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Nutrition = Sum of all the interactions between an
organism and the food it consumes. Nutrition is a
basic component of all aspects of health. It is
essential for:

1. Normal growth and development
2. Tissue maintenance and repair
3. Recovery from illness or surgery
4. Preventing certain diseases
• Nutrients: Substances obtained from food and
  used in the body to provide energy and structural
  materials and to promote growth, maintenance,
  and repair.
• Essential Nutrients: Nutrients a person must obtain
  from food because the body cannot make them for
  itself in sufficient quantity to meet physiological
   – Ex: Essential amino acids, water
          6 classes of nutrients
•   Water
•   Minerals
•   Vitamins
•   Protein
•   Carbohydrates
•   Fat
       What happens to food?
• Digestion: process of breaking down large food
  molecules so the intestinal tract can absorb them
• Absorption: passage of nutrients through
  intestinal walls and into the general circulation of
  the body
• Metabolism: all chemical reactions that take
  place in the body
 The amount of potential energy in food is measured in calories.

 A calorie (kilocalorie (kcal) is the amount of energy used to raise the
  temperature of 1 kilogram of water from 14 to 15 degrees Celsius
    Calculate Energy in a Food
If a food contains 15 grams of carbohydrates, 2
   grams of protein, and 5 grams of fat. How many
   kcalories is in that food?

      15 g of CHO x 4 kcal/g = 60 kcal
      2 g of protein x 4 kcal/g = 8 kcal
        5 g of fat x 9 kcal/g = 45 kcal
               TOTAL          = 113 kcal
 The body's metabolism, is expressed in a number called the

• BMR = the number of calories an organism must use in a set
  amount of time to maintain life.

 The BMR for females is 1300 to 1500 kcal per day.
 The BMR for males is 1600 to 1800 kcal per day

•   Of course your energy needs vary according the amount of activity taking place
    (i.e. the energy demand)
Nutritional Requirements of Diet
           The 6 major classes of nutrients

Organic Compounds            Inorganic Compounds
  Carbohydrates                     Water
• Body’s chief choice of energy.
Although not as concentrated a fuel as fats, sugars are the most important source
   of energy for many cells.
Carbohydrates provide the bulk of the calories (4 kcal/gram) in most diets, and
   starches provide the bulk of that.
• Found in plant foods and in milk.

             Sugars / Monosaccharides
• Three common sugars share the same molecular formula, the
  arrangement of atoms differs in each case.

They are:

 glucose, "blood sugar", the immediate source of energy for cellular
 galactose, a sugar in milk (and yogurt)
 fructose, a sugar found in honey.

• These are "single" sugars or monosaccharides.

• Two monosaccharides can be linked together to form a
     ‘Double’ Sugars / Disaccharides
The three common disaccharides are:

 sucrose - common table sugar = glucose + fructose

 lactose - major sugar in milk = glucose + galactose

 maltose - product of starch digestion = glucose + glucose
          Starches / Polysaccharides
• Starches are polymers of glucose.

The two types are:

 Amylose

 Amylopectin

• Plants convert excess glucose into starch for storage.

• White potato, plantain, rice, wheat, and corn are major sources of
  starch in the human diet.
               Storage of Glucose
• Excess glucose is used to synthesise glycogen

• The structure of glycogen is similar to that of a starch.

• The liver and skeletal muscle are major sites for the storage of

• Glycogen is broken back down into glucose when energy is

• Once the body’s capacity to store glycogen is reached, lipids
  are formed by lipogenesis
Fats/ Lipids

 Triglycerides
 Phospholipids
 Steroids
           Oils & Fats / Triglycerides
The two components are:
 Glycerol
 Fatty Acids

Fatty acids can be:
 Saturated – solid at room temperature
              - mostly found in animal fats
 Monounsaturated – liquid at room temperature
                     - found in olive & peanut oils
 Polyunsaturated – liquid at room temperature
              - found in sunflower, sesame and corn oils

 Triglycerides are highly concentrated sources of energy and provide
  twice as much energy as carbohydrates or protein
• Phospholipids are an integral part of the cell membrane

• The components are glycerol and fatty acids (as in
  triglycerides) with a phosphate group
 Both Triglycerides and phospholipids contain Fatty acids,
 Some fatty acids must come from the diet:

             Essential Fatty Acids
• Essential Fatty Acids
  – Body cannot produce, must be consumed
  – Both essential fatty acids, linoleic and linolenic
    are POLYUNSATURATED fatty acids
• Omega-6 Fatty Acids
   – Linoleic Fatty Acid
      • Found in vegetable oils, seeds, nuts, and whole-grain foods
• Omega-3 Fatty Acids
   – Linolenic Fatty Acid
      • Found primarily in fish, but also in soy oils and breast milk
• Steroids share the same molecular formula, the arrangement of atoms
  differs in each case.

