Blackmores Institute

According to the reviewers, asthma has been steadily rising since the 1980s while at the same time there has been a gradual global westernisation of diets.“Western diets typically emphasise the consumption of animal products at the expense of fruits, vegetables, whole grains, and legumes. Asthma prevalence has increased with the westernisation of dietary patterns. High fat intake and low fibre intake have been associated with airway inflammation and worsened lung function in asthmatic patients,” the authors explained.“An Australian study (n=202) found that severe asthmatic patients consumed diets higher in fat and lower in fibre (P= 0.014) than their healthy counterparts. These dietary patterns were associated with increased airway eosinophilia (P &lt; 0.05), while fibre intake was positively associated with forced expiratory volume in 1 second (FEV1) (P &lt; 0.001).”In addition, researchers found a reduced risk of developing asthma in children and adults in those with a high consumption of fruits and vegetables when compared with participants in the lowest intake group when examining meta-analyses.Researchers also reviewed the relationship between dairy foods and asthma, finding that several studies demonstrated a positive association between frequent dairy consumption and the odds of developing asthma. In other studies, dairy consumption led to increased bronchial hyperreactivity and decreases in FEV1. Based on the negative correlation between dairy intake and asthma control, the researchers suggest that the dietary guideline recommendations for dairy intake should be revisited.“Diets emphasising fruits, vegetables, and whole grains, while placing less emphasis on high-fat meats and dairy products, have been associated with reduced asthma risk and dietary components such as antioxidants, fibre, polyunsaturated fatty acids, total and saturated fat, and vitamin D consumption likely affect immune pathways involved in the pathophysiology of asthma,” the authors said. Researchers suggested that antioxidants found in plant foods may contribute to reduced airway inflammation and resulting improvements in FEV1 and forced vital capacity (FVC). Dietary antioxidants include vitamins E and C, carotene, ubiquinone, flavonoids, and selenium.The review found that in addition to their antioxidant roles the antioxidant nutrients played other roles in the prevention and relief of asthma symptoms. They noted that:
 <ul><li>Plasma alpha-tocopherol levels were positively associated with lung function in patients with and without asthma</li><li>Vitamin C supported the hydration of airway surfaces</li><li>Dietary carotenoids (including a-carotene, b-cryptoxanthin, lutein/zeaxanthin, and lycopene) are associated with improvements in lung function</li><li>Flavonoids exhibit anti-inflammatory and antiallergic activities Researchers found that dietary fibre intake has been positively associated with improvements in lung function, while dietary fats may influence airway inflammation, with some unsaturated fats playing a protective role and saturated fats inducing inflammation. </li></ul>Several epidemiological studies have suggested a relationship between asthma prevalence and vitamin D insufficiency and deficiency in children. Across all studies, the prevalence of vitamin D deficiency and insufficiency was significantly higher in asthma patients than controls, the authors stated.Adopting a Mediterranean or vegan diet may reduce the risk of developing or exacerbating asthma according to the review, but the authors also note that further trials are necessary “Recommendations to increase fruit and vegetable consumption, while decreasing saturated fat and dairy intake, are supported by the current literature. Fruit and vegetable intake have been associated with reduced asthma risk and better asthma control, while dairy consumption is associated with increased risk and might exacerbate asthmatic symptoms. Dietary components such as antioxidants, fibre, polyunsaturated fatty acids, total and saturated fat, and vitamin D consumption likely affect immune pathways involved in the pathophysiology of asthma. However, clinical trials examining the mechanism(s) by which dietary factors influence asthma outcomes are necessary to identify the potential use of nutritional therapy in the prevention and management of asthma,” the authors concluded.Source:
 Nutrition Reviews. 2020. DOI: <a href="https://doi.org/10.1093/nutrit/nuaa005">10.1093/nutrit/nuaa005</a>

Consuming a plant-based diet may be key to preventing and relieving symptoms of asthma a new review has reported in the journal, Nutrition Reviews.

Recommended for you

Understanding the research

Milk Thistle | From liver support to metabolic balance

Rethinking eye health in the digital age

Optimising exercise performance