There are things that cannot be said too often. In medicine, these are often related to issues that can save lives. In alternative medicine, it is worth remembering that there is nothing that can save more lives than the following rule: EVEN AN APPARENTLY HARMLESS REMEDY WILL BECOME LIFE-THREATENING, IF IT IS USED AS AN ALTERNATIVE TO AN EFFECTIVE THERAPY FOR A SERIOUS CONDITION.

Here is a publication that serves as a very sad reminder of this important axiom.

Japanese physicians recently published a case-report of 2-year-old girl who died of precursor B-cell acute lymphoblastic leukaemia (ALL), the most common cancer in children. She had no remarkable medical history. She was transferred to a hospital because of respiratory distress and died 4 hours after arrival.

Two weeks before her death, she had developed a fever of 39°C, which subsided after the administration of a naturopathic herbal remedy. Subsequently, she developed jaundice one week before death, and her condition worsened on the day of death.

Laboratory test results on admission showed a markedly elevated white blood cell count. Accordingly, the cause of death was suspected to be acute leukaemia. Forensic autopsy revealed the cause of death to be precursor B-cell ALL.

With advancements in medical technology, the 5-year survival rate of children with ALL is nearly 90%. However, in this case, the deceased’s parents preferred alternative medicine to evidence-based medicine and had not taken her to a hospital for a medical check-up or immunisation since she was an infant. The authors state that, if she had received routine medical care, she would have a more than 60% chance of being alive 5 years after diagnosis. Therefore, we conclude that the parents should be accused of medical neglect regardless of their motives.

Alternative practitioners who treat their patients in this way, are in my experience often full of good intentions. They remind me of something Bert Brecht one wrote: THE OPPOSITE OF GOOD IS NOT EVIL, IT IS GOOD INTENTIONS.

Few alternative remedies are more popular than colloidal silver, i.e. tiny particles of silver suspended in a liquid, and few represent more irresponsible quackery. It is widely promoted as a veritable panacea. Take this website (one of thousands), for instance; it advertises colloidal silver in the most glowing terms:

Here are some of the diseases against which Colloidal Silver has been used successfully Acne, Allergies, Appendicitis, Arthritis, Blood parasites, Bubonic plague, Burns (colloidal silver is one of the few treatments that can keep severe burn patients alive), Cancer, Cholera, Conjunctivitis, Diabetes, Gonorrhoea, Hay Fever, Herpes, Leprosy, Leukaemia, Malaria, Meningitis, Parasitic Infections both viral and fungal, Pneumonia, Rheumatism, Ringworm, Scarlet Fever, Septic conditions of eyes, ears, mouth, throat, Shingles, Skin Cancer, Syphilis, all viruses, warts and stomach ulcer.In addition it also has veterinary uses, such as for canine Parvo virus. You’ll also find Colloidal Silver very handy in the garden since it can be used against bacterial, fungal / viral attacks on plants.It would also appear highly unlikely that any germ warfare agents could survive an encounter with CS, as viruses such as E Bola and Hanta are in the end merely viruses and bacteria.Colloidal Silver is non-toxic, making it safe for both children, adults and pets. Colloidal Silver is in fact a pre 1938 healing modality, making it exempt from FDA jurisdiction.

So why haven’t you heard of it? It’s suspected that the user friendly economics of Colloidal Silver may have something to do with its low profile in the media. Colloidal Silver shines a spotlight on the over expensive and deadly nature of the pharmaceutical industry, who are larger than the Pentagon economically.

That’s right, plenty of bogus claims (it goes without saying that there is no good evidence to support any of them) and, for good measure, some conspiracy theory as well – the perfect mix for making a fast buck!

But sometimes things do not work out as planned. The following text was recently published on the website of Essex County Council:

A man claiming to sell a cure for cancer has been fined £750 following an investigation by Essex Trading Standards. Steven Cook, 54, of East Road, West Mersea, was charged with an offence under the Cancer Act after suggesting Colloidal Silver was a treatment for cancer.

Mr Cook pleaded guilty at Colchester Magistrates’ Court on Friday 12 September. Magistrates imposed a fine of £750 and ordered him to pay £1,500 costs. Cllr Roger Hirst, Essex County Council’s cabinet member for Trading Standards, said: “Trading Standards’ advice to people who are considering whether to take any substance not prescribed for a medical purpose, either preventative or as a treatment, is to consult their doctor first.

