An intriguing and possibly highly important study  has recently been published regarding the action of 6-shogaol (a ginger compound) against cancer cells. This study has been “doing the rounds” on social media but in many cases it has been misreported and highly misrepresented – either through misunderstanding of the (admittedly a little complex) science involved – or through deliberate exaggeration of the facts in order to create “headline sizzle”. Many of the social media articles we saw did not even link to the original research!
We’re going to do our best to clear it all up for you today, “joining the dots” with some of the other amazing research that is being done in this field and attempting to interpret the studies in terms that both make sense to the lay person and won’t offend persons of science.
The quick takeaway for those in a hurry: 6-shogaol, a compound in ginger, has been found to have amazing activity against breast cancer cells in cell cultures in the lab – including action against simulations of “stem cells” – the “mother ship” of cancer cells that chemo showed no activity against even at 10,000x concentration. The action of 6-Shogaol against the cancer cells happens at concentrations that do very little harm to healthy cells. Other studies have shown that these ginger compounds are bio-absorbed but are converted into other forms in the body, leaving some uncertainty as to whether these new forms are as active, more active or less active against actual cancer. Recent research however has found a strong possibility that ginger may have an actual anti-cancer action in vivo, leading us to conclude that ginger should be considered a prime candidate for inclusion in an “anti-cancer diet” (subject to approval from your physician of course! We have to say this; we do not make actual medicinal recommendations for legal reasons.)
Ginger Compound vs. Chemotherapy (Taxol):
In this in vitro study, 6-Shogaol showed astonishing activity against “spheroids” – stem cell-like simulations – against which taxol (standard chemotherapy treatment derived from yew tree) showed no activity at even 10,000x the concentration.  The inability of taxol to kill the stem cells has been a past stumbling block of cancer therapy. 6-shogaol was found “only” 2 to 5 times as active than taxol against the “regular” breast cancer cells (still an impressive result).
What’s really awesome is that 6-shogaol showed high selectivity – and normal (non-cancerous) cells showed strong resistance to it even after 6 days. 6-shogaol was effective in killing both breast cancer monolayer cells and spheroids at doses that were not toxic to noncancerous cells. 
This study adds to the impressive list of studies in which ginger compounds have been found highly active against cancer cells in vitro while also showing very high selectivity, not harming normal / healthy cells.
However what remains to be fully understood (this is an essential point) is the bioavailability of 6-shogaol after digestion. In other words, an in vitro study such as this does not indicate whether or not eating ginger will do you any good, because if 6-shogaol is broken down by stomach acids, it is unlikely to reach its intended site anyway. Even if it does make it into the bloodstream – how will it “get inside” the cancer? The “metabolic fate” of compounds which destroy cancer cells in in vitro studies are often overlooked by the casual researcher (and the numerous social media outlets reporting on such matters) – and so the “first step” in your education on this matter should be to understand that an in vitro study such as this cannot be considered as evidence in any way that the nutrient will have an effect on cancer.
That said, it might. We did a little research…
The chemical constituents of ginger (and ginger supplements) have been known for some years . 6-shogaol is one of the 4 main pungent constituents of ginger  (the others are 6-gingerol, 8-gingerol and 10-gingerol. Shogaols are chemically similar to gingerols – being the dehydrated form thereof. Interestingly, Shogaols are found in only small quantities in the fresh root and are mainly found in the dried and thermally treated roots; with 6-shogaol becoming the most abundant of these constituents when ginger is dried or cooked.  There are smaller amounts of other gingerols, shogaols and many further compounds in ginger; these are largely untested but may contribute significantly to the health benefits of the whole root.
Bioavailability Of 6-Shogaol:
As it happens, a 2010 study has investigated the bioavailability of 6-shogaol.  Their notes reported first of all that prior to that study, few studies had examined the bioavailability of 6-Shogaol. They stated: “Despite ginger being investigated in over 30 clinical trials in humans with over 2300 subjects, only a handful of studies in rats and our study in healthy volunteers have examined the absorption, bioavailability, metabolites and elimination of ginger constituents. In rat studies, only two of the pungent compounds, 6-gingerol and zingerone, have been investigated, and in two of the rat studies 6-gingerol was administered as an intravenous bolus, which is unlikely to be reflective of usual oral dosing. Moreover, until we conducted a study in healthy volunteers no pharmacokinetic studies have been conducted in humans nor had any studies in mammals or in vitro examined the other major pungent constituents, namely 8- and 10-gingerols and 6-shogaols.” 
A further study from the same team studied 6-shogoal in a clinical trial to determine whether it is passed to the bloodstream intact.  It was found that 6-shogoal is absorbed by the body after oral dosing but is bio-converted (either in the liver or intestinal mucosa, researchers were not sure) toglucuronide conjugates – which can be detected in serum for a few hours after ingestion; before being eliminated by the body’s natural processes.
The researchers summarized succinctly here: “In [previous] study, 6-shogaol [had been] found to induce apoptosis, autophagocytosis and growth inhibition in ovarian cancer cells at 2.21 μg/mL (7.5 μmol/L). All of these in vitro studies required higher concentrations of free ginger constituents than found in the serum in this study – putting the clinical validity of these and similar studies in question. However, gingerols and shogaols may reach higher serum concentrations within target tissue compared to serum, e.g., gut. Ginger conjugates may also be as or more biologically active compared to parent compound. Clearly, further research is needed to answer these questions and determine the cancer prevention relevance of ginger.”
Action Of Ginger Compounds Against Cancer In Vivo:
This research appears to be underway and we are getting closer to a positive result: A further studyfrom the esteemed Oxford University Press, published in Carcinogenesis (2014) , has found astonishing synergistic results for the anti-cancer use of whole ginger extract in vivo against human prostate cancer cell lines – demonstrating that ginger extract “showed 2.4-fold higher tumor growth-inhibitory efficacy than” isolated constituents. In addition, gingerol glucuronides were detected in feces upon intravenous administration confirming hepatobiliary elimination. 
This important result from a prestigious journal is a “double-win” for herbalism – being not only highly indicative that ginger metabolites may possibly be bioactive against cancer cells in the human body, but also demonstrating the importance of preserving the natural composition of whole extracts.
We await further study with anticipation! In the meantime, ginger is generally recognized as a healthy, safe addition to the diet and one noted by innumerable studies for its health benefits and potential for protection against disease. I believe that those considering an “anti cancer diet” should (with the advice of their physician) hold ginger in high esteem in both raw and dried/cooked form.
The message here is clear: Nature works best when not tampered with – and it makes sense. After all, we did evolve over hundreds of thousands of years in a pure natural environment. Researchers are starting to catch up to what herbalists have known all along – that we are bioattuned to nature and literally “designed by evolution” to thrive on food in the most natural state possible.