Nutritional medicine works both preventively and therapeutically to ensure that patients are following the diet and receiving an adequate supply of nutrients appropriate to their individual needs. Practitioners of nutritional medicine also screen their patients for food allergies and sensitivities, and access their digestive capacity in order to optimize the proper assimilation of the foods their patients eat. Eating optimally, along with proper nutrient supplementation, is an essential step in achieving and maintaining optimal health and safeguarding against illness. When illness is already present, nutritional medicine can play an important role in reversing disease conditions by supplying the body with the nutrients it needs to carry out its various healing functions. Nutrients fall into three primary categories: macronutrients, vitamins, and minerals. What follows is an overview of the nutrients in each category, and their health-giving properties.
MACRONUTRIENTS. The macronutrients are organic compounds and classified as either proteins, carbohydrates, or lipids (fats). Among their many functions, macronutrients serve as the body's source of energy.
Proteins, which account for20 to 25 percent of a person's body weight, are second only to water in terms of the body's overall composition. In addition to the carbon, oxygen, and hydrogen molecules that occur in all forms of macronutrients, proteins also contain nitrogen, and are essential for growth and maintaining the health of body tissue. They are also the primary building blocks for the body's muscles, internal organs, skin, hair, eyes, and nails, and play an integral role in the formation of immune system antibodies. Proteins are essential for the growth, maintenance, and repair of body tissues, as well as the production of various body substances, such as antibodies, enzymes, hemoglobin, hormones, and nerve chemicals. Proteins also help maintain the body's acid-alkaline (ph) balance, as well as regulating the amount of fluid within the cells and preserving normal sodium and potassium balance. When the body's fat and carbohydrate stores are low, the body also draws on dietary protein to maintain energy levels. When dietary protein isn't available, the body will break down tissue proteins, although its doing so will eventually result in energy depletion and disease if dietary protein is not replenished. Food sources of complete proteins include meats, cheese, eggs, fish, milk, and poultry, while grains, legumes, nuts, seeds, and various vegetables contain partial protein sources.
Proteins consist of a combination of 25 amino acids. In addition to serving as the building blocks for all proteins in the body, amino acids are also involved in a variety of vital biological processes, including energy production, bone and muscle growth, tissue repair (wound healing), and the formation of the brain's neurotransmitters. Eight amino acids have been classified as essential, due to the fact that the body cannot produce them on its own. Essential amino acids, therefore, must be supplied through the foods we eat. The eight essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. When all eight of these amino acids are supplied to the body in adequate amounts, it is able to synthesize the other 17 amino acids required for other biological processes. Three of these 17 amino acids, arginine, histidine, and taurine, are considered semi-essential, since they are vital for growth during infancy, childhood and adolescence, and also during pregnancy. The remaining amino acids are alanine, aspartic acid, carnitine, cysteine, gamma-aminobutyric acid (GABA), glutamine, glutathione, glycine, homocysteine, hydroxyproline, ornithine, proline, serine, and tyrosine. Although these amino acids are considered nonessential, they can be vital during times of extreme illness, and can help mitigate against the effects of a poor diet. Note: Although dietary protein is essential for optimum health, most Americans consume far more protein per day than they need, particularly from animal foods. Excessive consumption of animal foods, especially meats, has been associated with a number of degenerative conditions, including cancer and cardiovascular illness.
Carbohydrates are another class of macronutrients and serve as the body's primary source of energy. Carbohydrates are also vital to proper function of the nervous system, muscles, and internal organs. In addition, they help regulate fat and protein metabolism, as well as assisting the body's use of fats and proteins to fight infection, grow body tissue, and lubricate the joints. Whole, or unrefined carbohydrates, are also high in fiber, which aids the body in eliminating toxins via the colon. Carbohydrate foods include fruits, vegetables, grains, legumes, and tubers.
