Chapter 5: Prescribe nutrient supplement, functional foods and nutraceuticals

Nutrient supplements, functional foods, and nutraceuticals play a critical role in the practice of nutrition and dietetics, especially in addressing the diverse nutritional needs of Kenya's population. These products complement dietary intake by providing concentrated sources of nutrients or bioactive compounds that promote health and prevent disease. Understanding how to assess and prescribe these substances is essential for dietetics professionals working in clinical, community, and public health settings across Kenya. This chapter provides a comprehensive examination of the definitions, assessments, and prescription processes necessary for effective use of nutrient supplements, functional foods, and nutraceuticals.

5.1 Nutrient supplements, functional foods and nutraceuticals

Nutrient supplements, functional foods and nutraceuticals are three groups of products that add to or go beyond the food in a client's usual diet. They are used to correct a deficiency, to meet higher needs in illness or in a life stage such as pregnancy, and to support health or lower the risk of disease. The three groups overlap, and clients often confuse them, so the dietitian must define each term precisely and know the main types before prescribing. This topic names and describes them. How a client's need is assessed and how a product is prescribed are covered under the prescription of supplements, functional foods and nutraceuticals.

5.1.1 Definition of terms

The three terms differ in the form of the product, in how it is taken and in how it is regulated. A supplement is a concentrated nutrient product taken in addition to meals. A functional food is a food eaten as part of the diet that gives a health benefit. A nutraceutical is a concentrated product from a food or natural source, sold in medicine-like form, with a claimed health benefit.

Differences between the three terms

5.1.1.1 Supplement

A supplement is a product taken by mouth to add to the diet. It contains one or more nutrients such as vitamins, minerals, amino acids or fatty acids, or other substances such as herbs, and is sold as a tablet, capsule, powder, liquid, syrup or drops. Its purpose is to correct a deficiency or meet an increased need that food alone does not meet. A supplement does not replace a balanced diet.

Example: at an antenatal clinic, an expectant mother is given iron and folic acid tablets to prevent anaemia and neural tube defects. Periodic vitamin A doses for young children follow the national guidelines.

• Regulated product: In Kenya, supplements should be registered by the national regulator, mainly the Pharmacy and Poisons Board, and the dietitian checks that a product is registered before recommending it.
• Dose matters: Vitamin and mineral doses are chosen to meet the need. Excess vitamin A can damage the liver, and an iron overdose can poison young children.
• Interactions: Some supplements change how medicines are absorbed or act, so the client's medicine list is checked.
• Safe storage: Supplements are kept out of the reach of children and are not shared.
• Not a substitute: The client continues to eat a balanced diet.

5.1.1.2 Functional food

A functional food is a food, either natural or modified, that gives a health benefit beyond basic nutrition when eaten as part of the usual diet. The benefit may be to improve a body function or to lower the risk of disease. Functional foods are eaten in normal portions as part of meals and are not taken as a dose. Example: a client in a community nutrition group is advised to take orange-fleshed sweet potato, which is rich in beta-carotene that the body makes into vitamin A.

• Natural source: Some foods contain active components naturally, such as oats with beta-glucan fibre, fatty fish with omega-3 fatty acids, and tomatoes with lycopene.
• Modified source: Other foods are changed by adding or increasing a nutrient, as in fortified cooking oil.
• Part of the meal: They are eaten in normal portions in a meal and not as a pill or powder.
• Evidence for a benefit: A health claim should be backed by research on the food or its component.
• Cost and availability: Local foods that supply the same benefit are preferred to costly imported products.

5.1.1.3 Nutraceutical

A nutraceutical is a product obtained from food or another natural source and sold in medicine-like forms such as capsules, tablets or powders, with a claimed benefit for health or against disease. The word joins nutrition and pharmaceutical. The active component is purified or concentrated, so the amount is greater than in an ordinary portion of the food. Examples are omega-3 capsules, probiotic capsules, turmeric extract and moringa leaf powder capsules.

• Medicine-like form: The dose is measured in capsules or spoons and not in portions of food.
• Variable evidence: The research behind nutraceuticals ranges from strong to weak, and the client is told so.
• Uncertain status: Many fall between food and medicine in regulation, so quality and content need careful checking.
• Interactions: Some interfere with medicines, such as St John's wort with some antiretroviral medicines, and high doses of fish oil with medicines against blood clotting.
• Referral: Clients on medicines are advised to discuss the product with the doctor or pharmacist before use.

5.1.1.4 Types of supplements

Supplements are grouped by what they contain. The dietitian chooses a type from the client's assessed need.

• Single and combined products: A single nutrient product is used for a specific deficiency, and a multivitamin and mineral product for general cover.
• Forms: Tablets and capsules are cheap and easy to store, syrups and drops suit children and clients who cannot swallow tablets, and powders can be mixed into food or drinks.
• Therapeutic use: The product should supply what the assessment shows is lacking and not more than the safe limit.

5.1.1.5 Types of functional foods

Functional foods are grouped by the way their benefit is made.

• Conventional foods with natural active components: Oats, fatty fish, tomatoes, legumes, nuts and many fruits and vegetables contain fibre, healthy fats or plant compounds that support health.
• Fortified foods: Nutrients are added that were not present or were lost in processing. In Kenya, staples such as maize flour, wheat flour, cooking oil and salt are fortified under national food fortification rules.
• Enriched foods: Nutrients lost in processing are put back, as in refined flour with added B vitamins and iron.
• Enhanced foods: The food is changed so that it contains more of a beneficial component, for example eggs from hens fed to raise omega-3 fatty acids.
• Biofortified crops: Plant breeding raises the nutrient content of a crop, for example orange-fleshed sweet potato for vitamin A and iron-rich bean varieties.
• Probiotic and fermented foods: Yoghurt with live cultures and other fermented foods contain live microbes that may help gut health.

5.1.1.6 Types of nutraceuticals

Nutraceuticals are grouped by their active component.

• Probiotics, prebiotics and synbiotics: Probiotics are live bacteria that may help gut health, prebiotics are fibres that feed useful bacteria, and synbiotics combine both.
• Omega-3 fatty acids: Fish oil capsules supply EPA and DHA, used for raised triglycerides and as advised by the doctor.
• Plant antioxidants and polyphenols: Extracts of green tea, cocoa and berries supply compounds that are proposed to protect cells from damage.
• Carotenoids: Lycopene, lutein and beta-carotene are plant pigments sold as capsules.
• Dietary fibre products: Psyllium and other fibre supplements are used for constipation and for lowering cholesterol.
• Plant sterols and stanols: They lower the absorption of cholesterol and are added to some foods and capsules.
• Herbal products: Preparations of moringa, turmeric and other plants are used for health claims, and their effects and safety vary.

Chapter Summary

This chapter explored the assessment and understanding of nutrient supplements, functional foods, and nutraceuticals, starting with clear definitions and distinctions among these terms. It detailed the various types of supplements, functional foods, and nutraceuticals, emphasizing their unique roles in nutrition and health management. The prescription process was examined, highlighting how dietetic professionals determine appropriate interventions tailored to individual needs. Attention was given to the importance of accurate documentation and effective dissemination of prescriptions to ensure proper patient adherence and safety. Managing drug-nutrient interactions was also addressed, underlining the need for vigilance to prevent adverse effects and optimize therapeutic outcomes. Overall, the chapter provided comprehensive guidance for the responsible and informed use of these nutritional products within dietetic operations.