The different types of steroids include:

 Cholesterol – part of the cell membrane & foundation for synthesis of
  other steroids
 Sex hormones (oestrogen, Testosterone, etc) – regulate reproductive
 Cortisol – a hormone that regulates aspects of metabolism and
 Vitamin D – a hormone that regulates calcium storage for growth and
• Cholesterol is necessary for cell membranes
  and the production of vitamin D and certain
• Found only in animal foods
• High blood cholesterol levels associated
  with increased risk of heart disease
                 Needed to build, maintain, and repair cells

•   Proteins have the most diverse role of   Functions include:-
    the organic compounds in the body         Providing a structural framework
                                              Regulating (integral in endocrine and
                                                nervous system)
•   Some have a structural or mechanical      Providing the contractile units for body
    role, others have physiological roles       movement
                                              Providing protection (antibodies etc)
                                              Transport of oxygen (haemoglobin)
                                              Catalysing chemical reactions (enzymes)
Amino Acids bond to form proteins
                    Amino Acids
• Amino acids are the building blocks of proteins.

Bonding of amino acids form combinations known as:-
 Dipeptides –2 amino acids
 Tripeptide –3 amino acids
 Peptides – 4 to 10 amino acids
 Polypeptides – 10 to 100 amino acids
 Proteins - > 100 amino acids
• Comprised of 20 amino acids
   – 10 amino acids must be supplied by diet (“essential amino acids”)

• Complete proteins have all 10 essential amino acids
• Incomplete proteins lack one or more essential amino acids
          Complete Proteins
• Contains all of essential amino acids.
• Include meat, fish, poultry, eggs, milk, and
• Only plant protein that is complete is soy
• Foods that don’t contain all essential amino
  acids are incomplete proteins.
  Non-Energy Supplying
• Vitamins
• Minerals
• Water
• Vitamins do not provide energy or serve as raw materials for synthesis.
• Vitamins have a regulatory function, most as co-enzymes of digestion.

The two categories are:

 Fat soluble: A,D,E & K

 Water soluble: 8 different B vitamins and vitamin C
(B1, B2, B6, B12, Niacin, Pantothenic Acid, Folic Acid & Biotin and C)

• Provitamins are raw materials needed for the synthesis of certain vitamins
• Antioxidants (Vitamins C and E as well as beta-carotene) protect cells by
  reducing or preventing free radical formation
•   Serves as a solvent / suspending medium
•   Takes place in chemical reactions
•   Has a high capacity for heat absorption
•   Requires large amounts of heat to evaporate
•   Serves as a lubricant
     Minimum Water Needed
• Body must excrete a minimum of 500 ml
  per day.
• More you drink more dilute urine is.
• Recommendations:
  – 1 – 1.5 ml per calorie expended per day, which
    is about 2 to 3 liters of water per day for a
    person expending 2000 calories per day (8-12
Minerals in the Human Body
• Like vitamins, minerals are essential in regulatory
• Calcium is the most abundant mineral in the body, 99% is
  stored in the bones
• NaCl (salt) dissolve to form ions (anions and cations) in
  the intracellular and extracellular fluid
• Most of the iron in the body is a component of
  haemogloblin and myoglobin
• Zinc is a required cofactor by more than 100 enzymes
• Others take part in many body processes such as nerve
  impulse transmission or osmoregularity
        Dietary Reference Value (DRV)

• Recommended Nutrient Intakes (RDA and DRI)
  The Dietary Reference Intakes (DRIs) are nutrient-based reference
  values for use in planning and assessing diets. They are intended to
  replace the Recommended Dietary Allowances (RDAs)
           Vegetarian Diets
• Vegan – Restricts all animal foods
• Lacto-Ovo Vegetarian – Includes milk,
  eggs, and cheese
• Many other types
Mutual Supplementation
 Read and
USDA Food Pyramid
Mediterranean Pyramid
Reality check…

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