Petri Dishes Aren’t People: The Dangers of Extrapolating In Vitro Research to Clinical Practice – by Camille Charlier
People get excited about killing things — whether it’s cancer cells, candida, or antibiotic-resistant bacteria. Fair enough, especially if one of those things is mucking up your life. But before you read one viral article and take aim with the latest magic bullet, let’s consider for a moment whether what you’ve read means what you think it means. Something worked in a petri dish… wonderful! But does that mean it’ll work in a person?
We intuitively understand the distinction between that which is a living being and that which is a clump of cells on a plastic plate. But somehow when it comes to understanding the implications of scientific research, the lines blur. Perhaps it’s because we’ve learned to trust “Science,” or even just sciency-sounding writing. Maybe we’ve been let down by modern medicine and we’re looking for alternatives. Could be we’re going through a health crisis and nothing has worked and we’re desperate for something, anything, that will make it better.
There are plenty of valid reasons why people are hopeful, and eager, to believe what they see. But remember the golden rule: Not everything you read on the internet is true. So what do we do when we come across the latest article claiming that baking soda cures cancer? We’ll need to stop and think critically about claims that are being made, and the odds of their validity.
There are several arguments that tend to arise when dubious treatments are called out. You hear everything from “But it’s natural, it must be safe!” to conspiracy theorists convinced there’s no supporting evidence because it was suppressed by the nefarious pharmaceutical industry.
Now you might be thinking, “Can I believe anything I read? What treatments can I trust?” Well you’re in luck. In this article we’ll take a look at the problems with extrapolating in vitro findings to clinical practice, address the idea that “natural” = “safe,” debunk the notion that Big Pharma is squelching medical solutions, and conclude with a few tips on how to train your inner skeptic.
In Vitro vs. In Vivo
Let’s start by breaking down some basic terminology used in scientific research. The phrase in vitro comes from the Latin for “in glass,” and refers to experiments performed in test tube or petri dish. In vivo, on the other hand, describes experiments conducted on living organisms — “in life.” This difference matters, because unlike petri dishes and the cultures that occupy them, living organisms are wildly complex active agents.
It’s a fundamental principle of pharmacology — drugs don’t just act on us; we act on them. The effect of drugs on a living organism is described by the branch of pharmacology known as pharmacodynamics. This field of study investigates the physiological effect of drugs, and their mechanisms of action. It’s twin branch, pharmacokinetics, seeks to understand the fate of administered substances; in other words, the way that the body acts on them. Pharmacokinetics describes how substances are absorbed, their bioavailability, the way they’re distributed through the body, how they’re metabolised, the behavior of these metabolites, and the means by which they’re excreted from the body. Importantly, pharmacokinetics give us data about ideal dosing, toxicity, and the potential risks of ingesting, injecting, or topically applying a substance.
In vitro research is a good first step in the process of seeking out medical solutions, but it won’t give us the goods when it comes to how a substance behaves in an actual living body. For that, we need empirical data. This could be in vivo scientific research on animals, or even better, clinical trials on humans. Empiricism doesn’t fall exclusively under the purview of modern research science, though. Long histories of safe and effective use, such as those seen with Ayurveda, traditional Chinese medicine, or western herbalism, can also be valid sources of information.
Garlic, Silver, and Baking Soda: A Collection of Questionable “Cures”
These three substances seem like something out of a book of fairy tales, used to ward off vampires, werewolves, and bad smells. Strangely enough they’ve captured the imagination of scientists and laypeople alike as possible panaceas for everything from persistent Lyme disease to cancer. Let’s take a look at a few research articles that tackle these topics, and consider the specious conclusions that have been drawn.
We’ll start with garlic essential oil. A 2018 study, conducted by the Johns Hopkins Bloomberg School of Public Health and published in the journal Antibiotics, found that garlic essential oil exhibited strong killing activity against dormant and slow-growing “persister” forms of the Lyme disease bacterium Borrelia burgdorferi. “We found that these essential oils were even better at killing the ‘persister’ forms of Lyme bacteria than standard Lyme antibiotics,” senior author Ying Zhang reported.
After reading that, one might be tempted to buy a bottle of volatile garlic and start guzzling.
It’s well known, however, that garlic essential oil is caustic and can burn the skin when applied directly. That doesn’t bode well for the mucus membranes of the digestive tract if taken internally and without formulation precautions. Based on this preliminary experiment, we have no way of knowing proper dosage or toxicity, nor do we know if it even works in a human body. Ying Zhang sums things up succinctly: “At this stage these essential oils look very promising as candidate treatments for persistent Lyme infection,” he says, “but ultimately we need properly designed clinical trials” (Feng, et al., 2018).
