Chapter 1: Apply knowledge of nutrition

Nutrition and Dietetics professionals in Kenya require a strong foundation in the principles of human nutrition to effectively address public health challenges and improve individual wellbeing. This chapter introduces essential nutritional concepts and situates the field of nutrition and dietetics within its historical and professional context. Understanding these basics equips practitioners to make informed decisions, design appropriate interventions, and pursue diverse career opportunities in Kenya’s healthcare and community nutrition sectors.

1.1 Basic nutritional concepts

Nutrition and dietetics has its own vocabulary. A nutritionist or dietitian uses these terms every day: when writing an assessment, explaining a result to a client, or passing information to a nurse or doctor. A word used loosely, such as "food" for "nutrient" or "diet" for "a weight-loss plan", leads to wrong advice and misunderstanding within the care team. This topic fixes the meaning of the eleven terms on which the rest of the unit depends.

1.1.1 Definition of terms

Each term below has a precise meaning in the science of nutrition. Read them in order, because later terms build on earlier ones: nutrients come from food, macronutrients and micronutrients are groups of nutrients, a balanced diet supplies them in the right amounts, and malnutrition and nutrition status describe what happens when it does not.

1.1.1.1 Nutrition

Nutrition is both a science and a process. As a process, it is everything that happens from the moment food is eaten: ingestion, digestion, absorption, transport, use of nutrients by the cells, and removal of waste. As a science, it studies how food and its components affect growth, health and disease, and how diet can be improved to prevent illness.

Example: a mother feeds her toddler a bowl of porridge made from millet flour with a little milk. The porridge, the swallowing and digestion that follow, and the way the child's body then uses the energy and protein for growth are all part of nutrition. A nutritionist studying why that child is growing slowly looks at every step of that chain.

1.1.1.2 Nutrients

Nutrients are the chemical substances in food that the body needs to function, grow and repair itself. There are six classes: carbohydrates, proteins, lipids (fats and oils), vitamins, minerals and water. Dietary fibre is not digested like these, but it is needed for healthy bowel function and is usually taught alongside them.

Nutrients do three jobs: they supply energy, they build and repair tissues, and they regulate body processes such as blood clotting and fluid balance. An essential nutrient is one the body cannot make, or cannot make in enough quantity, so it must come from food. A non-essential nutrient can be made by the body from other substances.

Example: a boiled egg supplies protein, fat, vitamin A, vitamin D, vitamin B12 and iron. The egg is the food; protein, fat and the vitamins and minerals in it are the nutrients.

1.1.1.3 Macronutrients

Macronutrients are the nutrients needed in large amounts, measured in grams a day. They are carbohydrates, proteins and lipids. Carbohydrates, proteins and lipids all supply energy, and each also has its own building or protective roles. Water is also needed in large amounts and is often listed with them.

Example: a plate of ugali, beans and a spoonful of cooking oil carries all three macronutrients. The maize meal in the ugali supplies mostly carbohydrate, the beans supply protein together with carbohydrate, and the oil supplies lipid.

The structure, sources and functions of each macronutrient are taught in the chapter on macronutrients.

1.1.1.4 Micronutrients

Micronutrients are the vitamins and minerals. They are needed in small amounts, measured in milligrams or micrograms a day, yet the body cannot work without them. They do not supply energy, but they allow the body to release energy from macronutrients, to make blood, to build bone and to fight infection.

Example: iodised salt supplies iodine, orange-fleshed sweet potato supplies provitamin A, and dark green leafy vegetables such as kale supply iron, folate and vitamin C. A diet low in iodine can lead to goitre, and one low in vitamin A can lead to night blindness, even when the person eats enough energy.

The classes of vitamins and minerals are taught in the chapter on micronutrients.

1.1.1.5 Balanced diet

A balanced diet is one that supplies all the nutrients, in the right proportions and amounts, to meet the needs of a particular person. Needs depend on age, sex, body size, level of physical activity, and conditions such as pregnancy, breastfeeding or illness. A diet that is balanced for an adult farm worker is not balanced for a two-year-old or for a pregnant woman.

A balanced diet is built from variety. It includes foods from each of these groups:

• Staples: cereals, roots and tubers such as maize, rice, cassava and potatoes, which supply much of the energy.
• Legumes, nuts and animal-source foods: beans, peas, groundnuts, fish, eggs, meat and milk, which supply protein and many minerals.
• Vegetables: leafy and other vegetables, which supply vitamins, minerals and fibre.
• Fruits: fresh fruit, which supplies vitamins, fibre and some minerals.
• Fats and oils: used in small amounts to supply energy and carry fat-soluble vitamins.

Example: a supper of rice, green grams cooked with tomatoes and a little oil, steamed cabbage and a banana includes a staple, a legume, a vegetable, a fruit and a small amount of fat.

Dietary Reference Intakes

Dietary Reference Intakes are reference values that state how much of each nutrient groups of healthy people need, by age, sex and life stage. A dietitian uses them as a yardstick when judging whether an intake is adequate and when planning meals. They are values for groups, not exact measures for one person, so they are applied together with the client's own assessment.

