While the frenzy around weight-loss drugs is booming, the ongoing cost of the weekly jabs can, for some, be too high.

Instead, many are now turning to an unlikely – and cheap – natural supplement, with users claiming that as well as supporting weight loss, it helps control appetite and even improves skin quality after the excess weight has been lost.

Spermidine, which has long been popular among biohackers – people who make use of science, extreme diets and technology in a bid to live longer – due to its role in recycling damaged cells, is now attracting far wider attention for its potential role in tackling obesity and liver disease.

Scientists believe that the naturally occurring compound may support DNA repair, heart health and healthy ageing.

First identified in human semen – from which it got its name – and later discovered throughout the body, spermidine is also found in foods such as wheatgerm, mature cheeses, soybeans, mushrooms and green peppers.

It has also been sold as an over-the-counter supplement for about a decade, typically as a powder or capsule costing from about 16p to £1.20 per daily serving.

Among its celebrity devotees is former Countdown co-host Carol Vorderman, who has said she takes spermidine daily because she believes it helps slow ageing.

Now social media users devoted to longevity and weight loss are sharing tips on using spermidine in their weight-loss regime – with one claiming that they lost more than nine stone in less than a year.

But what does the science actually say?

Some studies suggest spermidine may mimic calorie restriction by triggering some biological processes activated during fasting.

When the body is deprived of nutrients, spermidine levels naturally rise, helping switch on a process called autophagy – the body’s cellular recycling system.

Professor Arshad Rather, consultant geriatrician at Medical Express Clinic, explains: ‘Autophagy clears away damaged proteins and worn-out cell parts, allowing cells to recycle them into new building blocks.

‘As we get older this process becomes less efficient, allowing damage to build up.

‘Scientists believe maintaining healthy autophagy may help protect against age-related conditions including metabolic disease, liver disease and heart disease.’

Laboratory studies have also suggested spermidine may increase the activity of genes involved in collagen and elastin production, meaning it could help reduce loose skin after rapid weight loss. However, so far there is little evidence this occurs in people.

Interest in the compound first surged after researchers found people whose diets naturally contained more of the compound had lower rates of cardiovascular disease and a lower risk of death from all causes.

One study, published last month in the European Journal of Nutrition, followed more than 2,600 older adults in Spain who were overweight or obese and had metabolic syndrome – a cluster of conditions that raises the risk of heart disease and type 2 diabetes.

Participants who increased their intake of spermidine-rich foods over a year saw greater improvements in liver health, blood sugar and cholesterol than those who ate less. They also experienced larger reductions in body weight and fatty liver disease markers.

In the UK, obesity is the leading driver of non-alcoholic fatty liver disease, which is estimated to affect up to one in three adults.

Professor Rather says the findings are encouraging but should be interpreted cautiously.

‘This study shows an association rather than cause and effect,’ he says. ‘More clinical trials are needed before we can say definitively that increasing spermidine intake leads to these outcomes.’

Leading nutritionist Gabriela Peacock adds: ‘Most of the encouraging findings around heart health, mortality, biological ageing and liver health come from studies looking at what people eat.

‘Simple changes could include adding wheatgerm to yogurt or porridge, using lentils or chickpeas in salads and soups, eating mushrooms regularly and replacing refined grains with wholegrains.’

Animal research has also hinted at potential liver benefits.

A study published in May found that spermidine reduced liver scarring and other liver damage markers in mice. However, scientists say it remains unclear whether over-the-counter supplements provide the same benefits as spermidine-rich foods.

And, surprisingly, a 2022 Chinese study found that obese adults actually had higher levels of the compound in their blood than people of normal weight. 

However, those with the highest levels were also less likely to gain weight over the following two years, leading researchers to suggest the compound may act as part of the body’s natural response to obesity-related metabolic stress.