November/December 2020 Issue
Clinical Nutrition: Dietary Guidance for COPD
By Jamie Santa Cruz
Vol. 22, No. 9, P. 14
Consuming more of the right foods and nutrients can help improve health outcomes.
COPD is the third-leading cause of death in the United States.1 The disease, which is most common in current or former smokers, is characterized by obstructed airflow and a heightened inflammatory response in the lungs. Its main symptoms are coughing or wheezing, excessive phlegm and mucus, and shortness of breath.2
While smoking cessation, breathing training, exercise, and medications all play a role in treatment, nutrition also is crucial. Clients with COPD often struggle to get sufficient nutrition, yet recent research suggests dietary factors are important both for preventing the disease and stemming its progress.
Nutrition is a uniquely important concern in COPD for two reasons. First, patients with COPD frequently are malnourished. Up to 40% of all patients with COPD have low body weight, and 25% experience moderate to severe weight loss.3 “One of the big obstacles [to good nutrition in COPD] is the disabling symptoms—feeling fatigued or tired, breathlessness, not getting enough air in your lungs—which may impact food-related activities, including shopping, cooking, and also eating meals,” says Jerlyn Jones, MS, MPA, RDN, owner of thelifestyledietitian.com. As a result, it’s easy to fall behind on food intake and lose weight.
Poor food intake and weight loss is a serious concern, since body weight in COPD is linked to mortality. According to Ellen Bowser, MS, RDN, RN, FAND, faculty nutritionist in the Pediatric Pulmonary Division of the University of Florida and coauthor of a 2019 evidence analysis on nutrition in COPD published by the Academy of Nutrition and Dietetics, “The lowest BMI group had the highest mortality rate compared with higher BMI groups. [In addition], there was clear evidence of an association between BMI and lung function.”4
A second reason why nutrition is uniquely important in COPD is that diet may have a direct effect on the underlying biological processes involved in lung function and the progression of COPD—namely, oxidative stress and systemic inflammation.
“The root cause for all disease […] appears to be inflammation,” says Andrew Freeman, MD, an associate professor of cardiology and director of cardiovascular prevention and wellness at National Jewish Health in Denver. “If you can cut that, it appears to be the magic bullet, if there is one.” To combat inflammation, Freeman recommends a low-fat, whole-food, plant-based diet to his cardiology and COPD patients. Although good nutrition doesn’t eliminate the need for medication, it does reduce disease burden, according to Freeman, and his COPD patients have fewer exacerbations (ie, symptom flare-ups) and fewer hospitalizations after changing their lifestyle.
Foods’ and Nutrients’ Protective Effect on Lung Function
The research on how diet may impact incidence and progression of COPD is mostly limited to observational studies, but evidence suggests a beneficial effect regarding the following foods:
• Fruits and vegetables: Repeated observational studies and at least two recent meta-analyses have found that consumption of fresh fruits (especially hard fruits, such as apples) and possibly vegetables is linked with improved lung function and lower risk of developing COPD.5-11 A recent large, population-based study of Swedish men found that for each additional serving of fruits and vegetables consumed, smokers had an 8% lower likelihood of developing COPD, and ex-smokers had a 4% lower risk (over a mean follow-up of 13 years).12
Only a few randomized controlled trials of fruit and vegetable consumption have been conducted in patients with COPD, with mixed results.13 However, one notable trial found that patients with COPD with greater intake of fresh fruits and vegetables saw improved FEV1 (an important measure of lung function in COPD) compared with the control group consuming a free diet.14 These benefits may be attributable to the fact that fruits and vegetables are high not only in antioxidants but also in polyphenols, which have anti-inflammatory properties and are associated with improved lung function in COPD.7
• Whole grains and dietary fiber: In observational studies, high intake of whole grains is linked to better lung function in COPD and lower mortality from chronic respiratory diseases.8,15 Whole grains are high in fiber, which has antioxidant and anti-inflammatory properties, possibly explaining the benefits of whole grains on lung function. Multiple studies, including at least one recent meta-analysis, have found that higher dietary fiber intake is associated with better lung function and reduced risk of COPD.11,16-19 Although fiber can come from a variety of sources, including fruits and vegetables, some evidence suggests cereal fiber may have an even greater protective effect against COPD than fiber from fruits and vegetables.18
