Nutritional Assessment by fjzhangxiaoquan


									  269 CHS (# 2)

Basics of nutrition
Study of nutrients and other substances in foods and the
body’s handling of them.
Foundation dependent on other fields: Biology, biochemistry,
Nutritional Genomics: a science studying the relationship
between human genome, nutrition and health. It can be
divided into two disciplines:
-nutrigenetics: studying of how genes affect the activities of
-nutrigenomics: studying how the nutrients affect the
 activities of genes
Genome: full complement of genetic material in (DNA) in the
chromosomes of a cell, carrying hereditary information for an
individual organism. The human genome is composed of 23
pairs of chromosomes (46 in total)
97% of the genes known to be associated with
human diseases result in monogenic diseases, i.e.
a mutation in one gene is sufficient to cause the
Modifying the dietary intake can prevent some
monogenic diseases.
e.g. phenylkenonuria, a genetic disease with a
defective phenylalanine hyroxylase enzyme, which is
normally responsible for the metabolism of
phenylalanine to tyrosine. This results in the
accumulation of phenylalanine and its breakdown
products in the blood and the decrease in tyrosine,
which increases the risk of neurological damage and
mental retardation. Phenylalanine-restricted tyrosine-
supplemented diets are a means to nutritionally treat
this monogenic disease.
In contrast, diseases currently in the world,
e.g. obesity, cancer, diabetes, and
cardiovascular diseases, are polygenic
diseases, i.e. they arise from the
dysfunction in a cascade of genes, and not
from a single mutated gene.
Dietary intervention to prevent the onset
of such diseases is a complex and
ambitious goal.
Recently, it was discovered that the health
effects of food compounds are related
mostly to specific interactions on molecular
i.e. dietary constituents participate in the
regulation of gene expression by
modulating the activity of transcription
factors, or through the secretion of
hormones that in turn interfere with a
transcription factor.
Gene expression is the process by which
inheritable information from a gene, such as
the DNA sequence, is converted first into
messenger RNA and then to a protein
(functional gene product)

Transcription is the synthesis of RNA
under the direction of DNA.
RNA synthesis, or transcription, is the
process in which genetic information
(nucleotide sequence) stored in a strand of
DNA is copied into a strand of RNA.
       Down          Adult bone   Diabetes       Iron deficiency
       Syndrome      loss                        (anaemia)

       Haemophilia   Cancer       Hypertension


       Sickle cell   Infectious   Heart          Poor resistance
       anaemia       diseases     diseases       to disease

Less nutrition-                                          More nutrition-
related (genetics)                                       related

Food—any substance the body can take in
        and assimilate
•Essential for life
•Derived from plant and animals sources
•A source of NUTRIENTS and non-nutrients

Diet—The foods and beverages a person
      usually eats and drinks.
A person who eats food of both plant and
animal origin, including animal flesh

A person who excludes from his diet
animal flesh and possibly other animal
products such as milk, cheese, and eggs
Indispensable: absolutely essential and body can not
function without them
Key Point:

Nutrients are important in food support
growth, maintenance, and repair of the body.

Conversely, deficiencies, excess, and
imbalances of nutrients lead to diseases of
Nutrient Deficiencies

Primary Deficiency: Nutrient deficiency
caused by inadequate dietary intake.

Secondary Deficiency: Nutrient deficiency
caused by something other than inadequate
intake (i.e. absorption, drug interaction,
   The Known 50 Essential Nutrients for Sustaining Human Life*

