biochemistry food and nutrition

Muhammad Ramzan Ul Rehman. 1


Biochemistry


Food & nutrition By Muhammad Ramzan Ul Rehman


Food. Any substance consumed to provide

nutritional support to the body is called Food. Any substance that is source of Nutrition, can

be metabolized by Human body to give energy & to build tissues & that provide mental stimulus for thinking is called food.


Nutrient Any substance that can be taken in & used in

organic synthesis & can be metabolized b human body to give Energy & build tissues is called Nutrient


Nutrition The organic process of nourishing or being

nourished by which an organism assimilate food & use for growth & maintenance is called Nutrition.


Diet Sum of foods consumed by organisms or

group or organisms is called diet. Prescribed food is called diet.


Balanced Diet The diet that contain adequate amount of all

necessary nutrients required for healthy growth and activity in a balanced proportion is called balanced diet.


Components of Energy Expenditure

BMR ( basal metabolic rate ) or RMR ( resting metabolic rate)

Thermogenic effect of food Daily physical activity & Exercise


basal metabolic rate

Body’s “Idling speed ” {The minimal working rate of Internal energy expenditure during (metabolism ,thermogenesis & body functions) at resting state }


Conditions to calculate BMR

Mentally and physically rest Temperature =25 C° Post absorptive state ( after 3 to 4 Hrm of

meal )


Organs that involve in continuous E expenditure

Heart Lungs Liver Kidneys


Resting metabolic rate

Combination of Basal metabolic rate Sleeping metabolism Arousal metabolism


Methods to calculate BMR

1.Direct method. Calorimeter used Energy produced is measured

2.In Direct method. Measured by the consumption of O2 and CO2.


Methods to Measure Metabolic Rate.

Substrate (CHO or Fat) + O2 + Energy (ATP)

CO2 + H2O + Energy (ATP) + Heat

Method #2

INDIRECT CALORIMETRY

Method #1

DIRECT CALORIMETRY


Energy from metabolism

40% ATP . 60% Heat.

Digesting Metabolism.Energy needed to digest the food. 10% of the metabolic demand.


Variations of BMR

Genetics. males 10 to 15% higher than females ( More

muscle mass & less body fat ). Age

Decreases with age After 20 year drop 2% every year

Weight Directly proportional to BMR


Body surface area Directly proportional . Thin & tall people more BMR.

Body fat %age Inversly proportional

Diet Directly proportional Dec diet intake BMR decrease upto 30%


Body temperature (internal) 1 degree increase will increase BMR 14%.

Body temperature (external) Exposure to cold increase BMR Exposure to hot if prolonged increase BMR

Glands Thyroid gland thyroxin directly proportional

Exercise Muscle mass inc. & fat %age dec. body BMR

increase


Energy

Capacity to do work is called Energy Nutritional Unit calorie The amount of heat energy required to raise

the temperature of 1 gram of water by 1°C is called Calorie


Calculation of the BMR

Men.

Women.


For more accurate calculations of BMR

S = +5 ( for males ) S = -161 ( for females )


For athletes more accurate formulas are

The Katch - McArdle Formula (BMR):

The Cunningham Formula (RMR):

M = Lean Body Mass in Kg ( metabolically active mass & fat cells

LB = mass in ponds 1LB =450 g


Additional Calorie Requirements Pregnancy

Placenta formation & fetus requirements Approximately 500 k cal additional required

Lactation 500 kcal additional required lactation

additional burden. Energy contents of milk + energy required to

produce Milk Puberty

Rapid growth


ENERGY BALANCE WITH RESPECT TO THE BODY

INPUT - OUTPUT = STORAGE OR DEPLETION

OUTPUT = INTERNAL WORK + EXTERNAL WORK

INTERNAL WORK HEAT

( )


STORAGE AND/OR DEPLETION

Input Energy & Output Energy match Energy balance

Positive Energy Balance Input more than Output storage in the form of

glycogen or fats Negative Energy Balance

Output more than input body Energy stores depleted


Energy expenditure.Liver 27%Brain 19%Heart 7%Kidneys 10%Skeletal muscle 18%Other organs 19%

http://en.wikipedia.org/wiki/Liver

http://en.wikipedia.org/wiki/Brain

http://en.wikipedia.org/wiki/Heart

http://en.wikipedia.org/wiki/Kidneys

http://en.wikipedia.org/wiki/Skeletal_muscle


Total Energy Requirement.


Step # 01 Calculation of RMR

Genetic factors ignored Masses used in Kg


Step# 02 Calculation of TEE

Thermic effect of exercise effect due to activity above the BMR

Sedentary: under the care of someone else. Resting metabolic rate + factor for minimal activities

playing cards , watching TV, reading, e.t.c


Lightly Active 8 Hr. sleep 16 Hr. sitting or standing [3 Hr. must include

light ] Most students, office workers, and

professionals.


Moderately Active Most persons in light industry Lightly Active category + 1.5 to 2 hours of

exercise per day (like jogging 5 to 6miles/day)


Very Active Full time athletes, unskilled laborers, some

agricultural workers moderate intensity activity for most of the

work day comparable to running 9 to 13 miles/day.


Extremely Active Heavy labor work Moderate to high level of physical activity for

most of the work day comparable to running 14 to 17 miles/day.