“I hope the public feel safer knowing that Essex Trading Standards will take action where traders are trying to sell products which are neither medically proven nor safe.”

Mr Cook runs a website,, selling various products containing silver. One of the products on sale was “Ultimate Colloidal Silver”, a liquid containing silver that Mr Cook made in his own home. Trading Standards said the website implied that the product can cure cancer – and this is an offence under the Cancer Act. Mr Cook has now updated the website and removed any claims that colloidal silver can cure some cancers.

So, there is some hope! Occasionally, fraudsters are being found out and punished. But the bad news, of course, is that this sort of thing occurs far too rarely and when it does happen, the punishment is far too lenient. Consequently, the public’s protection from fraudsters exploiting the most vulnerable patients is woefully insufficient.

Reiki healers believe they are able to channel ‘healing energy’ into patients’ body and thus enable them to get healthy. If Reiki were not such a popular treatment, one could brush such claims aside and think “let the lunatic fringe believe what they want”. But as Reiki so effectively undermines consumers’ sense of reality and rationality, I feel a responsibility to inform the public what Reiki truly amounts to.

This pilot study compared the effects of Reiki therapy with those of companionship on improvements in quality of life, mood, and symptom distress in cancer patients receiving chemotherapy. Thirty-six breast cancer patients received one of three treatments:

  1. usual care,
  2. Reiki + usual care,
  3. companionship + usual care.

First, data were collected from patients receiving usual care. Second, patients were randomized to either receive Reiki or a companionship during chemotherapy.

Questionnaires assessing quality of life, mood, symptom distress, and Reiki acceptability were completed at baseline and chemotherapy sessions 1, 2, and 4.

The results show that Reiki was rated relaxing with no side effects. Reiki and companionship groups both reported improvements in quality of life and mood that were greater than those seen in the usual care group.

The authors concluded that interventions during chemotherapy, such as Reiki or companionship, are feasible, acceptable, and may reduce side effects.

Yet another example of utterly bizarre conclusions from a fairly straight forward study and quite clear results. What they really demonstrate is the fact that Reiki is nothing more than a placebo; its perceived benefit relies entirely on non-specific effects. This view is also supported by our systematic review (its 1st author is a Reiki healer!): the evidence is insufficient to suggest that reiki is an effective treatment for any condition. Therefore the value of reiki remains unproven.

In other words, we do not need a trained Reiki master, nor the illusion of some mysterious ‘healing energy’. Simple companionship without woo or make-believe has exactly the same effect without undermining rationality. Or, to put it much more bluntly: REIKI IS NONSENSE ON STILTS.

In the past, I have been involved in several court cases where patients had complained about mistreatment by charlatans. Similarly I have acted as an expert witness for the General Medical Council in similar circumstances.

So, it is true, quacks are sometimes being held to account by their victims. But, generally speaking, patients seem to complain very rarely when they fall in the hands of even the most incompetent of quacks.

Here is one telling reminder showing how long it can take until a complaint is finally filed.

Dr Julian Kenyon is, according to his websitean integrated medicine physician and Medical Director of the Dove Clinic for Integrated Medicine, Winchester and London. Dr Julian Kenyon is Founder-Chairman of the British Medical Acupuncture Society in 1980 and Co-Founder of the Centre for the Study of Complementary Medicine in Southampton and London where he worked for many years before starting The Dove Clinic in 2000. He is also Founder/President of the British Society for Integrated Medicine and is an established authority in the field of complementary treatment approaches for a wide range of medical conditions. He has written approximately 20 books and has had many academic papers published in peer review journals* and has several patents to his name. He graduated from the University of Liverpool with a Bachelor of Medicine and Surgery and subsequently with a research degree, Doctor of Medicine. In 1972, he was appointed a Primary Fellow of the Royal College of Surgeons, Edinburgh.