   Water &          Protein         Lipids-Fat      Macro-       Micro-             Vitamins
   Energy        (amino acids)     (fatty acids)    Minerals    Elements
     (2)              (9)                (2)          (7)          (17)                (13)
Water           Histidine         Linoleic acid    Na           Fe            A
Carbohydrates   Isoleucine        Linolenic acid   K            Zn            D
                Leucine                            Ca           Cu            E
                Lysine                             Mg           Mn            K
                Methionine                         S            I             C (Ascorbic acid)
                Phenylalanine                      P            F             B1 (Thiamin)
                Threonine                          Cl           B             B2 (Riboflavin)
                Tryptophan                                      Se            B3 (Pantothenic acid)
                Valine                                          Mo            Niacin
                                                                Ni            B6 (Pyridoxal)
                                                                Cr            Folate
                                                                V             Biotin
                                                                Si            B12 (Cobalamin)
                                                                Co (in B12)

  *Numerous other beneficial substances in foods are also known to contribute to good health.
What are the nutrients in food?
-Fats (Lipids)
       Description of Nutrients -1
   Inorganic
   Indispensable
   The foremost of the nutrients
   Constantly lost and replaced
   Provides environment in which nearly all of
    the body’s activities are conducted.
   Not energy-yielding
Where's the Water?
66% of a person's total body weight is from water.
65% of total body water is intracellular.
35% of total body water is extracellular.
Well-hydrated muscles are about 75% water.
Bones are about 32% water.
Fat is essentially anhydrous, having only about
 10% water content.
Blood is about 93% water.
Average males are about 60% water weight.
Average females are about 50% water weight.
Obese individuals are about 40% water weight.
Athletes are about 70% water weight.
  Description of Nutrients -2
Energy-Yielding Nutrients: The body can
use the energy they contain.

                      -Fat (Lipids)
           Energy in food
Energy is measured in calories (calories,
kilocalories, kcalories, kcal)

One kcalorie =
Amount of heat energy needed to raise
the temperature of 1 kilogram of water
The calorie is a pre-SI (International System of
Units) unit of energy, in particular, heat.
In most fields, its use is outdated, and the SI
unit of energy, the joule, has become accepted.
However, it remains in common use as a unit of
food energy.
It was first defined by Professor Nicolas
Clement in 1824 as a kilogram-calorie, and this
definition entered French and English
dictionaries between 1841 and 1867.
Etymology: French calorie, from Latin calor
The unit calorie has historically been used in two
major alternate definitions that differ by a factor
of 1000;
The small calorie, gram calorie, or calorie
(symbol: cal) is the amount of heat (energy) required
to raise the temperature of one gram of water by
1 °C.

The   large calorie, kilogram calorie,
kilocalorie (symbol: kcal), or Calorie (capital C)
is the amount of heat (energy) needed to increase
the temperature of one kg of water by 1°C, exactly
1000 small calories, or about 4.184 kJ.
The second definition is the one commonly
used to express food energy, e.g. when
discussing dieting or nutrition plans.

Under this definition, 1 g of pure carbohydrate
yields about 4 Calories of energy, and the
recommended intake for an adult person is
about 2,000 - 2,500 Calories/day.

            Measuring Foods
Unit of weight: Gram
      Protein requirements
The recommended level of protein intake for
the general population is 12% to 15% of
total calories.
Therefore, someone consuming 2,000
calories per day has an energy equivalent of
240 to 300 calories (60 to 75 grams) of
protein per day.
Meats and dairy products provide all the
essential amino acids (derived only from
food as body cannot manufacture. They
perform various functions ) in a single food,
but plant sources of protein do not.
Therefore, vegetarians should be careful to
combine foods in a way that optimize
essential amino acid availability
  Carbohydrate Requirements
The Institute of Medicine recommends 130 grams
(520 kilocalories) of carbohydrate per day, which is
the average minimal usage of glucose by the brain.
The desirable range of carbohydrate intake is 45% to
65% of total caloric intake (also referred to as the
Acceptable Macronutrient Distribution Range, or AMDR),
and the Daily Value (DV) for carbohydrate on food
labels is based on a recommended intake of 60% of
total caloric consumption.
These recommendations also generally advise that
no more than 25% of carbohydrate intake be derived
from sugars (mono- and disaccharides)
              Fat requirements
The American Heart Association and the United
States Department of Agriculture recommend that fat
intake is limited to no more than 30% of daily
calories: 10% or less of calories come from
saturated fat, not more than 15% from
monounsaturated fat, and less than 10% from
polyunsaturated fat.
Saturated fats, which are generally solid at room
temperature, are the least healthy and tend to increase the
level of cholesterol in your blood.
Monounsaturated fats have been shown to raise the level of
HDL, the 'good' cholesterol that protects against heart attacks.
Although polyunsaturated fats come from plants and fish, but
they may be more likely to form free radicals and lead to
tissue damage.
    Description of Nutrients -3
Regulator Nutrients:
 Do not produce energy
 Act as regulators and assist in all body processes.
 Some minerals serve as parts of body structures.

