Like onions and garlic, asparagus (Asparagus officinalis) is a member of the lily family (Liliaceae). Asparagus is a good dietary source of folate, vitamin A (from its beta-carotene content), rutin, vitamin K, and fiber. Asparagus also contains some glutathione, quercetin, 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 liver cells against toxic insults such as alcohol.
Cancer-related effects of eating asparagus
Asparagus saponins have been shown reduce growth and induce apoptosis in human leukemia, liver, gastric and colon cancer cells in the laboratory. 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. Protodioscin has also been reported to increase the levels of androgens in men. No population studies have specifically evaluated the impact of consuming asparagus on risk of breast cancer.
Asparagus component rutin may reduce the cardiotoxic effects of Adriamycin
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, contains 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.
Note that while we are continually searching for new evidence concerning this food, there is not much interest in it among cancer researchers so few recent studies are available.