Nutrients and the Nitrogen Cycle

Most of you are aware of the fact that carbon, oxygen, hydrogen, and nitrogen are the elements that make up much of the living compounds which sustain us. When the sun’s energy generates photosynthesis in plants, carbon dioxide and water are utilized in complex chemical pathways to create glucose and other forms of carbohydrates. Within these molecules is stored the energy which all life forms must have to survive and multiply.

When glucose is “burned,” like gas in a motor, the energy to keep the body warm and all other functions sustained is realized. Multiple forms of carbohydrates prevail in fruits and vegetables and are the basis for the energy cycle that occurs in humans and animals. That energy cycle is called the KREB cycle, which utilizes glucose in the body and converts it to small forms of energy-containing molecules known as ATP, or adenosine tri-phosphate. That energy is then utilized in your body to maintain body temperature, to keep your brain working, and to keep your muscles going.

In addition to the carbon, hydrogen, and oxygen molecules, a fourth is equally important. That molecule is nitrogen, and it furnishes the basis of body proteins, enzymes, body structure, and all of the multiple organs of your body that incorporate protein. In order for our bodies to grow from infancy, we need protein with nitrogen plus all of the 32 essential vitamins and minerals, water, fat, and carbs.

This is where it becomes important to think about where nitrogen comes from in your food. Let’s look at a wild animal, such as a deer, or a domesticated large animal, such as a cow or bull. Even though they may weigh as much as 2,000 pounds, most of which is flesh and bone, they have never eaten meat because it is not part of their diet. Their protein comes from grass, which contains nitrogen and amino acids. In the case of man who is carnivorous, we eat meat and other protein on a daily basis unless we are vegetarians. Wild and domesticated animals derive nitrogen for protein from plants, which derived their usable nitrogen from elements in the soil, which have converted the nitrogen in the atmosphere to a more usable form which can ultimately make protein. Natural sources of nitrogen are vegetables, nuts, grains, and beans.

When plants grow, they need nitrogen as well as elements in the soil, carbon dioxide, and water in order to mature and bear fruit. When plants grow naturally, they are dependent on the nitrogen in the soil, which is created by the elements that convert that nitrogen to nitrates so that it can be utilized in plant growth. When crops are being grown yearly in the same fields and harvested, as is the custom in our culture (wheat fields, etc.), then it’s important to keep nitrogen in the soil at a level that will sustain crops. For example, plants that contain nitrogen have amino acids, which in the right combination can go on to make protein. Only one plant, the soybean, has what is considered a complete protein similar to animal source protein.

Throughout the centuries, man discovered that growing crops in the same field year after year depleted whatever the natural elements were that made the crops good. In China 4,000 years ago, soybeans were recognized for their ability to replenish the soil and were planted on alternate years in fields where valuable crops were grown. This acted as a natural fertilizer. American Indians put a fish in with every seed corn that was planted, and this acted as fertilizer.

Over the years, fertilizer came from manure, guano (bird manure), or human sources. When the population of the world began to increase so much, it became obvious that new sources of nitrogen would be necessary in order to grow enough crops to sustain the greater number of people. Since there was so much nitrogen in the air but not enough sources of usable nitrogen for crops, another source had to be found.

In 1899 a man called Karl Bosch in Germany began development of a process of converting elemental gas nitrogen into ammonia, a nitrogen and hydrogen compound. Once he discovered it was possible to do this, the technology gradually improved so that by 1913 an ammonia factory was developed in Germany. Having this new technology allowed the development of manufactured nitrates, which could go into a fertilizer, which would stimulate and sustain the growth of plants.

Production of this remained at a reasonably low level because of the population, but in the early 1950s the use of fertilizer increased with population growth to about 10 million tons a year. Until this point it was possible to grow more crops and feed more people with a different, but still nutrient-rich type of crop. Since then what has happened is that we now use artificial nitrogen fertilizer that lacks many of the other nutrient elements to make plants and fruits as good as they could be. For example, the nutrient content of foods now as compared to 40-50 years ago or compared to natural organic plants is very low.

So what does this mean to you as a consumer? It means that most of the wheat and corn used to sustain today’s population has nitrogen and starch or sugars contained within them, but they don’t have the wide variety of nutrients that would be available from soil that has been naturally sustained in a fertile manner. Therefore, you are eating foods with low levels of nutrients. When you eat a peach, it doesn’t really give you the nutrients that it did years ago, and the same is true for animal protein. For example, now cows are fed a mush product with protein and carbohydrates that allows growth of the flesh, but does not keep the nutrient level high. An animal that grazes in a pasture gets a lot more nutrients and elements of the soil by eating the grass in the pasture. These nutrients stay in the meat of the animal at slaughter and are therefore eaten when they come to the table as a healthier product.

I know this all sounds complicated, but it reminds us to think about what we are eating and what the sources of nutrients are for our food in general. Therefore, grass-fed beef and organic foods are better for you and are healthier. This is not only because they have natural nitrogen sources, but because they don’t contain pesticides or hormones.

Since the healthiest thing you can do overall is to eat less food than you are eating in general, you can eat smaller quantities of slightly more expensive organic meats and vegetables and still come out ahead. You’ll be healthier and have a more highly nutrient-filled body, which will function in a better manner to give you more energy, longer life, and the ability to fight disease. That sounds like a deal to me, so I think I’ll continue doing it.

James H. Carraway, M.D.

Dr. James Carraway is a full-time academic and practicing clinical plastic surgeon.  He is Director of the Cosmetic & Plastic Surgery Center of EVMS, is board certified in surgery and plastic surgery, and is a fellow of the American College of Surgeons.  Dr. Carraway has been teaching and practicing for 30+ years and has been director and chairman of residency training programs and fellowship programs in plastic surgery.
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