Nutrient

A nutrient is a substance that helps living things survive, grow, and make more of their own kind. Animals, plants, fungi, and protists all need nutrients to live. These nutrients can be used by cells for energy or to build things like hair, scales, feathers, or exoskeletons. Every living thing needs water, and different organisms need different types of nutrients.

For animals, important nutrients include energy sources, some amino acids that build proteins, certain fatty acids, vitamins, and minerals like iron. Plants need many minerals from the soil, plus carbon dioxide and oxygen from the air. Fungi get their nutrients from other living or dead organisms.

Nutrients can be divided into two main groups: macronutrients and micronutrients. Macronutrients, like carbohydrates, fats, proteins, and water, are needed in large amounts to give energy and build body parts. Micronutrients, such as vitamins and some minerals, are needed in tiny amounts to help the body work properly. Not getting enough nutrients can make it hard for living things to grow and stay healthy.

Types

Main article: Nutrition

Macronutrients

Macronutrients are foods we need a lot to give us energy and help our bodies grow. The big parts of our food are carbohydrates, proteins, and fats. We also need a lot of water, but it doesn’t give us energy.

Carbohydrates are made of sugar and give us quick energy. Proteins help build and fix our body parts. Fats help keep our cells healthy and keep us warm.

Micronutrients

Micronutrients are tiny parts of our food that we need, even in small amounts. These include vitamins and minerals like potassium, sodium, and iron. They help our bodies work properly and stay healthy.

Essentiality

Essential nutrients

An essential nutrient is something our bodies need to work properly, but we can't make it ourselves. We have to get it from food or drinks. Besides water, which we all need to stay alive, there are important nutrients we must get from eating. These include special kinds of building blocks for proteins called amino acids, certain fats called fatty acids, vitamins, minerals, and a compound called choline. Some nutrients become very important for us only when we are growing, sick, or in special situations.

Amino acids

Main article: Essential amino acid

Our bodies need certain amino acids that we can't make. These nine amino acids must come from our food: phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.

Fatty acids

Main article: Essential fatty acid

There are two kinds of fatty acids we must get from food because our bodies can't make them: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).

Vitamins and vitamers

Main article: Vitamin

Vitamins are special organic molecules we need but can't make ourselves. There are thirteen vitamins we need, and many of them come in related forms called vitamers. They help our body work properly. The vitamins are: vitamins A, C, D, E, K, thiamine (B₁), riboflavin (B₂), niacin (B₃), pantothenic acid (B₅), pyridoxine (B₆), biotin (B₇), folate (B₉), and cobalamin (B₁₂). Some people can make vitamin D if they get enough sunlight.

Minerals

Main article: Mineral (nutrient)

Minerals are important elements we need from our food. Some important minerals for humans are potassium, chloride, sodium, calcium, phosphorus, magnesium, iron, zinc, manganese, copper, iodine, chromium, molybdenum, and selenium. Cobalt is also important because it is part of vitamin B₁₂.

Choline

Main article: Choline

Choline is important for our bodies. It helps keep our liver and muscles healthy. We can make a little bit of choline ourselves, but we still need to get some from our food.

Conditionally essential

Sometimes our bodies can't make enough of certain nutrients when we are babies, growing fast, or sick. These include inositol, taurine, arginine, glutamine and nucleotides. These are especially important for babies.

Non-essential

Main article: Dietary fiber

Some things in food are not essential nutrients but still good for us. For example, dietary fiber isn't absorbed by our bodies but helps keep our digestion healthy.

Non-nutrients

Ethanol (like in alcohol) gives us energy but no nutrients. Alcoholic drinks have a lot of energy but no essential nutrients, so they are called empty calorie foods. There are also many plant compounds called phytochemicals that may be good for us, but we don't yet know enough to say they are real nutrients.

Deficiencies and toxicity

If a body does not get enough of a nutrient, it is called a deficiency. This can happen if a person does not eat enough of that nutrient, or if their body cannot use it properly. Problems with absorbing the nutrient, needing more of it, or losing too much of it can cause deficiencies.

Having too much of a nutrient can also be harmful, which is called toxicity. Different countries and groups suggest different amounts of nutrients that are safe to eat every day. For example, the amount of vitamin C that is recommended can vary from one place to another. The tables show these recommended amounts and the most that should be eaten to stay safe.

Plant

Main articles: Plant nutrition and Fertilizer

Plants get carbon, hydrogen, and oxygen from the air and soil as carbon dioxide and water. They also take in other nutrients from the soil. There are 17 important nutrients for plants. Some, like nitrogen, phosphorus, and potassium, are needed in larger amounts. Others, like iron and zinc, are needed in smaller amounts. These nutrients help plants grow and stay healthy. They come from things like water, air, and different compounds in the soil.