Fasting helps the body fight inflammation and chronic disease 

Scientists at the University of Cambridge have discovered a new aspect of how fasting mitigates inflammation, a harmful byproduct of the immune system that contributes to chronic diseases. 

The study reveals that fasting elevates a specific chemical in the blood known as arachidonic acid, which plays a key role in inhibiting inflammation. This finding might also shed light on the efficacy of certain drugs, including aspirin.

The impact of diet on inflammation

There is a well-established link between diet, particularly a high-calorie Western diet, and increased risks of diseases such as obesity, type 2 diabetes, and heart disease. These conditions are often associated with chronic inflammation in the body. 

Inflammation, while a natural response to injury or infection, can also be triggered by the inflammasome. This component within cells acts as an alarm system, initiating inflammation to protect the body against perceived damage. However, it can also unintentionally trigger inflammation, leading to the release of cell contents that further promote inflammatory responses.

Understanding chronic inflammation

Professor Clare Bryant from the University of Cambridge’s Department of Medicine emphasized the importance of understanding chronic inflammation. 

“We’re very interested in trying to understand the causes of chronic inflammation in the context of many human diseases, and in particular the role of the inflammasome,” said Professor Bryant.

“What’s become apparent over recent years is that one inflammasome in particular – the NLRP3 inflammasome – is very important in a number of major diseases such as obesity and atherosclerosis, but also in diseases like Alzheimer’s and Parkinson’s disease, many of the diseases of older age people, particularly in the Western world.”

Arachidonic acid

While fasting is known to reduce inflammation, the underlying reasons have been unclear. To investigate this, Professor Bryant’s team collaborated with colleagues at the National Institute for Health to conduct a study involving 21 volunteers.

The participants consumed a 500kcal meal, fasted for 24 hours, and then ate another 500kcal meal. The researchers discovered that calorie restriction increased levels of arachidonic acid, a lipid known for its role in energy storage and intercellular communication. Intriguingly, once the participants resumed eating, arachidonic acid levels decreased.

Critical new insights 

Upon examining the effects of arachidonic acid on immune cells in the lab, the team found that it reduces the activity of the NLRP3 inflammasome. This finding was unexpected since arachidonic acid was previously thought to exacerbate inflammation. 

“This provides a potential explanation for how changing our diet – in particular by fasting – protects us from inflammation, especially the damaging form that underpins many diseases related to a Western high calorie diet,” said Professor Bryant.

Further research is needed 

“It’s too early to say whether fasting protects against diseases like Alzheimer’s and Parkinson’s disease as the effects of arachidonic acid are only short-lived, but our work adds to a growing amount of scientific literature that points to the health benefits of calorie restriction.”

“It suggests that regular fasting over a long period could help reduce the chronic inflammation we associate with these conditions. It’s certainly an attractive idea,” said Professor Bryant.

Study implications 

The study also suggests that a high-calorie diet might elevate the risk of diseases by increasing inflammasome activity.

“There could be a yin and yang effect going on here, whereby too much of the wrong thing is increasing your inflammasome activity and too little is decreasing it,” said Professor Bryant. “Arachidonic acid could be one way in which this is happening.”

Anti-inflammatory drugs

Furthermore, the findings might explain the unexpected mechanism of non-steroidal anti-inflammatory drugs like aspirin. Aspirin impedes the breakdown of arachidonic acid, potentially leading to decreased inflammasome activity and inflammation.

“It’s important to stress that aspirin should not be taken to reduce risk of long terms diseases without medical guidance as it can have side-effects such as stomach bleeds if taken over a long period,” said Professor Bryant.

The study is published in the journal Cell Reports. 

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