OK, I know what a plant-based diet is. Let's skip straight on to why it’s been in the news.
A review that has been published states that a plant-based diet can help prevent and manage asthma, while dairy products and high-fat foods raise the risk.
Tell me about the research behind this review.
Scientists examined the evidence related to diet and asthma and found that certain foods – including fruits, vegetables, whole grains and other high-fibre foods – can be beneficial, while others – such as dairy products and foods high in saturated fat – can be harmful.
What else did they observe?
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. 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.
What about dairy and egg consumption having a negative impact?
One 2015 study found that children who consumed the most dairy and eggs 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.