The simple diet changes that can help tackle the most aggressive and hard-to-treat cancers... as experts hail groundbreaking treatment that could 'starve' tumours to death

Scientists are testing whether cutting out two natural compounds found in everyday foods such as meat and dairy could treat some of the toughest cancers.

The groundbreaking new approach may help treat children with one of the hardest-to-treat cancers, researchers say, as well as adults with mesothelioma, a rare but aggressive cancer linked to asbestos exposure.

Cancer treatment has traditionally relied on surgery, chemotherapy, radiotherapy and, more recently, immunotherapy – using drugs that harness the power of the body’s own defences to attack tumours.

The role of diet, however, has mostly been confined to ensuring patients stay healthy during treatment, rather than as a treatment in its own right.

But a study in the journal Nature last month found removing two amino acids (the building blocks of protein) – called arginine and proline – from the diet of mice with neuroblastoma, an aggressive cancer of the nerve cells that affects children, made the tumours less aggressive.

Both arginine and proline are common amino acids found in ­protein-rich foods such as meat, fish, eggs and dairy.

Scientists at the University Children’s Hospital Zurich, Switzerland, fed the mice a special diet free of arginine and proline. Neuroblastoma cells turn these into chemicals called polyamines that help them multiply and grow.

‘The aim was to exploit a weakness in the cancer’s metabolism – the way it uses nutrients,’ explains Dr Raphael Morscher, a paediatric oncologist at the hospital and a senior researcher on the study.

But researchers found an even bigger impact when the mice were also given DFMO, a drug already used to treat neuroblastoma, which suppresses the release of polyamines. When the two approaches were used together, the tumours shrank and survival rates doubled.

‘Removing arginine and proline depletes the nutrients needed to make polyamines,’ Dr Morscher told Good Health. ‘The combination of the drug and the dietary changes boosts the effect of an approved drug.’

However, researchers warned it would be unsafe to put very young children (most with neuroblastoma are under five) on such extreme diets. Instead, they hope to replicate the effect of the diet using drugs that remove the two amino acids from the bloodstream, starving the cancer. The first human trial using this technique is planned for next year.

And the same technique – depriving cancers of vital amino acids – has already been shown to work in adults. A major international trial, published earlier this year in JAMA Oncology, found that adding a weekly jab of a drug called pegargiminase – which strips the arginine from the blood – to standard chemotherapy extended survival in patients with non-epithelioid mesothelioma, which is associated with exposure to asbestos.

By stripping arginine out of the blood, pegargiminase leaves ­cancer cells under constant stress. They are weaker, grow more slowly and struggle to repair damage.

When chemotherapy is then given on top, the toxic drugs have an easier job of finishing off the cells. Patients on the combination therapy lived about 9.3 months on average, compared with 7.7 months for those on chemotherapy alone. Crucially, three-year survival was four times higher.

Peter Szlosarek, a professor of medical oncology at Barts Cancer Institute, who led the study, said that in some tumours, including mesothelioma and some brain cancers, a key gene – ASS1 – is missing, meaning the cancer cells cannot make their own arginine and must draw it from the bloodstream.

‘Pegargiminase degrades ­arginine in the bloodstream, effectively starving arginine-dependent ­cancers to death,’ he says. Healthy cells are unscathed.

But the same results cannot be achieved through diet alone, he warns, because even if someone stopped eating arginine, the body would still make some in the ­kidneys (from other amino acids, which the body recycles and ­converts into arginine). This would be enough to feed a tumour, says Professor Szlosarek.

Other amino acids have also been targeted in cancer treatments.

A 2023 study in Nature Metabolism found that cutting the amino acid methionine (also found in eggs, fish, meat and nuts) from the diet made chemotherapy more effective in mice with bowel and breast cancers.

Human trials are now under way in the US to test if methionine restriction could work safely alongside standard cancer treatments.

And a 2018 study in Nature showed lowering levels of amino acid asparagine – either by diet or with a drug called asparaginase – reduced the spread of breast ­cancer in mice.

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Experts say the idea of targeting cancer metabolism in this way is promising – but not all findings from mice can be safely replicated in humans.

Bernard Corfe, a professor of human nutrition and health at Newcastle University, said restrictive diets could be dangerous.

‘There is no good evidence to suggest diet alone can treat or cure a cancer,’ he says.

‘And cutting protein intake can cause serious harm because your body needs it to maintain muscle strength and to repair tissues – and to support the immune system during tough treatments, such as chemotherapy and radiotherapy.’

Dr John Riches, a clinical reader in cancer immuno-metabolism at Barts Cancer Institute, adds that any diet lacking in amino acids must be carefully planned to avoid malnutrition, especially in children.

But Dr Morscher, of the latest Swiss study, is convinced that changing eating habits could be a revolutionary way to treat some cancers. ‘We are now in an area of precision health,’ he said. ‘This study is a turning point in how we use diet to treat cancer.’