Recommended Dietary Allowance | The Chemistry Of Life | Siyavula

Recommended Dietary Allowance

1.6 Recommended Dietary Allowance (ESG4J)

In order to ensure that we consume adequate quantities of all the food types, nutritionists have compiled a list of guidelines known as the Recommended Dietary Allowance (RDA). The RDA defines the required intake of each nutrient type to meet the basic nutrient needs of almost all individuals in a gender group at a given life stage.

In order to ensure that we consume adequate quantities of all the food types, nutritionists have compiled a list of guidelines known as the Recommended Dietary Allowance (RDA). The RDA defines the required intake of each nutrient type to meet the basic nutrient needs of almost all individuals in a gender group at a given life stage. Food companies are required to advertise the nutrient composition on all products sold. This allows consumers to decide whether to purchase the food item. Table 1.6 shows the recommended dietary intake for males or females between 19 and 30 years old.

TEACHERS NOTE:

Learners DO NOT need to learn this table by heart, but they must be able to use it and interpret it if they are given such a table in tests / exams.

Recommended dietary allowance of vitamins and minerals

NutrientRDA (Male)RDA (Female)UnitTop Sources
Vitamins
Vitamin A900700microgramscarrots, carrot juice, turkey, pumpkin
Vitamin C7575milligramsorange juice, grapefruit juice, bell peppers
Vitamin D55microgramscereals, mushrooms, yeast, salmon, swordfish, trout, fish liver oil
Vitamin E1515milligramsfortified cereals, tomato paste, sunflower seeds
Minerals
Calcium10001000milligramsfortified cereals, cow's milk, cheese, orange juice
Iodine150150microgramsiodised salt
Iron1818milligramsliver, pilchards, red meat, spinach
Phosphorous700700milligramsmaize-meal, milk, wheat flour
Potassium47004700milligramspotatoes, bananas, tomato paste, orange juice
Sodium15001500milligramsonion soup mix, table salt

Table 1.6: RDA for males and females between 19 years and 30 years.

Macronutrients

The table below shows the relative quantities of macronutrients recommended for average adult (25-year old) male and female individuals.

SubstanceAmount (males)Amount (females)Sources of nutrient
Water2 L/day2 L/daywater
Carbohydrates300 g/day230 g/dayrice, potatoes, pasta, bread, mealie meal, fruits
Protein56 g/day46 g/dayduck, chicken, turkey, beef, fish, eggs, legumes (pulses and lentils), nuts, seeds, milk
Fat70 g70 gsunflower oil, olive oil, butter, margarine, lard, avocados, coconut, nuts, seeds, oily fish
CholesterolAs low as possibleAs low as possibleegg yolk, chicken giblets, turkey giblets, beef liver

Malnutrition, which is the lack of a balanced diet, is a major problem in South Africa. Key vitamins have been added to wheat and maize-meal in order to provide the recommended amounts. Iodine has been added to salt.

The nutritional needs of new-born babies are unique. A major challenge in South Africa is to encourage women to breastfeed children for their first six months after birth. Only \(\text{25}\%\) of babies are breastfed in this way. This leads to high levels of malnutrition, diarrhoea and poor growth.

Figure 1.23: Breastfeeding infants for first 6 months of life is vital to the infants' survival.

What makes up a balanced diet?

Video: 2CMY

Working out your daily nutrient intake

From our understanding of recommended dietary allowance we can understand what it is we consume and how important it is to our diet. The activity below requires you to use the information provided in these tables (and any other information you can find) in order to evaluate your diet with regards to the recommended daily allowances.

Measuring your daily nutrient intake (Essential investigation- CAPS)

  1. Keep a food diary for 3 days by writing down the food you eat. Make sure to note the time you eat, the type of food you eat, and how much of it you consume.
  2. Pick one of the days you recorded (that is the most typical of your normal diet), and draw a pie chart with the energy component of each food item you consumed. Make sure your pie chart includes a key. (See the Introduction to Life Skills Chapter if you are unsure of how to do this.)
  3. Draw another table with each food class (vitamins, proteins, carbohydrates, etc) listed. In one column, list the recommended dietary allowance and in the next column list the estimated amount of the food type you consume on a daily basis.
  4. Which food types do you consume in excess? Which ones do you consume too little of? What are the consequences of each?

The table below lists the energy components of some common food items. Study it and answer the following questions:

  1. Which food has the highest energy value? Why?
  2. Name the key food items you would include in a balanced diet

Nutrient composition of some common foods

Food typeEnergy (kJ)Protein (g)Carbohydrate (g)Total Fat (g)Sodium (mg)Iron (mg)Vitamin A (IU)Vitamin C (mg)
rice, brown (250 ml)9695482100.900
Muffin, blueberry (50 g)82443453171.1241
Beansprouts(250 ml)2746140122.54121
Carrots raw (1 medium)145181350.4226447
Apples, raw, with skin (7cm diameter)3410212.600.2738
Egg white, raw (1 egg)6930054000
Lamb stew (250 ml)9143309692.700
Chicken roasted (1/2 breast)21830010690.61070

Measuring your daily nutrient intake (Essential investigation- CAPS)

TEACHERS NOTE:

This answers to this activity will be learner-dependent.

Learners may use the Internet to look up food nutritional information, or simply use the information available on food packaging. It is important to note that this is a very complex, and personal activity for learners, and is likely to be challenging for a number of reasons:

  • Learner's from poor-income families may be embarrassed to do this activity and list their meals, especially if food is very scarce or basic.
  • Learners may be embarrassed by how little, or how much they eat.
  • This activity may be difficult for learners struggling with eating disorders, which are prevalent in this age-group, especially amongst teenage girls.
  • Obtaining accurate information will be challenging. The energy content of the food type will be affected by the cooking method and will vary tremendously, e.g. mashed potato with butter added vs. boiled potato vs. fried chips vs. oven chips.
  • It will be difficult for learners to establish their portion sizes accurately.
  • Packaging often only lists the energy content and macronutrients (carbohydrates, protein and fat) in a meal, and very rarely lists vitamins and minerals.

In light of the potential difficulties that may occur during this activity, both social and pragmatic, it is up to the teacher to decide how best to modify and asses this activity.