Plant-based diets help prevent and manage asthma, review suggests

30 Mar 2020 --- A plant-based diet could help prevent and manage asthma, while dairy products and high-fat foods raise the risk. That is according to a new study review published in the online journal Nutrition Reviews. Study author Dr. Hana Kahleova says the research “offers hope that dietary changes could be helpful,” and a plant-based diet is beneficial because it has been shown to reduce systemic inflammation, which can exacerbate asthma.

“Asthma is a chronic condition that affects more than 25 million US adults. Unfortunately, it can make people more vulnerable in the COVID-19 outbreak,” says Dr. Kahleova, Director of Clinical Research for the Physicians Committee.

Plant-based diets can be beneficial for an abundance of reasons, from a health perspective as well as for the planet. Just last week, NutritionInsight reported that consuming tofu and foods rich in isoflavones – such as plant proteins – was linked to lower risk of heart disease, especially for younger women and postmenopausal women not taking hormones. 

Researchers with the Physicians Committee for Responsible Medicine examined the evidence related to diet and asthma and found that certain foods – including fruits, vegetables, whole grains and other high-fiber foods – can be beneficial. Meanwhile others – such as dairy products and foods high in saturated fat – can be harmful.

The authors also highlight a prior 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. 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.

Plant-based diets are also high in fiber, 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 finds that dairy consumption can raise the risk for asthma and worsen symptoms. A 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 percent 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 percent decrease.

High fat intake, consumption of saturated fat, and low fiber intake were also associated with airway inflammation and worsened lung function in asthma patients.

“This groundbreaking 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,” explains Dr. Kahleova.

During the current COVID-19 pandemic, the US Centers for Disease Control and Prevention (CDC) urges those with asthma to have a plan in place – including stocking up on supplies, taking asthma medication as needed, avoiding crowds and practicing good hygiene.

Contrasting results
In contrast, a Greece-based study published earlier this month highlighted that plant-based diets have been widely promoted for cardiovascular disease (CVD) risk reduction, but not all kinds of plant-based diets are healthy. 

Meanwhile, a recent UK survey conducted by health advocate Action on Salt (AoS), has chipped at the health halo of plant-based meat analogs due to their notably high salt and saturated fat contents. Nearly two in five plant-based and vegan meals available in British fast food outlets and coffee chains contain more than 3 g of salt, which is half of an adult’s maximum daily intake of salt. 

Edited by Elizabeth Green