Thermic effect of the Exercise

TEE = RER x Activity factor


Step # 03 Safety factor

10% of the sum of the RER & TEE


Total Caloric Requirements

RER + TEE = X Caloric safety or thermic effect of food (TEF)

10 % of the X (10/100) x X = TEF

Total caloric requirements = X + TEF = Answer


Requirements of food available


FOOD AS FUEL

CARBOHYDRATE 4 CAL/G

PROTEIN 4 CAL/G

FAT 9 CAL/GRAM

ETHANOL 7 CAL/G


Balanced dietBalanced diet

nutrient Calories must be taken

Carbohydrate 55-60%

Lipids 30-35%

Proteins 15%


Method to calculate food required. For example for carbohydrates

Proportion of carbohydrates = 60% of total Cal Carbohydrates needed = total cal x (60/100)

=calories from carbohydrates

AND

4 Cal from carbohydrate =1g carbohydrate 1 Cal from carbohydrate =1/4 g carbohydrate

Carbohydrates needed = Cal from Carbohydrates/4 =answer in g


Amount of Carbohydrates in 100 g of Food


Proteins & Lipids

Similar methods [like carbohydrates] can be used for Other Nutrients ( fats & Proteins)


Balanced Diet.


Nutrient Intake with RDA


Total Nutrient requirements for Mothers


Balanced diet for Women


Balanced diet For adults


Energy Needs for Pregnant & Brest feeding.


Food Contents Recommended for Balanced diet


1. Breads cereals, Rice ,Pasta & Noodles

Carbohydrates


2. Vegetables & Legumes

Minerals & Vitamins


3. Fruits

Minerals & Vitamins


4. Milk, Yogurt & Cheese

Fats


5. Meats , Eggs ,Nuts & Legumes

Proteins


Diabetes

ALS

COPDDysphagia

Cancer

Palliative CareCeliac Disease

Constipation

SuperbugsCongestive

HeartFailure

PressureUlcers

MultipleSclerosis

Parkinson’sDisease

MalabsorptionSyndromes

Osteoporsis

GERD

Pneumonia

Falls

AlcoholAbuseStroke

Osteoarthritis

Anemia

Family RelatedIssues

Renal Disease

Nutrition Issues

System Issues

Dementia

Mental Illness

Obesity

Malnutrition


Caloric Imbalance

Due to Inc. or Dec. Intake of calories Imbalance

Malnutrition


Malnutrition

Malnutrition—extended inadequate intake of nutrient or severe illness burden on the body composition and function—affect all systems of the body.


Types of malnutrition

Kwashiorkor is protein malnutrition Marasmus is protein-calorie malnutrition Obesity over nutrition


Kwashiorkor

Protein malnutrition caused by inadequate protein intake in the presence of fair to good calories intake in combination with the stress response

Common causes chronic diarrhea, chronic kidney disease, infection, trauma , burns, hemorrhage, liver cirrhosis and critical illness


Clinical Manifestations

Marked hypoalbuminemia Anemia Edema Ascites Muscle atrophy Delayed wound healing Impaired immune function


Kwashiorkor


Marasmus The patient with severe

malnutrition characterized by calories deficiency

Common severe burns, injuries, systemic infections, cancer etc or conditions where patient does not eat like anorexia nervosa and starvation

Marasmus kawashirkhore both protein & E deficient


Clinical Manifestations

Weight loss lethargy Depletion skeletal muscle and adipose (fat)

stores Bradycardia Hypothermia


Risk factors for malnutrition

Medical causes Psychological and social causes


Medical causes(Risk factors for malnutrition)

Recent surgery or trauma Chronic illness Gastrointestinal disorders Anorexia, other eating disorders Dysphagia Recurrent nausea, vomiting, or diarrhea Pancreatitis Inflammatory bowel disease Gastrointestinal fistulas


Psychosocial causes

Alcoholism, drug addiction Poverty, isolation Disability Anorexia nervosa Fashion or limited diet


Consequences of Malnutrition

Malnutrition places patients at a greatly increased risk for morbidity and mortality

Longer recovery period from illnesses Impaired host defenses Impaired wound healing Impaired GI tract function


Obesity BMI of 25.0 to 29.9 kg per m2 is defined

as overweight BMI of 30.0 kg per m2 or more is

defined as obesity.


Body mass index

Also called Quetelet index is a measure for human body shape based

on an individual's weight and height


BMI prime

The ratio of the actual BMI to the Upper limit of BMI


CategoriesCategory BMI range – kg/m2 BMI Prime

Very severely underweight less than 15 less than 0.60

Severely underweight from 15.0 to 16.0 from 0.60 to 0.64

Underweight from 16.0 to 18.5 from 0.64 to 0.74

Normal (healthy weight) from 18.5 to 25 from 0.74 to 1.0

Overweight from 25 to 30 from 1.0 to 1.2

Obese Class I (Moderately obese) from 30 to 35 from 1.2 to 1.4

Obese Class II (Severely obese) from 35 to 40 from 1.4 to 1.6

Obese Class III (Very severely obese) over 40 over 1.6


Nutrient and Energy Model of Obesity

Obesity results from increased intake of energy or decreased expenditure of energy

Energy Intake

Adipose tissue

Energy Expenditure


Medical Complications of ObesityPulmonary diseaseabnormal functionobstructive sleep apneahypoventilation syndrome

Nonalcoholic fatty liver diseasesteatosissteatohepatitiscirrhosis

Gall bladder disease

Gynecologic abnormalitiesabnormal mensesinfertilityPCOS

Osteoarthritis

Gout

Phlebitisvenous stasis

Cancerbreast, uterus, cervixcolon, esophagus, pancreaskidney, prostate

Severe pancreatitis

CHD Diabetes Dyslipidemia Hypertension

Cataracts

Stroke


Jazak ALLAH

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