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Types of Nutrients
Jessica Harwood
Douglas Wilkin, Ph.D.
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AUTHORS
Jessica Harwood
Douglas Wilkin, Ph.D.
EDITOR
Douglas Wilkin, Ph.D.
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Printed: January 29, 2015
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C HAPTER
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Chapter 1. Types of Nutrients
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Types of Nutrients
Identify sources of nutrients.
Identify the roles of carbohydrates, proteins, and lipids.
Distinguish simple carbohydrates from complex carbohydrates.
Distinguish saturated fats from unsaturated fats.
What nutrients are in this meal?
There are many different nutrients that are present in this meal. For example, the steak is a source of protein. The
french fries are a source of carbohydrates. Both these nutrients help supply the body with energy.
Nutrients
Carbohydrates, proteins, and lipids contain energy. When your body digests food, it breaks down the molecules of
these nutrients. This releases the energy so your body can use it.
Carbohydrates
Carbohydrates are nutrients that include sugars, starches, and fiber. There are two types of carbohydrates: simple
and complex. Pictured below are some foods that are good sources of carbohydrates ( Figure 1.1).
Simple Carbohydrates
Sugars are small, simple carbohydrates that are found in foods such as fruits and milk. The sugar found in fruits
is called fructose. The sugar found in milk is called lactose. These sugars are broken down by the body to form
glucose (C6 H12 O6 ), the simplest sugar of all.
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FIGURE 1.1
Up to the age of 13 years, you need about
130 grams of carbohydrates a day. Most
of the carbohydrates should be complex.
They are broken down by the body more
slowly than simple carbohydrates. Therefore, they provide energy longer and more
steadily.
Where does glucose come from? Recall that glucose is the product of photosynthesis, so some organisms such as
plants are able to make their own glucose. As animals cannot photosynthesize, they must eat to obtain carbohydrates.
Through the process of cellular respiration, glucose is converted by cells into energy that is usable by the cell (ATP).
Complex Carbohydrates
Starch is a large, complex carbohydrate made of thousands of glucose units (monomers) joined together. Starches
are found in foods such as vegetables and grains. Starches are broken down by the body into sugars that provide
energy.
Fiber is another type of large, complex carbohydrate that is partly indigestible. Unlike sugars and starches, fiber does
not provide energy. However, it has other important roles in the body. For example, fiber is important for maintaining
the health of your gastrointestinal tract. Eating foods high in fiber also helps fill you up without providing too many
calories. Most fruits and vegetables are high in fiber. Some examples are pictured below ( Figure 1.2).
Proteins
Proteins are nutrients made up of smaller molecules called amino acids. Recall that there are 20 different amino
acids arranged like "beads on a string" to form proteins. These amino acid chains then fold up into a threedimensional molecule, giving the protein a specific function. Proteins have several important roles in the body.
For example, proteins make up antibodies, muscle fibers and enzymes that help control cell and body processes.
You need to make sure you have enough protein in your diet to obtain the necessary amino acids to make your
proteins.
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Chapter 1. Types of Nutrients
FIGURE 1.2
Between the ages of 9 and 13 years, girls need about 26 grams of fiber per day, and boys need about 31 grams
of fiber per day.
If you eat more than you need for these purposes, the extra protein is used for energy. The image below shows how
many grams of protein you need each day ( Figure 1.3). It also shows some foods that are good sources of protein.
Lipids
Lipids are nutrients, such as fats that store energy. Lipids also have several other roles in the body. For example,
lipids protect nerves and make up the membranes that surround cells.
Fats are one type of lipid. Stored fat gives your body energy to use for later. It’s like having money in a savings
account: it’s there in case you need it. Stored fat also cushions and protects internal organs. In addition, it insulates
the body. It helps keep you warm in cold weather.
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FIGURE 1.3
Between the ages of 9 and 13 years, you need about 34 grams of proteins a day. Seafood and eggs are other
good sources of protein.
There are two main types of fats, saturated and unsaturated.
1. Saturated fats can be unhealthy, even in very small amounts. They are found mainly in animal foods, such as
meats, whole milk, and eggs. So even though these foods are good sources of proteins, they should be eaten in
limited amounts. Saturated lipids increase cholesterol levels in the blood. Too much cholesterol in the blood
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Chapter 1. Types of Nutrients
can lead to heart disease.
2. Unsaturated fats are found mainly in plant foods, such as vegetable oil, olive oil, and nuts. Unsaturated lipids
are also found in fish, such as salmon. Unsaturated lipids are needed in small amounts for good health. Most
lipids in your diet should be unsaturated.
Another type of lipid is called trans fat. Trans fats are manufactured and added to certain foods to keep them fresher
for longer. Foods that contain trans fats include cakes, cookies, fried foods, and margarine. Eating foods that contain
trans fats increases the risk of heart disease.
Beginning with Denmark in 2003, many nations now limit the amount of trans fat that can be in food products or
ban these products all together. On January 1, 2008, Calgary became the first city in Canada to ban trans fats from
restaurants and fast food chains. Beginning in 2010, California banned trans fats from restaurant products, and in
2011, from all retail baked goods.
Summary
• Carbohydrates, proteins, and lipids provide energy and have other important roles in the body.
• Unsaturated fats are better for your health than trans fats or saturated fats.
Explore More
Use the resource below to answer the questions that follow.
• Nutrients Your Body Needs at http://www.pbs.org/wgbh/nova/body/nutrients-body-needs.html
1. What does your body use iodine for? What are good sources of iodine? What are some of the problems of
iodine deficiency?
2. What does your body use magnesium for? What are good sources of magnesium? What problems come from
magnesium deficiency?
3. What does your body use riboflavin for? What are good sources of riboflavin? What can happen if your diet
is deficient in riboflavin?
Review
1.
2.
3.
4.
Which nutrients can be used for energy?
What is starch?
Why is it important that you get enough proteins in foods?
What foods contain saturated fats? How much of these foods should you eat? Why?
References
1. Apple: Olle Svensson; Bread: Stacy Spensley; Squash: Pamela Carls. Until the age of 13, you need about
130 grams of preferably complex carbohydrates a day . CC BY 2.0
2. Broccoli: Liz West; Peas: Kari Söderholm; Pears: Richard North; Avocado: Jaanus Silla. Fiber is an impo
rtant part of a healthy diet . CC BY 2.0
3. Milk: Mark Skipper; Chicken: Flickr:TheCulinaryGeek; Beans: U.S. Department of Agriculture. Milk, ch
icken, beans, seafood, and eggs are good sources of protein . Milk, Chicken: CC BY 2.0; Beans: Public
Domain
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