Asparagus compound is linked to spread of breast cancer to other organs, study finds
‘This is one of the very few instances where there is a scientific rationale for a dietary modification influencing cancer’
Asparagine, an amino acid found in asparagus and other foods, was shown to aid in the spread of breast cancer to other organs of the body in mice, a new study published in the journal Nature found.
But when a diet light in asparagine was introduced to the animals, the researchers said that the number of malignant tumours outside of the breast tissue, like those found in the bones, lungs and brain – the No 1 cause of death in people with breast cancer – decreased dramatically.
“This is a very promising lead and one of the very few instances where there is a scientific rationale for a dietary modification influencing cancer,” said the study’s lead author, Greg Hannon.
Asparagine is a building block for proteins made in the body but is also a compound found in dairy, whey, beef, poultry, eggs, fish, seafood, potatoes, legumes, nuts, seeds, soy and whole grains. Low-asparagine foods include most other fruits and vegetables.
The study said that the research team was able to block asparagine in the mice via a drug called L-asparaginase and by removing most of the compound from their diets. The doctors then checked records of former breast cancer patients who died of the disease and found that those with multiple other tumours caused from their breast cancers also had the highest levels of asparagine.
It appears, according to the study, that asparagine helps cancer cells evolve and makes them easily transportable through the bloodstream; helping them to spread to other organs and grow into new tumours. Restricting asparagine in the body helped to prevent this from happening but it had no effect on the formation of initial breast tumours.
The next step of the study is to see if the findings in mice translate to people. If so, the future of breast cancer treatment may include low-asparagine diets and L-asparaginase drug therapy on top of traditional treatments like chemotherapy and radiation, especially considering the compound is so prevalent in a wide variety of common foods.
“This early discovery could offer a long-awaited new way to help stop breast cancer spreading – but we first need to understand the true role of this nutrient in patients,” said chief executive of Breast Cancer Now, Baroness Delyth Morgan. “On current evidence, we don’t recommend patients totally exclude any specific food group from their diet without speaking to their doctors. We’d also encourage all patients to follow a healthy and varied diet – rich in fruit, vegetables … and limited in processed meat and high fat or sugar foods – to help give them the best chance of survival.”
Prof Keqiang Ye, a cancer researcher at Emory University in Atlanta, said that lowering asparagine levels, either with drugs or dietary restriction, would help prevent cancer cells from spreading. But for patients, he said that drug treatments held more promise than changes to their diets.
“Asparagine is frequently found in various animal sources including beef, poultry, eggs, fish and seafood. It is also found in many vegetables including asparagus, potatoes, nuts, legumes and soy. Since these foods are so common, it seems that diet restriction may not be the ideal approach,” Ye said.
Additional reporting by The Guardian