Fuel for life

Damien O’Brien MPSI provides an overview of micronutrients and macronutrients, oral supplements, and the causes and effects of malnutrition

Introduction

Nutrition is the intake of food to meet the body’s dietary needs, and it plays an integral role in maintaining overall health and wellbeing. Nutrition impacts the development of each individual at every stage of their life cycle, from conception to death. Good nutrition is required for immunity, lowering the risk of disease, safer pregnancy and longevity. However, achieving adequate nutrition can be difficult for many adults, particularly the elderly and those with chronic diseases.

Physical difficulty eating, medical conditions and psychological issues can lead to malnutrition. Malnutrition is, therefore, a significant public health concern. Malnutrition can lead to worsening health outcomes, delayed recovery times and increased hospital admissions — causing a significant increase in morbidity and mortality. Pharmacists can play an important role in identifying and addressing nutritional challenges. This article delves into the importance of micronutrients and macronutrients, the causes and effects of malnutrition, and the importance of interventions such as oral nutritional supplements (ONS).¹

Good nutrition

For an adult, good nutrition involves a diet with appropriate consumption of macronutrients to allow energetic and physiological requirements to be fulfilled without excess intake. Good nutrition also encompasses sufficient micronutrients and hydration to meet the physiological requirements of the body.

Carbohydrates, fats and proteins are macronutrients that supply the body with energy necessary for the cellular processes required for daily functioning. Vitamins and minerals are micronutrients that are required in smaller amounts for the body to achieve normal growth, development, metabolism and physiological functioning.

Water is the principal component of the body and accounts for the majority of body mass. It provides essential hydration for the body and carries micronutrients and electrolytes. A diet with appropriate proportions of macronutrients and micronutrients, along with good intake of dietary fibre, is important for health and wellbeing. There are numerous benefits associated with good nutrition, including:

• Improved longevity.
• Supporting healthy skin, teeth and eyes.
• Building a stronger immune system.
• Supporting healthy pregnancy and breastfeeding.
• Strengthening bones and the musculoskeletal system.
• Lowering the risk of cardiovascular disease, type 2 diabetes and certain cancers.
• Improving functioning of the digestive system.
• Maintaining a healthy body mass.^2,3

Macronutrients

Macronutrients — carbohydrates, proteins and fats — are essential for energy production, growth and repair. Each has a unique set of properties that play an important role in cellular processes in the body. Adequate nutrition involves achieving the right balance of macronutrients, which is crucial for preventing malnutrition and optimising overall health and wellbeing.⁴

Proteins

Proteins are large molecules composed of one or more amino acid chains. Amino acids are linked by peptide bonds, which are hydrolysed in the stomach by hydrochloric acid and protease enzymes to allow the absorption of essential amino acids.

Protein is an essential nutrient in the human body for maintaining muscle mass, repairing tissue and supporting immune function. It is the major structural component of body cells and one of the building blocks of body tissue. Protein is also a fuel source, providing 4 kilocalories (kcal) or 17 kilojoules (kJ) per gram. Meat, fish, eggs and dairy products are excellent sources of dietary protein, while plant-based protein sources include nuts, seeds and legumes.

Adequate dietary protein intake is essential for maintaining lean body mass throughout adulthood. Brittle nails and hair, feeling weak or hungry, mood changes and muscle weakness may be signs of a protein deficiency. Protein deficiency may also predispose an individual to stress fractures of the bones.

Adequate daily protein intake can reduce the decline in physical functioning in the elderly.  This helps mitigate the age-related loss of muscle strength and function and reduces the likelihood of developing mobility limitations.^4,5

Carbohydrates

Carbohydrates are simple sugars, occurring either as monosaccharides or chains of monosaccharides that form disaccharides, oligosaccharides or polysaccharides. The bonds of these chains are either hydrolysed in the digestive tract or are resistant to hydrolysis, as in the case of dietary fibre.

Carbohydrates are the body’s primary source of energy, particularly for brain function and physical activity, providing 4 kcal or 17 kJ of energy per gram. Carbohydrates are also a component of important coenzymes and genetic material in the body, while dietary fibre plays a vital role in maintaining the proper function of the digestive system.⁴

Fats

Fats are composed of glycerol and fatty acids. They are a concentrated source of energy in adults, providing 9 kcal or 38 kJ per gram. Fats also play an important structural and metabolic role in the body. Additionally, they are essential for absorbing fat-soluble vitamins (A, D, E and K). Dietary sources of fats include meat, dairy products, eggs, oily fish, nuts and seeds.

Four categories of dietary fats exist: Monounsaturated fats, polyunsaturated fats, saturated fats, and trans fats. Omega-3 and omega-6 are essential fatty acids that must be obtained from dietary sources, with some evidence suggesting they are beneficial for reducing inflammation and supporting brain health.^4,6

Micronutrients  

Micronutrients include minerals and vitamins, which are required in smaller amounts in the body but are crucial for health and wellbeing. Micronutrient deficiencies are common among malnourished adults and can lead to many health complications. Vitamins A, D, E and K are fat-soluble vitamins, which are easily stored in body fat upon absorption. Vitamins B and C are water-soluble vitamins, which are not easily stored in the body and are eliminated through excretion.⁷

B vitamins are a diverse range of vitamins essential for cell metabolism, nerve function and red blood cell formation. These include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9) and cobalamin (B12). Dietary sources of B vitamins include meat, dairy products, eggs, spinach, and legumes.