                                       • Vitamins
                                       • Minerals
-Vitamins are essential for several enzymatic functions in human

-Thiamine was discovered in 1912 and was thought to be
 a vital amine compound & thus the term vitamin was invented

-13 vitamins are known, 4 fat soluble (KEDA) and 9 water soluble
 (C, Folate and the B group).
              Vitamer chemical
 generic                                            Deficiency
              name(s) (list not    Solubility
descriptor                                           disease

             Retinoids                          Night-blindness
Vitamin A    (retinol, retinoids      Fat       and
             and carotenoids)                   Keratomalacia

Vitamin B1 Thiamine                 Water       Beriberi
Vitamin B2 Riboflavin               Water       Ariboflavinosis
Vitamin B3 Niacin, niacinamide      Water       Pellagra
Vitamin B5 Pantothenic acid         Water       Paresthesia
Vitamin B6 pyridoxamine,            Water       Anaemia
  Biotin     Biotin                 Water
                                                Deficiency during
                                                pregnancy is
             Folic acid, folinic                associated with
Folic acid                          Water
             acid                               birth defects,
                                                such as neural
                                                tube defects
Vitamin B12 hydroxycobalamin,       Water
Vitamin C Ascorbic acid             Water       Scurvy

             Ergocalciferol,                     Rickets and
Vitamin D                             Fat
             cholecalciferol                     Osteomalacia
                                                Deficiency is very
                                                rare; mild
Vitamin E                             Fat       hemolytic anemia
                                                in newborn
             phylloquinone,                     Bleeding
Vitamin K                             Fat
             menaquinones                       diathesis
The total mineral content of the body is approximately 4% of
body weight.
Sixteen essential minerals are required to support human
biochemical processes by playing roles in cell structure and
function as well as electrolytes.
The required minerals are divided into macrominerals and

Macrominerals are present in the body in relatively larger
amounts than micro minerals (thus the name).
Microminerals (trace elements) are present in body
tissues in extremely small amounts but have critically
important roles to play in human nutrition.
The required intake of each micromineral is less than 100
milligrams per day, and the total body content of these
minerals is less than 5 grams.
Macrominerals include
Calcium (an important mineral for bone and tooth structure,
blood clotting, and nerve transmission),
Phosphorus (combines with calcium-about two parts calcium
for every part phosphorus- to produce healthy bones and teeth,
plays an important role in energy metabolism),
Magnesium (essential for human metabolism and for
maintaining the electrical potential in nerve and muscle cells),
Sodium (an essential mineral commonly referred to as salt. It is
involved in body water balance and acid-base balance and is
the major extracellular -outside the cell, including blood and
fluid- mineral),
Chloride (an extracellular mineral that is essential for the
maintenance of fluid balance and, therefore, normal cell
function, also it is an important component of gastric juices) ,
Potassium (the main mineral found inside cells -an intracellular
electrolyte- at a concentration that is 30 times greater than the
concentration of potassium found outside cells. It is involved in
water balance, nerve impulse transmission, and muscular
Microminerals include:
Iron (needed to form the oxygen-transporting compounds
hemoglobin (in blood) and myoglobin (in muscle) and is also
found in a number of other compounds involved in normal
tissue function),
Zinc (helps form a large number of enzymes, many of which
function in energy metabolism and in wound healing),
Iodine (needed to synthesize a key hormone of the thyroid
gland, thyroxin, which is involved in regulating metabolic rate,
growth, and development),
Selenium (an important mineral antioxidant in human
Copper (present in many enzymes and in copper-containing
proteins found in the blood, brain, and liver),
Manganese (involved in bone formation, immune function,
antioxidant activity, and carbohydrate metabolism), and
Chromium (is also known as glucose tolerance factor (GTF)
because of its involvement in helping cells use glucose).
The Challenge of Choosing Foods
Well-planned meals can convey pleasure and can
be nutritious
Building blocks for Nutritious Diet: -1
The diet provide all of the essential nutrients, fiber,
and energy in sufficient amounts to maintain health
and body weight

