Is this substance occurring in cabbage plants the holy grail of natural cancer therapy or just another epic fail of the anti-pharma movement?
A broccholi a day keeps the tumor away? CC0, from pixabay
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Hello everyone. Sorry that it took me (again) so long to translate my latest german post, but here it is – the English adaption.
So welcome to another attempt to communicate science in a field that is incredibly „rich“ on pseudo-science. This post is about a topic that my co-favourite-witness @felixxx wanted me to take care of… sulforaphane.
Last week, I wrote a detailed introduction, which I highly recommend to read first in order to understand this post.
Sulphoraphane is a substance that is found in various cabbage plants, but above all in broccoli (and there again mainly in the sprouts), and which is praised as THE agent against cancer, Alzheimer's disease and other diseases in various well-known health/lifestyle/biohacking sites/blogs.
Dr. Ronda Patrick is convinced: Brocholi sprouts kill cancer!
What is also very interesting is that sulforaphane is supposed to be able to both prevent cancer and combat existing cancer. Which is slightly suspect, and has triggered my interest, because that should be a contradiction in itself.
Why is that? Ah, that's the perfect introduction to the subject.
Chemoprevention vs chemotherapy
The thing is: If something "works against cancer", it can have two fundamentally different meanings:
- A chemopreventive effect is when a substance protects healthy cells against environmental influences, thus preventing cellular damage. As a result, the likelihood of developing cancer is reduced. This category includes many antioxidants, especially those with indirect antioxidant effects.
- Chemotherapy is about actively combating existing cancer cells. In other words, substances that act in this way act as cytotoxins. Ideally, they are more toxic to cancer cells than to healthy cells, but they always have some effect against healthy cells as well, which explains the severe side effects of many chemotherapeutics.
And that means that chemoprevention and chemotherapy are mutually exclusive:
If you are already suffering from cancer, it is counterproductive to protect cells with chemopreventive substances, since the goal must be to kill (cancer) cells. If one does not suffer from cancer, it is counterproductive to take chemotherapeutics, as these also damage healthy cells and thus often have a long-term carcinogenic effect.
So when I hear, as with sulforaphane, that a substance can be used both preventively and therapeutically, my bullshit alert bells start ringing. But let's analyze the full picture carefully and one by one step…
Sulforaphane in chemoprevention
The idea of why and how sulforaphane should prevent cancer, but also neurodegenerative (e.g. Alzheimer's) and cardiovascular diseases was already the topic of my the last post. The substance has been shown to act as an activator of the Nrf-2 signalling pathway, resulting in increased production of anti-oxidative enzymes in the cell, which in turn provides lasting protection against oxidative damage.ref
These effects are indeed relatively well documented for sulforaphane, including in vivo data. Chemopreventive effects could be observed in a number of animal experiments,ref as well as a preventive effect against cardiovascular diseases.ref What has to be mentioned, however, is that clinical studies in humans are completely missing, which of course creates a great uncertainty factor and keeps the debate going. There are also scientists who believe that the evidence is not yet strong enough to support a health recommendation of sulforaphane.
One reason for this is an effect that I have also described in my "introduction post":
Nrf-2 activators all act hormetic, i.e. they produce a positive effect at relatively low concentrations (from a certain threshold of action), which is converted into a negative (toxic) effect in high concentrations. In the case of Nrf-2 inducers, a high concentration leads to oxidative stress, which in turn is associated with carcinogenesis.
This means that the right dosage of sulforaphane is essential, otherwise you create bigger problems than you solve.
In addition, this circumstance limits the effect of the substance upwards. It has a certain positive effect, yes, but you can't increase it over a certain level, because with the further increase of the dose the effect is reversed into the negative. The same applies to the combination with other Nrf-2 activators - It’s just not a good idea to do this!
The dose needed for the positive effects (calculated for broccholi and human species) is about 200g broccholi per day, although there are also fluctuations depending on the origin and preparation.ref 200g daily are not necessarily standard diet, but not completely unrealistic.
But dosing food is difficult, and also people don't like eating broccoli every day. So the pill industry came up with the glorious idea of bringing out sulforaphane supplements.
