B vitamins are organic molecules that must be supplied in foods, because they cannot be produced in the body. They have a multitude of functions in wound healing; however, they are best known for their coenzymatic roles in energy and protein metabolism as well as immune functions. The primary way to classify vitamins is by their level of solubility in water. The water-soluble vitamins include the following B vitamins: vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B3 (nicotinic acid or nicotinamide), biotin, vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine, pyri-doxal, pyridoxamine), folate (folacin, folic acid, pteroyl glutamic acid), and vitamin B12 (cobalamin). Each vitamin will be referred to by its most common name throughout this chapter.
Recommended intakes of the B vitamins will be identified as either recommended dietary allowance (RDA) or adequate intake (AI) as defined by the U.S. Department of Agriculture (USDA).1 The RDA represents the average daily intake of a nutrient which meets the requirements of approximately 98% of all healthy people and is listed related to age and gender. The estimated average requirement is calculated from scientific evidence. When there is not enough scientific evidence about a nutrient to determine a specific estimated average requirement for an RDA, an AI is estimated. While the AI is based on current scientific research, further research is needed to determine a more exact amount of the specific nutrient. The AI is also designed to meet the needs of all healthy children and adults.1
Although the role of nutrition in the various phases of wound healing is well recognized, the action of each of the B vitamins in this regard is still being defined. It is clear that the B vitamins have specific metabolic functions, and that they interact with one another in order to ensure that wound-related energy metabolism and tissue synthesis occur appropriately. Studies have shown that B vitamins play initial coen-zymatic roles during the inflammatory phase and during the removal of dead tissue and bacteria. B vitamins also have critical roles in the proliferative and remodeling phases of wound healing in that they participate in the synthesis and interlinking of collagen and, therefore, the synthesis of new tissues and blood vessels. During the third or final phase of wound healing, myofibroblasts are dependent on B vitamins when they pull the edges of wounds inward and continue to strengthen the scar for up to 2 yrs.2 During all phases of wound healing, substantial amounts of energy (kcals) are required for the construction of compounds that are necessary for tissue rebuilding and are inherently dependent on an adequate supply of B vitamins. Multiple vitamin preparations given either intravenously or orally have B vitamins included, and these are routinely given to patients as part of an overall multivitamin regimen. DiBiasse and Wilmore3 recommended that uncomplicated critically ill patients should be provided with significantly greater amounts of all eight B vitamins as part of their normal care (Table 7.1).
In this chapter, background material about each of the B vitamins including information about normal absorption, metabolism, functions, deficiencies, toxicities, and recommended intakes will be presented. Specific wound-related research data regarding vitamins B1, B2, B5, and B6 will also be provided.
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