Balanced Diet and Nutrients
FoundationFood contains nutrients — carbohydrate, protein, fat, vitamins, minerals, dietary fibre and water. Eating in the proportions of the food pyramid, without being picky, gives the body complete nutrition.
- There are seven main nutrients: carbohydrate, protein, fat, vitamins, minerals, dietary fibre and water.
- Carbohydrate gives energy, protein helps growth and repair, and fat stores energy and protects the organs.
- Vitamins and minerals are needed in small amounts but do much: vitamin C strengthens resistance, calcium strengthens bones.
文體小知識：營養科普說明文把食物中的營養素和身體需要分點講清楚，學會按金字塔配搭食物就能吃得健康。
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1Food gives us more than energy; it also supplies the nutrients our bodies need. There are seven main kinds of nutrients. Carbohydrates are the body's most important source of energy, found richly in rice, bread and potatoes. Protein helps the body grow and repair tissues; fish, meat, eggs, beans and milk are all good sources. Fat stores energy and protects the organs, but eating too much makes people overweight.
2Vitamins and minerals are needed only in tiny amounts, yet they do a great deal. Vitamin C, from fresh fruit and vegetables, helps wounds heal and strengthens the body's resistance. Vitamin D helps the body absorb calcium, and the skin makes it in sunshine. Calcium keeps bones and teeth strong; milk, tofu and dark green vegetables are rich in it. Iron helps the blood carry oxygen; without enough of it we easily become anaemic and tired.
3Dietary fibre cannot be digested by the human body, but it helps the intestines work and prevents constipation; wholemeal bread, brown rice, vegetables and fruit are rich in it. Water is the most important substance in the body: it carries nutrients and regulates body temperature, and we should drink six to eight cups a day. To eat in a balanced way we cannot simply follow our preferences — we must follow the proportions of the healthy eating pyramid.
4The healthy eating pyramid divides food into four levels. At the base are grains, which we should eat most of. The second level is vegetables and fruit. The third level is meat, fish, eggs, beans and milk — eat these in moderation. At the top are oil, salt and sugar — eat the least of all. Eat many kinds of food in the right proportions, exercise regularly and sleep enough, and the body will grow healthily.
1Summary 重點摘要
Food contains nutrients — carbohydrate, protein, fat, vitamins, minerals, dietary fibre and water. Eating in the proportions of the food pyramid, without being picky, gives the body complete nutrition.
2Vocabulary cards Vocabulary
A substance in food that gives energy, supports growth and keeps the body healthy.
The body's main source of energy, found richly in rice and bread.
The nutrient that helps the body grow and repair tissues, rich in fish, meat, eggs, beans and milk.
The nutrient that stores energy and protects the organs; too much makes people overweight.
Nutrients needed in tiny amounts to keep the body working properly, such as vitamins C and D.
Inorganic nutrients the body needs, such as calcium and iron.
The substance in vegetables, fruit and whole grains that helps the intestines work and prevents constipation.
The mineral that keeps bones and teeth strong, rich in milk and tofu.
A guide that ranks food by how much we should eat: most from the base, least from the top.
3Step by step Steps
- Step 1: Know the seven nutrientsThe seven nutrients are carbohydrate, protein, fat, vitamins, minerals, fibre and water, and each has its own job. Carbohydrate and fat give us energy, protein helps muscles grow, and vitamins and minerals keep the body working well. For example, a bowl of rice gives us energy for running, and an egg helps muscles grow. We need all seven nutrients for the body to grow properly.
- Step 2: Learn what vitamins and minerals doWe need vitamins and minerals only in tiny amounts, but they keep the body working properly, and lacking different kinds causes different problems. For example, without vitamin C the gums bleed easily, so eat more oranges and kiwifruit; without iron we feel dizzy and tired, so beef and spinach help. So we should get enough of them from fruit and vegetables, meat and milk every day.
