Vitamins and minerals

Abstract

The human diet consists of both macro-and micronutrients. Macronutrients include carbohydrates, fats, and proteins, whereas micronutrients consist of vitamins and minerals. (See Table 15.1 for food sources of vitamins and minerals.) As their name implies, the macronutrients comprise most of the required dietary intake whereas the micronutrients are essential in much lower quantities. With the deficiency of micronutrients, athletic performance in addition to normal physiologic function will suffer. However, the very nature of being a micronutrient suggests that excess intake in well-fed athletes will not likely alter performance without an activity-associated increased need. For example, many vitamins and minerals are important in the catabolism of the macronutrients for energy production. Furthermore, many of the micronutrients are involved in endogenous antioxidant defense mechanisms. It has been hypothesized that athletes have an increased requirement for vitamins and minerals because of the increased energy expenditure and excess muscle damage that occurs during training or competition. TABLE 15.1 Food sources of vitamins and minerals. Nutrient Food sources Thiamin Emiched, fortified, or whole-grain products, bread and bread products, cereal Riboflavin Organ meats, milk, bread products, fortified cereals Niacin Meat, fish, poultry, emiched and whole-grain breads and bread products, fortified cereals Pantothenic acid Chicken, beef, potatoes, oats, cereals, tomato products, liver, kidney, yeast, egg yolk, broccoli, whole grains Vitamin B6 Fortified cereals, organ meats, fortified soy-based meat substitutes Folate Emiched cereal grains, dark leafy vegetables, emiched and wholegrain breads and bread products, fortified cereals Biotin Liver and smaller amounts in fruits and meats Vitamin B12 Fortified cereals, meat, fish, poultry Vitamin C Citrus fruits, tomatoes, tomato juice, potatoes, brussel sprouts, cauliflower, broccoli, strawberries, cabbage, spinach Vitamin E Vegetable oils, unprocessed cereal grains, nuts, fruits, vegetables, meats Vitamin A Liver, dairy products, fish, darkly colored fruits and leafy vegetables Vitamin D Fatty fish, fortified milk products, fortified cereals Vitamin K Green vegetables, brussel sprouts, cabbage, plant oils, margarine Calcium Milk, cheese, yogurt, com tortillas, broccoli Chromium Some cereals, meats, poultry, fish, beer Iron Fruits, vegetables, fortified bread and grain products (nonheme iron sources); meat and poultry (heme iron sources) Magnesium Green leafy vegetables, unpolished grains, nuts, meat, starches, milk Zinc Fortified cereals, red meats, certain seafoods Phosphorus Milk, yogurt, ice cream, cheese, peas, meat, eggs, some cereals and breads Selenium Organ meats, seafood, plants (depending on soil selenium content) During exercise, there is an excess production of various reactive oxygen species and free radicals. Free radicals are reactive molecules that contain one or more unpaired electrons in their outer orbital. Molecules with unpaired electrons are unstable and will oxidize various components of the cell including lipids, proteins, and nucleic acids. The body has multiple antioxidant defense systems to protect itself from these reactive molecules. In addition to endogenous antioxidant enzymes, dietary antioxidants (e.g., vitamin C and E) provide protection against the detrimental effects of reactive oxygen species and free radicals (i.e., oxidative stress). The following chapter is a review of vitamins and selected minerals. Vitamins are categorized into water-soluble and fat-soluble vitamins. Water-soluble vitamins are found in the fluid portion of the body and do not accumulate to a large degree. Fat-soluble vitamins are stored in the lipid portion of the body and, therefore, can accumulate to appreciable amounts. Moreover, almost all of the vitamins and minerals mentioned in this chapter are antioxidants or cofactors involved in the oxidation-reduction balance of the body. Therefore, antioxidant function is a main underlying focal point of this chapter. For each micronutrient, there is a brief description of its physiologic function, in particular its role in maintaining the oxidation-reduction balance of the cell, followed by a review of the scientific literature pertaining to its effect on aerobic, anaerobic, and strength performance. © 2008 Humana Press.