Like onions and garlic, asparagus (Asparagus officinalis) is a member of the lily family. Asparagus is a dietary source of asparagine, folate, quercetin, beta-carotene, rutin, vitamin K, and fiber. Asparagus also contains some glutathione, lutein, ferulic acid, and various saponins, most of which have been reported to have anti-cancer properties.
Asparagus has been shown to have antioxidant, mutagenic, cholesterol lowering and diuretic properties, as well as to protect the liver from toxic insults such as alcohol. Asparagus saponins have been shown reduce growth and induce apoptosis in human leukemia, liver, gastric and colon cancer cells in the laboratory.

Breast cancer-related effects of eating asparagus

Asparagus has components that both promote and inhibit breast cancer. However, the possible metastasis-promoting properties of asparagine, a nonessential amino acid abundant in asparagus, appear to outweigh the potential benefits of asparagus.

Breast cancer inhibiting components of asparagus

Diosgenin, an asparagus steroidal saponin also found in fenugreek and yams, has been shown to inhibit tumor growth in both estrogen positive (ER+) and estrogen negative (ER-) breast cancer tumors implanted in mice. Diosgenin has also been found to preferentially inhibit proliferation and induce apoptosis in HER2+ cancer cells in the laboratory.
Another asparagus saponin, protodioscin, has been found to have cytotoxic activities against a variety of cancer cell lines, including ER- human breast cancer cells. In addition, asparagus component rutin has been reported to reduce the cardiotoxic effects of Adriamycin.

Breast cancer promoting properties of asparagine

The metabolism of asparagine, an amino acid relatively abundant in asparagus, has been shown to be important in regulating and promoting the growth and metastasis of triple negative (ER-/PR-/HER2-) and hormone receptor positive (ER+/PR+) breast cancer cells.
Lower risk of breast cancer has been reported to be associated with higher blood concentrations of asparagine. However, most evidence points to a potentially harmful effect of asparagine in promoting breast cancer. Breast cancer cells cannot synthesize asparagine and therefore rely on its external uptake for their growth. Dietary restrictions or medications that impede asparagine have been shown to have tumor-suppressive effects.
Asparagine has been reported to promote tumor metastasis in mouse models of breast cancer. One five-year prospective study of women with early stage breast cancer reported that patients with high asparagine synthetase (an enzyme that synthesizes asparagine) expression in breast tissue had shorter survival time than those with low expression.

Additional comments

White asparagus, also known as spargel, is grown away from light to inhibit the development of chlorophyll. Purple asparagus, which normally is much smaller than green or white asparagus, incorporates anthocyanins, which have been shown to have anti-cancer properties.
A number of supplements based on asparagus or related plants such as Chinese asparagus (Asparagus cochinchinensis), or based on various saponins, are available. Diosgenin is sometimes marketed as "natural progesterone." Protodioscin has been shown to increase the level of DHEA and testosterone in men. Unfortunately, their efficacy, safety and appropriate dosages have not been established in clinical studies and we would not recommend them.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning this food and its components. For a more complete list of studies, please click on asparagus.