Clinical trials are the gold standard for understanding the effect of an intervention on a population of people, and are far more valuable sources of medical information than in vitro research. To put it in perspective, consider the organization of complex systems, which can be perceived at myriad levels from the molecular, macro-molecular, subcellular, cellular, tissue, organic, systemic, individual, population, communitary, to the ecosystemic. In vitro research investigates what is happening at the molecular, cellular, and tissue levels, severed from context. Humans are so much more than that.
If you’re still not convinced, just consider the plaintive question posted on ResearchGate by a University of Texas Medical School student conducting research on osteoblasts: “Why are there different results in in vitro and in vivo?” (Aseervatham, 2015).
Colloidal silver has been proclaimed, by colloidal silver manufacturers, to be a miracle cure that boosts the immune system, fights pathogens, and treats cancer, HIV/AIDS, shingles, herpes, eye ailments, and prostatitis. Turns out these claims lack valid supporting evidence, and ingestion of colloidal silver isn’t as “safe” as some might think.
Let’s take the example of the website The Silver Edge, “Home of the Micro-Particle Colloidal Silver Generator, the world’s #1 most popular colloidal silver generator!” (Exclamation point… definitely suspicious.) But more importantly, let’s look at the content. President Steve Barwick handily offers a collection of “Clinical Studies and Reports on the Antimicrobial Qualities of Colloidal Silver.” He writes, most convincingly, “These studies and reports are compiled here with the intent of giving the reader or researcher a general understanding of the many uses of antimicrobial silver, from a variety of viewpoints, both clinical and personal. The studies are not meant to convey efficacy of any particular colloidal silver product.”
He seems forthright, but strangely enough, as I perused the listed research, I found that it was consistently misrepresented. Barwick repeatedly refers to “clinical studies” that are anything but. In just one of his many blurbs describing research on colloidal silver he writes:
In a clinical study [emphasis mine] titled “Green Synthesis of Silver Nanoparticles Using Tephrosia tinctoria and its Antidiabetic Activity,” published in the journal Material Letters, Volume 138, in January 2015, the researchers wrote: “The antidiabetic ability of the silver nanoparticles was tested and the results showed significant free radical scavenging ability, inhibition of carbohydrate digestive enzymes (a-Glucosidase and a-Amylase) and enhancement of Glucose uptake rate.” In other words, it appears the silver nanoparticles mopped up free radicals (which are often generated in excessive numbers in diabetic patients, and can damage the pancreas), inhibited the activity of enzymes that tend to increase blood sugar levels through the digestion of carbohydrates, and aided in glucose uptake — all critically important factors for diabetics (Barwick, 2017).
It sounds so promising! But alas, this is no clinical study. If you look at the original research article, it becomes quickly apparent that the experiment was performed on red blood cells in a test tube, and the purported “antidiabetic effects” are purely theoretical when it comes to humans (Rajaram et al., 2015).
For charity’s sake we’ll assume it’s an honest mistake. But even so, it can be dangerous to suggest that orally ingested colloidal silver has antidiabetic activities in humans, without substantially more high-quality, indeed clinical, research.
Safety concerns regarding silver are not entirely erroneous. An article published in Regulatory Toxicology and Pharmacology reviewed the available literature on the oral toxicity of silver ions, silver nanoparticles, and colloidal silver, and found that accidental, self-, and parental-inflicted poisonings with ionic or colloidal silver do occur. These poisonings are often characterized by argyria, an irreversible blue–grey discoloration of the skin caused by silver deposits (Hadrup and Henrik, 2014).
The National Center for Complementary and Integrative Health (NCCIH) responds to the question “Is colloidal silver safe?” with the following statements:
Colloidal silver can cause serious side effects. The most common is argyria, a bluish-gray discoloration of the skin, which is usually permanent.
Colloidal silver can also cause poor absorption of some drugs, such as certain antibiotics and thyroxine (used to treat thyroid deficiency).
The FDA also warned in 1999 that colloidal silver isn’t safe or effective for treating any disease or condition.
The FDA and the Federal Trade Commission have taken action against a number of companies for making misleading claims about colloidal silver products.
The NCCIH answers questions about the efficacy of colloidal silver, too, writing, “Scientific evidence doesn’t support the use of colloidal silver dietary supplements for any disease or condition. Silver has no known function or benefits in the body when taken by mouth. Silver is not a nutritionally essential mineral or a useful dietary supplement” (NCCIH, 2017).
