Asthma is a very common chronic disease that affects 22 million Americans. Asthma, of course, is a respiratory disorder that usually causes constriction of the smooth muscles in the airway with symptoms including wheezing and shortness of breath. For those who live with this disorder, it often requires lifelong treatment with medication. Exercise-induced-asthma (EIA) or exercise-induced-broncospasm (EIB) is an asthma variant in which exercise or physical activity triggers bronchospasm in those with heightened airway reactivity.
Conjugated linoleic acids (CLA) are naturally occurring fatty acids. Specifically, they are found naturally in animal products of ruminant origin (any of the hoofed animals) including meat and dairy products. CLAs have gained attention by researchers for their effects on body composition, weight reduction, and immune system modulation. However, many of the encouraging study results, particularly for promoting weight loss, are from studies involving rodents. In human studies, the results have been less promising.
Asthma and obesity association:
Obesity itself contributes to a pro-inflammatory state which may partially explain the known association between asthma and obesity. Leptin is an adipocytokine that stimulates inflammation and is itself an independent predictor of asthma. Leptin levels are elevated in proportion to your body fat percentage, so obese subjects have higher circulating levels of this protein hormone. Conversely, levels of the hormone, adiponectin, are inversely correlated with body fat percentage.
Conjugated linoleic acid and asthma:
Researchers in British Columbia published a study in the journal, Clinical & Experimental Allergy (Macredmond et al, 2010), which explored the efficacy and safety of conjugated linoleic acid supplementation on mild asthma. ***Note, the subjects in the study took their regular asthma medication during the study.
The intervention in this study included conjugated linoleic acid taken at a dose of 4.5g/day (or placebo) for 12 weeks. 28 subjects who had mild asthma were included in this study. On average, subjects in this study were overweight with a BMI of 27.9 kg/m2.
Does conjugated linoleic acid supplementation work?
- Significant improvement in airway hyperresponsiveness in the CLA group at week 12 compared to baseline (week 0).
- No differences in quality-of-life scores or adverse events
- The CLA group had a significant reduction in weight and BMI compared to placebo (-.5kg/m2 for CLA vs. +.8kg/m2 for placebo)
- This weight loss in the CLA group works out to 2.5% of their body weight.
- Weight reduction was associated with a reduction in leptin/adiponectin ratio
- Subjects in the CLA group reported improvements in exercise-induced bronchoconstriction, though this was not directly measured by the researchers.
Conclusions about conjugated linoleic acid:
“CLA treatment as an adjunct to usual care in overweight mild asthmatics was well tolerated and was associated with improvements in airway hyperresponsiveness (AHR) and body mass index (BMI).”
From the results of this study, conjugated linoleic acid may be a beneficial supplement for those who suffer from mild asthma when taken with their usual asthma medication. As well, CLA supplementation may have particular use for those who suffer from exercise-induced asthma or obese subjects with asthma to possibly promote weight loss. Further research is necessary to study the efficacy of CLA in these populations.
Supplementation with conjugated linoleic acid also promoted metabolically favorable (for weight loss) ratios of the hormones leptin and adiponectin.
- Macredmond R, Singhera G, Attridge S, Bahzad M, Fava C, Lai Y, Hallstrand TS, Dorscheid DR. Conjugated linoleic acid improves airway hyper-reactivity in overweight mild asthmatics.Clin Exp Allergy. 2010 Jul;40(7):1071-8.