2-Balance (In proportion to one another)
Providing foods of a number of different types in
proportion to each other. Such that foods rich in
some nutrients do not crowd out of the diet foods
that are rich in other nutrients
Building blocks for Nutritious Diet: -2

3-Calorie control
    -Control of energy intake
    -A feature of a sound diet plan

    -Provide constituents within set limits
    -Nothing in excess

    -Provide a wide selection of food
    -The opposite of monotony
 Role of Nutrition in
Prevention of Disease
        Functions                            production,
                                           storage, release

enzyme activation               Energy
 cell messengers
  gene induction                                           Structure,
                Regulatory                 Lean Body Mass, activities
                Functions                    Skeletal Mass

                      Synthesis of                            membrane
                       Bioactive                              potentials,
       enzymes                           Acid-Base
      hormones        Compounds                            neuromuscular
                                          Balance         activity, plasma &
  immune substances
                                                        cellular fluid volumes
Determinants of Nutrient Needs
   Absorption Efficiency
   Metabolic Demand
   Excretion Levels
           1- Absorption Efficiency
                                   Absorption Efficiency

                    Health                                     Disease

Bioavailability   Imbalances   Deficiencies       Diarrhea     Vomiting        Fat
     Iron           Ca:Fe       B12-Folate      Electrolytes   General    Malabsorption
   Calcium          Fe:Zn       D-Calcium         General                  Vitamins A,
    Zinc            Zn:Cu      Mg-Calcium                                    D, E, K
    Nutrient Interactions
Zinc deficiency interfere with vitamin A
metabolism in several ways:
It decreases the synthesis of retinol binding
 protein, which transports retinol to tissues.
It decreases the activity of the enzyme
 retinyl palmitate, which is necessary for
 release of retinol from the liver.
Zn is needed for the enzyme that convert
 retinol into retinal.
    Nutrient Interactions/2
Iron & vitamin A.
Vitamin A deficiency may exacerbate IDA ِ
Vitamin A supplementation improves
 iron status among children & pregnant
Combining vitamin A with iron controls
 IDA more quickly & effectively than
 using iron alone.
2- Excretion Levels
            Excretion Levels

   Health                  Disease

 Imbalances              Medications
   Na>Ca                 Diuretics-K
   Na>K               Sequestrants-Folate
                     3- Metabolic Demand

                        Health                                               Disease

      Growth            Stress        Dietary Excess            Infection   Alcoholism   Medications
Iron, Zinc, Folate     Thiamin       K, Zn, Mg, Cr, B1         Iron, Zinc    Thiamin      Vitamin D
    Pyridoxine       Ascorbic Acid       Pyridoxine            Pyridoxine   Magnesium       Folate
  A,D, Calcium        Magnesium         Antioxidants              A, C        Zinc, A    Pyridoxine
Goals of Nutrition in Disease
1. Optimize cellular activity and tissue/organ
2. Reduce metabolic burden imposed by
   environmental    factors   on     cardiac,
   pulmonary,    renal,     hepatic,     and
   musculoskeletal systems
3. Support cellular defenses that protect
   tissue integrity

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