Indeed, the colloidal silver industry has a spotty history of making unsubstantiated claims of both efficacy and safety — everything from propaganda that Americans were suffering from “silver deficiency,” to insisting that colloidal silver is “absolutely safe for humans.” Researchers in the ‘90s investigated a selection of commercial silver products and found that some of them were contaminated with microorganisms, many of them were ineffective at inhibiting the growth of Staphylococcus aureus bacteria in a petri dish, and that the amount of silver listed in the product label was often inaccurate.
As cases of argyria popped up, the FDA cracked down on purveyors of colloidal silver products for making spurious claims. The FDA has issued over 50 warning letters to companies making unsubstantiated therapeutic claims about their products. Australia banned and fined various companies that sell products for making colloidal silver (Barrett, 2019).
For an example of more trustworthy reporting, let’s take a look at this well-measured article published in Scientific American. Author Brian Owens heralds the good news that “Silver Makes Antibiotics Thousands of Times More Effective,” but is sure to include appropriate caveats:
Vance Fowler, an infectious-disease physician at Duke University in Durham, North Carolina, says the work is “really cool” but sounds a note of caution about the potential toxicity of silver. “It has had a checkered past,” he says.
In the 1990s, for example, a heart valve made by St. Jude Medical, based in St. Paul, Minnesota, included parts covered with a silver coating called Silzone to fight infection. “It did a fine job of preventing infection,” says Fowler. “The problem was that the silver was also toxic to heart tissue.” As a result the valves often leaked.
Before adding silver to antibiotics, “we’ll have to address the toxicity very carefully”, says Fowler. Ingesting too much silver can also cause argyria, a condition in which the skin turns a blue-grey color — and the effect is permanent.
Collins [biomedical engineer at Boston University] says that he and his colleagues saw good results in mice using non-toxic amounts of silver. But, he adds, there are ways to reduce the risk even further. “We’re also encouraging people to look at what features of silver caused the helpful effects, so they can look for non-toxic versions,” he says.
Solid evidence that we can all be excited by science while still keeping things in perspective.
That being said, there are myriad wonderful topical applications for silver. It has a rich tradition of usage in preventing the spread of infection, and has been used topically on burns, ulcerations, and infected wounds. Silver has been explored as a coating for medical devices (unfortunately unsuccessful in the case of the Silzone heart valve), but may be promising in other contexts (Politano, et al., 2013). A meta-analysis of non-healing chronic wounds found that silver-releasing dressings were effective in wound healing and improved patients’ quality of life (Lo, et al., 2009).
In our final example of erroneous extrapolation, let’s look at the use of intravenous baking soda “treatments” to “cure” cancer.
We’ll by affirming that there is absolutely fascinating research about the potential uses for sodium bicarbonate in the treatment of cancer. Several in vitro studies found that cancer cells elicit a state of lactic acidosis which protects them from glucose starvation or deprivation. Furthermore, tumors are known to have regions deprived of oxygen, which sends them into a quiescent, treatment-resistant state. One study found that this mechanism was reversed by buffering the acidity with sodium bicarbonate — baking soda. In mice given baking soda in their drinking water, the acidity of the tumor environment was reversed, and the cells “awakened.” This is thought to make the cancer cells more responsive to treatment (Ludwig Cancer Research, 2018).
Sounds great, what’s the problem? Turns out people have taken this concept and run a little too far with it. There have been a number of dubious characters running cancer “clinics” based on the theory that if cancer survives in an acidic environment, then surely the cure must be to alkalinize the body.
Tullio Simoncini, for example, claimed that cancer is caused by a fungus, and can be cured with the administration of sodium bicarbonate. To “eliminate fungal colonies,” he administered sodium bicarbonate orally, by intravenous infusion, and via intra-arterial catheters proximal to the tumor site. He claimed that tumors disappear in half of patients who received this treatment, but no evidence of this supposed outcome has ever been forthcoming. Unfortunately, the highly concentrated solutions he administered can disturb the mineral balance in the body and lead to serious, even fatal complications.
Indeed, when a patient of Simoncini’s died after being treated at his clinic, the Public Prosecutor and the Netherlands Health Care Inspectorate (IGZ) opened an investigation of the case. IGZ concluded that the administration of sodium bicarbonate to cancer patients is hazardous. A new release stated:
Based on the expert report, the IGZ has first of all reached the conclusion that there are no scientific data that justify the administration of sodium bicarbonate to patients with cancer for other indications than described in the official prescription information. There is no scientific proof whatsoever showing that this therapy cures or can slow its progress.
