Download Food and Nutrition

WMST 245
SECTION 8
FOOD AND NUTRITION
HUMANS NEED NOURISHMENT. THEY GET IT FROM
SIX KINDS OF NUTRIENTS – ALL ARE IMPORTANT, AND
THE FIRST THREE GIVE US ENERGY
1. CARBOHYDRATES
2. FAT
3. PROTEIN
4. VITAMINS
5. MINERALS
6. WATER
HOW MUCH FOOD DO HUMANS CONSUME EACH DAY?
WE CAN’T EXPRESS THIS AS OUNCES OF CEREAL OR
LBS OF CHEESE, BECAUSE WE CAN’T COMPARE
THESE. WE HAVE TO USE AN INDEX CALLED KILOCALORIES
THE AVERAGE CONSUMPTION OF KCALS EACH DAY
DEPENDS ON WHERE PEOPLE LIVE.
THE AVERAGE IN THE USA IS ABOUT 3,770 [as much as
40% may be wasted, making the net figure 2,262].
THE AVERAGE IN ETHIOPIA IS ABOUT 1,850
HOW MUCH ENERGY DO WE NEED TO LIVE?
IT DEPENDS:
•
•
•
•
•
•
•
AGE
HEIGHT
WEIGHT
CLIMATE
MALE OR FEMALE
WORK/ACTIVITY
PREGNANT OR LACTATING?
HOW MUCH ENERGY DO WE NEED TO LIVE?
BASAL METABOLIC RATE (BMR) IS THE
“MINIMAL EXPENDITURE OF ENERGY COMPATIBLE
WITH LIFE”
Height (ins.)
Weighta (lb)
18-30 years
(kcal/day)
30-60 years
(kcal/day)
>60 years
(kcal/day)
Men
63
67
71
75
125
140
158
175
1540
1650
1770
1890
1530
1620
1710
1800
1250
1350
1450
1560
Women
59
63
67
71
104
119
134
150
1190
1290
1390
1500
1240
1300
1360
1420
1090
1160
1230
1310
a. Weight is a median acceptable weight for height; body mass index (Wt/Ht2) = 22 for men, 21
for women
HOW MUCH ENERGY DO WE NEED TO LIVE?
ADULT PHYSICAL ACTIVITY LEVEL (PAL)
MULTIPLY BMR BY THE PAL COEFFICIENT
Activity Level
Chair-bound
Seated work
Standing work
Strenuous physical work
Significant sports (30-60 minutes, 4-5X per
week)
PAL coefficient
1.2
1.4-1.7
1.8-1.9
2.0-2.4
+0.3 (increment)
Women Work Crew Builds a Road in Lesotho, 1969
Women working with plow in the field: As women struggle to subsist
with labor and capital scarcity, they often are forced to adjust
cropping patterns that can decrease production or damage the
environment.
HOW MUCH ENERGY DO WE NEED TO LIVE?
CHILDREN (KCals per Day)
Age (years)
Boys
1
5
10
15
Girls
1
5
10
15
Weight (lbs)
Light Activity
Mod. Activity
Heavy Activity
23
41
69
125
854
1346
1885
2659
942
1486
2126
2991
2370
3406
22
39
72
118
783
1226
1706
2048
865
1352
1933
2331
2160
2613
HOW MUCH ENERGY DO WE NEED TO LIVE?
COLD CLIMATES
We need more energy if we live in cold climates:
At 15 degrees C (59 degrees Fahrenheit) add 100 Kcal per day
At 10 degrees C (50 degrees Fahrenheit) add 200 Kcal per day
At 5 degrees C (41 degrees Fahrenheit) add 300 Kcal per day
Inuit women drying fox skins on a rack, at Bernard
Harbour, Northwest Territories (Nunavut)
HOW MUCH ENERGY DO WE NEED TO LIVE?
