Vitamins and minerals are only needed in very small quantities by humans, and these are called micronutrients. Macronutrients are the large molecules that supply the main elements that make up the bulk of our bodies, mainly carbon, hydrogen and oxygen. The three classes of macronutrients are carbohydrates, fat and protein. Most of our diet can be classifed into one of these three categories, and they each have an essential role to play.

Linoleic acid (omega-6) and α-linolenic acid (omega-3) are essential fatty acids. Click on Fat and Cholesterol link to find out about them.

Carbohydrates

We are carbon life forms, and about two thirds of our bodies are made of water, so you can imagine the importance of carbohydrates, which supply carbon, hydrogen and oxygen to our cells. Carbohydrates come in two forms: simple sugars and complex carbohydrates.

Simple sugars

The most common simple sugars are monosaccharides and disaccharides. The most common monosaccharides are glucose, galactose and fructose. Glucose is the form of sugar found in your blood, galactose is found in milk products and fructose is found in honey.

Disaccharides are made of two monosaccharides linked together. For example, sucrose = glucose + fructose, lactose = glucose + galactose, and maltose = glucose + glucose. Sucrose is table sugar, and lactose is found in milk. People who are lactose intolerant cannot break this disaccharide apart to digest it. Maltose is rarely found in nature, but is formed during the digestion of starches.

Complex carbohydrates

Complex carbohydrates are more than two monosaccharides linked together, and are called polysaccharides. Starches such as those found in grains and starchy vegetables like potatoes are complex carbohydrates. The cellulose in plants is a polysaccharide made with glucose, but formed in such a way that humans cannot digest it. Dietary fiber is a form of cellulose, which is discussed more on that section of the web site. Eating more complex carbohydrates (especially whole grains) can help you to maintain your blood sugar levels, since they take longer to break down and go into your blood stream.

All carbohydrates are eventually broken down to glucose, which is a molecule made up of carbon, hydrogen and oxygen. The main function of glucose is to provide energy for the body, and the brain and nervous system require glucose in order to function properly. Extra glucose is taken out of the bloodstream and stored by the liver in the form of glycogen. Once the body stores enough glycogen, then any extra carbohydrates will be stored as fat.

Do we absolutely need carboyhydrates to stay alive? Well, many people nowadays eat a very low carb diet. The body can use protein molecules for fuel too, although it would rather use carbohydrates. we can also burn our fat reserves for fuel. So in the short term, you can go without carbohydrates in your diet. In the long term it isn't healthy to cut an entire food group out of your diet. Foods that provide complex carbohydrates, especially whole grains and vegetables, come packaged with many vitamins, minerals and phytochemicals that your body needs.

See your daily requirement for carbohydrates.

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Proteins

All of the cells in our bodies are built from protein. Protein also makes up enzymes, hormones, neurotransmitters, cell transfer receptors, blood cells and many other important parts of the body.

Amino acids are made from different arrangements of the following atoms: carbon, hydrogen, oxygen, nitrogen and sulfur.

There are many amino acids found in nature, and of these there are 20 amino acids that our body needs in order to build protein. Of these 20, our body can synthesize 10 from substances we already have such as carbon compounds. The remaining 10 amino acids are called the essential amino acids, and we must get them through our diet. The first two, arginine and histidine, are only essential in the diets of children. Adults can synthesize these two amino acids, therefore there are really only 8 essential amino acids for adults.

The essential amino acids include:

Arginine (for children)
Histidine (for children)
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

Proteins that come from animal sources, such as meat, milk, eggs or cheese, are considered to be complete proteins of high biological value. This is because they have all 8 of the amino acids that we need to get in our diet. Plant sources do not usually have all of the essential amino acids present in one food, so they are incomplete proteins. Their biological value depends on how many of the amino acids they have, and in what quantities. You can combine plant foods to form complementary proteins or groups that contain all of the essential amino acids.

Some complementary protein plant foods are

Seeds, such as sesame or sunflower + legumes, dried beans and peas
Grains + legumes, dried beans and peas
Milk products + grains

Vegetarians should be careful to get complete proteins in their diet since they are not eating meat, the no-brainer protein. An excellent source of information and recipes for complementary proteins is Diet for a Small Planet by Frances Moore Lappé.

See your daily requirement for proteins.

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Fat and cholesterol

Fats are often considered the bad guys of the diet, but they are actually an essential nutrient. If you don't have enough fat in your diet you will notice your skin, hair and nails are not as healthy as they should be. The fat soluble vitamins can't be absorbed and processed properly without fat in the diet. Fat can help to regulate blood sugar, especially for diabetics. It also gives you the feeling of satiety after you eat, or basically lets you feel full, like you are done eating and satisfied. Try eating a few very low fat meals and you'll find that you never quite feel satisfied.