The IGZ concludes that the administration of sodium bicarbonate even has risks for patients with high blood pressure, patients with diseases of lungs, heart, or kidneys and for patients with cancer. This is certainly the case if a number of specific blood levels are not monitored daily before, during and after the treatment. The balance of the body can become completely disturbed when large amounts are administered. In severely ill patients, this may lead to organ damage. In sick people, there is in fact irresponsible health care if this product is administered without monitoring (Koene and Jitta, 2008).
There’s a similar story about Robert O Young, “Father of the Alkaline Diet,” and proponent of baking soda as a cancer cure. Young believes that, in order to maintain the pH of our blood, we need to eat “alkaline” foods, and that “all sickness and disease can be prevented by managing the delicate pH balance of the fluids of the body.” In his mind, “cancerous” is synonymous with “acidic.”
As you may have guessed, this story doesn’t end well. A British army officer with breast cancer paid $77,000 for Young’s “alkaline treatment,” which consisted mainly of intravenous infusions of baking soda at his “pH Miracle Ranch” on the outskirts of San Diego. After about three months at Young’s facility the patient’s condition worsened, and she was taken to the hospital. After returning to the UK to be with her family, she died at the age of 27.
At this point, there isn’t a single scrap of evidence that intravenous infusions with baking soda have any effect against cancer. When asked about this, Young responded, “These things need to be studied” (Yeo and Quinn, 2017). That may be the only thing he’s right about.
Natural ≠ Safe
People are skeptical about the rise of our pop-a-pill culture and, in many ways, that’s justified. There’s a whole crowd of people eager to reach for a “natural” supplement over a prescription drug, people who don’t want to become dependent on drugs, or experience unpleasant side effects. Sure, there are times where that is absolutely appropriate and reasonable, but then again there are times it’s not. Best to know the difference.
The idea that naturally-derived treatments are inherently human-friendly is totally false. Certainly some human-manufactured medications can exert appalling side effects, and the compulsion towards medication in western medicine can be troubling. But that doesn’t mean that “natural” substances are necessarily superior, or even safe.
Examples of natural things that are decidedly dangerous to humans:
Cosmic rays (Zielinski, 2010).
Can we now agree that “natural” products for human consumption should be approached with the same rigor and skepticism as synthetic substances? Great.
Are “Natural” Cures Being Suppressed by Big Pharma?
Skeptoid science writer Brian Dunning puts the problem succinctly: “Beware! Pop culture tells us that the big pharmaceutical companies know all about the simple, natural cures for everything — cancer included — but are jealously covering them up.”
It’s always the same story — some cheap, readily available cure is suppressed by Big Pharma because they can’t patent it to line their own pockets. People with a distrust of the establishment and disgust towards capitalism may find this theory tempting… Wouldn’t it make sense that the pharmaceutical industry, and even governments, were hiding cures for cancer to maximize their profits on existing drugs?
In his article “The Big Pharma Conspiracy,” Brian Dunning points out that “Big Pharma” isn’t one organized entity, but “a complicated industry filled with conflicting roles and interests.” It’s unlikely such a haphazard conglomeration would manage to perfectly and completely conceal the existence of viable cures. He also points out incidents where corruption in the industry was exposed and ameliorated — by the industry itself. He also offers the example of Laetrile, a cancer product that was banned by the FDA, or “suppressed,” as some would like to think. Turns out, after two decades of clinical trials, it was found to have no effect on cancer, and was sometimes fatal as a consequence of cyanide poisoning.
And then he delivers the finishing blow:
Finally, we can point to one more piece of evidence that any alleged Big Pharma Conspiracy does not seem to have any effect, and this is that the market for these allegedly-suppressed cures is just as big as Big Pharma’s market. Americans spend almost exactly the same amount of money on FDA-approved pharmaceutical drugs as they do on unapproved drugs, basically supplements, vitamins, and all other herbal or natural remedies. In 2017 they’ll spend just under $40 billion on unapproved drugs — a number which grows strongly each year. The market for FDA-approved drugs is 11 times as big — just under $450 billion; but since insurance pays for the majority of that, what Americans pay out of pocket is about the same (Dunning, 2017).
Cancer Research UK approaches the theory of a Big Pharma conspiracy through a different lens; that of a cancer research and awareness charity. Cancer Research UK’s news liason Oliver Childs writes:
There’s no doubt that the pharmaceutical industry has a number of issues with transparency and clinical trials that it needs to address (the book Bad Pharma by Ben Goldacre is a handy primer). We push regulators and pharmaceutical companies hard to make sure that effective drugs are made available at a fair price to the NHS – although it’s important to remember that developing and trialling new drugs costs a lot of money, which companies need to recoup.
Problems with conventional medicine don’t automatically prove that alternative ‘cures’ work. To use a metaphor, just because cars sometimes crash doesn’t mean that flying carpets are a viable transport option.
