By Monica Serra, PhD, RD, ATC
Unfortunately, athletic injuries are unavoidable, regardless of sport or participation level. Identifying ways to minimize the impact of the injury to enhance recovery, and thus prevent time away from activity and loss of muscle mass, strength and function, are of utmost importance. Although the physical rehabilitation modalities, including rest, ice, elevation and massage, are prevalent, the role of nutrition in recovery is often overlooked.
Following an injury, it’s necessary to ensure enough total calories as well as optimal macro- and micronutrient profiles. The recommendation for these nutrients depends on the athlete’s nutritional status at the time of injury, phase of injury, severity of the injury and type of tissue undergoing healing. During the acute phase of injury, when rest and immobilization are most common, the nutritional goal is to help prevent loss of muscle mass, while allowing the tissue to heal. Following the period of rest, rehabilitation often focuses on promoting activity of the injured site and nutritional goals shift to promoting strength gains and increasing muscle hypertrophy.
Calories and Macronutrients
Calories: Total caloric intake recommendations depend upon the severity of the injury, body composition, age, and treatment regimens. Several predictive equations are available to estimate energy requirements following injury,1 with expenditure increased by up to 50 percent in patients who are severely injured. Adequate energy intake is necessary to allow tissue to repair and prevent exacerbation of inflammation, which is observed following injury when energy intake is suboptimal.2 While the use of assistive devices for ambulation may further increase energy requirements, this should be balanced with the decreased energy expenditure occurring with immobilization and/or inactivity to prevent weight change. The delivery of nutrients though small meals every three to four hours is recommended to avoid an upset stomach and boost metabolism. Further, the need for soft foods may be required if injuries to the head and/or neck were sustained. It is especially important to prevent negative energy balance so patients do not utilize protein as energy.
Protein: Protein is involved in many aspect of tissue repair following injury, including collagen synthesis, growth of new capillaries and epithelialization of wound closure. Protein depletion is associated with inflammation and inhibited wound remodeling. There is no consensus as to the amount of protein necessary following injury; however, studies suggest that protein intakes as high as 1.5 to 3 g protein/kg/day are necessary to prevent muscle loss in periods of negative energy balance.3 Age of the athlete (older adults may have higher protein requirements due to decreased ability to synthesize protein), the timing of protein intake with exercise/rehabilitation, the amount per meal and the type of protein must be considered.
Carbohydrates and fats: Other than to maintain total energy and prevent macronutrient deficiencies, research does not indicate the need to change the percentage of calories coming from carbohydrates or fats.
Fluid: Increased fluid needs may be increased for a variety of reasons following injury, including profuse sweating/fever, diarrhea and draining wounds. Additionally, adequate fluids following the development of a wound are needed for transport of nutrients to and waste away from the wound. Several general formulas are used to calculate an individual’s fluid requirements, including 30 mL/kg and one mL/kcal consumed; however, more specific predictive formulas are available for more severe injuries.4
Micronutrients
Although preventing deficient of all micronutrients through consumption of a balanced diet is important to maintain overall health, the following nutrients may be important to tissues undergoing healing. In general, research supporting the use of supplementation of specific nutrients above the recommended dietary allowance (RDA) is lacking in previously healthy individuals, while those with nutrient deficiencies may benefit from repletion.
Amino acids: Beyond their role in total protein, several amino acids have been identified as having beneficial effects on the healing process. Food sources: meat, chicken, fish, dairy products and eggs
Arginine: Arginine is a non-essential amino acid that appears to enhance wound repair and immune function. Arginine supplementation in surgical patients results in higher collagen deposition, protein accumulation and immune activity compared to controls.5
Branched chain amino acids: Supplementation of these essential amino acids is suggested to ameliorate the loss of muscle during disuse and/or immobilization6 and enhance recovery after surgery.7 Newer research is focused on the effects of leucine specifically since its ingestion can increase muscle protein synthesis.8
Glutamine: This non-essential amino acid is involved in inflammatory and immune cell proliferation. Although a benefit of supplementation has been observed in critically ill patients,9 it is unknown whether it enhances wound healing in less severe conditions.
