Fig. 5.1 Sources of Vitamin C, Carotene and fibre
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Lesson Five: Balanced Diet
Teaching suggestions: Lecture, Demonstration, individual and group work activity.
Pose focus questions
Let the students mention the different food groups from their locality for a better nutrition. According to their food habits, the students might list only some of the food items. A balanced diet provides all of the nutrients our bodies need, by the consumption of an appropriate amount of elements that contain energy. It is has no nutritional or calorific imbalances that might lead to inappropriate body weight (being under- or overweight) or to general health problems.
A person’s nutritional and energy requirements depend on their age, occupation and sex.
For example, Adolescents do not have the same needs as a sedentary elderly person, a pregnant woman or a professional sportsperson. Our diet must be varied and the food we eat on an everyday basis must contain as wide a variety of foods as possible to guarantee our intake of nutrients, so that we do not develop deficiencies. It is important to remember that there is no one food that provides all of the nutrients that our bodies need. We must make sure that our diet contains products from different sources and food groups include vegetables, pulses, meat, fish, olive oil, cereals, dairy products, fruit, nuts etc.
For better nutrition and health benefits, the following food groups should be stated.
Fruit and fruit juices provide water, sugars, vitamins (such as vitamin C), carotene, Minerals (such as potassium and selenium) and fibre. Juices only provide vitamins and minerals and lack most of the fibre contained in whole fruits. Dried fruits (prunes, chestnuts, raisins, dates) are characterized by their lower water content. It is important that we should eat fruit that is high in vitamin C on a daily basis (citrus fruits, kiwis, strawberries, etc.).
Green vegetables and other vegetables are an important source of vitamins, minerals, fibre and antioxidants, and it is therefore recommended that they be eaten on a daily basis. The best way to ensure we make the most of all of the vitamins and minerals is to eat them raw, alone or in salads. Roasting or grilling are other tasty options. If they are boiled, the water can be used to make soups or purees, because many of the minerals are left behind in the cooking water. Steamed vegetables keep most of their nutrients.
Fig. 5.1 Sources of Vitamin C, Carotene and fibre
Fig. 5.2 Sources of Vitamins, Minerals, Anti-oxidantsand fibre
Dairy products (milk, yoghurt, cream cheese, hard cheeses, cream etc.) are an important source of high-quality protein, lactose, vitamins (A, D, B2 and B12) and calcium, an extremely important mineral that is required for the formation of bones and teeth and to prevent osteoporosis. We should consume two to four portions of dairy products each day, according to our age and physiological situation (pregnancy, breastfeeding, etc.). Milk is a very good food at all stages of life, particularly during breastfeeding, growth and the menopause, as well as for elderly people. A school-age child who drinks half a liter of milk each day obtains 50% of the protein and over 80% of the calcium and vitamin B2 she needs from this source. With the same amount, an adult meets 30% of his or her daily protein requirements and 100% of his or her calcium requirements.
Meat is an important source of protein with a high biological value, vitamin B12, iron, potassium, phosphorus and zinc. Because of the high saturated fat content, it is very important to choose lean cuts of meat. Meat contains iron that can be absorbed easily by the body. Fatty sausages should only be consumed occasionally, as they contain large amounts of saturated fats, cholesterol and sodium, which can affect our cardiovascular system.
Eggs are a very nutritional food, providing high-quality protein, vitamins (A, D and B12) and minerals (phosphorus and selenium). Eggs also contain nutrients that are essential during growth and at times of special physiological circumstances such as pregnancy, breastfeeding and old age. The consumption of eggs should be alternated with eating meat and fish, foods that have similar nutritional qualities.
Eating 3 -4 eggs per Week is a good alternative to meat or fish
Fig. 5.6. Sources of Proteins, Minerals, and Vitamins
The energy or calorific value of a food corresponds to the amount of energy obtained once the food is oxidized or metabolized.
The average values of some nutrients in terms of calories are:
A person’s individual energy requirements depend on their physical make-up, their age, their sex and, most importantly, the amount of physical activity they do. Energy requirements can vary between 2,600 and 3,000 kilocalories each day, or even more in the case of an adolescent who is very physically active.
How can the appropriate nutritional state and body weight be established for each person?
There is a parameter known as the body mass index (BMI) that compares the height and weight of people aged over 18.
The body mass index (BMI) is calculated by applying the following formula:
BMI = Weight (kg) / (Height)2 (m2)
This calculation is only applicable to adults. For under-18s, tables that are specially adapted to the bodily variations that take place during growth should be consulted.
Appropriate BMI values, according to WHO figures published in 1997, are shown in the table below:
Classification of BMI
BMI Value
Less than 18.5 Underweight
18.5........................................ 24.9 Ideal weights
25........................................... 29.9 Overweight
30........................................... 34.9 Grade 1obesity
35........................................... 39.9 Grade 2 obesity
Greater than 40 Grades 3 obesity
A brief summary of the lesson should be given here. Either the students or the teacher may summarize the lesson.
Assessment Questions
Let the students:-