Why Protein is a Critical Component to Wound Healing

Protein is a critical component to the wound healing process. Wound healing creates a hypermetabolic state where nutritional needs are increased above that required for daily activities.¹ Proteins are not only used to build new tissue, they are essential in almost every process including the immune system and transport of oxygen. So, how do you determine a patient’s protein status? Albumin and pre-albumin are no longer considered the core determinant of protein status, and a deficiency in albumin or pre-albumin is indicative of the chronic inflammation that is a cause of impaired wound healing.² Better indicators of nutritional status that can be assessed in the outpatient environment include weight loss (both gradually over time and recent) and nutritional intake. Screening patients through assessment questions or weighing them at each clinic visit along with asking basic questions about meals per day and what a meal consists of can give enough information to the clinician to know whether to suspect malnutrition.

Patients with wounds are supplemented with protein to prevent the body from turning on itself and decreasing lean body mass. The National Pressure Ulcer Advisory Panel (NPUAP) recommends 1.25-1.5g of protein per kg of body weight per day for patients with wounds.³ As of 2016, the average US male weighed 197lbs, and the average US female 170 lbs.⁴ This means recommendations for the average US citizen with a wound would include 112-134g of protein per day for the average male, and 96-115g of protein per day for the average female. We know the average daily protein intake in the US is 90-100g/day,⁵ so in patients without other limiting disease states supplementing with an over-the-counter protein drink 1 to 2 times per day is usually sufficient as these drinks range from 10-30g each. It is important to reinforce the need for patients with diabetes to consider the carbohydrate content of these over-the-counter protein supplements as some contain upward of 15-20g of sugar per beverage. Most distributors offer a formula for patients with diabetes. Another caveat are our patients that are still anticoagulated on warfarin. Many over-the-counter protein drinks are high in vitamin K. If you decide to recommend these supplements to patients anticoagulated on warfarin international normalised ratio monitoring and warfarin dosing should be adjusted accordingly.

Studies of protein restriction in patients who are non-nephrotic with chronic kidney disease and are not on dialysis have inconsistent results; however, generally if the is glomerular filtration rate (GFR) is <60mL per minute, a moderate protein restriction is recommended of 0.8g/kg per day.⁵ The goal is to slow the progression of the kidney disease and prevent transplant, patient mortality, and starting dialysis. Using our body weight averages previously stated that is about 70g of protein per day for the average male and about 60g for the average female. Even with inconsistent evidence the moderate benefit in GFR reduction can result in additional years of time where patients do not require dialysis. In the short term, the benefit of healing a wound in a timely manner vs the risk of GFR reduction can allow for increased protein supplementation in patients who are non-nephrotic with chronic kidney disease while their wound is healing.

Patients with kidney disease who are receiving dialysis have high dietary protein requirements, and low protein intake is associated with poor outcomes, including increased mortality.⁶ These patients typically have access to a specialized renal dietitian through their dialysis center, but it is always good to double check that they have seen someone and reinforce the teaching they have received.

Patients who are obese are another challenging population in terms of protein supplementation. Supplementing protein will usually increase caloric intake. Often weight loss is recommended for assistance in managing comorbidities that are also contributing to delayed wound healing in the obese population, including diabetes and lymphedema. Clinicians should also keep in mind that excess calorie consumption that results in obesity does not mean that nutrient dense food is being ingested. Patients who are obese also present with malnutrition, and supplementation is required.

In summary, most nutritional research in wound care patients involves trauma patients, so acute wounds, and those with pressure injuries,⁷ which is not useful for the majority of chronic wound patients in outpatient centers. In using recommendations for pressure injuries, a good brief nutritional screen for all patients presenting to wound centers can include weight loss and current nutritional intake. Most patients can be offered a goal for a daily protein intake of 110g.

References

1. Demling R. Nutrition, anabolism, and the wound healing process: an overview. Eplasty. 2009;9:e9.
2. White JV, Guenter P, Jensen G, Malone A, Schofield M. Consensus statement of the Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition: characteristics recommended for the identification and documentation of adult malnutrition (undernutrition). J Acad Nut Diet. 2012;112:730-738
3. National Pressure Ulcer Advisory Panel and European Pressure Ulcer Advisory Panel. Prevention and treatment of pressure ulcers: clinical practice guidelines. National Pressure Ulcer Advisory Panel, 2009.
4. Body Measurements. Center for Disease Control and Prevention. Data 1999-2016. Accessed at https://www.cdc.gov/nchs/fastats/body-measurements.htm
5. Cho M, Beddhu S. Dietary recommendations for patients with nondialysis chronic kidney disease. UpToDate. Feb 21, 2020. Accessed November 18, 2020.
6. Qunibi, W. & Henrich, W. Protein intake in maintenance hemodialysis patients. UpToDate. Jan 18, 2019. Accessed November 18, 2020.
7. Molnar JA, Underdown MJ, Clark WA. Nutrition and chronic wounds. Adv Wound Care (New Rochelle). 2014;3(11):663-681. doi:10.1089/wound.2014.0530