Researchers from the Physicians Committee for Responsible Medicine have undertaken a review examining the evidence related to diet and asthma, led by Hana Kahleova, MD, PhD, director of clinical research for the Physicians Committee, and found that a plant based diet can be beneficial for those with asthma while dairy products and foods high in saturated fat can be harmful.
Speaking about the review in a The Exam Room 'Asthma and Coronavirus' podcast hosted by committee, Dr Kahleova points out that those with asthma are more than six times as likely to die from the coronavirus than someone with no underlying condition.
She says the recent review, published in Nutrition Reviews, offers hope that dietary changes could be helpful to these vulnerable people.
"What can people with asthma do to protect themselves against a viral infection? Fruit and veg consumption in general is definitely helpful because of the high content of antioxidants and fibre, all of which are anti-inflammatory," she said.
Also speaking in the podcast, co-author Neal Barnard, MD, added that those with asthma should 'put nutrition to work'.
"You still have to do everything else. You still have to wash your hands and maintain the appropriate public health measures but plug in the nutrition part of it and all the evidence that we have today says that this is a good idea."
He adds that prior research has also shown that dairy proteins seem to make your body more sensitive to seasonal allergies.
The review highlights a study finding that when compared to a control group, asthma patients who consumed a plant-based diet for eight weeks experienced a greater reduction in use of asthma medication and less severe, less frequent symptoms (M. Seltz, PhD, unpublished data, September 2006). In another study, asthma patients adopted a plant-based diet for a year and saw improvements in vital capacity--a measure of the volume of air patients can expel--and other measures.
The authors suggest that a plant-based diet is beneficial because it has been shown to reduce systemic inflammation, which can exacerbate asthma. Plant-based diets are also high in fibre, which has been positively associated with improvements in lung function. The researchers also highlight the antioxidants and flavonoids found in plant foods, which may have a protective effect.
The review also finds that dairy consumption can raise the risk for asthma and worsen symptoms. One 2015 study found that children who consumed the most dairy had higher odds of developing asthma, compared with the children consuming the least.
In another study, children with asthma were placed in either a control group, where they made no dietary changes, or in an experimental group where they eliminated dairy and eggs for eight weeks.
After eliminating dairy, the experimental group experienced a 22% improvement in peak expiratory flow rate -a measure of how fast the children were able to exhale - while children in the control group experienced a 0.6% decrease.
High fat intake, consumption of saturated fat, and low fibre intake were also associated with airway inflammation and worsened lung function in asthma patients.
"This ground-breaking research shows that filling our plates with plant-based foods and avoiding dairy products and other high-fat foods can be a powerful tool for preventing and managing asthma," says Dr. Kahleova.
Plant-based diet advice
Speaking in the Exam Room podcast, Dr Kahleova added that it's important to get vitamin D through fortified plant-based 'milks' and by spending 30 minutes in the sunshine each day if possible.
Asthma prevalence has been steadily rising since the 1980s. According to national surveillance data from the Centers for Disease Control, an estimated 6.8 million people had asthma in 1980. This number increased to 25.7 million persons diagnosed in 2010. In children, asthma prevalence was reported to be 3.5% in 1980. Thirty years later, that figure had jumped to 9.5% of children aged 0–17 years.
The disease can be fatal. In 2009, the rate of deaths with asthma as the underlying cause per 10,000 persons with asthma was 1.9 in adults and 0.3 in children. The asthma death rate was highest among individuals aged 65 years and older.
Source: Nutrition Reviews
Alwarith. J., et al
The role of nutrition in asthma prevention and treatment