Human nutrition

Food gives our bodies what we need to live.

We get many things from our food. Some parts give us energy to move.

These parts are called macronutrients. They include things like fats and proteins. We also need smaller parts called micronutrients. These are vitamins and minerals. Our bodies cannot make these parts on their own. We must get them from the food we eat. Eating good food helps us grow well.

It also keeps our bodies healthy.

Food gives our bodies what we need to stay healthy.

To do this, food provides nutrients. Nutrients are parts of food that support life. Some nutrients are called macronutrients. These are needed in large amounts. They include carbohydrates, fats, and proteins.

These three types provide power, or energy, for our bodies. Carbohydrates and proteins give about 17 kJ of power per gram. Fats give much more. They give 37 kJ of power per gram.

Other nutrients are called micronutrients. These are vitamins and minerals. We only need them in small amounts. Water and fiber are also important. They are macronutrients, but they do not give power. Our bodies cannot make essential nutrients on their own. We must get them from the food we eat. If we do not get enough, we can get sick. Good nutrition helps children grow in body and mind.

Food provides the essential nutrients our bodies need to stay healthy.

These nutrients support human life and help children grow in body and mind. If people do not get enough nutrients, it is called malnutrition. This can lead to serious problems like disabilities or even death. Poor nutrition is often linked to poverty or not knowing what the body needs.

Getting the right balance of food is a vital part of staying well.

Nutrients are divided into two main groups based on how much we need. Macronutrients are needed in large amounts to provide energy and building materials. These include carbohydrates, fats, and proteins.

Some macronutrients, like water and fiber, do not provide energy at all. Micronutrients are vitamins and minerals that we only need in small amounts.

Our bodies cannot make essential nutrients on their own. We must get them directly from the food we eat.

Different nutrients work in different ways to power our bodies. Carbohydrates and proteins provide about 17 kJ of energy per gram. Fats provide much more energy at 37 kJ per gram.

Some nutrients are used for structure, like the amino acids that build proteins. Fats can also build cell membranes. Some vitamins can be stored in the body for later. Other nutrients must be taken in more or less continuously to work.

Scientists use special guides to help people know how much to eat. The Recommended Dietary Allowances, or RDAs, were first published in 1943 during World War II.

These were created to set standards for the best possible nutrition. In the United States and Canada, people now use the Dietary Reference Intake (DRI). The National Academy of Medicine created the DRI in 1997 to expand on older rules. The United Kingdom uses different standards called Dietary Reference Values (DRVs).

Understanding these nutrients helps us make better choices every day. For example, fats can be saturated or unsaturated. Saturated fats are often solid at room temperature, like butter. Unsaturated fats are often liquids, like olive oil.

Some fats, called essential fatty acids, must come from food. These include omega-3 and omega-6 fatty acids. By learning about these different parts of food, we can better support our health.

Human nutrition is the study of how essential nutrients in food support life and health. These nutrients are necessary for normal biological development and mental growth in children. When a person does not receive enough nutrients, they experience malnutrition. Malnutrition is a major contributor to disabilities, physical deformities, and deaths worldwide. This issue is often linked to poverty, food security, or a lack of understanding regarding nutritional needs.

Nutrients are categorized into two main groups: macronutrients and micronutrients. Macronutrients are required in large amounts to provide energy and structural materials. This group includes carbohydrates, fats, and proteins. Water and fiber are also macronutrients, though they do not provide energy. Micronutrients are vitamins and minerals, which the body requires in much smaller quantities.

Macronutrients serve different roles in the body's chemistry. Carbohydrates and proteins provide approximately 17 kJ of energy per gram. Fats are more energy-dense, providing about 37 kJ per gram. These nutrients also provide the building blocks for the body. For example, amino acids are the components used to build proteins. Lipids, or fats, are used to construct cell membranes and signaling molecules.

Carbohydrates are a diverse group of substances found in foods like rice and bread. They are classified by the number of sugar units they contain. Monosaccharides, such as glucose and fructose, contain one unit. Disaccharides, like sucrose, contain two units. Polysaccharides, such as starch and glycogen, contain three or more units and are called complex carbohydrates. While not an essential nutrient, carbohydrates are a primary energy source.

Fats, or lipids, typically consist of triglycerides. A triglyceride is made of three fatty acids attached to a glycerol backbone. Fats are classified as saturated or unsaturated based on their chemical structure. Saturated fats have hydrogen atoms bonded to every carbon in their chains. Unsaturated fats have one or more double-bonds between carbon atoms. These are further divided into monounsaturated or polyunsaturated fats, such as omega-3 and omega-6 fatty acids.

Proteins are essential for life because they contain nitrogen atoms. The fundamental building blocks of protein are nitrogen-containing amino acids. Some of these are "essential," meaning the human body cannot synthesize them internally. In these cases, they must be obtained through food. If the body lacks glucose, it can undergo gluconeogenesis. This process converts certain amino acids into glucose to produce energy.

To ensure people eat enough nutrients, scientists developed specific guidelines. The Recommended Dietary Allowances (RDAs) were first published in 1943 during World War II. Originally intended for national defense, the RDAs helped set standards for optimal nutrition. In 1997, the National Academy of Medicine established the Dietary Reference Intake (DRI) in the United States and Canada. The DRI expanded upon the older RDA standards to provide a broader range of recommendations.

The United Kingdom uses a different system called Dietary Reference Values (DRVs). These standards help assess and plan dietary intakes for the population. The DRVs include the Reference Nutrient Intake (RNI), which meets the needs of 95% of people. They also include the Estimated Average Requirement (EAR) for 50% of the population. Finally, the Lower Recommended Nutritional Intake (LRNI) addresses the needs of 5% of the population.