Dr Victoria Smith
GP Asthma Group, National Asthma Council Australia
Breastfeeding and a balanced diet are best for asthma
Many of the 2.2 million Australians with asthma are unaware that what they eat can affect their asthma symptoms and control, even in people without food allergies.1
The effects of diet start early. There is strong evidence that exclusive breastfeeding for the first 6 months of life can protect against allergic rhinitis, wheezing, asthma and atopy.2 Beyond infancy, there is mounting evidence that following a diet that is good for general health is also good for asthma.1
As with many other chronic conditions, increasing body mass index is associated with increased prevalence of asthma in both adults and children. The good news is that weight loss in overweight and obese people with asthma can help them gain better asthma control.1
Food allergy
Food allergens are uncommon triggers for asthma in any age group; as few as 2.5% of people with asthma react to foods in blinded challenges.3 Inhaled allergens such as dust mites, pollen, pet dander and tobacco smoke are far more frequent asthma triggers.
Confirmation of the responsible allergen is important and will usually entail referral to an allergy specialist.1 Treatment of proven food allergies includes avoidance of foods known to cause symptoms. The presence of asthma is a risk factor for fatal food
induced anaphylactic reactions, and people with asthma and a history of anaphylaxis should be managed accordingly.1
The milk myth
The ‘milk myth' - the notion that milk makes mucous or that dairy triggers asthma - has now been debunked by several studies.4 Indeed, findings from one group suggest that there may be an association between milk intake and reduced incidence of asthma symptoms in children.5
This widespread misconception has led to some people with asthma (or their carers) limiting their dairy intake, which can have significant health and nutrition consequences.1 Most people with asthma can regularly include dairy in their diet, unless an allergy to cow's milk is proven.
Food additives
Sulphites are the main class of food additives that affect people with asthma, causing bronchoconstriction in the 5-10% who are sensitive to them.6 Sulphites are added most commonly to dried fruit and wine as a preservative.
Practice points
- The majority of people with asthma are not affected by food allergens.
- Following a healthy balanced diet is good for asthma.
- People with asthma who are overweight or obese should be encouraged to lose weight to improve asthma control.
- Most people with asthma can freely consume dairy products but some should avoid sulphites.
- Exclusive breastfeeding for the first 6 months of life should be encouraged for all infants, especially those in atopic families.
For information on asthma diagnosis and management visit the National Asthma Council Australia website at www.nationalasthma.org.au .
For information on food allergies visit the Australasian Society of Clinical Immunology and Allergy at www.allergy.org.au .
References
To receive a pack of ten Good health recipe books and/or a pack of 25 asthma and dairy patient education sheets, forward your
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1. National Asthma Council Australia. Asthma management handbook 2006. Melbourne: National Asthma Council Australia, 2006. Available at: www.nationalasthma.org.au/cms/index.php
2. National Health and Medical Research Council. Dietary guidelines for children and adolescents in Australia. Canberra: NHMRC, 2003.
3. Woods RK, Weiner J, Abramson M, Thien F, Walters EH. Patients' perceptions of food-induced asthma. Aust N Z J Med 1996;26:504-12.
4. Wüthrich B, Schmid A, Walther B, Sieber R. Milk consumption does not lead to mucus production or occurrence of asthma. J Am Coll Nutr 2005;24(6Suppl):S547-55.
5. Wijga AH, Smit HA, Kerkhof M et al. Association of consumption of products containing milk fat with reduced asthma risk in preschool children: the PIAMA Birth Cohort Study. Thorax 2003;58:567-72.
6. Mathison DA, Stevenson DD, Simon RA. Precipitating factors in asthma. Aspirin, sulfites, and other drugs and chemicals. Chest 1985;87:S50-54.
Acknowledgement
Eat well to breathe well
Originally published in GP Review, November 2007. Reproduced with permission.
Download a PDF of this article from the GP Review website: http://www.racgp.org.au/gpreview/200711/20804
Content Updated November 2007
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