take high doses of niacin thinking “more is better.” However, taking too much niacin, as with taking too much of any vitamin or mineral, can be detrimental to health and exercise performance. More research is needed to determine how niacin affects the depletion of glycogen stores and, therefore, its potential to indirectly affect performance.1


PANTOTHENIC ACID


Pantothenic acid, a water-soluble vitamin whose biologically active forms are CoA and acyl carrier protein, is involved in acyl group transfers, such as the acylation of amino acids.9,16


Pantothenic acid coenzymes are


also involved in lipid synthesis and metabolism and oxidation of pyruvate and α-ketoglutarate. Acetyl CoA is an important intermediate in fat, carbohydrate, and protein metabolism.14


In a more recent human study,


researchers confirmed that supplementation of D-pantothenic acid and L-cysteine did not affect fuel selec- tion in the muscle or work output.16


Although this research indicates that there may be an increased need


for pantothenic acid with exercise, definite conclusions cannot be made for the human model. It would be prudent to suggest that athletes consume the AI for pantothenic acid. Dietary sources for pantothenic acid are listed in Table 5.1.


BETAINE


Betaine, a metabolic derivative of choline widely found in many plant food, acts similarly to choline (donat- ing a methyl group in the same metabolic pathways), thus reducing the amount of choline required.17 Betaine supplementation may work as an ergogenic (performance-enhancing) aid in improving power out- put.18,19


While Lee and colleagues found


It is important for people who exercise to obtain the DRI for


niacin to ensure adequate intake and prevent alterations in fuel utilization, but they should not exceed the UL. Dietary sources of niacin are listed in Table 5.1.


Lee and colleagues conducted a randomized, double-blind, crossover study to determine if betaine


supplementation increased strength and power performance. Significant increases (P<.05) in force and power production were observed in the upper but not the lower body.20


significant changes in force and power production in the upper body, Hoffman and colleagues reported that the effects of betaine supplementation were more evident in the vertical jump vs the bench press throw.21


research on betaine supplementation in athletes.


Antioxidants and Oxidative Damage Antioxidants are compounds that help counteract the damaging effects of free radicals in the body. Free radicals, reactive oxygen species, and reactive nitrogen species are compounds that contain one or more unpaired electrons that can lead to tissue damage and contribute to chronic disease.22


and exercise.24,25 produced.25,26 Although the research designs and measures varied, these studies provide a foundation for future


Free radicals are


endogenously produced in the body through oxidation reactions, such as energy metabolism; however, they are also created through exogenous sources, such as excess micronutrient intake (eg, vitamins C and A)22,23


may decrease physical performance and health.27


and conditioning may lead to responses that adapt to the increased oxidative stress and prevent associ- ated damage.28


It is also important to note that many in vivo experiments use fruit and vegetable extracts


to elucidate the effect of individual antioxidants. Tis can be misleading because the combination of vari- ous micronutrients and phytochemicals may contribute to the desired outcomes. A number of researchers combine supplementation of vitamins and minerals in their research; therefore, caution must be used in attributing individual outcomes to one antioxidant or micronutrient.17


VITAMIN C Vitamin C, also referred to as ascorbic acid, ascorbate, or ascorbate monoanion,9


is a water-soluble vita- min involved in maintaining collagen synthesis, oxidizing fatty acids, and forming neurotransmitters. It is 84 SECTION 1: SPORTS NUTRITION BASICS


Exercise type, mode, duration, and intensity all affect the amount of free radicals When free-radical production overwhelms antioxidant availability, the resultant oxidation It is important to note, however, that regular exercise


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