Malnutrition is an imbalance in diet that occurs in one of two ways. In its first manifestation, malnutrition is caused by a diet that includes too little food, resulting in a caloric shortfall in the body. When the body cannot process sufficient food to generate the energy that it requires for its purposes, the person is stated to be malnourished.
Malnutrition is also the result of insufficient nutrients being consumed and available to the body through diet. In this form of malnutrition, it is possible for the body to be adequately nourished in terms of calorie consumption, but subject to deficiencies of both macronutrients such as protein, the building blocks used by the body for muscle and tissue construction and maintenance, and micronutrients, those trace amounts of vitamins and minerals that are essential to the function of a multitude of bodily processes.
A significant contributor to the two forms of malnutrition is the failure to provide adequate amounts of fiber in diet. Fiber is essential to the optimal digestion of all foods. Fiber is itself not a food group, it is not an energy source, and it is not digestible. However, fiber is often linked to foods that possess substantial quantities of various micronutrients; when fiber is below optimal levels, the body will not properly digest and process those foods.
Malnutrition is a matter of degree. In children, particularly those in less-developed nations, malnutrition is a leading cause of death. This worst-case aspect of malnutrition is the starvation of the child. In less pronounced but serious circumstances, children who are malnourished will not develop to their fullest physical or mental capabilities. A deficiency in the amount of calories consumed results in children who are undersized, as their bone and muscle development is stunted. The combination of an inadequate caloric intake and essential vitamins and minerals will often limit the intellectual development and mental capacity of the child.
An aspect of inadequate food intake is a condition known as protein energy malnutrition. The generation of energy by the body ultimately results in the generation of a substance known as adenosine triphosphate (ATP), a process that occurs within the individual cells. Where the body has too few carbohydrates available to produce the energy source glucose, the body will break down its proteins to resolve the shortfall.
The deficiencies in various vitamins and minerals that result in malnutrition are reflected in a variety of conditions, some of which are capable of remedy, others of which are permanent in their physical consequences. Among the most prominent of these deficiencies is that involving the mineral calcium, a condition that often occurs in conjunction with a shortage of vitamin D. Calcium is the key mineral in the formation and maintenance of the skeletal bone structure; calcium is the most prominent mineral in the body. Vitamin D is essential to the processing of calcium in bone formation, maintenance, and repair. A shortage of either substance will result in structural problems in bone formation. A prolonged deficiency in either of these micronutrients will create permanent skeletal weaknesses.
A number of other conditions flow from vitamin and mineral deficiency. For the athlete whose body is subjected to the stresses of muscular activity and the competitive environment, even a small deficiency in one of the micronutrients can have a negative impact on athletic performance. For example, while a vitamin A deficiency impacts function of the immune system, a deficiency of the B complex has a broad range of negative impacts. The various components of the B vitamin complex are crucial to the breakdown of carbohydrates into useful energy sources, the maintenance of healthy skin and other organs. Vitamin C is essential to the maintenance of the health of the body's connective tissues, the central nervous system, and the function of the adrenal glands.
The deficiencies in other minerals, particularly sodium, potassium, iron, and magnesium impact on a number of essential human systems. As an example, when the presence of the electrolytic minerals such as sodium and capacity is reduced, as often occurs if the body is dehydrated, the fluid-leveling ability of the body is significantly impaired. Iron is crucial to the function of the ability of the cardiovascular system, through the red blood cell component hemoglobin, to transport oxygen in the creation of energy.
Nutritionists recommend that, whenever possible, both macronutrients and micronutrients should be obtained from food sources. Information concerning the best sources is widely available. Dietary supplements, including vitamin and mineral formulations, are commonly used by athletes to ensure that they have no hidden or undetermined deficiency that has arisen through the stresses of training.