carbohydrates in diet


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Both carbohydrate and fats are catabolized for energy and thus spares proteins from being used for this purpose.

Dietary fats may also depress the SDA of protein.

Action of carbohydrates on plasma lipids ?

Relation with Vitamin-B ?

Role of cellulose: provides bulkiness of stool and removes constipation.

Role of lipids in diet


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The main function of lipids is to provide energy.

Its indirect function – as carrier of certain fat-soluble vitamins.

Dietary fat has high “Satiety” value.

Under usual condition, fat provides 20-35% of the calories.

Restriction of fat intake.

And, substitution of polyunsaturated FA for saturated FA, helps in

lowering the cholesterol concentration.

Role of lipids in diet


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Excess of fat intake: excess fat intake inhibits gastric secretion

leading to “Anorexia” and “gastric discomfort”.

Intestinal irritation and diarrhea may result from excess amount

of FA in intestine.

Excess of saturated fats in diet may reduce the gastric

digestion of protein because fat digestion starts in intestine

thus preventing exposure of food proteins to pepsins.

Delay/failure of fat absorption may also reduce Ca2+

absorption as calcium forms insoluble soaps with higher FA in

intestine.

Dietary Fats and Plasma Lipids


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Triacylglycerol is quantitatively the most important

class of dietary fat.

Fat

Saturated fat

Unsaturated fat

Monounsaturated fat

Polyunsaturated fat

Myristic acid (14C), Palmitic

acid (16C), Stearic acid

(18C)

Dietary Fats and Plasma Lipids


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Trans Fatty Acids


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Increases catabolism of apo-A1.

Increasing LDL levels.

Decreasing HDL levels.

Increasing the abnormal clotting of blood.

Substitution for reducing fat intake 43

Instead of Try

1. Whole milk Skimmed milk

2. Ice cream Ice milk

3. Butter or margarine Yogurt, Olive oil

4. Fried chicken Baked chicken without skin


Role of Protein in diet


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Studying protein into two headings:

1. Quality of Protein

2. Quantity of Protein

Quality of proteins depends on

1. Biological value of protein / Net Protein Utilization (NPU)

2. AA composition of dietary protein.

3. Availability of AA from foods.

4. Supplementary relationship of AA.

% of protein nitrogen absorbed that can be

retained in the body.

Biological value of protein 45

Protein Efficiency Ratio (PER) = 𝐰𝐞𝐢𝐠𝐡𝐭 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐝

𝐠𝐫𝐚𝐦𝐬 𝐨𝐟 𝐩𝐫𝐨𝐭𝐞𝐢𝐧 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞

Net Protein Utilization (NPU) = 𝐃𝐢𝐠𝐞𝐬𝐭𝐢𝐛𝐢𝐥𝐢𝐭𝐲 𝐜𝐨𝐞𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐭 ×𝐁𝐢𝐨𝐥𝐨𝐠𝐢𝐜𝐚𝐥 𝐯𝐚𝐥𝐮𝐞

𝐏𝐫𝐨𝐭𝐞𝐢𝐧 𝐢𝐧𝐭𝐚𝐤𝐞 (𝐠𝐦)

Biological value of protein= 𝐫𝐞𝐭𝐚𝐢𝐧𝐞𝐝 𝐧𝐢𝐭𝐫𝐨𝐠𝐞𝐧

𝐚𝐛𝐬𝐨𝐫𝐛𝐞𝐝 𝐧𝐢𝐭𝐫𝐨𝐠𝐞𝐧× 𝟏𝟎𝟎

Role of protein in diet 46

Proteins are not primarily meant for generating

energy but rather to synthesize tissue proteins.

Dietary protein and their influence in growth.

Growth is manifested by the formation of tissue proteins at

the rate exceeding that of their degradation.

Quality of protein is more important than quantity.

So, what are the consequences of protein deficiency?

How much amount or protein we should be consuming on daily basis

to maintain N-equilibrium?

Consequences of protein deficiency


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In child, growth retardation.

In adult, weight is lost.

Hemoglobin formation is impaired with consequent anaemia.

Wound healing is delayed.

Because of deficiency, excess fat may accumulate in liver producing fatty

liver.

Prolonged deficiency may result to inadequate synthesis of plasma proteins

– specially albumin and fibrinogen.

Resistance to infections may be diminished as a result of impaired capacity

for forming g-globulins antibodies (IgGs)

Protein and Amino acids requirements

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Determined by measuring “nitrogen balance”.

Dietary intake and output of nitrogenous compounds.

Major dietary source of nitrogen: Protein

mg N × 6.25 = mg protein

“N” is 16% of most protein


Protein and AA requirements

(Nitrogen balance) 49

Nitrogen balance

Negative nitrogen

balance

Equilibrium Positive nitrogen

balance

Nitrogen balance

(I = U+F+S)

N-equilibrium until critical intake level above 0.25 to 0.33 gram/kg

body wt.

Protein and AA requirements

(Nitrogen balance)

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Higher consumption of protein doesn’t necessarily

mean “positive nitrogen balance”.

Higher protein diet higher “diet-induced

thermogenesis”.

Average daily requirement = 0.6g of protein/kg

body weight

~55 g/day.


Daily protein recommendation

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Protein Energy Malnutrition (PEM) /

Protein Calorie Malnutrition (PCM)


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PEM

Marasmus Kwashiorkor Marasmic-kwashiorkor

Factors affecting nitrogen balance

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Growth

Gain of 5 kg weight, 1 kg protein is added to body

Hormones

Insulin and androgens positive nitrogen balance

Corticosteroids negative nitrogen balance

Pregnancy

Convalescence

Acute & chronic illness

Protein deficiency


Caloric value (Atwater Factors)

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Metabolisable energy = (Gross energy in food) – (Energy lost in

Faces, Urine, Secretion, and Gases)

Calculating Atwater factor

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Solids 95.6% Factor Kcal/ gram

Protein 38.8% 0.388 4 1.552

Fat 42.2% 0.422 9 3.798

Carbohydrate 9.0% 0.090 4 0.360


Recommended Daily Allowance (RDA)

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Total Fat 65 g

Saturated Fatty Acids 20 g

Cholesterol 300 mg

Sodium 2400 mg

Potassium 4700 mg

Total Carbohydrate 300 g

Dietary Fiber 25 g

Protein 50 g

For person >4 years of age.

Harris-Benedict equation

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Energy requirements (kcal/day) = 66.5+13.8 (weight in

kg) + 5.0 (height in cm) – 6.8 (age in years).

Energy requirements (kcal/day) = 655.0+9.6 (weight in

kg) + 1.8 (height in cm) – 4.7 (age in years).


Factors that determine energy requirement: age, gender, height

and weight.

References 58

Nutrition for MBBS II

Science

Transcript of Nutrition for MBBS II