Should we avoid asparagine to stop breast cancer spread?

A recent study published in the prestigious journal Nature, entitled “Asparagine bioavailability governs metastasis in a model of breast cancer” (1) has been making the rounds lately. I first heard about it from a friend, who urged me not to eat asparagus out of a vegetable & dip platter at a party. Asparagine is an amino acid present, among other foods, in asparagus.

As usual, news media have latched on the study to publish eye-grabbing headlines, such as:

“Spread of breast cancer linked to compound in asparagus and other foods” (The Guardian)
“Food may influence cancer spread” (BBC News)
“Could cutting asparagus from your diet stop the spread of cancer?” (USA Today)
“Potential key to halting breast cancer’s spread discovered by scientists” (Independent – UK)
“Amino acid in asparagus could cause the spread of cancer, study says” (AJC.com)
“Compound found in asparagus linked to spread of breast cancer” (NY Daily News)

As it’s often the case, this particular study needs to be taken with a large pinch of salt for many reasons, including:

This is an animal/in vitro study. Animal and in vitro studies are valuable and easier to perform than human studies but people are not mice nor cell cultures.
“Foods rich in asparagine include dairy, whey, beef, poultry, eggs, fish, seafood, asparagus, potatoes, legumes, nuts, seeds, soy, and whole grains. Foods low in asparagine include most fruits and vegetables.” (2) Therefore, a low-asparagine diet would exclude most of the foods that form the base of a healthy diet.
The diets in the experiment included different levels of asparagine, presumably as an isolated amino acid, and not as part of a whole foods diet.
This should be pretty obvious but this study looked at the spread of already existing breast cancer. Please do not make the mistake of assuming asparagus (or any other food containing asparagine) will give you breast cancer.

References

Knott SRV, Wagenblast E, Khan S, Kim SY, Soto M, Wagner M, et al. Asparagine bioavailability governs metastasis in a model of breast cancer. Nature. 2018;554:378.
Diet & the Spread of Breast Cancer. Oncology Times. 2018;40(5):8.

[Photo by Christine Siracusa on Unsplash]

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