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How is climate change affecting our immunity?

Studies show the warming world is having a profound effect on our ability to fight off diseases

Emma Cole
18 Nov 2022

2021 was the sixth warmest year since records began, and research has shown that this warming is placing a great burden on the human immune system.

‘The changing climate is affecting the spread of infectious diseases, putting populations at higher risk of emerging diseases and co-epidemics,’ found the 2022 Lancet Countdown report, an annual study which tracks climate change and health over time.

Another study by researchers at Mamoa’s University of Hawaii revealed that more than 58 percent of human diseases have worsened because of climate change.

The study, which was published in August, looked at the impact of ten climatic hazards worsened by greenhouse gas emissions on human diseases, such as droughts, heatwaves, and wildfires.

Researchers found that out of the 375 diseases considered, 218 were affected by climate change.

The bad news doesn’t stop there either. These diseases range from the tropical to the relatively ordinary including hayfever and asthma.

According to the American Academy of Allergy Asthma & Immunology, climate change has increased the intensity of the pollen season and prolonged its duration, thus increasing the risks and severity of asthma attacks and causing more allergies.

‘Undoubtedly, the human condition is inherently linked to world around us,’ explains Dr Ross Walton, Immunologist and founder of clinical research company, A-IR.

‘This interwoven, complex network of cause and effect is only just beginning to become elucidated.’

Why is our immune system important?

Credi: Jane Doan

‘The immune system plays an underlying role in nearly every health condition and infectious disease, explains Walton.

‘With the potential for this to be affected by the consequences of climate change, there exists the possibility for vast and broad changes to our systemic condition.

‘At present we are seeing striking effects on the respiratory and cardiovascular system made evident during the recent pandemic.’

What are the effects of climate change on our health?

Credit: Pavel Danilyuk

‘Environmental change is altering breeding patterns and geographical distribution of disease vectors such as ticks, mosquitos and birds, shifting disease emergence to areas with no pre-existing immunity such as malaria and Lyme disease,’ says Walton.

‘As the pathogens adapt to become stronger under changing circumstances, conversely human immunity has the potential to become weaker.

‘Alterations of rainfall, temperature and wildfire along with human actions such as deforestation and increased urbanisation increase the frequency of human exposure to wild animals, increasing potential for zoonotic (animal to human) infections which can cause severe illness.

‘Crop loss and yield change affects caused by drought and flooding alters the nutritional content of foods, with potential to lead to poor dietary intake of essential nutrients. This directly reduces efficacy of our immune response alongside driving populational migration which in turn increases spread of communicable disease.

‘Drought, flooding and wildfires alter soil biodiversity which in turn affects our microbiome and our immune response. This can lead to increased autoimmune disease, cardio and metabolic conditions and increased mental health problems. Our microbiome, a rich and finely balanced community of microbes which inhabit the human body, is critically important for good immune functionality.

‘Air pollution, heat, UV radiation and wildfire exposure directly blunt our immune responses.’

Credit: Pixabay

The impact of climate change on our immune system doesn’t stop there. Mental health and stress disorders are also intertwined with immunity.

‘Chronic psychological stresses caused by food, water and habitat insecurity, financial burden of living in a changing climate, increased infectious disease and chronic inflammatory conditions all caused by climate change can lead a worsening of mental health and an increase in post-traumatic stress disorders, stimulating the neuroendocrine system to produce cortisol which suppresses our immune system,’ adds Walton.

What about cyclists in particular?

Credit: Leo Patrizi via Getty

By the very nature of our sport – cyclists spend a lot of time outdoors – we are more exposed to environmental hazards such as air pollution.

This is especially prevalent when riding in cities, behind lorries and buses, as cyclists are often literally in the thick of it. (Although it's worth noting that air quality inside cars can actually be worse than outside as this 2001 study in Copenhagen found.)

‘Alongside the negative broader impact of climate change on our immune response, exposure to poorer air quality and increased pollution leads to both a reduction in immune function and a rise in chronic inflammatory airways disease such as atopic disease and asthma,’ explains Walton.

‘These can all lead to impaired cardiovascular functionality, repair and recovery.

‘A phenomenon evident during the Covid-19 pandemic where individuals living in areas of high pollution saw high infection rates and risk of severe disease and mortality.’

How can we combat the effects?

Credit: Vanessa Loring

Walton says that in order to help maintain strong immunity, cyclists should place adequate importance on rest and recovery and their diet.

‘It is never more important to maintain good immunological fitness, both in terms of protecting our general health but also for improved recovery and reduced enforced time away from training and performance,’ says Walton.

‘This comes through maintenance of the key components of diet, exercise and recovery. As dietary intake becomes impacted by direct (food yield and nutritional content) and indirect (utilisation and cost of climate change) factors, it is of increasing importance to support our immunity with intake of varied fresh fruit and vegetables.’

Credit: Ready made

Walton also advocates the use of supplements where necessary.

‘In addition, during the darker winter months, it can be difficult to maintain appropriate vitamin D levels, vital for immune functionality.

‘With athletes particularly susceptible to upper airway infections such as colds and flu, there is a growing body of scientific data to support the use of fresh echinacea extract in reducing frequency and severity of respiratory infection symptoms. Further, more detailed studies in the interesting population of athletes are required for greater understanding of true efficacy.’

Featured image credit: Richard Drury via Getty

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