The Major Nutrients: Proteins, Carbohydrates, and Fats
In Anatomy & Physiology text books, you will discover the body is made up primarily of four different organic compound groups. These are proteins, carbohydrates, fats, and nucleic acids. To a scientist, organic means that the chemicals are carbon-based. It has nothing to do with being pesticide free.
A brief review of these major compounds appears below with links to other posts that give more detail and helpful information. Since we do not need to eat nucleic acids to build what need, we will not discuss them here.
It is important to remember that our body is made up of a lot of water; most authorities indicate 60-70% of our body weight. Water is not organic, so it is not discussed here. Minerals are also not organic, and a few, such as calcium, make up an important percent of our body. Vitamins are organic, but are found in such minute quantities that they are considered vital, but not a major constituent of our body.
Protein
Proteins are normally large molecules that build up strong structures in our body, such as hair, nails, cartilage, ligaments, tendons, and the outer layer of the skin.
Other proteins perform physiological functions, such as muscle proteins that contract, blood albumins that hold water in the blood, fibrin that helps our blood clot, and antibodies that help us become immune to disease-causing organisms.
A third major type of protein are the enzymes. They cause the chemical reactions in our body that we call metabolism. They break down food, which is digestion, and they help us build the chemicals we need, which is synthesis.
Proteins are made up of chains of their building blocks called amino acids and are folded in several patterns that make them very complex. There are 21 types of amino acids that we use to build our proteins. Of these, 9 are considered essential because we are only able to obtain them from our food. The other 12 kinds of amino acids do not have to be eaten because we are able to make or convert them from whatever amino acids we have available.
The essential amino acids are obtained in sufficient quantities and balance by most of us that eat meats, fish, eggs, and milk products. Vegetarians need to know a lot about which foods contain which amino acids and the balance so they can remain healthy. They must study nutrition information written for vegetarians.
Most Americans eat enough proteins in their diet, and it is unlikely they will eat such quantities that they could cause damage to their kidneys. Urea is a waste product of breaking down amino acids.
The biggest concern is that many people do not have sufficient protein in their blood due to overeating, or that they are blocking full digestion by using one of the acid blocking drugs such as the proton pump inhibitors. This is discussed at Nutrition of Proteins: Poor Digestion with Drugs.
More information is available on the protein web page.
Carbohydrates
Carbohydrates (carbs) have gotten a lot of attention in recent years; much of it was misinformation or facts distorted because of the limited knowledge of the writers. Carbohydrates do serve as the major energy source in the body, but we do not raise our energy level by ingesting them.
The building blocks of carbohydrates are the sugars. Simple sugars are essentially like a single bead and they are called monosaccharides. If we hook two simple sugars together, we build a disaccharide. If we string many of these simple sugar beads together, we form a long chain we call a polysaccharide.
The most commonly known monosaccharide is glucose. This is the actual sugar that we find in our blood and that we burn for energy. Some food manufacturers call it dextrose on food ingredient lists to try to confuse us. Other simple sugars include fructose, or fruit sugar, and lactose, or milk sugar.
An example of a disaccharide is sucrose. This is the white crystalline sugar we call table sugar. Brown sugars are simply sucrose crystals with some molasses covering them.
Polysaccharides are long chains made up of one or more types of simple sugars. Starch is made up entirely of glucose units which are easily broken apart in our body, which is why it affects the body exactly like glucose. Fiber is a complex carb which can not be digested by our bodies. This allows it to pass through our digestive system with many beneficial effects. Other complex carbs are in our foods, and may be important, but scientists are only beginning to study them in detail.
Our main concern with carbs is that the various sugars and starches are all converted into glucose and they cause a rise in blood sugar. This rise can lead to Type II Diabetes and can also affect our thinking processes as well as our driving abilities.
Fats and Oils
Fats, oils and lipids are all the same materials. We use the word fat if the fat is solid at room temperature. Oils are fats that are normally liquid at room temperature. Lipids is a more technical term for fats.
All fats are composed of a ‘backbone’ of glycerol and then have different types and amounts of fatty acids hanging on that backbone. They can be quite complex and this is actually important to our body.
To a large extent, we can break down the fats for easier understanding into the good lipids, the not so good lipids, and the poisonous lipids. These are covered at Good Fats and Bad Fats. Other types of fats are discussed at Cholesterol and at MUFA.
Trans fats, including hydrogenated oils, should be completely avoided, as should the new replacement fats. Saturated fats need to be eaten in limited quantities. Good fats, such as the omega-3’s and olive oil may be enjoyed in good quantity, just be careful about the number of calories.
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