The role of macronutrients

Published 2:13 pm Tuesday, March 21, 2023

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According to the World Health Organization, a nutrient is a substance required by the body for survival, growth, and reproduction. In other words, nutrients give us energy and allow our bodies to perform essential functions. 

Nutrients can be subdivided into two categories – micronutrients and macronutrients. The word macronutrient comes from the Greek “makro,” meaning long or large, and the Latin word “nutrire,” meaning “to feed, nurse, support, or preserve.” Macronutrients are compounds our bodies need in larger amounts to help every physiological system function properly. 

The main macronutrients are carbohydrates, proteins, fats, fiber, sugar and water. Sugars and fiber, fall into the carbohydrate profile. Carbohydrates are the primary source of energy for our bodies and provide the body with glucose, which is converted to energy used to support bodily functions and physical activity. They are found in a wide array of both healthful and unhealthful foods, including fruits, vegetables, legumes, bread, beans, popcorn, potatoes, cookies, spaghetti, soft drinks, corn, pies, cakes and milk products. Foods high in carbohydrates are an essential part of our diets. However, carbohydrate quality is important, as some types of carbohydrate-rich foods are better than others. The most healthful, are unprocessed or minimally processed carbohydrates such as whole grains, vegetables, fruits, beans, and legumes.   

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Proteins are the body’s building blocks. Every cell in the human body contains protein. The basic structure of protein is a chain of amino acids. Indeed, there are relatively 500 amino acids in nature, but just 20 amino acids make up the proteins found in the human body. Eight of those amino acids are referred to as essential, which simply means they must be obtained from the diet. A fundamental task of proteins is to help the body repair cells and make new ones. 

Proteins also function as catalysts, allowing chemical reactions to take place. A catalyst is a substance that speeds up a chemical reaction. Proteins are found in a variety of foods, including meat, fish, eggs, dairy products, and plant-based products like legumes and tofu. Even though protein is an essential macronutrient, all culinary sources are not created equal. For example, plant-based proteins do not have the same amino acid profile as animal-based proteins. 

My favorite source is egg protein. In fact, scientists often use egg protein (albumin) as the standard against which all other proteins are judged. Based on the essential amino acid ratios it provides, egg protein is second only to mother’s milk for human nutrition.       

Much like carbohydrates, dietary fats are an important energy source for the body. The body can manufacture certain types of fats it needs from other fats or raw materials. That’s not the case for fatty acids. Essential fatty acids are compounds that can increase health, help in treating certain diseases, and even improve body composition, mental health and physical performance. Fat serves another crucial role in the absorption of fat-soluble vitamins such as vitamins A, D, E and K. In addition, fats play an invaluable role in maintaining healthy skin and hair, insulating organs, and supporting brain function.   

Water is frequently classified as a macronutrient. This is because water is needed in relatively large amounts in order to survive. Water’s main functions in the body are to keep a regular temperature, moisten tissues of the eyes, nose, and mouth, protect organs and tissues, and disperse oxygen and nutrients to cells.

Receiving the proper balance of macronutrients is necessary for maintaining a healthy diet, and preventing chronic diseases such as obesity, diabetes, and coronary disease. Each individual’s need for macronutrients may vary, depending on factors such as age, sex, weight, and activity level. Next week, we’ll learn about micronutrients and their role in optimum health and well-being.

David Crocker is a nutritionist and master personal trainer. Questions? Email David at, or text to 864-494-6215.