There are three categories of carbohydrates: sugars, starches, and fibers. Sugars occur in two forms: simple, or monosaccharides, and multiple, or disaccharides. Simple sugars are primarily found in fruits and honey, and include glucose, fructose, and galactose. Multiple sugars, which commonly occur as table and malt sugar, include maltose and sucrose. Lactose, or milk sugar, is another form of disaccharide. Foods high in either simple or multiple sugars can cause rapid shifts in glucose levels in the blood, which can contribute to a number of disease conditions. For this reason, holistic physicians recommend avoiding sugar carbohydrates, with the exception of fresh fruits.
Starches, also known as complex carbohydrates or polysaccharides, are considered the healthiest form of carbohydrates, since they contribute to more balanced blood sugar levels, as well as sustained energy. The best food sources of complex carbohydrates are potatoes, root vegetables, corn, wheat, rice, and other whole grains.
Fibers, while supplying the body with little caloric energy, play an important role in maintaining proper gastrointestinal function and elimination. The average American diet is notoriously lacking in fiber, however, which is the main reason why each year in the U.S. billions of dollars are spent on laxatives to deal with constipation. Because fibers are indigestible, they absorbed water and bind toxins in the gastrointestinal tract. Certain fibers can also help reduce fat absorption and lower cholesterol levels. Common food fibers include cellulose, contained in the skins of fruits and vegetables and in the outer hull of grains; psyllium seed husks, carrageen, guar gum, pectin, and agar and alginate, both of which are derived from seaweed.
Lipids (fats) are the final class of macronutrients. In addition to acting as insulation for the body, fats play an essential role in the transport of "fat-soluble" vitamins (see below), and, as part of cell membranes and fatty tissues, protect internal organs from the effects of trauma and shifts in temperature. The body also uses lipids as energy reserves, burning fats when more energy is needed than the diet supplies. Lipids aid in the digestion and assimilation of other nutrients, as well. On average, lipids comprise between 10 to over 30 percent of an adult person's total body weight.
The primary form of lipids are known as triglycerides, which make up approximately 95 percent of the lipid content in foods. Triglycerides are the only form of fat that provides the body with caloric energy. Triglyceride fatty acids are either saturated or unsaturated, with unsaturated fatty acids being either monounsaturated or polyunsaturated. Saturated fatty acids are primarily derived from animal sources (including butter, cheese, and yogurt), and are also found in margarine, lard, and coconut and palm oils. Unsaturated fatty acids are derived from plants, with monounsaturated fatty acids occurring in avocados, as well as olive, almond, and canola oil. Corn, cottonseed, peanut, safflower, sesame, and soybean oil are all good sources of polyunsaturated fatty acids.
Three types of polyunsaturated fatty acids, linoleic, linolenic, and arachidonic acids, cannot normally be manufactured in the body, and are therefore classified as essential fatty acids (EFAs). EFAs are essential for proper growth and for protecting the skin and other body tissues through lubrication. Linoleic and arachidonic fatty acids are known as Omega-6, while linolenic fatty acids are called Omega-3 oils.
Phospholipids are another form of lipids and play a vital role in maintaining membrane structure. The most common phospholipid is lecithin. Other forms of phospholipids are phosphatidyl choline, phosphatidyl inositol, phosphatidyl anolamine, phosphatidyl serine, and sphingomyelin. Among the functions of phospholipids are maintaining the health of the brain, supplying brain cells with vital nutrients, and protecting nerve cells.
The third class of lipids are known as sterols. These include cholesterol, plant sterols (phytosterols), and certain steroid hormones. Cholesterol is manufactured in all body tissues except those of the brain, and is a component of bile acids and salts, and a precursor of vitamin D and the body's sex hormones. It is most highly concentrated in the liver, blood and brain and nerve tissue, and is found in all animal tissue. Without adequate supplies of cholesterol, the body would not be able to properly form cells of the brain and nervous system, nor would these cells be able to function correctly. However, excessive amounts of cholesterol, especially when it becomes oxidized, has been linked to heart disease, stroke, and atherosclerosis.
Most health practitioners agree that no more than 20 to 30 percent of one's diet should consist of calories derived from lipids, with 10 to 15 percent being essential. The fat content of the average American diet is over 40 percent, however.
