Nutrients and Nutrition Labels

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1Summary 重點摘要

The six nutrients have their own types, functions and sources, and dietary goals differ by age. Learning to read the 1+7 nutrition label on prepackaged food and comparing values per 100 g helps spot malnutrition risks and make smart choices.

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3Step by step Steps

1. Three energy-giving nutrientsNutrients are substances in food the body absorbs and uses; protein, carbohydrate and fat supply energy and are called the energy-giving nutrients. Protein builds and repairs tissue and supplies enzymes and antibodies; carbohydrate is the body's first-choice fuel; fat stores energy, protects organs and helps absorb fat-soluble vitamins. For example, in a cha chaan teng breakfast the scrambled eggs and milk give protein, the toast gives carbohydrate and the butter gives fat — each nutrient has its own role, and missing any one unbalances the diet.
2. Carbohydrate and dietary fibreCarbohydrate is made of sugars, starch and cellulose: sugars give quick energy, starch breaks down gradually into glucose in the small intestine for a steady supply, while cellulose cannot be digested yet keeps the bowels moving, prevents constipation and adds fullness. Common sources are rice, noodles, bread, potatoes, fruit and whole grains. For example, a dinner of brown rice and vegetables the night before an exam releases energy slowly and keeps you steady next morning, while sweets give a quick rise and fall in blood sugar that leaves you tired.
3. Types and roles of fatFats fall into two families: animal fats such as lard, butter and fatty meat are higher in saturated fat and usually solid at room temperature; peanut, corn and olive oils are vegetable oils, higher in unsaturated fat and liquid at room temperature. Fat stores energy, protects organs, keeps us warm and helps absorb fat-soluble vitamins, but too much raises the risk of obesity and heart disease. For example, fry with vegetable oil in moderate amounts; pastries and instant noodles are high in fat and hard on the heart if eaten often.
4. Dietary goals by ageDietary goals differ across age groups: children grow fast and need ample protein, calcium and iron for bones and blood; adults have slower metabolisms and should match energy intake to activity, cutting fat, salt and sugar; older people chew and digest less well and need soft, digestible, calcium-rich, high-fibre food with less salt to protect blood pressure. For example, at the same dinner a child tops up with tofu or dairy, a working adult watches the rice and sauces, and grandparents have softer, steamed dishes instead of fried ones — everyone eats to his own goal.
5. Causes of malnutritionMalnutrition includes both under- and over-intake. Chronic under-intake causes undernutrition through picky eating, crash dieting, illness or food shortage, leading to stunted growth, anaemia, osteoporosis and weak immunity; over-intake raises weight and the risk of hypertension, heart disease and type 2 diabetes. Diet and health are closely linked, and eating habits settle in the teenage years. For example, girls who diet severely lack iron and become anaemic and dizzy, while someone who drinks sugary drinks every day stores the extra sugar as fat even if the meals themselves are small.
6. The 1+7 nutrition labelHong Kong law requires prepackaged food to show the 1+7 nutrition information: energy plus seven core nutrients — protein, carbohydrate, sugars, fat, saturated fat, trans fat and sodium — stated per 100 g or per serving, with the per-100-g basis easiest to compare. Labels may also carry nutrition claims such as low fat or high calcium, which are regulated by law and must meet set conditions. For example, two brands of crisps both claim less oil, but the labels show brand A has 600 mg of sodium per 100 g while brand B has only 380 mg — the data beats the slogan.
7. Choosing with the labelRead a label in three steps: first check whether the basis is per 100 g or per serving and compare on the same basis; then compare energy, sugars, saturated fat and sodium of similar products — lower is better — while dietary fibre and protein may be higher; finally check the ingredient list, the dates and allergen information. For example, cereal A has 38 g of sugars per 100 g but cereal B only 13 g; choosing B with fresh milk and a banana gives enough sweetness with far less sugar. Bringing label skills into the supermarket starts a balanced diet at the very moment of shopping.

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8Recap Recap

• Protein, carbohydrate and fat are the three energy-giving nutrients, each with its types, functions and sources
• Dietary goals differ by age: growth for children, less fat, salt and sugar for adults, digestible calcium-rich high-fibre food for the elderly
• Malnutrition includes both undernutrition and over-nutrition; balance is the key to health
• Prepackaged food in Hong Kong must carry 1+7 nutrition information, best compared per 100 g
• Check the basis, compare sugars and sodium, verify the claims — smart choices start at the supermarket