Turning Food Into Nutrients
Vitamins and minerals are critical to body metabolism—the chemical reactions that involve building up or breaking down substances in the body. Metabolism is the process by which the body’s cells modify nutrient molecules and use them to create energy, or as building blocks for new cells and tissues. Metabolism, for any living organism, is life itself. Metabolism comes from a Greek word meaning “change,” and that is what cells do with nutrients. They change the chemical substances from foods into molecules that are needed to do the body’s work. We do not eat nutrients; we eat foods, which are too chemically complex for cells to use. The foods we eat must be broken down into simpler chemical substances—the nutrients—so that they are available to the cells. Foods go through three steps before nutrients are available to the body’s cells. These processes are digestion, absorption, and metabolism.
Digestion begins in the mouth, where teeth and the enzymes in saliva begin breaking down foods. Once in the stomach, food is exposed to gastric juices, and the chemical breakdown turns it into a thick liquid called chyme. Chyme moves to the small intestine. Here, with the help of more chemicals from the pancreas and gallbladder, it is broken down into nutrient components. (Unusable food substances move to the large intestine and are excreted by the body.) The nutrients are now absorbed into the bloodstream through the intestinal walls. Vitamins and minerals can be carried to every cell in the body, via the bloodstream. Amino acids from proteins, glucose from carbohydrates, and fatty acids from fats also are now usable and ready to be metabolized by the cells. The nutrients pass through the cell membranes and into the cells themselves, where more chemical reactions take place.
Once inside the cell, a molecule of glucose is broken down to release its energy. When nutrient molecules are broken down and energy is released, the process is called catabolism. But cells may use energy from nutrients to build more complex molecules, too. For example, a cell membrane may be damaged and need repair. This process is known as anabolism. In this case, people use the “bodies” of potatoes, broccoli, and fish, for instance, to maintain and build up their own bodies. The nutrient material in food is transformed to construct the building blocks of the human body. Scientists say that the nutrients we ingest can be thought of as the metabolic pool used by the cells for construction. Just as carpenters, bricklayers, and roofers use nails, tiles, bricks, mortar, glue, and wood to build a house, cells use the substances from nutrients to construct body parts.
The strength of the house depends on the quality of the building materials; the health of the body depends on the quality of the substances in the metabolic pool. To repair a cell membrane, new protein molecules are needed. These will be built through anabolism, using the amino acids in the metabolic pool. The new protein molecules may consist of hundreds or even thousands of amino acids. Different nutrient molecules may be metabolized in different ways or for different purposes, but all cells’ metabolic processes occur in a similar way. Millions of nutrient molecules are absorbed and utilized with every meal. Many end up as part of the body, although some are excreted from the body as unneeded or unusable. Many of these nutrients, especially vitamins, minerals, and proteins, are used to construct or build up enzymes. Enzymes are the chemicals that control the cellular processes of anabolism and catabolism. They also direct how fast a cell’s chemical reactions take place. Some vitamins protect the cells from damaging themselves as they metabolize nutrients. Nutrients build new bone, muscle, and blood cells in the body. They fuel the cells that make thinking, moving, and breathing possible. They keep bodies alive by continually building new cells as old ones die. Two million red blood cells die and two million are replaced by the blood-manufacturing cells in bone marrow every second. That means an intense, ongoing need for all the proper nutrients.
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Dr. Sunita Banerji received her MBBS degree from The Armed Forces Medical College, Pune, one of India’s leading Medical Institutes and received her DGO credentials in Obstetrics and Gynecology in 1982. She started her successful Aesthetic Medicine practice in Lokhandwala, in 1989 after undergoing extensive training in London. She was far ahead of her time in starting this type of practice in India. Eternesse – The Best Skin Treatment Clinic in Mumbai – her brainchild helps treat major medical problems related to lifestyle, aging and cosmetic treatments and surgery.