An amino acid found in asparagus could be responsible for the spread of breast cancer, according to a new study. So should you stop eating it?
Scientists discovered that restricting an amino acid called asparagine stopped cancer cells from invading other parts of the body in mice. Amino acids are the building blocks that cells use to make proteins. The body can make asparagine, however it’s also found in high concentrations in foods like asparagus, seafood, soy, dairy and poultry products.
Despite the startling findings, researchers and breast cancer experts agree that people with cancer and the general public should not stop eating asparagus or other products rich in asparagine. Baroness Delyth Morgan, chief executive at Breast Cancer Now, said in a statement: “On current evidence, we don’t recommend patients totally exclude any specific food group from their diet without speaking to their doctors.”
How does cancer spread?
The place where a cancer starts in the body is called the primary cancer or primary site, according to Cancer Research UK. Cells from the primary site may break away and spread to other parts of the body through the bloodstream or lymphatic system. There they can start to grow into new tumours. This is known as metastases or secondary cancer.
Most breast cancer patients do not die from their primary tumour, but from the spread of cancer to the lungs, brain, bones or other organs. Currently, around 11,500 women die from breast cancer each year in the UK. Finding ways to stop this from happening is therefore fundamental to increasing survival.
How did researchers stop it from spreading?
Researchers at the Cancer Research UK Cambridge Institute did two things: they put the put the mice on a low-asparagine diet and were able to block the body’s production of asparagine with a drug called L-asparaginase.
Both of these changes greatly reduced breast cancer’s ability to spread.
Interesting, the drug L-asparaginase is already used to treat acute lymphoblastic leukaemia, which is dependent on asparagine. Professor Charles Swanton, Cancer Research UK’s chief clinician, said in response to the study: “It’s possible that in future, this drug could be repurposed to help treat breast cancer patients. The next step in the research would be to understand how this translates from the lab to patients and which patients are most likely to benefit from any potential treatment.”
Could this apply to other types of cancer?
Researchers examined data from breast cancer patients, which showed the greater the ability of breast cancer cells to make asparagine, the more likely the disease was to spread. In several other cancer types, increased ability of tumour cells to make asparagine was found to be associated with reduced survival.
In future, the scientists believe that alongside conventional treatments like chemotherapy, breast cancer patients could be given a diet in hospital that restricts asparagine to help stop the disease spreading and improve outcomes. However more research needs to be done to confirm this.
They said their findings could also have implications for other cancer types, including kidney, and head and neck cancers.
So should you give up asparagus?
In short, no. Martin Ledwick, Cancer Research UK’s head nurse, said: “At the moment, there is no evidence that restricting certain foods can help fight cancer, so it’s important for patients to speak to their doctor before making any changes to their diet while having treatment.”
While asparagine is investigated further by scientists, Baroness Delyth Morgan, chief executive at Breast Cancer Now, encourages cancer patients to follow a healthy and varied diet rich in fruit, vegetables and pulses, and limited in processed meat and high fat or sugar foods. This, she said, will “help give them the best chance of survival”.