Let's look at how some nutrients work together. 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.

Calcium helps build strong bones and teeth, and 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.

Fats are nutrients the body uses to build cell membranes, nerve tissue and hormones, and 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. Vitamin A helps you see in dim light.

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. Vitamin C 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.

Sodium is a mineral the body uses to control blood volume and for muscles and nerves to work; table salt is sodium chloride. Iodized salt is table salt with iodine added, and it is the main food source of iodine. Potassium is a mineral found in most foods that helps the heart muscle work and balances fluids in the body. Zinc helps the body make new cells and heal wounds. Zinc is needed for the senses of smell and taste.

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. 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. Stomach muscles mix food with digestive juices.

The squeezing movement of muscles that pushes food through the digestive tract is called peristalsis. 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

• fortified: vitamins added
• collagen: tissue protein
• peristalsis: food-pushing squeeze
• kernel: grain seed
• mineral: element from soil