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DEPARTMENTS: NUTRITION MATTERS

Where's the Protein?

Posthauer, Mary Ellen RD, CD, LD

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Meeting the increased energy and protein demands resulting from pathologic or severe stress caused by an infection or a major wound poses a challenge for the health care professional.

This stress results in numerous changes in the body. The inflammatory response-the body's protective mechanism during times of stress-causes the body to alter blood flow to the injury or infection site. At the same time, the metabolic rate increases (hypermetabolism) to mobilize nutrients into glucose and amino acid pools. In severe stress, the body uses glycogen stores and protein to make glucose and stress factors (such as the cytokines interleukin-1, interleukin-6, and tumor necrosis factor). Hormonal changes during stress shift the balance between insulin and the counter regulatory hormones (including catecholamines, cortisol, and glucagon). Insulin assists carbohydrate and lipid storage and protein synthesis. But during stress, the rise of the counterregulatory hormones is greater than the rise in insulin. Metabolic and total energy rates increase as the patient's body continues to deplete protein stores.

Hormonal changes also occur in severe stress, resulting in increased glycogen breakdown and mobilization of free fatty acids. Glucagon breakdown increases and accelerates glucose production from amino acids. As this continues, storage of glucose, fatty acids, and protein declines. Protein from the skeletal muscle, connective tissue, and the gastrointestinal tract is converted to provide the glucose and amino acids needed to support the synthesis of stress factors and immune cells1Figure 1.

Figure 1
Figure 1:
METABOLIC RESPONSE TO SEVERE STRESS

Cytokines-cell-mediated proteins-enhance the immune defenses by stimulating production of cells to attack foreign organisms; however, these cytokines can also cause fever and anorexia.2 The increase in cytokines accelerates protein breakdown or catabolism as well2,3Figure 2. In addition, fat metabolism increases and plasma levels of the essential fatty acids (linoleic [omega-6 fatty acid] and linolenic [omega-3 fatty acid]) decrease. Some studies show that clinical signs of fatty acid depletion can develop in 10 days.4 Cells in the intestinal tract may also shrink and lose some of their absorptive ability and immune function as the protein in the gastrointestinal tract is used in response to stress.

Figure 2
Figure 2:
EFFECTS OF CYTOKINES ON NUTRITION

These physiologic changes are seen in patients every day, particularly in the long-term-care setting. The following case study illustrates the issues and suggests options for managing these patients.

Case Study

Mrs T, 85, has dementia and a nonhealing, draining Stage IV pressure ulcer on her coccyx. She is 66″ tall and weighs 120 pounds, having lost 10 pounds in 30 days. The staff reports that she consumes only 50% of her meals, or about 900 calories per day. Because she prefers liquids to solid food, most of these calories come from beverages; her protein intake averages only 16 to 20 grams/day.

Neither Mrs T's weight nor her pressure ulcer shows any sign of improvement. Her body is clearly under stress and needs increased energy and protein to promote the healing process. To achieve these goals, Mrs T would need at least 1636 to 1910 calories per day, including 66 to 109 grams of protein and 1636 to 1800 mL of fluid. Unfortunately, the traditional intervention of enhancing her meals with fortified foods is failing to achieve a positive nitrogen balance because Mrs T refuses to eat them.

The most cost-effective way to achieve Mrs T's protein and caloric requirements would be to offer calorie-dense foods high in complete proteins. Meat, fish, eggs, poultry, and milk are examples of complete proteins that provide all of the essential amino acids needed for growth and maintenance of cells. Because Mrs T prefers liquids over solid foods, supplements formulated to enhance protein synthesis and reduce protein breakdown should also be considered.

Supplemental Nutrition

A variety of therapeutic supplements targeted to treating wounds and restoring lean body mass are currently available. Each product contains ingredients formulated to promote cell production and to assist in collagen synthesis, wound contraction, and remodeling. Several products contain arginine, which has 32% nitrogen and glutamine-conditional amino acids that, under times of stress, support the immune system and protein synthesis.5-8

Supplemental products may also contain cysteine, an amino acid required by the cells to synthesize glutathione, an antioxidant that enhances healing and homeostasis. Omega-3 and omega-6 fatty acids are often included in the formulas as well. Omega-3 affects T cell proliferation, cell-to-cell adhesion, and cytokine production.9

Most products offer zinc and vitamins A, C, and E. Several of the liquid protein products now available provide 15 to 18 grams of protein in a volume of 30 to 45 mL. The protein source is whey protein isolate or hydrolyzed collagen fortified with tryptophan. This type of supplement also provides arginine, glutamine, zinc, and vitamins A, C, and E.

β-Hydroxy-β-methylbutyrate (HMB), arginine, and glutamine are the 3 ingredients in 1 drink mix. HMB is the metabolite of the amino acid leucine, which has a role in maintaining the structure of muscle cells. It is a precursor to cholesterol.10 HMB provides an extra source of cholesterol, a component of all cell membranes, and enhances the integrity of cells. This preserves lean body mass and muscle integrity.10

The dietitian and the health care team should become familiar with the research on each nutritional supplement in the facility's wound care protocol and the role of these products in patient management, and they should evaluate these products for cost, availability, taste, and patient acceptance. Once the health care team identified an appropriate supplement for Mrs T, which she accepted, her weight began to improve and her wound healed. Keep in mind that supplements enhanced with proteins are more expensive than traditional supplements. However, they can play an important part in the diet plan for patients with whom the health care professional has not had success with other nutritional methods.

No single treatment is appropriate for every patient. This is why the nutrition plan must be individualized to the patient's needs.

REFERENCES

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9. Field CJ. Use of T-cell function to determine the effect of physiologically active food components. Am J Clin Nutr 2000;71(6 Suppl):1720S-1725S.
10. Nissen SL, Aumbrad NN. Nutritional role of leucine metabolite β-hydroxy-β-methylbutyrate (HMB). J Nutr Biochem 1997;8:300-11.
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