How to get the anti-ageing benefits of fasting without having to give up eating

Telegraph

22-07-2025

Humans have been practising fasts for millennia. Our bodies are built to fast: 'It is literally the reason we carry body fat,' explains Dr Jason Fung, a nephrologist, fasting expert and the author of The Obesity Code. When the body goes into fasting mode it supports cellular rejuvenation and longevity. However, most of us cannot stick to an extended fast, drinking nothing but water, and still live a normal life.
Cue a little known molecule called spermidine, found in everything from blue cheese and mushrooms to wheat germ and soybeans, that is rapidly becoming one of most talked-about topics in longevity research. Some scientists even believe it may be one of the key reasons why some people live longer than others because it helps to rid the body of damaged cells linked to ageing.
'There is no other longevity compound on the market that packs as big a punch as spermidine. By activating the body's vital cell renewal and recycling process – called autophagy (which also occurs when you fast) – it targets ageing at the source. This looks like reduced inflammation, rejuvenated cells and enhanced hair growth, all a result of the cellular clean-up occurring within,' says Leslie Kenny, the founder of Oxford Healthspan and co-founder of the Oxford Longevity Project.
'I make a point of eating spermidine-rich food every day – such as lentils, beans, peas and mushrooms. I also add a food-derived spermidine supplement with the minimum effective daily dose (1mg) shown to improve memory in older adults with subjective cognitive decline,' she says.
Recent research backs up what she says.
And unlike some other longevity trends, spermidine isn't just for lab mice. Human studies, including a 13-year observational trial and several clinical studies in older adults, have linked higher spermidine intake with better memory, lower blood pressure and even a reduced risk of death.
Spermidine is a naturally occurring compound found in a variety of foods, especially those from plant sources and fermented products. Plants, animals and microbes produce spermidine naturally during metabolism. So, any fresh or unprocessed food will contain it to some degree.
What makes spermidine stand out is its ability to stimulate a process called autophagy, a kind of internal cellular spring-cleaning that clears out damaged cells and helps cells work more efficiently.
As we age, this process slows down, contributing to the development of chronic conditions like cancer, cardiovascular disease and neurodegeneration. But spermidine appears to reactivate autophagy even in older cells, offering a drug-free method of slowing ageing.
'Think of it as a molecular amplifier for health,' says Nektarios Tavernarakis, the author of a study in Nature Cell Biology into the health effects of spermidine. 'It helps cells tidy themselves, boosting resilience, energy production and potentially warding off disease.'
His research identified spermidine as essential to the longevity benefits of fasting. Fasting naturally increases autophagy, the body's cellular 'clean-up' process, and spermidine mimics and enhances this effect by promoting the same pathways.
This cellular renewal helps reduce age-related damage and inflammation.
Spermidine and brain health
Cognitive decline is one of the most feared consequences of ageing, but spermidine could offer hope. A clinical trial published in Alzheimer's & Dementia found that three months of spermidine supplementation improved memory in older adults with mild cognitive impairment. The SmartAge trial, published in GeroScience, also found improvements in memory and reductions in inflammatory markers in participants aged 60 to 90.
So, how does it work?
'Spermidine stimulates autophagy, which breaks down faulty proteins that otherwise accumulate in the brain and are linked to Alzheimer's disease,' explains Tavernarakis. This 'cellular housekeeping' clears the way for neurons to function better.
Andrew Steele, who worked at the Francis Crick Institute decoding DNA and author of Ageless: The New Science of Getting Older Without Getting Old, is cautiously optimistic: 'It's likely spermidine provides a general slowing of biological ageing. That may benefit the brain just as much as the heart or gut.'
He adds: 'In animal studies, it's helped restore cognitive and motor function. And in humans, we've seen memory improvements.'
'Evidence suggests those consuming more spermidine, mostly in a Mediterranean diet, have better brain (function) and higher life expectancy,' says Dr Stefan Kiechl, a professor of neurology at Innsbruck University, Austria, and one of the world's leading researchers into the health effects of spermidine.
How spermidine improves heart health
Heart disease remains the world's leading cause of death. New research suggests spermidine could also protect your heart.
In aged mice, spermidine supplementation has been shown to enhance heart elasticity, reduce fibrosis (stiffening) and improve mitochondrial function, which supports energy production within cells. 'It mimics some of the benefits of exercise and caloric restriction,' says Tavernarakis, who has studied spermidine's effects on cardiometabolic health.