Creatine: Studies suggest that creatine supplementation can ameliorate muscle loss following immobilization10 and stimulate muscle hypertrophy and strength gains during rehabilitation.11 However, these effects are not universally observed as other studies show no benefits to muscle preservation11 or strength12 with immobilization. Due to these inconsistencies, supplementation is not supported to promote wound healing at this time. Food sources: wild game meats, including rabbit, venison and elk
Calcium and vitamin D: In addition to the well-established effects of calcium and vitamin D on bone mineralization, there also is evidence for their need in soft tissue repair as calcium serves as a modulator in keratinocyte proliferation and differentiation. Not only is there evidence for altered bone formation,13 but also delayed epidermal14 wound healing in animals lacking the vitamin D receptor when placed on a low-calcium diet. However, currently, there is no evidence for the need for supplementation above the RDA to aid in recovery from injury. Food sources: calcium: dairy foods, spinach, kale and soybeans; vitamin D: fatty fish, like tuna, mackerel, salmon and foods fortified with vitamin D (some dairy products, orange juice, soy milk and cereals)
Omega 3 fatty acids: Evidence exists suggesting that following an injury, the percentage of fat coming from omega-3 fatty acids should be increased as they may ameliorate muscle loss by aiding muscle protein synthesis, protect against bone loss and counteract free radicals that can cause oxidative damage and inflammation. Fish oil supplementation may be indicated if inflammation is in excess or chronic.15 Further, although the majority of research is limited to animal models, studies suggest that diets supplemented with anti-oxidants can normalize oxidative damage induced by a traumatic brain injury.16 However, careful consideration for the use of anti-inflammatory nutrients should be given considering the importance of inflammation on optimal healing. In fact, there is some evidence of impaired wound healing with supplementation of omega-3 fatty acids.17 Food sources: fatty fish, flaxseed, canola oil and walnuts
Vitamin A: Vitamin A enhances early inflammation by increasing monocytes and macrophages at the wound site and is required for epithelial and bone tissue development, cellular differentiation and immune function. Research suggests supplementation may be beneficial in patients who have low immune function or are steroid treated. Concern about potential toxicity, however, has prevented the recommendation of a dose above the RDA. Food sources: sweet potatoes, carrots, dark leafy greens and winter squashes
Vitamin C: Vitamin C is an essential cofactor for collagen synthesis and other components of the intracellular matrix involved in bones, skin and connective tissue formation. Vitamin C also enhances neutrophil migration, increases angiogenesis and acts like an antioxidant. Clinical manifestations of deficiency include bleeding gums, poor immunity and slow fracture and wound healing. The majority of research suggests that only those with ascorbic acid deficiency, uncommon in Westernized diets, demonstrate benefits of supplementation. Food sources: cantaloupe, citrus fruits and juices, kiwi and mango
Vitamin E: The effects of vitamin E in healing are complex, as it appears to have differing effects dependent upon the type of wound. It can act as an antioxidant to prevent lipid peroxidation and improve cell membrane stability, but also can inhibit the inflammatory response and collagen synthesis, thereby impeding the healing process. Vitamin E often is used topically as anecdotal reports claim it speeds healing and cosmetic appearance of the scar; however, research of topical application does not support an effect on scar thickness or appearance.18 Food sources: nuts, seeds and oils
Zinc: Zinc is necessary for maintain the structural integrity of dermal tissue and mucosal membranes, which is likely why deficiency is associated with decreased breaking strength of wounds. Demands appear are highest immediately following the time of the injury. Although data suggesting zinc supplementation improves healing in non-deficient patients is lacking, evidence suggests the zinc content of food supplies may be inadequate to meet zinc requirements for approximately 15 to 20 percent of the world’s population.19 Further, supplementation may be necessary in patients with chronic diarrhea. Food sources: seafood, meat, seeds and cooked dried beans
Foods to Avoid
The focus of this review has been on what nutrients to consume; however, the recommendation for avoidance of several nutrients also should be addressed.
Alcohol: Alcohol impairs muscle protein synthesis, increases muscle loss during immobilization, and may reduce the inflammatory response,20 thus should be avoided during wound recovery.
Simple carbohydrates: Excessive sweets and candies should be avoided, especially if metabolic disorders, such as type 2 diabetes mellitus, are present because hyperglycemia can impede healing and result in immune dysfunction.
Caffeine: Caffeine, which is known to have antioxidant properties, hinders keratinocyte proliferation and migration, suggesting that it may have an inhibitory effect on wound healing and epithelialization21 and should be avoided during the recovery process.
Summary
In summary, there is still much to be learned. While the relationship between nutrient deficiencies and poor wound healing is well documented, the impact of dietary supplementation of specific nutrients is relatively unknown, with the majority of research suggesting that as long as total energy and protein is sufficient, additional micronutrient intake above the RDA does not appear warranted. More extensive trials are needed to evaluate the safety and efficacy of these nutrients. Ask a sports dietitian for scientific advice on nutrients involved in healing and recovery.
About the author: Monica C. Serra is an assistant professor at the University of Maryland School of Medicine in the Division of Gerontology and Geriatric Medicine and a Research Health Scientist at the Baltimore VA Medical Center in the Geriatric Research Education and Clinical Center. She received her bachelor’s degree from Duquesne University in athletic training, her master’s degree in nutrition from Case Western Reserve University and her PhD from Baylor University in exercise, nutrition and preventative health. She is a registered dietitian and athletic trainer. Her research focuses on the loss of functional independence and cardiovascular disease risk in older chronically disabled adults and the effects of nutritional and exercise rehabilitation in these populations.
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