PREGNANCY & LACTATION
To support pregnancy needs additional Kcals of energy, which
may be obtained by reducing activity or increasing food
consumption. The optimal amount of additional energy is
about 96 Kcal per day in the first trimester, 265 Kcal per day in
the second trimester, and 430 Kcal per day in the third
trimester. A woman who is breastfeeding needs an additional
500 Kcals per day to support lactation.
HOW DO WE MEASURE WHETHER ANYONE IS
GETTING ENOUGH TO EAT?
FOUR GROUPS OF MEASURES
•CLINICAL – bodily symptoms like hair pigment,
edema (swelling), eyesight problems
•BIO-CHEMICAL – metabolic symptoms in blood or
other fluids e.g. anemia
•DIETARY – food intake surveys
•ANTHROPOMETRIC – measurements of weight
and height
MONITORING GROWTH IN CHILDREN
ASSESSING UNDER-NUTRITION WITH
ANTHROPOMETRIC MEASURES
•Weight-for-Height
•Height-for-Age
•Weight-for-Age
•Mid-Upper Arm Circumference (MUAC)
•Skinfolds
•Head Circumference
•Proxies for Length
•Body Mass Index
BODY MASS INDEX
BMI (BODY MASS INDEX) = Weight/Height2
When weight is measured in kilograms (kg) and height in metres (m), the
“acceptable” range of BMI is 18.5 to 25
e.g. someone five feet eight inches tall weighing 150 lbs has a BMI of 22.8
e.g. someone five feet ten inches tall weighing 180 lbs has a BMI of 25.8
[[to get in the “acceptable range” this person would need to weigh between 129
and 174 lbs]]
e.g. someone five feet four inches tall weighing 135 lbs has a BMI of 23.2
e.g. someone six feet tall weighing 200 lbs has a BMI of 27.1
e.g. someone six foot four inches tall weighing 280 lbs has a BMI of 34.1
e.g. someone six foot two inches tall weighing 240 lbs has a BMI of 30.8
Note: 1 kg = 2.2046 lbs; 1 metre = 3.280833 feet
The degree of athletic activity is important in assessing BMI
DIETARY DEFICIENCIES
THE BIG THREE:
IRON: DEFICIENCY CAUSES ANEMIA, TIREDNESS,
REDUCED CAPACITY TO WORK, INCREASED
SUSCEPTIBILITY TO INFECTION; SPECIAL PROBLEMS
FOR PREGNANT WOMEN
IODINE: DEFICIENCY CAUSES GOITER, AND WHEN
SEVERE, LOSS OF IQ, POOR BRAIN FUNCTION, AND
CRETINISM; IT IS “THE LARGEST PREVENTABLE CAUSE
OF MENTAL RETARDATION”
VITAMIN A: DEFICIENCY CAUSES NIGHT-BLINDNESS,
AND WHEN SEVERE, BITOT’S SPOT AND TOTAL
BLINDNESS; ALSO CAUSES PREMATURE DEATH FROM
RESPIRATORY, & GASTRO-INTESTINAL DISEASE
OTHER DIETARY DEFICIENCIES
VITAMIN D: DEFICIENCY CAUSES RICKETS (SOFT
& DEFORMED BONES, BOW-LEGGEDNESS)
VITAMIN C: DEFICIENCY CAUSES SCURVY
(BLEEDING GUMS & GUM DISEASE, LOOSENING
OF TEETH)
B-VITAMINS: BERI-BERI (THIAMINE: degeneration
of the central nervous system and gastro-intestinal
system); PELLAGRA (NIACIN: dermatitis, gastrointestinal problems, central nervous system symptoms);
“PERNICIOUS ANEMIA” (B12)
ZINC: DEFICIENCY RETARDS CHILD GROWTH,
CAUSES DIARRHEA, DIFFICULTY ABSORBING
OTHER MICRONUTRIENTS
SECONDARY MALNUTRITION
UNDERNUTRITION ATTRIBUTABLE NOT TO LACK OF FOOD
AVAILABILITY BUT TO INABILITY TO ABSORB NUTRIENTS.