'People with high spermidine intake tend to have lower blood pressure and a reduced risk of cardiovascular disease,' he says. A study from Nutrients (2024), using UK Biobank data, reported not only fewer heart attacks but a significant reduction in all-cause mortality for those with high dietary spermidine.
'In our population studies, individuals with higher spermidine consumption, primarily from Mediterranean diets, had better heart health,' notes Kiechl. 'And the anti-inflammatory effects may also play a key role.'
Other studies support his claim and a 2024 UK Biobank study also linked higher polyamine intake with fewer heart problems and an 18 per cent reduction in early death.
Spermidine and cancer
Emerging research highlights spermidine's potential in cancer prevention through several mechanisms. By triggering autophagy, spermidine can lower the chance of cells turning cancerous. A 2018 review in Nature Reviews Cancer found how autophagy can prevent the initiation of tumours by maintaining healthy cells in the body.
Spermidine also supports immune function, particularly by rejuvenating T cells, which are crucial for identifying and eliminating cancer cells. A 2020 study published in Nature Communications demonstrated that spermidine supplementation restored T cell function in aged mice, improving immune surveillance against tumours.
Spermidine and gut health
Another area where spermidine shows promise is the gut, particularly through its influence on the gut microbiome.
The gut plays a dual role when it comes to spermidine. It is where spermidine from food gets absorbed into the body. But also many of the beneficial microbes in your digestive system, especially in the colon, naturally produce spermidine as part of their normal activity.
'Because it boosts autophagy, spermidine supports the gut barrier and helps maintain healthy microbial balance,' says Steele. 'This could be important for preventing chronic gut inflammation and related disorders like inflammatory bowel disease or metabolic syndrome.'
Although research is still in the early stages, some studies suggest that spermidine may help keep the lining of the gut strong and intact, preventing harmful substances, like toxins, bacteria and partially digested food particles, from leaking into the body and triggering inflammation. There is also evidence that it helps gut-residing immune cells function better, which could be especially beneficial as we age.
Adding spermidine to your diet
One of the easiest and safest ways to get more spermidine is through your diet. Aged cheese, mushrooms, soy products, whole grains and legumes are all good sources. Wheat germ is especially high in spermidine, which you can sprinkle on your yogurt or cereal at breakfast.
A tablespoon of wheat germ provides around 1.2 milligrams of spermidine, and 100g of mushrooms or cheddar can offer up to 10mg.
Studies suggest that a daily intake of 5mg to 10mg may support health benefits, which can be achieved through a balanced mix of these foods consumed regularly throughout the week.
A large US study found that people with the highest spermidine intake from foods like cereals, vegetables, legumes and cheese had significantly lower risks of cardiovascular disease and all-cause mortality.
Kiechl advises a measured approach for now. 'Evidence is strong but there are no 'gold standard' large-scale intervention trials which are necessary for standard medical recommendations,' he says.
As spermidine is naturally found in a wide range of everyday foods, it should be easy to boost intake if you don't want to use supplements.
That said, for those who prefer a more targeted approach, there are now a number of spermidine supplements on the market that are specifically tested for purity, safety and consistency. These supplement options provide a potential alternative for those who want to explore spermidine's health benefits in a measured, evidence-aware way, while science continues to catch up.
Kenny says spermidine has had a dramatic impact on her health,after she was diagnosed with lupus, rheumatoid arthritis and Hashimoto's thyroiditis in her late 30s. 'The biggest area has been in my hsCRP (high-sensitivity C-reactive protein), a biomarker of systemic inflammation in the body. Mine is 0.3 – the same as a healthy teenager. In addition, my biological age, as measured by the GlycanAge test, which measures many other inflammatory markers, shows my biological age as 21. This matters because at 39, I was told inflammation in my body was so out of control, I had only five years left to live.
'Other places I notice are my hair quality and colour – I am 60 and don't dye my hair, or need any hair treatments, because my hair, lashes and brows are all healthy and growing as they would when I was younger. I also get consistently strong deep-sleep scores (60-plus minutes) on my Oura Ring when I take it before bed. This is important because it's only during deep sleep that the glymphatic system, the brain's 'washing machine', gets to work to remove the rubbish that piles up during the day that is associated with dementia.'
Spermidine supplements
Primeadine Original spermidine, from Oxford Healthspan, co-founded by Leslie Kenny, is developed in Japan from non-GMO wheat germ and is third-party laboratory tested.
Longevity Box offers a plant-based spermidine supplement aimed at supporting cellular renewal and healthy ageing.