Bowel cancer less likely to develop in asparagus lovers
Eating asparagus probably helps protect against bowel cancer. Researchers at the University of Strasbourg in France drew this conclusion after doing experiments with colon cancer cells and rats. Asparagus strengthens a system that healthy cells use to protect themselves against cancer cells.
The protein that plays an important role in the French study is called TNF-related apoptosis-inducing ligand, or TRAIL for short [structural formula on the right]. Healthy cells produce this protein and it then attaches itself to the death receptors of cancer cells. If everything proceeds according to the Great Engineer's plan, when a healthy cell turns into a cancer cell, TRAIL stimulates the production of suicide proteins such as caspase-8 and -3, which induce the cell to commit suicide.
TRAIL is hip right now in the world of cancer researchers, even though no effective medicines based on TRAIL have yet been developed. Nevertheless, researchers who spend their time exposing cancer cells in test tubes to natural substances that we consume everyday via our food see spectacular things happening via the TRAIL pathways.
In vitro study
The French research is one of these studies. The researchers exposed human SW480 and SW620 colon cancer cells to a methanol extract of asparagus, and observed that this inhibited the growth of the cells. SWS80 is a cancer cell from a patient's colon; SW620 is a metastasised colon cancer cell.
The asparagus extract boosted the production of caspase-8 and caspase-3 in the cancer cells.
Encouraged by their positive results, the researchers performed animal studies. For these they used rats that had been treated for two weeks with the carcinogen azoxymethane. For a period of 7 weeks half of the rats were given drinking water in which asparagus extract had been dissolved.
The rats consumed 14 mg asparagus extract per kg bodyweight daily. The human equivalent of this dose is about 2.3 mg per kg bodyweight per day.
A control group was given regular drinking water.
After 7 weeks the researchers measured the amount of aberrant crypt foci [ACF] they found in their lab animals. Aberrant crypt foci are one of the earliest signs of tumour development. The researchers discovered that asparagus supplementation more than halved the number of aberrant crypt foci.
When the researchers examined the rats' colon cells at molecular level, they saw that the asparagus extract [Asp] had not only boosted the production of TRAIL, but also that of the death receptor-5 [DR5]. So it seems that asparagus not only induces healthy cells to produce more cancer inhibitors, but it also makes the cancer cells more sensitive to these substances.
The researchers do not write about which substances in Asparagus officinalis might protect the body against colon cancer.
The study was funded by the European Regional Development Fund for the region Oberrhein/Rhin Supérieur. Asparagus growing is an important economic activity in that region.
Int J Oncol. 2013 Aug;43(2):394-404.
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