Nutrition, Anabolism, and the Wound Healing Process: An Overview

Robert H. Demling, MD

Disclosures

ePlasty. 2009;9:65-94. 

In This Article

Principles of Macronutrient Utilization (Adaptive Metabolism)

Before discussing the principles of nutritional support for healing, it is important to understand the normal utilization of nutrients and the normal metabolic pathways to energy production and protein synthesis, which maintain the LBM compartment.[30–37]

Understanding the metabolic concept of macronutrient nutrient partitioning into an energy and protein compartment and methods to optimize an efficient nutrient channeling into either energy production or protein synthesis is the first step to understanding the nutritional support principles. In addition, the role of anabolic agents becomes clearer when considering their role as agents channeling protein substrate in protein synthesis.

In general, normal metabolism is directed by hormones that adjust when needed to and alter energy production to meet needs and also to restore daily protein balance through the natural tissue synthesis and breakdown pathways.[30,31,34–37]

Energy Pathway

Normally, the energy pathway is fueled almost completely by carbohydrates and fat.[31–33]

Protein Pathway

Protein when consumed is metabolized into amino acids and peptides. With normal anabolic hormone activity, nearly all of the protein by-products are used for protein synthesis, not for energy. Only 5% is typically used for energy. However, energy is required for the protein synthesis process (Fig 8).[34–37]

Figure 8.

Macronutrients enter the metabolic pathways directly by hormones. Carbohydrates and fats enter the energy system or are stored as fat, while more than 90% of consumed protein enters the protein synthesis process. Normal skin prevents any energy drain through a wound.

With starvation, there is preservation of LBM compartment, as the majority of the calories come from the fat mass and only about 5% from protein.[16,33] Metabolic rate and energy demands are decreased, cortisol levels (catabolic) decrease, and human growth hormone (HGH) levels (anabolic) increase (Fig 9).

Figure 9.

Starvation mode: protection of LBM. Hormone adaptation increases fat use for fuel with energy demands being decreased overall. A minimal amount of gluconeogenesis occurs to only maintain glucose to obligate users. LBM is in large part preserved.

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