Nutrition at a Glance

Tony Sheehy, Fariba Kolahdooz, Tony Sheehy, Fariba Kolahdooz

• Éditeur: Wiley-Blackwell
• Année: 2015
• ISBN:
  9781118661000
• Édition: 2
• Sujet: Medicina
• Sous-sujet: Nutrición, dietética y bariatría

Nutrition at a Glance introduces key nutrition facts, such as the role of key nutrients in maintaining health, and addresses the concepts of nutrient metabolism, nutritional intake and what makes an adequate diet. It covers food safety, allergy and intolerance, GM foods, diet-related diseases and nutrigenomics. Nutrition at a Glance: • Is superbly illustrated, with full colour illustrations throughout
• Includes nutrition 'hot topics' such as gene-nutrient interactions and dietary supplements
• Has strong international appeal, with different dietary requirements provided for many countries
• Is a reference text suitable for post-docs and junior scientists, including those working in public health and dietetics
• Includes a companion website at www.ataglanceseries.com/nutrition featuring interactive multiple choice questions, abbreviations, a glossary, references and further reading, and Appendix B 1: Global dietary guidelines and Dietary Reference Intakes

Part I
Nutrients including carbohydrates, fat, proteins, vitamins, minerals, and alcohol

Chapters

• 1 Introduction to the nutrients
• 2 The relationship between diet, health and disease
• 3 Energy intake: Food sources
• 4 Energy: Control of food intake
• 5 Energy: Measurement of requirements
• 6 Energy requirements: Components of energy expenditure
• 7 Carbohydrates: Simple and complex carbohydrates
• 8 Carbohydrates: Digestion and utilisation in the body
• 9 Fats: Types of fatty acids
• 10 Fats: Compound lipids (triglycerides, phospholipids, cholesterol, and phytosterols)
• 11 Fats: Digestion and utilisation in the body
• 12 Proteins: Chemistry and digestion
• 13 Proteins: Functions and utilisation in the body
• 14 Proteins: Needs, sources, protein quality and complementation
• 15 Dietary supplements
• 16 Micronutrients: Fat-soluble vitamins
• 17 Micronutrients: Water-soluble vitamins
• 18 Micronutrients: Major minerals
• 19 Micronutrients: Trace elements
• 20 Micronutrients: Role in metabolism
• 21 Micronutrients and circulatory system I
• 22 Micronutrients and circulatory system II
• 23 Micronutrients: Protective and defence roles I
• 24 Micronutrients: Protective and defence roles II
• 25 Micronutrients: Structural role in bone I
• 26 Micronutrients: Structural role in bone II
• 27 Alcohol
• 28 Fetal alcohol spectrum disorder
• 29 Fluids in the diet

1
Introduction to the nutrients

Aims

1. To show how nutrients are classified and discuss their main roles
2. To describe how nutrients may interact to fulfil similar roles

Food is composed of a large variety of chemical substances, some of which are recognised as nutrients. Over the past century or so, scientists have identified the roles of these nutrients in the body and the consequences of insufficient intakes. Many other substances are present in foods of plant origin that help promote the plant’s growth, protect it against predators or contribute to its appearance or smell to attract animals that will spread its seeds. Although these substances (phytochemicals) are not recognised as nutrients, some may be biologically active in humans and could have either beneficial or harmful effects.

Classification of nutrients

Traditionally, the major nutrients have been classified according to the amounts in which they are required by the body, their chemical nature and their functions. The principal distinction is between macronutrients and micronutrients:

1. Macronutrients are required in relatively large amounts, usually expressed in terms of grams per day.
2. Micronutrients are required in small amounts, usually expressed in terms of milligrams or micrograms per day.

Some classifications also include ultratrace nutrients. These are found in the diet in very small amounts (typically <1 µg/g of dry food). For many of these substances, their roles are, as yet, uncertain.

Water is an essential component of the diet, as an adequate intake of fluid is vital to sustain life.

Macronutrients

This category comprises carbohydrates, fats and proteins:

• Carbohydrates and fats are the major providers of energy, although proteins can also be used to provide energy.
• They all have a structural role in the body, the most important in this respect being proteins.
• All contain carbon, hydrogen and oxygen. In addition, all proteins contain nitrogen, while some amino acids (cysteine and methionine) that are found in proteins contain sulphur.

Carbohydrates

Carbohydrates are the most important source of food energy in the world. Carbohydrates occur in the diet in various degrees of complexity, ranging from simple sugars (mono- and disaccharides) to larger units such as oligosaccharides and polysaccharides. Simple sugars include the monosaccharides glucose, fructose and galactose and the disaccharides sucrose and lactose. Oligosaccharides include maltodextrins and fructo-oligosaccharides. Important polysaccharides include starch and glycogen.

The main function of carbohydrates is to act as a source of energy, in the form of glucose. However, some carbohydrates resist digestion and are termed ‘non-glycaemic’ (see Chapter 8). They comprise the non-starch polysaccharides (NSP), which are part of the category known as ‘dietary fibre’. These carbohydrates p...