Let's look at how scientists found vitamins. There are 13 vitamins that your body needs. In 1897 Christiaan Eijkman concluded that a substance in the husk of rice protected against the symptoms he had seen in hens fed milled rice; it was later named vitamin B1. Around 1910 Frederick Hopkins found that young rats fed only pure nutrients stopped growing, but a small amount of milk started their growth again. Hopkins's rat experiments led to the idea that unknown substances, later called vitamins, are needed in small amounts for life processes.

In 1912 biochemist Casimir Funk was the first to coin the term vitamin in a research publication accepted by the medical community. The word vitamin comes from vita, meaning life, and amine, a nitrogenous substance essential for life. Eijkman and Hopkins shared the 1929 Nobel Prize in Physiology or Medicine for discovering vitamins. The discovery of all the vitamins occurred by 1948.

Some vitamins dissolve in fat. Fats are nutrients the body uses to build cell membranes, nerve tissue and hormones. Vitamins A, D, E and K are fat-soluble: they dissolve in fat and are stored in the body. Fat-soluble vitamins are absorbed with the help of fat, so some fat in the diet is needed to absorb vitamins A, D, E and K. Vitamin K helps blood to clot, so cuts and scrapes stop bleeding quickly, and vitamin A helps you see in dim light. Oily fish such as salmon and sardines are particularly high in long-chain omega-3 fatty acids.

Other vitamins dissolve in water. Vitamin C and the B vitamins dissolve in water and are not stored, so the body needs a fresh supply each day, and the body loses unused water-soluble vitamins mostly in urine. Vitamin C helps the body heal wounds, and it is needed to make collagen, a fibrous protein in connective tissue. Vitamin B12 is not found naturally in fruit, vegetables or grains; it comes from animal foods or fortified foods.

Calcium helps build strong bones and teeth, and milk, yogurt and cheese are dairy foods that contain calcium. Vitamin D helps the body absorb calcium, which is needed for normal bone formation. The body makes vitamin D when sunlight shines on the skin, and very few foods naturally contain vitamin D, so many foods are fortified, which means vitamins have been added. As of November 2026, most milk in the United States is fortified with 400 IU of vitamin D per quart.

Minerals are elements from soil and water that plants absorb and animals eat. Iron helps make red blood cells, which carry oxygen around the body. Beans, nuts and dried fruit are plant foods that contain iron. Foods rich in vitamin C, such as citrus, strawberries, tomatoes and potatoes, increase iron absorption, and tea can bind iron so the body cannot use it. Eating some meat, fish or poultry with beans or dark leafy greens can improve absorption of plant iron up to three times.

Your body needs protein to repair cells and make new ones, and protein is found throughout the body, in muscle, bone, skin, hair and almost every other tissue. Beans are a plant food that gives your body protein, and fish, eggs and meat are foods from animals that give your body protein. Foods from animals such as milk, eggs and fish, and from plants such as soy and beans, both supply the amino acids in protein. Nine amino acids are called essential because they must come from food.

Food gives your body energy. Starches are also called complex carbohydrates, and starchy foods are the main source of carbohydrate in our diet. Whole grains such as brown rice, oats, barley and quinoa are starchy foods. Whole grain kernels have three parts, the bran, germ and endosperm, and each holds different nutrients. In a grain kernel, the bran is the fibre-rich outer layer, the germ is the core of the seed where growth occurs, and the endosperm holds carbohydrates and protein.

Let's follow a bite of food. Food is broken into tiny pieces so the body can absorb the nutrients it needs. Saliva starts to break down starches in food while the food is still in your mouth. After you swallow, muscles push food down the esophagus into the stomach, and stomach muscles mix food with digestive juices. Your digestive system breaks proteins into amino acids, fats into fatty acids and glycerol, and carbohydrates into simple sugars.

The small intestine takes digested nutrients into the blood. The large intestine absorbs water and turns waste into stool. Fibre is a type of carbohydrate that the body cannot digest, and it is a part of plant foods that helps other food and waste move through the gut.

Fibre-rich foods include whole grains, beans, vegetables, fruits, nuts and seeds. Different fruits and vegetables contain different mixes of fibre, vitamins and minerals, so a variety gives the body more. Eating a mix of different foods is the best way to get the vitamins and minerals you need.

Words to know

• vitamin: needed nutrient
• husk: outer shell
• fortified: vitamins added
• esophagus: food tube
• calcium: bone mineral