What Are Functions of Proteins, Carbohydrates, Fats, Water, Vitamins and Minerals?

Essential nutrients are substances that must be obtained from foods because the body isn't able to synthesize them. These include water, proteins, carbohydrates, fats, vitamins and minerals, says Washington State University. Each dietary component has specific functions that promote health.

The National Institutes of Health Genetics Home Reference describes proteins as long chains of hundreds or thousands of building units called amino acids. In making proteins, the body chooses among 20 amino acids, and their sequence within each type of protein determines the structure and function. Antibodies, enzymes and hormones are all proteins. Other types of proteins perform structural and transportation functions.

Protein foods come from both plants and animals, notes the USDA. Plant sources are beans (including soy products), peas, nuts and seeds. Animal sources are eggs, seafood, poultry and red meat.

For a healthy eating strategy, consume a variety of proteins, advises the USDA. Eat types of fish that are plentiful in omega-3 fatty acids, such as salmon or tuna, at least twice a week. Bean dishes like lentil soup or veggie burgers are examples of using plant protein sources as a main dish. Limit your intake of red meat and processed meat because they're linked to some cancers, warns the National Cancer Institute.

The three kinds of carbohydrates are starches, sugar and fiber. The body breaks down starches and sugar into glucose, which is the only energy source for red blood cells and the preferred energy source for the brain and the central nervous system. When the diet is deficient in glucose, the body breaks down protein in muscles to supply sufficient glucose to the brain.

As the part of carbohydrates not broken down, fiber promotes satiety and weight management. The two types of fiber are soluble, which decreases cholesterol and can help regulate blood glucose, and insoluble, which facilitates the movement of stools through the digestive tract and fosters regularity. In addition, evidence shows fiber reduces the risk of chronic disease, according to Dietary Guidelines for Americans.

The Centers for Disease Control and Prevention (CDC) lists sources of starches as grains, lentils, peas, beans and starchy vegetables, such as potatoes, corn, parsnips, yams and winter squash. Sugar food sources involve the natural sugars found in fruit and milk, as well as honey, molasses, corn syrup, white sugar and brown sugar.

Fiber sources include lentils, peas, beans, fruits, vegetables and nuts like pecans, almonds and peanuts. Other high-fiber food sources are whole grains such as oats, brown rice, barley and foods comprised totally of whole grain flours. The latter involve breads, cereals, tortillas and pastas made of 100-percent whole wheat or whole grains.

Refined grains includes white rice and pasta made with white flour, says the CDC. Other sources are bread and baked goods made with white flour such as crackers, cookies, cakes and muffins. Such foods don't contain fiber and they're lacking in nutrients.

The CDC advocates choosing healthy carbohydrates, which refers to those that are low in sugar, calories and fat but rich in fiber, water and vitamins. For example, eat whole fruit instead of drinking fruit juice and opt for brown rice rather than white rice. Select bread made with 100-percent whole-grain or whole-wheat flour, and avoid bread made with white flour. Try a stewed apple with cinnamon in place of a slice of apple pie.

In other words, get your daily carbohydrate intake from fruits, vegetables and whole grains instead of from refined grains and simple sugars.

Read more: List of Starchy Carbs

Fats supply energy and facilitate the absorption of vitamins A, E, D and K, states MedlinePlus. Nutrients from fat include linoleic and linolenic fatty acids, which lower inflammation and contribute to blood clotting and brain development.

The consumption of saturated fat and trans fat is associated with unhealthy cholesterol levels, but the consumption of monounsaturated and polyunsaturated fat is linked to lower cardiovascular risk, says MedlinePlus. Omega-3 fatty acids are connected to anti-inflammatory effects, but omega-6 fatty acids are tied to pro-inflammatory effects, notes the Arthritis Foundation.

Limit intake of foods high in saturated fat, such as meat, cheese and butter, along with foods that contain trans fat like margarine and shortening. The Academy of Nutrition and Dietetics recommends eating the aforementioned fatty fish like salmon. Nuts, avocados, flaxseed, eggs and olive oil are also healthy fat choices.

Read more: 18 Fat-Rich Foods That Are Good for You

The functions of water are varied. It lubricates joints, regulates body temperature, helps prevent constipation, aids the kidneys in flushing out wastes and protects organs and tissues, says the Mayo Clinic. Water also moistens tissues and carries nutrients to the cells.

Functions of vitamins and minerals are many and wide-ranging. For instance, vitamin A preserves vision and keeps the skin healthy, and vitamin C reduces the risk of the common cold. Calcium helps build strong bones and teeth, iron enables oxygen transport in the blood and zinc boosts the immune system.

Brain development during pregnancy and the first two years of life determines lifetime brain function, asserts Harvard Health Publishing. During this time, nerves grow, connect and are encased in an insulating sheath called myelin. The process creates a system that plays a pivotal role in attention, learning, memory, processing speed, impulse control and mood. Once created, this system is permanent and cannot be changed.

Harvard Health Publishing says that, aside from nondietary factors like nurturing, certain nutrients are critical for healthy brain development. These include protein and long-chain polyunsaturated fatty acids like omega-3 fatty acids. Important vitamins include the following:

• Choline from eggs, dairy, meat and many vegetables
• Folate from spinach
• Vitamin A from carrots, spinach and sweet potatoes
• Vitamin B6 from fish, potatoes and noncitrus fruits
• Vitamin B12 from fish, dairy products and eggs

These minerals are also critical:

• Zinc from fish, nuts and dairy products
• Iron from beans, lentils, baked potatoes and dark leafy vegetables
• Iodine from iodized salt, dairy products and seafood

A February 2018 study published in Pediatrics emphasizes how necessary the adequate intake of protein, fat and glucose is for the developing brain. Deficits in any of these nutrients is linked to lower IQ scores and more behavioral problems.

While nutritional inadequacies result from undernutrition, they can also be due to obesity because excess calories often come at the expense of required dietary components. Both undernutrition and obesity can impair brain development, and it's possible for them to coexist in a person.