• Vitamin D: Several studies have shown a correlation between vitamin D levels and lung function. In addition, many studies, including two randomized controlled trials, have found that supplementation with oral vitamin D reduces risk of COPD exacerbations, particularly in COPD patients who are deficient in vitamin D (baseline serum 25(OH)D levels lower than 10 ng/mL).20-22
• A “prudent”/Mediterranean diet pattern heavy in whole plant foods: According to a recent review article, research on dietary patterns consistently suggests that a Western-style diet (ie, a diet high in red and processed meats, refined grains, refined sugars, and desserts) is associated with an increased incidence of COPD and greater severity of the disease. Conversely, prudent/Mediterranean-style diets, which emphasize fruits, vegetables, whole grains, legumes, nuts, fish, and low-fat dairy, are consistently linked to improved lung function and respiratory symptoms, decreased incidence of COPD, and reduced mortality for respiratory diseases.13
• Fish, nuts, and seeds: It’s been suggested that increased intake of fish and omega-3 fatty acids, prevalent in fish and nuts and seeds, might reduce the incidence of COPD or the severity of symptoms, because omega-3 fatty acids have strong anti-inflammatory properties. Indeed, several early studies did show a link between intake of omega-3 fatty acids (especially in the form of fatty fish) on lung function and symptoms of COPD. However, these studies didn’t adjust for other dietary factors.13
More recent research hasn’t been able to establish an independent association between fish consumption and a reduction in COPD risk or symptoms. Fish consumption seems to lower COPD risk only when part of an overall healthful dietary pattern, suggesting that the overall health of the diet rather than the fish itself may be the key to lowered risk.23
• High-fat/low-carb diets: A high-fat/low-carbohydrate dietary pattern is sometimes touted as being beneficial in terms of reducing inflammation and potentially protecting lung function. However, the 2019 Academy of Nutrition and Dietetics evidence analysis found that there was very little research supporting a beneficial effect of this diet pattern in COPD, and the evidence wasn’t sufficient to recommend any particular macronutrient composition.4
Foods to Avoid in COPD
Just as certain foods may have beneficial effects on COPD, research suggests the following should be avoided:
• Processed red meats: Processed red meats contain nitrites as well as saturated fatty acids, both of which can trigger inflammation in the lungs and elsewhere. Consumption of processed meats has been linked in multiple studies to poorer lung function, increased risk of COPD, and greater risk of hospital readmission for COPD.24-30
• Soda: Higher levels of soft drink consumption are associated with higher incidence of COPD.31-33 This may be because soft drinks are linked to hyperglycemia, which causes inflammation and is associated with impaired lung function and adverse outcomes in COPD.34-36
• Broth, clear soups, and too much liquid in general: The goal in COPD is “to make sure all the food [COPD patients] are eating and all the beverages they’re drinking are nutrient dense,” according to Jones, and drinking liquids in abundance can make patients feel prematurely full without providing adequate nutrition.
Recommendations for RDs
Based on the research surrounding nutrition’s impact on COPD, dietitians can use the following strategies to help guide them when counseling patients:
• Assess energy intake. Since energy intake from food is tied to improved outcomes and lower mortality, it’s imperative that dietitians determine intake during counseling sessions.
• Check vitamin D levels. According to the 2019 Academy of Nutrition and Dietetics evidence analysis, vitamin D status is particularly important if a patient with COPD is having two or more exacerbations per year. Patients who have low levels should take an oral supplement.
• Coach clients on how to time meals. “Because people with COPD oftentimes fatigue very easily, what we encourage them to do is have small, frequent meals,” Bowser says.
According to Jones, patients with COPD should rest before eating. “Don’t do any strenuous activity before you have a meal,” she says. Also, “eat more food earlier in the morning if you’re usually too tired to eat later in the day.”
• Recommend batch meal prep. If clients prepare meals a couple times per week and freeze leftovers, “it’s easier for them to take something out that they’ve prepared and put it in the microwave, [which helps] minimize exertion,” Bowser says.
Finally, though exercise isn’t in the realm of nutrition per se, dietitians should help patients understand its importance. “Diet alone isn’t the only solution,” and exercise “really does some serious wonders,” Freeman says. In combination, nutrition interventions and physical activity can “significantly reduce disease burden and medications.”
— Jamie Santa Cruz is a freelance writer of health and medical topics based in Parker, Colorado.
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