EXAMPLES ARE:
 EATING DISORDERS
 DIARRHEA FROM INTESTINAL PARASITES OR UNSAFE
DRINKING WATER (only a part of the food eaten is available to
the body – the rest is not digested properly or is shared with
parasites)
 INFECTIOUS DISEASES SUCH AS MEASLES (the body’s
immune system uses a lot of energy to try to fight off the diseases;
some of the food eaten is used to supply this energy to the immune
system)
Young girl receives a measles vaccination at a health clinic
in Demak, Indonesia
UNDERNUTRITION
UNDERCONSUMPTION OF PROTEIN AND
CALORIES IS THE PROBLEM RELATED
TO FOOD SHORTAGE
PROTEIN AND CALORIES ARE NUTRIENTS
THAT PEOPLE GET ALMOST
EXCLUSIVELY FROM FOOD -- NOT FROM
“SUPPLEMENTS” OR “FORTIFICATION”
UNDERNUTRITION
WHERE DO CALORIES AND PROTEIN
COME FROM?
CALORIES: TRANSFORMING SOLAR
ENERGY INTO HUMAN ENERGY BY
“PHOTOSYNTHESIS”
PROTEIN: GETTING NITROGEN INTO THE
CHEMICAL EQUATION:
•
•
•
LIGHTNING STORMS
NITROGEN FIXING BACTERIA
SEA ALGAE
NUTRITIONAL ROLE OF PROTEIN
1. BUILDING CELLS THAT MAKE UP MUSCLES,
MEMBRANES, CARTILAGE, HAIR
2. CARRYING OXYGEN AROUND THE BODY
3. CARRYING NUTRIENTS INTO AND OUT OF
CELLS AND HELPING TO ASSIMILATE FOOD
4. CONTRIBUTING TO DEVELOPMENT OF
ANTIBODIES THAT FIGHT DISEASE
5. WORKING AS ENZYMES TO SPEED UP
DIGESTIVE PROCESSES
QUALITY OF PROTEIN
PROTEIN IN THE BODY IS CONSTRUCTED
FROM 22 AMINO ACIDS – THE BODY MAKES 13 OF
THEM, BUT:
9 “ESSENTIAL” AMINO ACIDS
CANNOT BE MADE BY THE BODY
THEY MUST BE IN THE DIET.
A FOOD THAT CONTAINS ALL 9 ESSENTIAL
AMINO ACIDS IN SUFFICIENT CONCENTRATIONS
TO MEET HUMAN NEEDS IS CALLED
A “COMPLETE PROTEIN”
ANIMAL PRODUCTS (MEAT, MILK, EGGS)
ARE “COMPLETE PROTEINS”
PLANT PRODUCTS (CEREALS, LEGUMES) ARE
MISSING ONE OR MORE OF THE ESSENTIAL
AMINO ACIDS OR CONTAIN THE ACID IN TOO
LOW A CONCENTRATION
THE NEED FOR BALANCE AMONG THE ESSENTIAL
AMINO ACIDS: THE BODY MUST HAVE AMINO
ACIDS IN CORRECT PROPORTIONS IN ORDER TO
PRODUCE PROTEINS
VEGETABLE VS ANIMAL?
CALORIE DEFICIENCY
APPEARS TO BE BIGGER PROBLEM
THAN PROTEIN DEFICIENCY
NUTRITIONIST NEVIN SCRIMSHAW:
“ADULT PROTEIN NEEDS ARE MET BY MOST
TRADITIONAL DEVELOPING COUNTRY DIETS
WHEN THEY ARE CONSUMED IN SUFFICIENT
QUANTITY TO MEET NORMAL ENERGY NEEDS.”
1995 FOOD AVAILABLE IN SUB-SAHARAN AFRICA
CALORIES: 2144 PROTEIN: 51.6 gms.
If you get enough calories, chances are you get enough protein.