It simply doesn’t make sense that pharmaceutical companies would want to suppress a potential cure. Finding a highly effective therapy would guarantee huge worldwide sales.
And the argument that treatments can’t be patented doesn’t hold up. Pharma companies are not stupid, and they are quick to jump on promising avenues for effective therapies. There are always ways to repackage and patent molecules, which would give them a return on the investment required to develop and test them in clinical trials (a cost that can run into many millions) if the treatment turns out to work.
Finally, it’s worth remembering that we are all human — even politicians and Big Pharma executives — and cancer can affect anyone. People in pharmaceutical companies, governments, charities and the wider ‘medical establishment’ all can and do die of cancer too.
Here at Cancer Research UK we have seen loved ones and colleagues go through cancer. Many of them have survived. Many have not. To suggest that we are — collectively and individually — hiding ‘the cure’ is not only absurd, it’s offensive to the global community of dedicated scientists, to the staff and supporters of cancer research organisations such as Cancer Research UK and, most importantly, to cancer patients and their families (Childs, 2014).
How to Train Your Inner Skeptic
Now you’re probably wondering, “What sources can I trust? Is everything on the internet bogus?” Here are a few simple tips for how to handle your health in the Age of Information:
1. Roll your eyes at “miracle cures.”
When you see websites declaring that hydrogen peroxide or apple cider vinegar “cures cancer,” little red warning flags should be flying up in your head. Cancer is not one single disorder, but a collection of related diseases. Each type of cancer can have a different cause, unique disease progression, and often targets different tissues (National Cancer Institute, 2007).
The simplicity of a single panacea is certainly tempting, but it is unlikely that any one treatment would be the solution for such a broad spectrum of pathophysiologies. This is true of diets, “cleanses,” coffee enemas, and more. The body is complicated, and disease is complicated — no individual herb, supplement, or product will be a “miracle cure” for all disease.
2. Beware the technobabble.
Proponents of the aforementioned “miracle cures” will often direct potential consumers to “sources” riddled with technical-sounding jargon. These articles likely lack a reasonable explanation for how the product actually works, and if you dive into the supporting “science,” you’ll find it is anything but that.
3. Seek out clinical studies.
Avoid extrapolating internal applications from in vitro research — substances don’t necessarily behave the same in the human body as they do in a petri dish. Take alcohol, for example. Ethanol is excellent for sterilizing lab workspaces, but does it elicit antimicrobial effects in the body? Absolutely, but at the concentrations required to kill bacteria it would likely burn a hole in your gut. In one study of 47 healthy human volunteers, direct exposure of the lower stomach to alcohol resulted in stomach lining erosion and bleeding, with damage directly proportional to the concentration of alcohol.
Sure, some gut bacteria might be wiped out in the short term, but the treatment would do serious damage. Furthermore, chronic alcohol use can actually lead to small intestinal bacterial overgrowth, which is thought to be linked to the gastrointestinal symptoms such as diarrhea, nausea, and vomiting, associated with alcoholic patients (Ho, 2017).
4. Don’t take everything you read at face value.
Recall the example of the Silver Edge website claiming that studies were clinical trials when they were actually in vitro experiments? Yup. Double-check references, and when possible, go directly to the source.
5. Be cautious of testimonials.
Testimonials, even if sincere, are unreliable. The placebo effect is strong, and any number of people who use a “treatment,” whether it’s a pharmacologically active or not, will experience improvement. That doesn’t mean it will work for everyone, or that it’s safe.
It should also be noted that, while it’s illegal to fake testimonials, false advertising has been known to happen (Heilpern, 2016).
6. Consider history of use.
Many herbs, like mint and ginger, have long and lauded histories of use. Other natural substances, like mercury, do not.
7. Look for information from unbiased sources.
Prioritize research by third parties with no vested financial interest in experimental outcomes.
8. Seek competent guidance.
Well-trained integrative practitioners can help you navigate the minefield of information about herbs, supplements, and dietary/lifestyle changes. There are health experts who have dedicated their lives to sifting out sound practices from the snake oil. Some good starting places:
The American Herbalist Guild is an association of herbal practitioners that holds educational standards for their professional members. Use their “Find a Registered Herbalist” search function to seek out skilled practitioners in your area.
The bottom line? It’s simple: Let’s use treatments that we know are safe and effective. Sure, ol’ reliable herbs and supplements aren’t as exhilarating as a new magic bullet, but at least they won’t turn us permanently blue.
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“What Is Cancer?” National Cancer Institute, 17 Sept. 2007, https://www.cancer.gov/about-cancer/understanding/what-is-cancer.
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