*[I found only 4 on Medline]

Kenyon has been on sceptics’ radar for a very long time. For instance, he is one of the few UK doctors who use ‘LIVE BLOOD ANALYSIS’, a bogus diagnostic method that can harm patients through false-negative or false-positive diagnoses. A 2003 undercover investigation for BBC 1 South’s ‘Inside Out’ accused Dr Julian Kenyon of using yet another spurious diagnostic test at his clinic near Winchester. Kenyon has, for many years, been working together with George Lewith, another of the country’s ‘leading’ complementary doctors. In 1994, the two published an article about their co-operation; here is its abstract:

This paper outlines the main research effort that has taken place within the Centre for the Study of Complementary Medicine over the last 10 years. It demonstrates the Centre’s expertise and interest in a whole variety of areas, including the social implications and development of complementary medicine, clinical trial methodology, the evaluation of complementary medical machinery, the effects of electromagnetic fields on health and the investigation of the subtle energetic processes involved in complementary medicine. Our future plans are outlined.

Lewith and Kenyon have been using a technique called electrodermal testing for more than 20 years. Considering the fact that the two doctors authored a BMJ paper which concluded that electrodermal machines couldn’t detect environmental allergies, this seems more than a little surprising.

Using secret filming, ‘Inside Out’ showed Dr Kenyon testing a six-year-old boy and then deciding that he is sensitive to dust mites. Later, Dr Kenyon insists that he made his diagnosis purely on the boy’s symptoms and that he didn’t use the machine to test for dust mites. The BBC then took the boy for a conventional skin prick test, which suggested he didn’t have any allergies at all. But Dr Kenyon then says the conventional test may not be accurate: “He may be one of the 10% who actually are negative to the skin tests but benefit from measures to reduce dust mite exposure.”

Despite this very public disclosure, Kenyon was able to practice unrestrictedly for many years.

In December 2014, it was reported in the Hampshire Chronicle that Dr Kenyon eventually did, after a complaint from a patient, end up in front of the General Medical Council’s conduct tribunal. The panel heard that, after a 20-minute consultation, which cost £300, Dr Kenyon told one terminally-ill man with late-stage cancer: “I am not claiming we can cure you, but there is a strong possibility that we would be able to increase your median survival time with the relatively low-risk approaches described here.” He also made bold statements about the treatment’s supposed benefits to an undercover reporter who posed as the husband of a woman with breast cancer.

After considering the full details of the case, Ben Fitzgerald, for the General Medical Council, had called for Dr Kenyon to be suspended, but the panel’s chairman Dr Surendra Kumar said Dr Kenyon’s misconduct was not serious enough to warrant a ban. The panel eventually imposed restrictions on Kenyon’s licence lasting for 12 months.

I estimate that patients are exposed to quackery from doctors and alternative practitioners thousands of times every day. Why then, I ask myself, do so few of them complain? Here are some of the possible answers to this important question:

  • They do not dare to.
  • They feel embarrassed.
  • They don’t know how to.
  • They cannot be bothered and fear the agro.
  • They fail to identify quackery and fall for the nonsense they are being told.
  • They even might perceive benefit from treatments which, in fact, are pure quackery.

Whatever the reasons, I think it is regrettable that not far more quacks are held to account – regardless of whether the charlatan in question as studied medicine or not. If you disagree, consider this: not filing a complaint means that many more patients will be put at risk.

The regular consumption of fish-oil has a potentially favourable role in inflammation, carcinogenesis inhibition and cancer outcomes. An analysis of the literature aimed to review the evidence for the roles of dietary-fish and fish-oil intake in prostate-cancer (PC) risk, aggressiveness and mortality.

A systematic-review, following PRISMA guidelines was conducted. PubMed, MEDLINE and Embase were searched to explore PC-risk, aggressiveness and mortality associated with dietary-fish and fish-oil intake. 37 studies were selected.

A total of 37-studies with 495,321 participants were analysed. They revealed various relationships regarding PC-risk (n = 31), aggressiveness (n = 8) and mortality (n = 3). Overall, 10 studies considering PC-risk found significant inverse trends with fish and fish-oil intake. One found a dose–response relationship whereas greater intake of long-chain-polyunsaturated fatty acids increased risk of PC when considering crude odds-ratios [OR: 1.36 (95% CI: 0.99–1.86); p = 0.014]. Three studies addressing aggressiveness identified significant positive relationships with reduced risk of aggressive cancer when considering the greatest intake of total fish [OR 0.56 (95% CI 0.37–0.86)], dark fish and shellfish-meat (p < 0.0001), EPA (p = 0.03) and DHA (p = 0.04). Three studies investigating fish consumption and PC-mortality identified a significantly reduced risk. Multivariate-OR (95% CI) were 0.9 (0.6–1.7), 0.12 (0.05–0.32) and 0.52 (0.30–0.91) at highest fish intakes.