While deficiency is possible for all B vitamins, toxicity is rare due to their water solubility. Vitamin C is vital for wound healing, bone formation, collagen synthesis, immune system support, and iron absorption. It is found in citrus fruits, berries, and other fruits and vegetables. Deficiency can lead to scurvy, poor wound healing, bleeding gums, and tooth loss.⁷

Vitamin D is required for the maintenance of serum calcium concentration within the normal physiological range for musculoskeletal health. It can be obtained through dietary consumption of oily fish, meat, liver, eggs and dairy products. It is also produced in the skin upon exposure to sunlight. Vitamin D deficiency is particularly prevalent in the winter months due to limited sunlight exposure. Deficiency, especially in older adults, can increase the risk of osteoporosis and fractures.⁷

Vitamin A is essential for cellular differentiation, immune function, and vision. A deficiency of vitamin A can lead to vision problems. Meat, fish, dairy products and colourful fruits and vegetables are common sources of this vitamin. Vitamin E is an antioxidant, protecting cells from oxidative stress and regulating immune function. It is found in a wide range of foods, including nuts, seeds, fish, and vegetables.

Vitamin E deficiency is very rare and usually observed only in individuals with fat absorption issues. Vitamin K is required for maintaining normal coagulation in the body. It is obtained from the diet though green leafy vegetables, meat, and dairy products. Dietary deficiency is also rare but can lead to reduced blood clotting, increased bleeding, and increased prothrombin time.⁷

There are also several minerals required by adults, in varying quantities, to perform a wide range of physiological functions for maintaining overall health and wellbeing. Calcium is vital for bone and dental health, with deficiency potentially leading to osteoporosis.

Iron is critical for red blood cell formation, and its deficiency can result in anaemia. Magnesium is important for enzymatic and muscular function, while chloride and sodium regulate body fluids and maintain electrolyte balance. Zinc and selenium are essential for immune function and wound healing. Potassium and iodine are also essential trace minerals, contributing to various physiological processes.⁷

Malnutrition                      

Malnutrition refers to an imbalance in nutrient intake, resulting in deficiencies or excesses. Under-nutrition occurs when the body does not obtain sufficient macronutrients and micronutrients required for the normal functioning, while over-nutrition occurs when the body receives excessive nutrition.

It is estimated that one-third of adult patients admitted to acute hospitals or long-term care facilities are at risk of malnutrition. Malnutrition particularly affects vulnerable populations, including the elderly, individuals with chronic diseases, and those recovering from surgery or illness.^8,9

Causes of malnutrition

There are several potential causes of malnutrition, which can be physical, medical or psychosocial. Physical causes may include dysphagia — difficulty swallowing — common among stroke patients and individuals with neurological disorders, leading to malnutrition due to an inability to swallow. Poor dental health can also make eating painful or difficult.^8,9

There are a wide range of medical causes of malnutrition. Inflammatory bowel disease can disrupt an individual’s ability to digest food or absorb nutrients. Nausea, vomiting, dry mouth or altered taste perception caused by disease or treatment can reduce dietary intake and lead to malnutrition. Chronic diseases, including cancer, chronic obstructive pulmonary disease and diabetes, may increase energy needs while decreasing appetite.

Psychosocial factors can also play a significant role in malnutrition. Mental health conditions may greatly impact appetite and eating habits. Additionally, financial constraints, low education levels, and substance abuse may contribute to malnutrition.^8,9

Consequences of malnutrition

Malnutrition affects the function and recovery of every organ system, leading to severe health consequences. Reduced muscle strength and function are among the primary consequences, contributing to frailty and falls. Malnutrition also weakens the immune system, increasing the risk of infections and delaying wound healing and recovery from illness. Furthermore, malnutrition may contribute to cognitive decline and poor mental health outcomes. Lastly, malnutrition can negatively affect cardiac, respiratory and gastrointestinal function.⁸

Oral nutritional supplements (ONS)

ONS are food products specifically designed to provide energy, protein and other nutrients. They are a mainstay in managing malnutrition in adults with reduced appetite or specific dietary restrictions. ONS are nutritionally complete and provide a balanced blend of micronutrients and macronutrients in an easy-to-consume formulation. Patients should continue consuming regular meals and snacks, with ONS serving as an addition to, rather than a replacement for, regular meals.

ONS come in various forms, including powdered supplements, ready-made milk-based supplements, or juice-style supplements. For patients with difficulty swallowing, semi-solid or pudding-type supplements may be prescribed. Evidence has demonstrated that ONS can effectively increase protein intake, improve nutritional status, enhance muscle strength and function, and improve the quality of life for patients with malnutrition or at risk of malnutrition. ONS are also valuable for patients recovering from illness or surgery. For individuals with swallowing difficulties, texture-modified diets or thickened liquids may be necessary to reduce the risk of aspiration.^10,11

Role of the pharmacist

Malnutrition is a significant and often overlooked issue among adults, particularly affecting the elderly and those with chronic illnesses. Pharmacists, as accessible healthcare professionals, play a critical role in promoting adult nutrition. They are often the first point of contact for individuals experiencing loss of appetite, weight loss and fatigue. Pharmacists can recognise these signs and refer patients to appropriate healthcare providers.

Pharmacists have the knowledge to educate patients on nutrient-dense foods, highlighting the importance of macronutrients and micronutrients. This is particularly important for vulnerable groups and may involve advice on dietary intake and supplementation. They can also counsel patients on ONS options, explaining how to integrate them into their diet and developing suitable plans for nutritional supplementation.

Additionally, pharmacists collaborate with dietitians, general practitioners and other healthcare professionals to develop comprehensive management plans for patients, ensuring continuity of care and optimising patient outcomes.