There are six essential nutrients that the body needs to function properly. A nutrient must have a specific human biological function to be considered essential. Furthermore, its absence impairs certain biological functions in the body.
Nutrients supply the body with energy (measured in kilocalories), provide the building blocks for growth and development, and keep the bodily functions running smoothly.
The essential nutrients are divided into two main categories. Carbohydrates, proteins, fats, and water are needed in large quantities and are therefore called macronutrients. Vitamins and minerals are required in small amounts in our diet and are thus called micronutrients.
Grains, tuber crops, fruits, and vegetables are the primary source of carbohydrates. Carbohydrates are made up of a combination of the elements carbon, hydrogen, and oxygen. Small carbohydrate structures are called sugars or simple carbohydrates (e.g. glucose and sucrose). Larger carbohydrate structures are called polysaccharides or complex carbohydrates (e.g. starches, fiber, and glycogen).
Most of the cells in the body rely on glucose for energy. Glucose is produced by the body from simple carbohydrates and starches taken in as food. Glucose and other forms of carbohydrates produce an average of 4 calories per gram (kcal/g). Fiber, because of its indigestible nature, provides little or no energy.
When the body takes in too little carbohydrates to produce sufficient glucose, the body is forced into ketosis. During this metabolic process, the body produces glucose from protein sources.
Meat, eggs, dairy products, and legumes are the primary sources of proteins. Proteins are made up of the elements carbon, hydrogen, oxygen, and nitrogen. This macronutrient is the main structural material that constitutes the muscles, blood cells, enzymes, and cell membranes.
Proteins are formed by the combination of amino acids. There are 20 common amino acids and 9 of them are essential to the body. These 9 amino acids cannot be produced by the body and have to be sourced from food.
As an energy source, protein provides 4 calories per gram (kcal/g) on average. The body typically does not depend on protein for energy, but it may become a major source of fuel when the body is low on glucose.
Fats or lipids are generally sourced from animal fats and vegetable oils. Essential fatty acids play an essential role in regulating blood pressure and nerve transmissions, as well as forming structural components of cell walls.
Like carbohydrates, fats are made up of the elements carbon, hydrogen, and oxygen. Most fats are categorized into two basic types depending on their chemical structure. Oils from plants are usually categorized as unsaturated fats, which remain liquid at room temperature and tend to be healthier. Animal fats are usually saturated and usually solidify at room temperature. Saturated fats may raise blood cholesterol and may clog arteries, thus leading to cardiovascular disease.
As an energy source, fats provide 9 calories per gram (kcal/gram) on average, making it the highest energy source. Triglyceride is the major form of fat in foods and a major form of energy stored in the body. This fat is composed of 3 fatty acids bound to a glycerol molecule.
Vitamins are composed of different chemical structures from elements such as carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus and others. They do not provide any usable energy for the body but are essential in enabling many chemical reactions necessary for proper body function. For example, they help release energy in carbohydrates, proteins, and fats.
There are 13 kinds of vitamins and they are divided into fat-soluble vitamins (Vitamins A, D, E, and K) and water-soluble vitamins (Vitamin C and B vitamins – thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate, and cobalamin).
Water-soluble vitamin are usually destroyed during cooking and are much more readily excreted by the body. Fat-soluble vitamins are less likely to be destroyed during cooking, but have the tendency to accumulate more in the body and cause toxicity in excess amounts.
The above-mentioned nutrients thus far are considered organic compounds. This means that their chemical structure contains carbon atoms bonded to hydrogen atoms. Organic in this sense does not refer to organic farming but chemical structure only.
Minerals are inorganic substances and therefore do not contain carbon and hydrogen bonds. These are typically made out of one or more of the same atoms or a combination of different minerals. Since minerals are elements, they are not destroyed during the cooking process.
Minerals are not sources of energy, but play a key role in normal body function. There are two groups of minerals. Major minerals are those needed by the body in larger amounts (grams), while trace minerals are those needed by the body in small amounts (milligrams or micrograms). Major minerals include sodium, chloride, calcium, potassium, and phosphorus. Trace minerals include copper, zinc, and selenium.
Water is often overlooked as a nutrient, but it is the most necessary macronutrient for proper body function. It acts as a solvent and lubricant, as well as the means for transporting nutrients to the different cells in the body. It is also very useful in maintaining normal body temperature.
Water can be taken in its purest form or in beverages and foods that contain it. In some instances, the body produces water as a by-product of metabolism.
Fun Fact: While alcohol does provide the body with energy, it is not considered an essential nutrient.
There are 6 essential nutrients that the body needs to function properly. Carbohydrates, proteins, and fats provide the body with energy. Protein provides the building blocks for muscles. Vitamins and minerals do not provide energy but are essential in chemical processes and reactions. Water is necessary for transporting nutrients to the cells, regulating body temperature and so much more.
Other substances are beneficial for the body and may provide energy, but may not be considered essential. Alcohol, for instance, is rich in energy but has no required function. Phytochemicals and zoochemicals from plants and animals may provide health benefits, but are also not considered essential for proper body function.