The authors concluded that fish and fish-oil do not show consistent roles in reducing PC incidence, aggressiveness and mortality. Results suggest that the specific fish type and the fish-oil ratio must be considered. Findings suggest the need for large intervention randomised placebo-controlled trials.

Several other recent reviews have also generated encouraging evidence, e.g.:

Available evidence is suggestive, but currently inadequate, to support the hypothesis that n-3 PUFAs protect against skin malignancy.

…omega-3 fatty acids may exert their anticancer actions by influencing multiple targets implicated in various stages of cancer development, including cell proliferation, cell survival, angiogenesis, inflammation, metastasis and epigenetic abnormalities that are crucial to the onset and progression of cancer.

If I was aiming for a career as a cancer quack, I would now use this evidence to promote my very own cancer prevention and treatment diet. As I have no such ambitions, I should tell you that regular fish oil consumption is no way to treat cancer. It also is no way to prevent cancer. If anything, it might turn out to be a way of slightly reducing the risk of certain cancers. To be sure, we need a lot more research, and once we have it, fish oil will be entirely mainstream. Raising false hopes regarding ‘alternative cancer cures’ based on fairly preliminary evidence is counter-productive, unethical and irresponsible.

Complementary treatments have become a popular (and ‘political correct’) option to keep desperate cancer patients happy. But how widely accepted is their use in oncology units? A brand-new article tried to find the answer to this question.

The principal aim of this survey was to map centres across Europe prioritizing those that provide public health services and operating within the national health system in integrative oncology (IO). A cross-sectional descriptive survey design was used to collect data. A questionnaire was elaborated concerning integrative oncology therapies to be administered to all the national health system oncology centres or hospitals in each European country. These institutes were identified by convenience sampling, searching on oncology websites and forums. The official websites of these structures were analysed to obtain more information about their activities and contacts.

Information was received from 123 (52.1 %) out of the 236 centres contacted until 31 December 2013. Forty-seven out of 99 responding centres meeting inclusion criteria (47.5 %) provided integrative oncology treatments, 24 from Italy and 23 from other European countries. The number of patients seen per year was on average 301.2 ± 337. Among the centres providing these kinds of therapies, 33 (70.2 %) use fixed protocols and 35 (74.5 %) use systems for the evaluation of results. Thirty-two centres (68.1 %) had research in progress or carried out until the deadline of the survey. The complementary and alternative medicines (CAMs) more frequently provided to cancer patients were acupuncture 26 (55.3 %), homeopathy 19 (40.4 %), herbal medicine 18 (38.3 %) and traditional Chinese medicine 17 (36.2 %); anthroposophic medicine 10 (21.3 %); homotoxicology 6 (12.8 %); and other therapies 30 (63.8 %). Treatments are mainly directed to reduce adverse reactions to chemo-radiotherapy (23.9 %), in particular nausea and vomiting (13.4 %) and leucopenia (5 %). The CAMs were also used to reduce pain and fatigue (10.9 %), to reduce side effects of iatrogenic menopause (8.8 %) and to improve anxiety and depression (5.9 %), gastrointestinal disorders (5 %), sleep disturbances and neuropathy (3.8 %).

As so often with surveys of this nature, the high non-response rate creates a problem: it is not unreasonable to assume that those centres that responded had an interest in IO, while those that failed to respond tended to have none. Thus the figures reported here for the usage of alternative therapies might be far higher than they actually are. One can only hope that this is the case. The idea that 40% of all cancer patients receive homeopathy, for instance, is hardly one that is in accordance with the principles of evidence-based practice.

The list of medical reasons for using largely unproven treatments is interesting, I think. I am not aware of lots of strong evidence to show that any of the treatments in question would generate more good than harm for any of the conditions in question.