Fat molecules are made up of the same elements as carbohydrates: carbon, hydrogen and oxygen. However they are arranged differently to make a molecule that is not soluble in water.

Three types of natural fats

Saturated fatty acids

Saturated fats get their name because the molecule is saturated with hydrogen atoms, or in other words all the spaces along the fatty acid chain have been filled up with hydrogen. You can tell a saturated fat because it is solid at room temperature. You need to apply heat in order to make it a liquid. The butter sitting on your counter and the fat marbling your steak are saturated. Saturated fats usually come from animals, but some plants also have them, such as coconut and palm oil. Your fat intake should be made up less of saturated fats, and more of the next two types of fats, MUFA's and PUFA's.

Monounsaturated fatty acids (MUFA)

Monounsaturated fats have one place on their chain where they are missing a hydrogen atom. They form a double bond between the carbon atoms there instead. This gives them quite a different chemical structure - for one thing they are no longer a straight chain, but they bend at that place. These fats are liquid at room temperature, like the bottle of vegetable oil in your cupboard. They are oils that come from plants. Some good sources of monounsaturated fats are canola, olive, peanut, high oleic safflower and sunflower oils, and nuts.

Polyunsaturated fatty acids (PUFA)

Polyunsaturated fats have more than one place on the chain where they are missing a hydrogen atom. Therefore they have several double bonds between the carbons, and the molecule bends at each of these spots, making a more twisty and complex molecule. Like MUFA's they are liquid at room temperature, and come from plant sources.

Unnatural fats, or trans fats

Trans fatty acids are unsaturated fats they have been saturated with hydrogen atoms by an artificial process. Food processors have used this process to make margarines and shortenings that will be solid at room temperature and have a much longer shelf life. This makes them cheaper and easier for large food processors to store and work with - and even easier for home cooks. For example a pie crust made with shortening (Crisco) is much flakier and easier to make than one made with vegetable oil. For years people were told that margarine was better for their health, because it didn't contain saturated fats. However now studies are showing that trans fats can increase your cholesterol and raise your risk of heart disease. So, maybe you should have been eating butter all along! The best rule of thumb is to stick to natural foods, and limit how much saturated fats you eat across the board. So enjoy your butter, but eat it in moderation.

Essential fatty acids

Most of the fatty acids can be synthesized by the body when it needs them, but there are two PUFA's that the body is not able to make. These are linoleic acid (omega-6) and α-linolenic acid (omega-3). Symptoms of deficiency include dry and itchy skin, brittle nails and hair, constipation, frequent colds, depression, cardiovascular disease, type 2 diabetes, accelerated aging, fatigue, inability to concentrate and joint pain. Linoleic acid is commonly found in vegetable oils such as corn, safflower, sunflower, canola, walnut or soybean. α-Linolenic Acid is found in fatty types of fish, flax oil, walnut oil, pumpkin seeds and dark green leafy vegetables. People take supplements of omega-3 fatty acids (fish oil) to help with a huge range of disorders from cancers to inflammatory bowel disease to depression and schizophrenia. Studies have shown that omega-3 supplements can help reduce blood pressure, lower triglycerides, reduce inflammation associated with joint problems like arthritis, and deposit calcium in the bones. Omega-3 is involved in several important nerve functions and studies have shown supplements to decrease the amount of depression and hostility that people feel. Several psychological disorders such as bipolar, schizophrenia and ADHD are being studied. As you can see, these two fatty acids have a very important and wide-ranging effect on the body.

Cholesterol

Cholesterol is not a fat. Technically it's a lipid, made up of the same atoms (carbon, hydrogen and oxygen) as most of the other macronutrients. Cholesterol always comes from animal sources. Foods like peanut butter, mayonnaise and vegetable oils do not contain cholesterol, because they aren't made with animal products. Although our bodies need cholesterol to function, we don't need to eat it at all. Our bodies produce their own cholesterol. High cholesterol levels are linked to heart disease and one of the ways to lower your cholesterol level is to stop eating so much of it. Since your body also makes cholesterol, there are other things besides diet you can do to lower your level, including medications. The American Heart Association can give you more information about cholesterol.

Visit The Bad Fats Brothers web site for a fun explanation of dietary fats. Warning - the little video about bad fats will make you hungry - don't watch on an empty stomach!

See your daily requirement for fats, including the two essential fatty acids, linoleic and α-linoleic acid.

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The information on this page is not meant to be used in treatment of medical conditions. Please seek the advice of a physician about any medical condition or symptom. Those with medical conditions should consult a medical professional about the appropriateness of taking dietary supplements or diet therapy, and how these methods will interact with their medications.