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Diabetic Foot Ulcers and Nutrition: Making the Connection

Nutrition often is not the first thing clinicians think about when treating patients with a diabetic foot ulcer (DFU), but it is a critical component of the wound healing process. Nutrition is connected to every facet of healing, including immune function, glycemic control, weight management, and physical ability.

It is important to take advantage of every wound clinic visit to discuss nutrition issues with patients while providing their wound treatment. A few minutes spent focusing on food can go a long way toward helping patients recover. 

Keeping Blood Glucose Levels Under Control

The number-one goal of any diabetes management plan is keeping long-term blood glucose levels in the desired range. High blood glucose levels interfere with wound healing and can lead to defective white blood cell function, making a DFU susceptible to infection. High blood glucose levels also can affect the production of inflammatory molecules, interfere with collagen synthesis, and change cellular morphology. In a study at Johns Hopkins University, elevated A1c was significantly associated with a poor wound healing rate.1 

Food choices, including the timing and carbohydrate content of meals and snacks, can impact glycemic control. Any form of carbohydrate when eaten in excess, including whole grains and not just simple sugars, can affect blood sugar levels, so portion control of all carbohydrates is important. Choosing whole-grain breads and cereals instead of refined grains provides added fiber, vitamins, and minerals. A registered dietitian nutritionist (RDN) can help patients learn to choose appropriate carbohydrate portions and balance food with oral medication and insulin to help optimize glycemic control.

Often the simple act of losing extra weight can help with glucose control and, in turn, wound healing. However, this is easier said than done. It proves very challenging for most patients, even though weight loss can improve glycemic control and reduce complications, thus improving quality of life. This is where a referral to an RDN with expertise in diabetes can help. 

Focusing on Nutrition Through Screening 

Nutrition education does not require something fancy or complicated. Sometimes all it takes to begin a helpful talk is inquiring about what patients ate that day. A more formal way to begin a nutrition discussion is to ask patients to complete a nutritional screening questionnaire, such as the MNA® Mini Nutrition Assessment (https://www.mna-elderly.com) (Figure 3). This validated, six-question tool takes just a few minutes to complete and can identify those at risk for malnutrition, as well as those who are possibly already malnourished. The MNA is available in over a dozen languages, allowing patients to complete it independently in the waiting room and then hand it to the clinician for review. 

In general, nutrient deficiencies can affect the complex process of wound healing in a multitude of ways. Malnutrition and/or nutrient deficiencies can impair collagen synthesis, prolong inflammation, decrease phagocytosis to cause dysfunction of B and T cells, and decrease the mechanical strength of the skin. For these reasons, it is important to ask patients about their food intake and help them understand the importance of eating a variety of nutrient-dense foods each day. A validated nutrition screening tool is an easy way to begin to do this. 

Providing Chairside Advice

Once the risk information is obtained, clinicians may face challenges in deciding what to say to patients when a problem is uncovered. Many times, they advise patients to eat “better” or “healthy foods,” but this vague advice needs a bit of refinement in order to truly help patients make changes in their intake. 

Here are some easy answers to three of patients’ most common questions. 

‘What foods are the best to eat?’

  • Protein-rich foods, including:
    • Lean meats and seafood
    • Skinless poultry
    • Eggs
    • Tofu
  • Whole-grain and high-fiber carbohydrates, such as:
    • Whole-grain breads, cereals, and pasta
    • Brown rice
    • Beans
    • Fruits with the skin
    • Berries
  • Low-fat dairy products
  • Non-starchy vegetables, such as:
    • Cauliflower
    • Tomatoes
    • Peppers
    • Carrots
    • Broccoli
    • Cabbage
    • Kale
    • Spinach

Remind patients to read food labels on all foods and to look for the sugar content. For example, yogurt often has hidden sugar, so stress the importance of getting into the habit of looking at food labels. 

‘What can I snack on?’

The snacks listed below average 15 g total carbohydrate: 

  • One whole Thomas® Light Multi-Grain English Muffin with 1 Tbsp nut butter 
  • 2 Tbsp raisins and ¼ C almonds
  • Hard-cooked egg and one slice of whole-grain toast with ½ tsp margarine 
  • One half banana or one medium apple with 1 Tbsp peanut butter
  • ½ C low-fat cottage cheese and ½ C lite peaches
  • 4 oz Kozy Shack® No Sugar Added Rice Pudding and ¼ C nuts
  • Kabobs made with 1 C melon and 1 oz low-fat cheese 
  • Celery and dip made from 1 Tbsp peanut butter and 2 Tbsp raisins 
  • ½ C sugar snap peas and 2 Tbsp hummus (bean dip)
  • Five Reduced Fat Triscuits® with 1 oz low-fat cheese
  • ½ C light tuna or egg salad on one-half of a whole-wheat pita 
  • One whole Thomas Light Multi-Grain English Muffin topped with tomato slices and 1 oz low-fat mozzarella cheese, and then baked
  • 10 Multi-Grain Wheat Thins® with 1 oz low-fat string cheese  

‘Should I take vitamins?’ 

This question is a little more complex because it depends on how well patients are eating, if weight loss has recently occurred, and many other factors, including other medical conditions. In general, a multivitamin and mineral supplement is probably a good idea. An optimal diet alone usually is adequate to meet all the vitamin and mineral requirements of healthy individuals. Unfortunately, not many people consume an optimal diet every day, and most patients with a DFU and comorbid conditions have increased needs for specific vitamins and/or minerals. A supplement can fill any gaps and acts as a good insurance policy. 

