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
2
Rajesh Chaudhary

Questions regarding diet/nutrition?
Monday, October 12, 2015Rajesh Chaudhary
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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 Monday, October 12, 2015
 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
Rajesh Chaudhary Monday, October 12, 2015
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, NutsMilk, 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)
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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
(2H2O18O)
 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
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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
Nutrition24
 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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Rajesh Chaudhary
 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?

Rajesh Chaudhary
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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

Rajesh Chaudhary
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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
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Three proximate principles of diet:
carbohydrate, fat and protein.
Proximate principles of diet
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Rajesh Chaudhary

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
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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 protein45
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
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 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)
52
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.

Nutrition for MBBS II

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Nutrition for MBBS II