The amount of nutrients required depends on a number of factors...
1. Sex: Men have a larger body mass than women and therefore usually require larger quantities of each nutrient. For example, a girl aged 16 requires 53g of protein a day compared to 72g for a boy of the same age.
2. Age: Older people tend to be less active and require less energy, and lower levels of body building nutrients than busy children and teenagers. For example, a man over 75 years requires 2150kcal a day compared to a boy of 16 who needs 2880kcal.
3. Activity: People who have very active jobs or who play a lot of sport will have higher energy requirements. For example, a moderately activeman of 30 requires 2900kcal a day compared to a very active one who needs 3350kcal.
4. Special conditions: For example, pregnancy, lactation (breastfeeding), teenagers. Each of these groups would require greater amounts of one or more nutrients. For example, a pregnant woman requires 1200mg of calcium a day compared to an active woman who needs only 500mg.
Measuring the amounts of nutrients needed...
DRV (Dietary Reference Values): These are estimates of the nutritional requirements of different groups of healthy people of different ages.
EARs (Estimated Average Requirements): These are an estimation of the needs of most people in a particular group.
RDA (Recomended Daily Allowance): This amount is often used on packaging to indicate whether or not a food productis a good source of a particular nutrient.
RNI (Reference Nutrient Intake): This is the amount of a nutrient, which will satisfy 97.5% of the population in a particular specified group.
A paper published by the Government in 1992, entitled 'The Health of the Nation', set out the following targets, which should have been achieved by 2005...
So you know that there are lots of different nutrients that we need, but how do you know that you're getting the amount you need?
Have a look at the following two tables and then answer the questions underneath...
|A: Egg mayonnaise||961 (237)||10.7||17.6||14.9|
|B: Roast chicken salad||957 (236)||11.2||18.5||13.6|
|C: Tuna and cucumber||560 (130)||9.9||19.4||3.2|
|D: Prawn mayonnaise||1264 (310)||11.9||18.8||21.8|