Many micronutrients are involved in wound healing, including vitamin A, vitamin C, magnesium, copper, and zinc. Unfortunately, not many studies are available to help determine optimal intake levels or if supplementation is beneficial. What is known is that every patient should meet the Dietary Reference Intakes (DRIs) for vitamins and minerals for these and other nutrients daily. In addition, sometimes supplementation of specific nutrients is recommended if a deficiency is confirmed or suspected. 

The big unanswered question is whether to supplement above the DRI level, and if so, how much above? Many clinicians recommend additional vitamin C and zinc. Vitamin C is water soluble and may help in other areas including immune function, so if patients take additional vitamin C, it is not of much concern. Zinc, however, is more concerning because it is not water soluble, and long-term zinc supplementation may in turn cause a copper deficiency. Additional zinc is typically recommended only for correcting a known or suspected deficiency. 

Vitamin D deficiencies are quite common and are easily identified by a simple blood test. If a deficiency is confirmed, patients should receive supplementation along with a recommendation to sit in the sunshine for 10-15 minutes every day. Individuals with darker skin will require a longer time in the sun for complete vitamin D synthesis. 

Supplementing Diets With Amino Acids

A newer treatment beyond vitamins is supplementing with amino acids. Amino acids are the building blocks of protein. 

A polypeptide chain is comprised of the following three categories of amino acids:

  • Indispensable amino acids, also known as essential amino acids, are not synthesized by humans and must come from the diet. 
  • Dispensable amino acids, also known as nonessential amino acids, are produced by the body in sufficient amounts under normal, healthy conditions. 
  • Conditionally indispensable amino acids (CIAAs) are in a special category because while they are produced in sufficient amounts by healthy individuals, many conditions may increase demand for certain CIAAs and supply may run short. In other words, in the presence of certain disease states or underlying physiological stress, such as a chronic wound, supplementation may help achieve an adequate supply of CIAAs. Two CIAAs that often are supplemented are arginine and glutamine. In addition, a metabolic byproduct of leucine called β-hydroxy-β-methylbutyrate (HMB) often is supplemented as well. 

Arginine is an amino acid that supports nitric oxide production, and thereby blood flow, and is a building block for protein, which can contribute to wound healing. Glutamine plays a role in collagen production in fibroblast cultures and supports the immune system. HMB is a compound found in small amounts in the body and in small amounts in certain foods, such as grapefruit, alfalfa, and catfish. Approximately 5% of leucine is converted to HMB, which helps produce new tissue by slowing muscle breakdown and enhancing protein synthesis. Because the conversion rate is not very high and the foods it is found in are not typically consumed in great amounts, supplements are used. 

In order to replenish the specific amino acids needed in an efficacious amount, a medical nutrition supplement often is used. For example, a powdered drink mix, such as Juven® (Abbott Nutrition, Abbott Park, IL), often is recommended. Each packet of Juven contains 7 g of arginine, 7 g of glutamine, and 1.5 g of HMB, plus a small amount of collagen protein and some key vitamins. Each packet of flavored powder is mixed with about 8 fl oz of water or juice.  Fluid-restricted patients can mix the unflavored powder with food. 

Promoting Wound Healing Through Nutrition

Nutrition is a critical component of healing DFUs, particularly as it relates to immune function, malnutrition, glycemic control, and weight loss and weight maintenance. It is very important not to overlook nutrition screening to identify any problems and then take the necessary steps to address any nutritional gaps. 

Healing begins from the inside out. Building new tissue requires calories, protein, and many vitamin and mineral cofactors. Poor nutrition can hinder the success of healing diabetic foot wounds, so make sure to ask patients about how their meals are going. If you discover a complex nutritional problem that is beyond a simple discussion, refer patients to an RDN. Medical nutrition therapy for patients with diabetes is often a covered benefit on many insurance plans, as well as Medicare Part B. 

Nancy Collins is a wound care-certified dietitian specializing in the relationship between nutrition and wound healing. She is also a medico-legal expert dedicated to improving provider-patient communication and bettering the patient experience. To contact her, visit her website, www.drnancycollins.com.

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Nancy Collins, PhD, RDN, LD, NWCC, FAND
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References

1. Christman AL, Selvin E, Margolis DJ, Lazarus GS, Garza LA. Hemoglobin A1c predicts healing rate in diabetic wounds. J Invest Dermatol. 2011;131(10):2121-2127. 

Further Reading 

2. Jones MS, Rivera M, Puccinelli CL, Wang MY, Williams SJ, Barber AE. Targeted amino acid supplementation in diabetic foot wounds: pilot data and a review of the literature. Surgical Infect (Larchmt). 2014;15(6):708-712. 

3. Pham HT, Rich J, Veves A. Wound healing in diabetic foot ulceration: a review and commentary. Wounds. 2000;12(4):79-81.

4. Tsourdi E, Barthel A, Rietzsch H, Reichel A, Bornstein SR. Current aspects in the pathophysiology and treatment of chronic wounds in diabetes mellitus. BioMed Res Int. 2013;385641.able at http://www.hindawi.com/journals/bmri/2013/385641/. Accessed Apr 21, 2019.

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