- Step 3: Plan meals by the healthy eating pyramidThe healthy eating pyramid sorts food into levels: eat the most grains at the bottom, plenty of vegetables and fruit in the middle, a moderate amount of meat, fish, eggs, beans and milk above them, and the least oil, salt and sugar at the top. For example, a balanced lunch is a bowl of brown rice, a plate of choy sum, an orange and a piece of steamed fish, with only a little oil, salt and sugar. Eating by the pyramid keeps our nutrition balanced.
- Step 4: Limit oil, salt and sugarOil, salt and sugar make food tastier, but too much of them raises the risk of obesity, high blood pressure and tooth decay, and many processed foods already contain a lot of salt and sugar. For example, a pack of instant noodles often contains sodium near the daily limit; use less soy sauce and oyster sauce when cooking and drink plain water instead of sweet drinks. Getting used to lighter flavours from a young age helps our health.
- Step 5: Drink enough water every dayWater is the most important substance in the body: it carries nutrients, controls body temperature and removes waste, so we should drink more after sweating or in dry weather. Primary students need about six to eight cups a day. For example, fill an 800-millilitre bottle, drink half in the morning and half in the afternoon, and add water at home morning and night. Choose plain water rather than sweet drinks when you are thirsty.
- Step 6: Eat from every food groupEach kind of food gives different nutrients, so eating only a few favourite foods leaves the body short of some of them. Someone who never eats vegetables easily becomes constipated; someone who refuses milk lacks calcium and has weaker bones. We should eat from every food group and keep sugary, oily processed snacks to a minimum, so that our nutrition is complete and our bodies grow healthily.
- Step 7: Balance eating with exercise and sleepA balanced diet must go with daily exercise and enough sleep for the body to develop well. Exercise uses up energy and makes muscles and bones stronger, while sleep gives the body time to rest and grow. For example, a bowl of rice gives about two hundred kilocalories; skipping rope for half an hour uses about three hundred. Balance eating and moving, and you will be neither overweight nor underweight.
4Diagrams Diagrams
5Worked example Example
Example: Ming's breakfast every day is a pack of instant noodles and a bottle of soft drink, and he hardly eats any vegetables at lunch or dinner. Analyse the problems in his diet and design a more balanced breakfast.
- Instant noodles are fried, so the fat is high, and the soup base contains a lot of salt; soft drinks are high in sugar — one bottle already exceeds the suggested daily amount.
- With hardly any vegetables or fruit all day, he lacks dietary fibre and vitamin C, so he may become constipated and his resistance falls.
- Balanced breakfast one: a cup of skimmed milk, two slices of wholemeal bread with egg, and a banana — providing protein, carbohydrate, calcium and dietary fibre.
- Balanced breakfast two: a bowl of oatmeal with a few raisins and a cup of plain soymilk — filling, with less sugar and fat.
- Replace the soft drink with water or plain soymilk, and add a serving of fruit and a plate of vegetables every day to complete the vitamins and fibre.
- Answer: Ming's diet is high in fat, salt and sugar and short of vegetables and fruit. A balanced breakfast should include grains, milk or eggs or beans, and fruit — for example skimmed milk with wholemeal egg bread and a banana — and water instead of soft drink.
6Common mistakes Mistakes
7Quick check Quick check
Q1Which nutrient helps the body grow and repair tissues?
Q2Which nutrient helps the intestines work and prevents constipation?
Q3What foods are at the base and the top of the healthy eating pyramid?
Q4Which mineral keeps bones and teeth strong? Which foods are rich in it?
Q5How many cups of water should we drink each day?
8Recap Recap
- There are seven main nutrients: carbohydrate, protein, fat, vitamins, minerals, dietary fibre and water.
- Carbohydrate gives energy, protein helps growth and repair, and fat stores energy and protects the organs.
- Vitamins and minerals are needed in small amounts but do much: vitamin C strengthens resistance, calcium strengthens bones.
- Follow the healthy eating pyramid: most grains, then vegetables and fruit, moderate meat, eggs and milk, and the least oil, salt and sugar.
- Drink six to eight cups of water a day, never be picky, and exercise regularly — then the body grows healthily.