February 20, 2017

Healthy eating in lung disease

Professor Lisa Wood, PhD, RNutr, Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute and University of Newcastle

The New Year is the time when we often stop and think about the year ahead and what we could be doing differently, or better. We often think about eating more healthily – what exactly does this mean and for people with respiratory diseases, what is most important?

What is ‘healthy eating’?

Healthy eating means eating a variety of foods from each of the five food groups every day, in the right amount. This includes plenty of fruit and vegetables and cereal foods, such as wholegrain breads, rice, pasta and oats. It also includes protein-rich foods such as lean meats, poultry, fish, eggs, legumes, beans, nuts and dairy products such as milk, yoghurt and cheese. Every food group is important as each represents a different set of nutrients that are essential for normal growth and good health.

Are any particular foods helpful for patients with respiratory diseases?

Fruit and vegetables: Focusing on eating more fruit and vegetables is a simple, yet very effective strategy for getting healthier. Fruit and vegetables are rich in vitamins, minerals and fibre and a study by our group, the Priority Research Centre for Healthy Lungs, has shown they are beneficial for the lungs. The study asked people with asthma to eat a high fruit and vegetable diet (seven servings per day) or a low fruit and vegetable diet (three servings per day) for three months. It found that the people on the low fruit and vegetable diet were more than twice as likely to have an asthma attack during the study period.1 Another study in COPD patients showed that a high fruit and vegetable diet lead to improved lung function.2 Fruit and vegetables are also low in energy meaning they are helpful for controlling weight.

Dairy foods and their alternatives: To keep your bones healthy, you need plenty of calcium in your diet and dairy foods provide a good source. Looking after your bones is particularly important if you have a disease like severe asthma or COPD, where you need high doses of steroids to control the inflammation in your lungs. Steroids, as well as smoking, poor diet and limited sunlight exposure, can reduce bone strength, so ensuring an adequate calcium intake (three to four serves of calcium-rich foods per day) is vital. We know that many people with asthma and COPD avoid eating dairy products because of the myth that dairy intake worsens mucus production and symptoms. While a small number of people have a dairy allergy, this is uncommon and should be confirmed by an immunologist, in which case alternative sources of calcium can be consumed. Avoiding dairy foods unnecessarily is unwise, as this reduces healthy food choices and is likely to compromise bone health.

Protein-rich foods: For some respiratory patients, particularly people with COPD, malnutrition and being underweight becomes a serious problem and they develop a low body mass index and lose muscle tissue. There are many reasons that this happens. Often people eat less because they are feeling breathless or have a poor appetite and at the same time, they may use more energy to breathe and fight respiratory tract infections causing them to lose weight. This can impair respiratory muscle function, exercise capacity, the immune system and overall health status.3 In patients who are underweight, protein and calorie intake can be boosted using high energy, nutrient-rich foods such as milk powder, cheese, cream, custard, peanut butter, milkshakes or nutritionally complete oral supplements, for example Sustagen.

What foods should I avoid?

Highly processed and takeaway foods should be avoided, as they are often full of saturated fat, refined sugar and/or sodium. Over recent years, research has linked fast/takeaway foods and soft drink to an increased risk of developing asthma and COPD.4-8 We published a study in which we asked adults with asthma to consume a high energy, fast food meal and we monitored them for four hours. We found that their airway inflammation worsened and their Ventolin did not work as effectively.9 Instead of lasting for four to six hours as you would expect, it wore off after only two to three hours. Eating fresh foods, cooked from scratch whenever possible, is a much healthier option.

Do I need to lose weight?

Whether or not you have lung disease, being overweight or obese increases your risk of developing metabolic diseases such as type 2 diabetes mellitus, cardiovascular disease, certain types of cancer and sleep apnoea. It also puts your lungs under increased pressure and makes exercising more difficult. We know that in obese people with asthma, weight loss is beneficial, with just a 5 – 10 per cent weight loss leading to improvements in asthma control and quality of life in most patients.10 In other respiratory diseases, such as COPD, there are no clinical guidelines for managing obese patients. However, we do know that any attempts to lose weight should involve increasing physical activity, because not only does this help use up stored energy, it also helps to preserve muscle mass, which is necessary for achieving good outcomes. Lifestyle changes and weight loss can be challenging so consulting a dietitian may be helpful.

To conclude, you breathe what you eat! So why not make 2017 the year of healthy eating for your lungs? For more information on healthy eating visit https://www.eatforhealth.gov.au/.

References

1. Wood LG, et al. Manipulating antioxidant intake in asthma: a randomized controlled trial. Am J Clin Nutr 2012;96:534-43.
2. Keranis E, et al. Impact of dietary shift to higher-antioxidant foods in COPD: a randomised trial. Eur Respir J 2010;36:774-80.
3. Vestbo J, et al. Body mass, fat-free body mass, and prognosis in patients with chronic obstructive pulmonary disease from a random population sample: findings from the Copenhagen City Heart Study. Am J Respir Crit Care Med 2006;173:79-83.
4. Wickens K, et al. Fast foods – are they a risk factor for asthma? Allergy 2005;60:1537-41.
5. Carey OJ, et al. The effect of lifestyle on wheeze, atopy, and bronchial hyperreactivity in Asian and white children. Am J Respir Crit Care Med 1996;154:537-40.
6. Varraso R, et al. Prospective study of dietary patterns and chronic obstructive pulmonary disease among US women. Am J Clin Nutr 2007;86:488–95.
7. Varraso R, et al. Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men. Thorax 2007;62:786-91.
8. Shi Z, et al. Association between soft drink consumption and asthma and chronic obstructive pulmonary disease among adults in Australia. Respirology. 2012 Feb;17(2):363-9.
9. Wood LG, et al. A high-fat challenge increases airway inflammation and impairs bronchodilator recovery in asthma. J Allergy Clin Immunol 2011;127:1133-40.
10. Scott HA, et al. Dietary restriction and exercise improve airway inflammation and clinical outcomes in overweight and obese asthma: a randomized trial. Clin Exp Allergy 2013;43:36-49.

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