5. DIETARY FIBRE
Most of the molecules contained in our foods and our cells contain belong to one of three major nutrient groups: carbohydrates, lipids (fats, oils, cholesterol) and proteins. This guide is a breakdown of these nutrient groups.
A minor but equally important nutrient group present in our foods and our cells is the nucleic acids.
Essential nutrients that must be provided by foods or by supplements include vitamins, minerals (and
elements), essential fatty acids and essential amino acids.
Carbohydrates, fats, oils and amino acids can serve as fuel “burned” by the body to provide energy
(calories) for muscular work, body heat, cell building and biochemical processes.
Fats and oils are also used to build the membranes that surround our cells. Fats and oils (mostly oils)
provide 2 essential fatty acids, nutrients that the body cannot make, requires for health and must obtain from foods or from supplements. Essential fatty acids are precursors of hormone-like prostaglandins.
Cholesterol is used to stabilize cell membranes and to protect skin and is also the material from which the body makes Vitamin D, male and female hormone, the stress hormone cortisone and hormones that regulate kidney function.
Proteins, the sources of amino acids, provide building materials for enzymes, structural proteins and
antibodies. Proteins also provide 8 essential amino acids, nutrients the body cannot make, requires for
health and must obtain from foods or from supplements. Children require 10 essential amino acids for
health and premature babies require 11 amino acids to be present in their food supply in order to survive and thrive.
Nucleic acids provide nucleotides, building materials for the production of each body’s unique genetic
material (DNA) and its blueprint from which cells make proteins (RNA). Nucleic acids are also enzyme co-factors in energy-producing reactions and energy storage molecules.
Minerals (and elements) are essential catalysts and co-factors for the functions of enzymes, which allow biochemical reactions necessary to life to take place – reactions that would be impossible without them. Catalytic functions of minerals often depend on their ability to take up or give off electrons. Minerals
cannot be made by the human body and must therefore be provided by foods or by supplements. Human beings require 22 or 23 minerals and elements for health.
Vitamins are essential co-factors in biochemical reactions, providing three-dimensional keys with
electrical properties that are just precisely necessary for these reactions. About 13 vitamins are essential to humans. They are required for health, cannot be made in the body and must come from foods or from supplements.
The body obtains its energy by “burning” (or oxidizing) nutrients present within each cell. We measure the energy made available by this process in calories. Oxidation of 1 gram of carbohydrates produces 4 calories, 1 gram of protein (or amino acids) also produces 4 calories, 1 gram of fat produces 9 calories and 1 gram of alcohol produces 7 calories. The body prefers to use carbohydrates for fuel because carbohydrates are “clean” fuel. When they “burn”, they are converted into water, carbon dioxide and energy, leaving no “smoke” or residue.
The body uses proteins and fats for fuel only when its supply of carbohydrates falls short, or if its supply of fats and protein is excessive. When the body burns proteins for energy, the toxic substance ammonia is generated in addition to water and carbon dioxide. Ammonia burdens the liver and other inner organs.
When the body burns fats for energy, toxic ketones are produced in addition to water and carbon dioxide. Ketones also burden the kidneys and other inner organs. The practical importance of this information is that for best health, we should eat enough protein (12 - 15% of calories) and fats (15 - 20% of calories) to build, maintain and repair cell structures and to consume complex carbohydrate for energy production (65 - 75% of calories).
The body burns alcohol for energy as one means of protection against the toxic effects of this poisonous substance. Physiological processes occur only if the required energy is available. For instance, a molecule of the digestive enzyme pepsin can be made only if, besides amino acids (building materials), the energy needed to link them together is available.
Energy is required in physiological processes such as the contraction of heart muscle, muscular activity, brain function, nerve conduction, cell division and for thousands of other processes that continually take place in cells, tissues and organs. Energy is also required for all activities of the organism: breathing, sensing, thinking, feeling and acting.
When more fuel is available than the body can use for its normal functions, it can burn this extra fuel by increasing body heat. This reaction explains why some people experience “night sweats” when they sleep on a full stomach from eating too late in the evening.
Another way in which the body deals with excess fuel — from excess carbohydrates, proteins or fats — is to turn the excess energy into fats and cholesterol and to store these lipids for energy requirements at a later date. If we continually consume more calories than the body can use for its normal functions, the excess is turned into fats and cholesterol and obesity results with all of its detrimental effects on health.
Using specific enzymes, the cells can change amino acids to other non-essential amino acids or to
carbohydrates, or can oxidize them to produce energy. The body can convert carbohydrates into lipids.
This is why excess sugar consumption leads to fat deposition. Carbohydrates can also be converted into the “backbones” for amino acids. Fats, on the other hand, cannot be turned into sugars again, nor into amino acids or nucleic acids. To get rid of them, the body must burn them for energy.
Amino acids and carbohydrates can be used to construct purines and pyrimidines — components of the building blocks for DNA (genetic material) and RNA (its blueprint for making proteins). This
rearrangement of molecular structures is basic to physiology.