With the effect that there are now surely people who take 2 or 3 daily pills instead of the recommended one pill to be even better protected against cancer and thus end up with sulforaphane doses which they could never reach by eating broccholi and which are anything but healthy.
The big problem with supplements is often the consumer, whose intentions are too good.
broccholi sprouts, from which sulforaphane for food supplements is extracted. There are no pictures of supplements under creative commons. Sorry. CC0, from pixabay
Suforaphane as a „natural“ chemotherapeutic
As mentioned at the beginning, sulforaphane is also attributed to being able to actively combat cancer. And as also mentioned at the beginning, I am more than sceptical of this claim, because the material would then have to be healthy and unhealthy at the same time.
But of course there's a potential loophole here: Hormesis is a problem in prevention but it could theoretically enable sulforaphane‘s use as a cytotoxin at high concentrations. Of course, here we are no longer talking about broccholi, but about highly concentrated medical preparations of sulforaphane. The only remaining "natural" thing is that the substance is also found in plants.
But there is still a big problem: I have already mentioned that chemotherapy is about causing significantly more damage to cancer cells than to healthy ones. The better the ratio of cancer cell damage to "good cell" damage, the more specific the effect of a therapeutic drug is. The more specific, the better, and the fewer side effects.
Now causing oxidative stress - sulforaphane’s main way of action - is a fucking non-specific mechanism of action, and harms healthy cells hardly less than cancer cells. There are also a few other (less important) ways of action that are discussed in the community, but the results of attempts to using sulforaphane as a chemotherapeutic agent have been – on the contrary to what people are reading in the internet - quite meagre so far.
Even German wikipedia is full of bullshit, as it states:
In neueren experimentellen Studien vom Universitätsklinikum Heidelberg und Deutschen Krebsforschungszentrum konnte gezeigt werden, dass der Inhaltsstoff Sulforaphan aus Broccoli und verwandtem Gemüse das Krebswachstum von Bauchspeicheldrüsenkrebs hemmen kann [...].
Recent experimental studies by the University Hospital of Heidelberg and the German Cancer Research Centre have shown that sulforaphane from broccoli and related vegetables can inhibit the growth of cancer in pancreatic cancer […].
Uh, wow!, I was thinking, and checking up on the sources. And what do I have to read there?
These are just in vitro data!
I.e. data from cultivated cells. Not even from an animal experiment, lest a clinical trial! Of course drawing any conclusion about the effects on a real tumor on the base of these data is completly invalid.
The only type of cancer for which there are actually some kind of reliable data seems to be prostate cancer, where sulforaphane caused a certain delay of tumor growth in animal experiments.ref However, some of the related clinical studies with humans have now been running for 10 years without any positive results being published - in a discipline that is very much characterized by competition between different research groups, this is usually a sign that there are no desired effects.
Scientists are therefore currently less interested in using sulforaphane as a stand-alone drug than in combining it with conventional forms of therapy (radiation, chemo), where possible synergistic effects could be exploited to increase the chances of success.ref
Overall, I am much more in favor of English wiki, which states:
Although there is basic research on how sulforaphane may affect mechanisms in vivo, there is no high-quality evidence to date for its efficacy against human diseases.
Conclusion and personal remarks
Sulforaphane in broccholi seems to be actually healthy. Although it has not been explicitly proven that it has a certain degree of preventive effect against cancer, Alzheimer's disease and the like in humans, the idea is not far-fetched and the data from animal experiments speak in favour of it.
However, there is no need to take pills. Eat broccoli and sprouts and believe that it will help you - but don't expect a miracle cure! The effect is limited by the fact of hormesis.
But if you already have cancer... well... If then concentrated sulforaphane could possibly support regular chemotherapy in certain cases.
But curing cancer by putting broccoli sprouts into a smoothie? Or by taking this green magic pill without side-effects?
In my blog, I'm stating my honest opinion as a researcher, not less and not more. Sometimes I make errors. Discuss and disagree with me - if you are bringing the better arguments, I might rethink.