Nutrients and health Flashcards
What are macronutrients?
Lipids,Carbohydrates,protein and alcohol
Everything we eat in bulk
What are micronutrients?
Only only needed in tiny amounts
( g, mg or µg per day);
- vitamins,
- essential minerals,
- essential amino acids
- essential fatty acids
Why are the food tables not as accurate as they could be?
Who determins these requirements?
Requirements
* Difficult to be specific about individual energy and nutrient requirements
* vary depending on: age, gender, activity levels etc
* guidelines for groups within the population
** Food Standards Agency
**
What is the requirement for a nutrients?
Classically, amount needed to prevent deficiency
Societies expect more than that
Storage for times of low/no intake
How is the requirements determined?
Looking at :
* the intake of X in groups of people with no deficiency e..g vitamin c
* the intake in groups of people with deficiency scurvy
* intakes that would cure clinical deficiency
* intakes that are associated with a marker of nutritional adequacy (enzyme saturation, tissue concentration) - RBC
That allows to work out the estimated average requirement
EAR
How is normal distribuition used to work out requirements?
Mid line - 50% of population would be satistified
Blue is 1 sd. from the mean - accounts for about 68% of the population that would be satified by this amount of nutrients
2 standard deviations from the mean (blue and brown) account - 95%
three standard deviations (blue, brown and green) account for about 99.7%.
What are the three Dietary Reference Values (DRVs)?
-
Estimated Average Requirement (EAR)
The notional mean requirement of a nutrient (for a group of healthy individuals in a population); Vitamin C -
Reference Nutrient Intake (RNI)
Two standard deviations above the EAR, sufficient of a nutrient to meet the needs of most of the population;
(Formerly termed: Recommended Daily Allowance.) -
Lower Reference Nutrient Intake (LRNI)
Two standard deviations below the EAR; intakes of a nutrient below this level are almost certainly inadequate for most individuals.
What are the three Dietary Reference Values (DRVs) in regards to Vitamin C?
EAR for adults in the UK is 25mg
( 25mg per day is the estimated average requirement & sufficient for the needs of 50% of the population *).
RNI for adults in the UK is 40mg
( 40mg vitamin C per day is sufficient to meet the needs of ** 95% of the population**).
LRNI for adults in the UK is 10mg
( diets containing < 10mg vitamin C per day would only provide sufficient for 5% of the population).
* N.B. It follows that a diet containing < the RNI is not automatically providing insufficient vitamin C.
What are the problem with using normal distribution with energy requirements?
we dont go two sd over for energy requirements as we would get large
When are nutritional requirements useful?
- For nutritional programmes for groups of people
e.g. babies, pregnant women, children, adults, the elderly, ethnic groups - For formulation of feeds for babies, schools, institutions e.g prisons
- for clinical nutrition ie patients on enteral or parenteral (fed through tube) nutrition
How do we know how much X we are taking in ?
Food tables
UK the standard work is The chemical composition of foods
How are chemical compositions of food calculated and displayed?
Many samples of a particular food are analysed, the mean content of:
- available energy,
- water,
- protein,
- fat,
- carbohydrate,
- alcohol,
- vitamins,
- minerals,
- dietary fibre etc … can be calculated
Food tables
UK the standard work is The chemical composition of foods
Are food tables accurate?
will not have strict accuracy,
e.g. fat content of milk varies with season
but they can still be of use
e.g in the analysis of an individual’s nutrient and energy intakes
In formulation of diets where certain foods must be avoided
e.g diets for diabetics, people with high cholesterol , on dialysis etc
Who/What groups usually suffer from undernutrition
In Developed contries
** Usually specific deficiencies i.e. proteins, vitamins, minerals
Main groups:
* Elderly,at home on their own or in institutions
* Young people on junk food
* Some Asian women and children in traditional clothes
* Slimmers and people on fad diets
* Cancer and AIDS patients
* People with eating disorders
* Up to 40% of hospitalised patients
- many developing countries E.g. South Asia, sub-Saharan Africa, parts of South America
Who/What groups usually suffer from overnutrition?
What is overnutrituition?
The main nutritional problem in the developed world (and increasing in the developing)
* Too much fat
* Too much sugar
* Too much salt
* Too much food in general
What is the body mass index?
What are the classification?
Body mass index = wt/ht2 (kg/m2)
wt= weight (in kg)
ht= height (in m)
2 = squared
Trend of obesity across social classes
Prevelence of a BMI over 30 decreases with increasing class
increases from Social Classes 1 to V
Fruit and vegetable consumption decreases from Social Classes
I to V
