Classes of Nutrients

1. Introduction to the Six Classes of Nutrients

Nutrients are substances required by our body to perform its basic functions. All foods we eat have nutrients and since our bodies cannot make these nutrients, we rely on foods for them. In our bodies, nutrients provide energy (in the form of calories), help us build muscle and bone, and regulate chemical processes. All of these functions are essential for humans to maintain life.

We divide nutrients into six classes. These are carbohydrates, lipids, proteins, water, vitamins, and minerals. From these six classes, we are able to have two main groups: macronutrients, and micronutrients. Macronutrients include carbohydrates, fat, protein, and water. The micronutrients are vitamins and minerals. Foods also contain non-nutrients like preservatives or antioxidants.

term to know

Nutrients

Substances required by our body to perform its basic functions.

2. The Key Functions of the Six Essential Nutrients

The key function of the six essential nutrients are the following:

key concept

Nutrient	Function
Protein	Necessary for tissue formation, cell reparation, and hormone and enzyme production. It is essential for building strong muscles and a healthy immune system.
Carbohydrates	Provide a ready source of energy for the body and provide structural constituents for the formation of cells.
Fat	Provides stored energy for the body, functions as structural components of cells, and signaling molecules for proper cellular communication. It provides insulation to vital organs and works to maintain body temperature.
Vitamins	Regulate body processes and promote normal body-system functions.
Minerals	Regulate body processes, are necessary for proper cellular function, and comprise body tissue.
Water	Transports essential nutrients to all body parts, transports waste products for disposal, and aids with body temperature maintenance.

Let’s take a deeper dive into the essential nutrients.

2a. Macronutrients

Macronutrients are those nutrients needed by our bodies in large amounts. The four classes of nutrients that are in the macronutrient group are carbohydrates, lipids, proteins, and water. Remember when we talked about calories before? A unit of measurement of food energy is the calorie. A kilocalorie (Calorie) is the amount of heat generated by a particular macronutrient that raises the temperature of 1 kilogram of water by 1 degree Celsius. Water is also a macronutrient but it does not provide calories.

2b. Carbohydrates

Carbohydrates are a macronutrient that is necessary for energy. Carbohydrates' main function is to provide energy for the body and, specifically, the brain. The brain solely relies on carbohydrates to provide energy for it to function. Carbohydrates are made up of starches, fiber, and sugar. Classification for carbohydrates consists of simple carbohydrates or complex carbohydrates. Examples of all types of carbohydrates include bread, pasta, rice, vegetables, fruits, potatoes, milk, and legumes.

Carbohydrates are broadly classified into two forms based on their chemical structure: simple carbohydrates and complex carbohydrates.

Simple carbohydrates consist of one or two basic units of glucose. These are called mono- or di-saccharides. Examples of simple sugars include table sugar (sucrose) and glucose, the type of sugar that circulates in your blood.

Complex carbohydrates are long chains of simple sugars that can be unbranched or branched. These are called polysaccharides.

During digestion, the body breaks down most of the complex carbohydrates into glucose. The glucose goes into our bloodstream and is transported to our cells, stored, or used to make energy.

Another complex carbohydrate is called fiber. What makes fiber different is that our digestive enzymes cannot break it down, so it passes through our digestive tract undigested unless the bacteria living in our colon or large intestine break it down. This is why having a healthy gut microbiome is so important, and we will learn about that more later on.

One gram of carbohydrates yields four calories of energy. Glucose can be stored for later or used immediately. In humans, the storage molecule of carbohydrates is called glycogen, and in plants, it is called starch.

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Complex Carbohydrates

Long chains of simple sugars that can be unbranched or branched. These are called polysaccharides.