If you get enough protein, you may not get enough calories.
HOW MUCH OF A NUTRIENT IS ENOUGH”?
(HOW DO WE SET STANDARDS?)





DIFFERENT PEOPLE HAVE DIFFERENT NEEDS
A CHILD’S NEEDS ARE DIFFERENT FROM AN ADULT’S
A WOMAN’S NEEDS ARE DIFFERENT FROM A MAN’S
A WOMEN PREGNANT OR LACTATING NEEDS MORE
AN ACTIVE PERSON HAS DIFFERENT NEEDS FROM A
SEDENTARY PERSON
 LIVING IN A COLD CLIMATE INCREASES NEEDS
 NEEDS DIFFER WITH HEALTH STATUS
 SOME PEOPLE HAVE DIFFERENT NEEDS FOR
UNEXPLAINED REASONS – THEY HAVE “DIFFERENT
METABOLISM”
EVEN AFTER SPLITTING
THE POPULATION INTO GROUPS
THERE ARE DIFFERENCES IN
NUTRIENT REQUIREMENTS AMONG
MEMBERS OF A SINGLE GROUP:
E.G. NOT ALL WOMEN BETWEEN AGES
OF 25 & 35 HAVE THE SAME NUTRIENT
REQUIREMENTS
Bell-shaped curve showing the distribution of nutrient
requirements in the population, and how the RDA is set
at two standard deviations above the mean, greater
than the needs for 97.5 % of the population:
RDA: recommended
nutrient level
2.5% of the
population
2.5% of the
population
some people
need fewer
nutrients than
the average person
average
or mean
level
some people
need a lot of
calories or
protein
WHO SETS THE STANDARDS?
IN THE USA, STANDARDS ARE SET BY THE FOOD &
NUTRITION BOARD OF THE NATIONAL ACADEMY OF
SCIENCES INSTITUTE OF MEDICINE
IN THE LATE 1990S, THE BOARD REVIEWED STUDIES, AND
ISSUED MORE COMPREHENSIVE GUIDELINES
INCLUDING THE FOLLOWING ELEMENTS:
 RDA (Recommended Dietary Allowance): average daily intake
sufficient to meet needs of almost all (97-98%) healthy persons
 AI (Adequate Intake): estimated only when RDA can’t be
determined; based on observed intakes by health persons
 UL (Upper Intake Level): the highest daily intake likely to pose no
risks of toxicity for almost all persons
 EAR (Estimated Average Requirement): intake meeting the need
of half of all healthy individuals in the population
REFINING THE STANDARDS
EACH OF THE REFERENCE VALUES OF THE FOOD &
NUTRITION BOARDS TAKES INTO ACCOUNT GENDER,
DIFFERENT LIFE STAGES, BIOAVAILABILITY OF
NUTRIENTS FROM DIFFERENT SOURCES, INTERACTIONS
BETWEEN NUTRIENTS AND BETWEEN NUTRIENTS &
DRUGS, AND INTAKE FROM FOOD FORTIFICATION AND
SUPPLEMENTATION
IN JAN. 2001 THE BOARD RELEASED INTAKE
RECOMMENDATIONS FOR VITAMINS A & K, AND 12
MINERALS: arsenic, boron, chromium, copper, iodine, iron,
manganese, molybdenum, nickel, silicon, vanadium, and zinc.
Recommendations for calcium, fluoride, magnesium, phosphorus
and selenium were released previously
http://www.iom.edu
PROBLEMS WITH NUTRITIONAL
STANDARDS
•DIFFERENT INDIVIDUALS HAVE
DIFFERENT NUTRITIONAL NEEDS
• COMPARING DISTRIBUTIONS OF
NEEDS AND INTAKE.
• THE NUTRITIONAL NEEDS OF AN
INDIVIDUAL MAY CHANGE OVER TIME.
•IMPORTANCE OF QUALITY OF PROTEIN