1.1.1.6 Malnutrition

Malnutrition means poor nutrition caused by a lack, an excess or an imbalance of energy and nutrients. It is wrong to think of it as only thinness: it has three broad forms.

• Undernutrition: wasting (low weight for height), stunting (low height for age) and underweight (low weight for age).
• Micronutrient malnutrition: a lack of one or more vitamins or minerals, such as iron, iodine or vitamin A, or, less often, an excess of them.
• Overnutrition: overweight and obesity, and the diet-related diseases that follow, such as type 2 diabetes and high blood pressure.

Different forms can exist in the same community, and even in the same household. A child may be stunted while the mother is overweight.

Example: at a community health unit, a nutritionist measures a three-year-old who is much shorter than other children of the same age (stunting). In the same visit, the child's father is found to have a raised blood pressure and a large waist (overnutrition). Both are cases of malnutrition, and each needs a different response.

1.1.1.7 Food

Food is any solid or liquid that is eaten or drunk and that supplies the body with nutrients, energy or both. Foods come from plants, animals and a few minerals such as salt. A food is a mixture of many nutrients, and it also carries flavour, colour, texture and cultural meaning, which is why people choose foods and not nutrients.

It helps to keep the difference between a food and a nutrient clear. A food is what is bought, cooked and served. A nutrient is a part of the food. A dietitian talks to clients about foods, because clients eat foods, but plans and measures in nutrients.

Example: a freshly cooked tilapia is a food. The protein, the fat, the vitamin B12 and the calcium in its flesh are nutrients.

1.1.1.8 Dietetics

Dietetics is the science and practice of applying nutrition knowledge to feed people, both in health and in disease. It turns the findings of nutrition science into practical diets, using knowledge of food composition, human physiology and the way illness changes the body's needs. Its practitioners are dietitians.

Where nutrition asks "what do people need and why", dietetics asks "what should this person or group eat, and how can they do it". It includes planning therapeutic diets, advising on feeding during illness, managing food supply for groups, and counselling clients to change eating habits.

Example: a client with type 2 diabetes needs a meal plan that spreads carbohydrate foods across the day, uses foods the family can afford, and fits the client's work. Preparing and explaining that plan is dietetics.

1.1.1.9 Nutrition status

Nutrition status is the condition of the body that results from the balance between the nutrients taken in and the nutrients the body needs and uses. It can be good, when intake meets needs, or poor, when there is undernutrition, overnutrition or a specific deficiency or excess.

Nutrition status cannot be seen from a single measurement, so it is judged from several kinds of evidence together. A dietitian looks at body measurements, laboratory results, physical signs and the client's diet and medical history. These are collected during nutrition assessment, which is taught in the Nutrition Care Process unit.

Example: an adult who weighs a healthy amount for height, has a normal haemoglobin level, no physical signs of deficiency and a varied diet is said to have a good nutrition status. A child with a low weight for height and pale inner eyelids has a poor nutrition status.

1.1.1.10 Nutritionist

A nutritionist is a professional trained in the science of nutrition who promotes health and prevents disease through food. A nutritionist assesses the nutrition status of individuals and communities, plans and runs nutrition programmes, educates clients and groups, and works with other sectors such as agriculture and social services.

In Kenya, nutritionists and dietitians are registered and licensed by the Kenya Nutritionists and Dieticians Institute under the Nutritionists and Dieticians Act, 2007, so a graduate registers with the Institute before practising. A nutritionist advises on food and nutrition but does not prescribe drugs. The detailed roles of the nutritionist are taught under Roles of the nutrition care team.

1.1.1.11 Dietician

A dietitian (also spelt dietician) is a professional trained to apply nutrition science to the treatment of disease. Dietitians work closely with doctors and nurses. They assess a patient's nutrition status, decide on the nutrition problem, plan and give diets suited to the condition, counsel patients and families, and review progress.

A dietitian is registered and licensed in the same way as a nutritionist. Dietitians usually work with sick clients, for example on a ward or in an outpatient nutrition clinic, where they handle therapeutic diets and feeding plans. A dietitian does not prescribe drugs. The difference between the two roles is one of emphasis: the nutritionist focuses mainly on prevention, promotion and communities, while the dietitian focuses mainly on treatment through diet. The full roles of each are covered under Roles of the nutrition care team.

Chapter Summary

This chapter provides a foundational understanding of key nutritional concepts by defining essential terms such as nutrition, nutrients, macronutrients, micronutrients, balanced diet, malnutrition, food, dietetics, nutrition status, nutritionist, and dietician. It then traces the development of dietetics as a discipline and highlights the importance of studying nutrition for health promotion and disease prevention. The chapter also explores various career pathways within the nutrition and dietetics field, demonstrating the diverse opportunities available. Furthermore, it outlines the roles of the nutrition care team, detailing the specific functions of nutritionists, dieticians, pharmacists, and nurses in providing comprehensive nutritional care. Together, these topics equip learners with a broad perspective on nutrition principles and the collaborative nature of nutrition-related healthcare. This knowledge forms a critical foundation for applying nutritional science in practical settings.