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How do vitamins and minerals support our bodies?

This is an excerpt from Practical Guide to Exercise Physiology 3rd Edition With Web Resource by Robert Murray,W. Larry Kenney.

Vitamins are essential nutrients the body cannot make, so there’s no doubt that you need to consume vitamins on a daily basis to ensure that all cells are supplied with the substances needed for metabolism—not just energy metabolism but metabolism of all sorts. Even though the body contains over 35 trillion cells, each cell needs only a tiny amount of vitamins to operate efficiently. Consuming more vitamins than a cell can use is like having more hammers on a construction site than the workers can use. The extras do no good.

Some vitamins are soluble in water and others in fat. That distinction is important because fat-soluble vitamins (A, D, E, K) are stored and used in the liver and in fat, whereas water-soluble vitamins (B vitamins, C) are used in the watery environments inside muscle and other cells. All are needed in small amounts to support cell functions. Figure 2.12 provides an overview of the functions of vitamins and minerals.

Vitamins play an important role in energy metabolism. That’s especially true of the B vitamins because they act as cofactors in a variety of enzymatic reactions in the steps that break down glucose and fatty acids to produce ATP. Once each of the muscle cells has enough vitamins to act as cofactors, the body has no choice but to excrete the extra water-soluble vitamins in the urine. Because enzymes, like all other proteins in the body, break down and are replaced on an ongoing basis, you need to consume small amounts of vitamins every day to ensure that the cells have a steady supply. Table 2.4 lists the recommended daily values for important vitamins and minerals. Consuming the daily values is easily accomplished with a balanced diet. However, as with protein needs, if athletes have poor dietary habits or are on restricted diets, a low-dose multivitamin and mineral supplement can be a cost-effective and low-risk way to ensure adequate intake.

As with vitamins, the body needs a small supply of minerals each day because minerals are lost in urine and sweat. Minerals play a variety of roles in the body (figure 2.12). Many minerals are involved in ATP production in glycolysis, the citric acid cycle, and the electron transport chain, while other minerals are essential for nerve conduction, bone formation, red blood cell production, and so on. Although all cells need minerals, the daily requirement is small and can easily be met by consuming a balanced diet, especially if you are not physically active. Table 2.4 provides general guidelines for mineral intake; however, the amount of minerals required in the diet varies significantly due to variations in mineral use and loss, both within and between individuals. Whenever you sweat, mineral loss is increased because sweat contains minerals such as sodium, chloride, potassium, calcium, and magnesium. (Minerals are also referred to as electrolytes or ions because each carries either a positive or negative charge.) The faster you sweat, the greater the salt content of your sweat. A rapid sweat rate overwhelms the capacity of the sweat glands to reabsorb sodium and chloride. During intense exercise, the sodium concentration in sweat can increase by 175%. Loss of sodium and chloride makes it more difficult for your body to maintain a normal blood volume.

For some athletes, daily sweat loss can exceed 8 liters (roughly 8.5 quarts), resulting in high daily mineral loss. In most cases, eating food supplies more than enough minerals to replace the mineral losses from sweat, so mineral deficiencies are very rare. One possible exception is the calcium needs of female athletes. Because many females do not consume enough calcium-rich foods to meet the daily recommendation of 1,300 milligrams, and because calcium is lost in sweat, female athletes should be educated on the importance of consuming adequate calcium on a daily basis.

All vitamins and minerals play various roles in metabolism. For example, vitamin C is an antioxidant that aids in iron absorption and is involved in collagen synthesis and amino acid metabolism. Calcium is essential for muscle contraction, bone structure, nerve transmission, enzyme activation, and the permeability of cell membranes.

More Excerpts From Practical Guide to Exercise Physiology 3rd Edition With Web Resource

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