Sometimes, in the day-to-day cycle of eat, sleep, repeat, you can lose track of why you're doing it all in the first place. Eating food isn't just something you do when you get hungry; it's something you do to provide your body with energy and nutrients used to build and repair cells.
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All food groups — carbohydrates, proteins, fats, vitamins and minerals — work together to give your body energy and nutrients. They help build and maintain body cells and tissues.
How Body Cell Repair Works
Your body is made up of approximately 100 trillion cells that are so tiny that they can only be seen under a microscope. These cells are like building blocks because they group to make tissues, tissues group together to make organs, organs group together to make systems and systems group together to make you, an organism.
The cells in your body are not all the same. There are more than 200 different types of cells in your system. Your bones are made of bone cells, for example, and those cells are not the same as the cells in your lungs. When your cells die or get damaged in any way, your body generates new cells to replace them.
This happens through a process called cell division, where one cell splits into two identical cells, those two split into four, and so on. Some cells mature and don't reproduce very often, but others, like skin cells or blood cells, for example, are constantly dividing.
The body's ability to repair itself is astounding. The U.S. National Library of Medicine notes that even if half your liver is damaged, your body can repair the damage or grow new liver cells to maintain most of your liver capacity.
So, where does food come in? The food you eat provides energy as well as the nutrients that the cells in your body use for growth, repair and regulation of bodily functions. There are over 50 known nutrients that help build and maintain the body's cells and tissues.
Carbohydrates Supply Energy
According to the National Institutes of Health (NIH), carbohydrates are your body's primary source of energy. The European Food Information Council (EUFIC) explains that when you eat carbohydrates, your body breaks them into glucose, which is released into the bloodstream for energy. Glucose is also converted into glycogen and stored in your liver and your muscles as a ready source of fuel to power your activity.
Each gram of carbohydrates supplies 4 calories of energy. One gram of fiber, which is also a type of carbohydrate, supplies 2 calories. The NIH notes that fruits, vegetables, dairy products and grains all contain carbs in some form. These carbohydrates are preferable to those in sugar, syrups, sweets and sugary drinks because they also offer nutrients, like vitamins and minerals, in addition to energy.
According to the EUFIC, carbohydrates also play a critical role in the structure and function of your cells, tissues and organs.
Proteins Build and Repair Tissues
According to the NIH, proteins are often referred to as the building blocks of your body because they are critical to the growth and repair of your cells. In fact, protein is a major part of each of your hair, skin, nail, muscle, bone and organ cells, and it's also found in most of your bodily fluids.
Your body can also use proteins as an energy source. Like carbohydrates, each gram of protein supplies 4 calories. Proteins consist of amino acids. There are 20 different types of amino acids, of which nine are considered essential because your body cannot make them on its own and needs to obtain them from food.
The NIH lists lean meat, eggs, poultry, seafood, beans, peas, soy products, dairy products, nuts and seeds as some of the sources of protein. Animal proteins are considered to be complete proteins as they contain all nine essential amino acids.
With a few exceptions, plant proteins are incomplete proteins because they don't contain all the essential amino acids. However the NIH notes that they are still extremely healthy as they don't have any cholesterol, are lower in saturated fat and provide fiber and other nutrients that help build and maintain cells and tissues.
Fats Build Cells and Membranes
According to the Academy of Nutrition and Dietetics, fats help provide structure to your cells and also cushion your cell membranes to help prevent them from getting damaged. Fats are also a concentrated source of energy.
Each gram of fat supplies your body with 9 calories. That's more than twice the energy you'd get from carbs or protein. Your body also needs fats to absorb fat-soluble vitamins, such as vitamins A, D, E and K.
The NIH notes that fats occur naturally in many foods, including meat, poultry, eggs, seafood, nuts, seeds, dairy products, avocados and coconuts. Oils are also a source of fat.
There are different types of fats. Monounsaturated and polyunsaturated fats are the healthiest, saturated fats are not as healthy and trans fats are the worst.
Saturated fats are found in higher-fat meats, butter, palm oil, cakes, cookies, pizzas, burgers, tacos and casseroles. Trans fats are found in processed foods, and although manufacturers are phasing them out, they're still found in some foods like microwave popcorn, dessert, frozen pizza and margarine. The NIH recommends replacing saturated fats and trans fats in your diet with unsaturated fats.
Vitamins and Minerals Promote Health
According to the Academy of Nutrition and Dietetics, vitamins and minerals are micronutrients that play an important role in cell metabolism and support overall health. Your body needs vitamins to heal wounds, form bones, maintain your immunity, keep your eyes and skin healthy and produce energy. Minerals are important for cardiovascular function and provide structure to your skeleton.
These nutrients are used to build and repair cells. Calcium, for example, is the building block for bone cells. Iron is the building block for your blood. The Academy of Nutrition and Dietetics notes that your blood cells only last for a few months, so your body constantly requires iron and protein to make new blood.
Vitamins also have antioxidant properties and protect the cells in your body from damage. Vitamins A, C and E all serve as antioxidants and fight harmful substances known as free radicals. Free radicals can weaken healthy cells and make them more prone to cancer and cardiovascular problems.
Eating a healthy, balanced diet rich in whole fruits, a variety of vegetables, dairy products, high-protein foods and whole grains can make it easier to meet your vitamin and mineral requirements.
Correction: An earlier version of this story incorrectly identified the number of cells in the body.
- Cancer Research UK: “How Cells and Tissues Grow”
- Mayo Clinic: “Metabolism and Weight Loss: How You Burn Calories”
- National Institutes of Health: “Important Nutrients to Know: Proteins, Carbohydrates and Fats”
- European Food Information Council: “The Functions of Carbohydrates in the Body”
- Breastcancer.org: “How Your Body Gets Nutrients From Foods”
- Food and Drug Administration: “Protein”
- Academy of Nutrition and Dietetics: “How to Explain Basic Nutrition Concepts”
- USDA: “2015–2020 Dietary Guidelines for Americans”
- Academy of Nutrition and Dietetics: “Antioxidants - Protecting Healthy Cells”