2c. Protein

Proteins are made of amino acids. Amino acids are simple subunits composed of carbon, oxygen, hydrogen, and nitrogen. Protein can provide energy, but its main function is to provide structure and function to cells, muscles, bones, and skin. There are multiple types of protein sources, such as animal proteins like chicken, beef, fish, and cheese. There are also plant-based proteins, such as beans, legumes, and seeds. Consuming diets that are too high in protein could lead to health issues including metabolic issues of the liver, kidneys, and bones, and increase the risk of cardiovascular disease. Not consuming enough protein could lead to weakness, fatigue, possible anemia, and muscle loss. Proteins provide four kilocalories of energy per gram.

term to know

Amino Acids

Simple subunits composed of carbon, oxygen, hydrogen, and nitrogen.

2d. Lipids

Lipids (or fats) are also a family of molecules composed of carbon, hydrogen, and oxygen. Fat provides energy, protects our organs, plays a critical role within cells and hormones, and regulates our body temperature. Fat can be categorized into triglycerides, phospholipids, and sterols. Fats can also be separated into trans fat, saturated fat, and unsaturated fat. Examples of fat include olive oil or any type of vegetable oil, butter, and nuts. Excessive consumption of fats could lead to hyperlipidemia or possible obesity. If not enough fat is consumed, this could lead to vitamin deficiencies because fat helps with the absorption of other nutrients. Lipids provide nine calories per gram versus four calories per gram of carbohydrates and proteins.

2e. Water

Water is a macronutrient but does not provide any energy. Water's main function is for transportation, chemical reactions, and body temperature regulation, digestion, and lubricating joints. Water is unique because humans can only go three days without water. Drinking too much water can lead to water intoxication leading to confusion, headaches, dizziness, and bradycardia. Not drinking enough water could lead to dehydration, constipation, dizziness, fatigue, and dry mouth.

2f. Micronutrients

Micronutrients are required by the body in smaller amounts but are still essential to help our bodies function well. There are 16 minerals and 13 vitamins that are considered essential micronutrients. Micronutrients do not provide direct energy (calories), but they help to make energy when they act as components of enzymes (coenzymes). Enzymes are proteins that catalyze chemical reactions. Enzymes are important for almost all of our body functions and help with digestion.

term to know

Enzymes

Proteins that catalyze chemical reactions.

2g. Minerals

Minerals are used for fluid balance, enzymes, synthesis of hormones, and protecting against free radicals. Minerals are broken down into trace minerals and major minerals. The trace minerals include iron, zinc, iodine, selenium, copper, manganese, fluoride, and chromium. The major minerals are sodium, chloride, potassium, calcium, phosphorus, magnesium, and sulfur. Taking excessive amounts of minerals creating mineral toxicity can lead to nausea, vomiting, diarrhea, suppressed immunity, brittle nails and hair, and constipation. Mineral deficiencies could be expressed as abdominal cramps, and issues, irregular heartbeat, nausea, vomiting.

2h. Vitamins

Vitamins play an important role in many chemical functions in the body, such as immunity, vision, and making new cells. Vitamins are broken into two sections water-soluble vitamins, such as thiamin, riboflavin, pantothenic acid, folate, biotin, niacin, pyridoxine, vitamin C, and B12, and fat-soluble vitamins, vitamins A, D, E, and K. Not all vitamins have a toxicity limit, but taking too much of a vitamin can lead to nausea, vomiting, diarrhea, headaches, and possibly blurred vision. Not taking enough vitamins could lead to anemia, bone abnormalities, neurological problems, and blood clotting problems, depending on the vitamin.

Overall each nutrient plays an important role in everyday life to provide energy and other functions within the body. Consumption of each nutrient in adequate amounts is recommended to avoid toxicity or deficiencies.

REFERENCES

Macronutrients. NAL. (n.d.). Retrieved May 11, 2022, from www.nal.usda.gov/legacy/fnic/macronutrients

Youdim, A. (2022, April 18). Overview of nutrition - nutritional disorders. Merck Manuals Professional Edition. Retrieved May 11, 2022, from www.merckmanuals.com/professional/nutritional-disorders/nutrition-general-considerations/overview-of-nutrition