A closer look at the research into asparagine – a compound in asparagus – and breast cancer
Recent headlines reported that “Asparagus may influence the spread of breast cancer.” These reports were based on a paper in the journal Nature which showed that depriving cancers of the amino acid asparagine can stop breast cancer spreading beyond the breast. Asparagine is found in many protein foods and vegetables including asparagus, and is also made in the body.
This paper described a series of studies in mice in which asparagine did not affect the initial development or growth of breast cancer, but appeared to have a role in its spread beyond the breast. Limiting foods with asparagine is not a realistic way to control their levels in the body since asparagine is present in many protein foods including beef, poultry, eggs, fish and seafood, as well as many vegetables including asparagus, potatoes, nuts, and legumes. Asparagine can also be made in the body from other amino acids and even from carbohydrate.
The most effective way to stop breast cancer spreading in these studies was to use a drug which lowered levels of asparagine. These ‘asparaginase’ drugs have been used to treat other cancers like leukaemia for a number of years. Further research will show whether similar drugs can help treat breast cancer. In the meantime the advice is to eat a Mediterranean diet including healthy proteins i.e. fish, chicken, pulses and plenty of fruit and vegetables including asparagus and not to attempt to eat a diet low in asparagine.
Knott SRV et al Asparagine bioavailability governs metastasis in a model of breast cancer. Nature. 2018 Feb 7. doi: 10.1038/nature25465