Scientists from Cambridge Discover a Fresh Mechanism Through Which Fasting Assists in Inflammation Reduction

Cambridge researchers have discovered that fasting spikes arachidonic acid levels in the blood, which inhibits inflammation, thus shining a light on the potential health benefits of fasting and the anti-inflammatory impacts of drugs, such as aspirin, on chronic diseases.

The scientists believe they may have revealed a new way fasting can diminish inflammation, an unwanted repercussion of immune system activity, which is often the origin of various chronic conditions.

The team's research, divulged in Cell Reports, explains how fasting amplifies a chemical known as arachidonic acid in the blood which suppresses inflammation. They also say this could clarify some of the positive effects of drugs such as aspirin.

It has been known for a while that our dietary habits, particularly a calorie-rich Western diet, can heighten our risk of chronic inflammation-related conditions such as obesity, type 2 diabetes, and heart disease.

Inflammation is a natural bodily response to injury or infection, but other mechanisms, including elements known as 'inflammasomes', can initiate this process. The inflammasome behaves like an alarm within body cells and triggers inflammation when it perceives damage. However, inflammation can also be stimulated unintentionally by these inflammasomes, especially when they try to eliminate unwanted cells, causing these cells' contents to leak into the body and incite inflammation.

Professor Clare Bryant from the Medicine Department at the University of Cambridge expressed their interest in investigating chronic inflammation causes within a myriad of human diseases, particularly focusing on inflammasome's role.

She stated that it has become clear over the years that one inflammasome, the NLRP3 inflammasome, plays a crucial role in major diseases such as obesity, atherosclerosis, Alzheimer's disease, and Parkinson's disease.

The act of fasting can help mitigate inflammation, but the reasoning behind this has remained unclear. To gain insight, a team led by Professor Bryant carried out a study on blood samples from 21 volunteers who consumed a 500kcal meal, fasted for 24 hours, and then had another 500kcal meal.

The team discovered that limiting caloric intake boosted levels of a lipid called arachidonic acid. Lipids serve significant roles in our bodies, such as storing energy and transmitting information amongst cells. They observed that arachidonic acid levels reduced once subjects consumed a meal.

The research team found that in the lab, arachidonic acid reduced the NLRP3 inflammasome's activity within cultured immune cells, noteworthy since it was previously believed that arachidonic acid was associated with increased inflammation.

Professor Bryant suggested that these findings provide a possible explanation as to how alterations in our diet, particularly through fasting, might protect us from inflammation, specifically from its damaging form linked with diseases pertaining to a high-calorie Western diet.

However, she expressed it is premature to determine whether fasting could protect against Alzheimer's and Parkinson's disease since the effects of arachidonic acid are momentary. Yet she also believes their work contributes to the growing scientific evidence supporting the health benefits of caloric restriction and suggests that regular fasting might help reduce the chronic inflammation related to these conditions.

The study also alludes to how a high-calorie diet might magnify these diseases' risks. Research has shown that some patients on a high-fat diet have increased inflammasome activity.

Professor Bryant posited that arachidonic acid could be influencing this phenomenon of a balance between too much inflammasome activity stemming from overconsumption and too little stemming from underconsumption.

The research team indicated that their discovery might offer insights into an unexpected mechanism through which non-steroidal anti-inflammatory drugs such as aspirin operate. Normally, arachidonic acid is swiftly broken down in the body. Still, aspirin inhibits this process, resulting in a rise in arachidonic acid levels, subsequently reducing inflammasome activity and subsequently inflammation.

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