Scientists at Cambridge could have uncovered a novel mechanism by which fasting can scale back irritation – a probably dangerous consequence of the immune system’s exercise that’s on the root of a number of persistent sicknesses.
In analysis printed in Cell Reports, the workforce describes how fasting raises ranges of a chemical in the blood often known as arachidonic acid, which inhibits irritation. The researchers say it could additionally assist clarify a number of the helpful results of medication equivalent to aspirin.
The Link Between Diet and Chronic Inflammation
Scientists have recognized for a while that our weight-reduction plan – significantly a high-calorie Western weight-reduction plan – can enhance our danger of illnesses together with weight problems, sort 2 diabetes, and coronary heart illness, that are linked to persistent irritation in the body.
Inflammation is our body’s pure response to damage or an infection, however this course of could be triggered by different mechanisms, together with by the so-called ‘inflammasome’, which acts like an alarm inside our body’s cells, triggering irritation to assist defend our body when it senses injury. But the inflammasome can set off irritation in unintentional methods – one among its capabilities is to destroy undesirable cells, which may outcome in the discharge of the cell’s contents into the body, the place they set off irritation.
Research Findings on Fasting and Arachidonic Acid
Professor Clare Bryant from the Department of Medicine on the University of Cambridge mentioned: “We’re very in making an attempt to know the causes of persistent irritation in the context of many human illnesses, and in specific the position of the inflammasome.
“What’s turn into obvious over latest years is that one inflammasome in specific – the NLRP3 inflammasome – is essential in plenty of main illnesses equivalent to weight problems and atherosclerosis, but in addition in illnesses like Alzheimer’s and Parkinson’s illness, most of the illnesses of older age folks, significantly in the Western world.”
Fasting may help scale back irritation, however the purpose why has not been clear. To assist reply this query, a workforce led by Professor Bryant and colleagues on the University of Cambridge and the National Institute for Health in the USA studied blood samples from a gaggle of 21 volunteers, who ate a 500kcal meal after which fasted for 24 hours earlier than consuming a second 500kcal meal.
The workforce discovered that proscribing calorie consumption elevated ranges of a lipid often known as arachidonic acid. Lipids are molecules that play essential roles in our our bodies, equivalent to storing power and transmitting data between cells. As quickly as people ate a meal once more, ranges of arachidonic acid dropped.
When the researchers studied arachidonic acid’s impact in immune cells cultured in the lab, they discovered that it turns down the exercise of the NLRP3 inflammasome. This stunned the workforce as arachidonic acid was beforehand considered linked with elevated ranges of irritation, not decreased.
Implications and Future Directions
Professor Bryant, a Fellow of Queens’ College, Cambridge, added: “This supplies a possible rationalization for a way altering our weight-reduction plan – in specific by fasting – protects us from irritation, particularly the damaging type that underpins many illnesses associated to a Western high-calorie weight-reduction plan.
“It’s too early to say whether or not fasting protects towards illnesses like Alzheimer’s and Parkinson’s illness as the results of arachidonic acid are solely short-lived, however our work provides to a rising quantity of scientific literature that factors to the health advantages of calorie restriction. It means that common fasting over an extended interval might assist scale back the persistent irritation we affiliate with these circumstances. It’s definitely a sexy concept.”
The findings additionally trace at one mechanism whereby a high-calorie weight-reduction plan would possibly enhance the chance of those illnesses. Studies have proven that some sufferers which have a high-fat weight-reduction plan have elevated ranges of inflammasome exercise.
“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,” mentioned Professor Bryant. “Arachidonic acid could be one way in which this is happening.”
The researchers say the invention might also provide clues to an surprising manner in which so-called non-steroidal anti-inflammatory medicine equivalent to aspirin work. Normally, arachidonic acid is quickly damaged down in the body, however aspirin stops this course of, which may result in a rise in ranges of arachidonic acid, which in flip reduces inflammasome exercise and therefore irritation.
Professor Bryant mentioned: “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.”
Reference: “Arachidonic acid inhibition of the NLRP3 inflammasome is a mechanism to explain the anti-inflammatory effects of fasting” by Milton Pereira, Jonathan Liang, Joy Edwards-Hicks, Allison M. Meadows, Christine Hinz, Sonia Liggi, Matthias Hepprich, Jonathan Mudry, Kim Han, Julian L. Griffin, Iain Fraser, Michael N. Sack, Christoph Hess and Clare E. Bryant, 23 January 2024, Cell Reports.
The analysis was funded by Wellcome, the Medical Research Council, and the US National Heart, Lung, and Blood Institute Division of Intramural Research.