What follows from all of this is worrying, in my view: thousands of desperate cancer patients are being duped into having bogus treatments paid for by their national health system. This, I think, begs the question whether these most vulnerable patients do not deserve better.

Reiki is a form of energy healing that evidently has been getting so popular that, according to the ‘Shropshire Star’, even stressed hedgehogs are now being treated with this therapy. In case you argue that this publication is not cutting edge when it comes to reporting of scientific advances, you may have a point. So, let us see what evidence we find on this amazing intervention.

A recent systematic review of the therapeutic effects of Reiki concludes that the serious methodological and reporting limitations of limited existing Reiki studies preclude a definitive conclusion on its effectiveness. High-quality randomized controlled trials are needed to address the effectiveness of Reiki over placebo. Considering that this article was published in the JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE, this is a fairly damming verdict. The notion that Reiki is but a theatrical placebo recently received more support from a new clinical trial.

This pilot study examined the effects of Reiki therapy and companionship on improvements in quality of life, mood, and symptom distress during chemotherapy. Thirty-six breast cancer patients received usual care, Reiki, or a companion during chemotherapy. Data were collected from patients while they were receiving usual care. Subsequently, patients were randomized to either receive Reiki or a companion during chemotherapy. Questionnaires assessing quality of life, mood, symptom distress, and Reiki acceptability were completed at baseline and chemotherapy sessions 1, 2, and 4. Reiki was rated relaxing and caused no side effects. Both Reiki and companion groups reported improvements in quality of life and mood that were greater than those seen in the usual care group.

The authors of this study conclude that interventions during chemotherapy, such as Reiki or companionship, are feasible, acceptable, and may reduce side effects.

This is an odd conclusion, if there ever was one. Clearly the ‘companionship’ group was included to see whether Reiki has effects beyond simply providing sympathetic attention. The results show that this is not the case. It follows, I think, that Reiki is a placebo; its perceived relaxing effects are the result of non-specific phenomena which have nothing to do with Reiki per se. The fact that the authors fail to spell this out more clearly makes me wonder whether they are researchers or promoters of Reiki.

Some people will feel that it does not matter how Reiki works, the main thing is that it does work. I beg to differ!

If its effects are due to nothing else than attention and companionship, we do not need ‘trained’ Reiki masters to do the treatment; anyone who has time, compassion and sympathy can do it. More importantly, if Reiki is a placebo, we should not mislead people that some super-natural energy is at work. This only promotes irrationality – and, as Voltaire once said: those who make you believe in absurdities can make you commit atrocities.

After the usually challenging acute therapy is behind them, cancer patients are often desperate to find a therapy that might improve their wellbeing. At that stage they may suffer from a wide range of symptoms which can seriously limit their quality of life. Any treatment that can be shown to restore them to their normal mental and physical health would be more than welcome.

Most homeopaths believe that their remedies can do just that, particularly if they are tailored not to the disease but to the individual patient. Sadly, the evidence that this might be so is almost non-existent. Now, a new trial has become available; it was conducted by Jennifer Poole, a chartered psychologist and registered homeopath, and researcher and teacher at Nemeton Research Foundation, Romsey.

The aim of this study was to explore the benefits of a three-month course of individualised homeopathy (IH) for survivors of cancer.  Fifteen survivors of any type of cancer were recruited from a walk-in cancer support centre. Conventional treatment had to have taken place within the last three years. Patients saw a homeopath who prescribed IH. After three months of IH, they scored their total, physical and emotional wellbeing using the Functional Assessment of Chronic Illness Therapy for Cancer (FACIT-G). The results show that 11 of the 14 women had statistically positive outcomes for emotional, physical and total wellbeing.
The conclusions of the author are clear: Findings support previous research, suggesting CAM or IH could be beneficial for survivors of cancer.

This article was published in the NURSING TIMES, and the editor added a footnote informing us that “This article has been double-blind “.

I find this surprising. A decent peer-review should have picked up the point that a study of that nature cannot possibly produce results which tell us anything about the benefits of IH. The reasons for this are fairly obvious:

  • there was no control group,
  • therefore the observed outcomes are most likely due to 1) natural history, 2) placebo, 3) regression towards the mean and 4) social desirability; it seems most unlikely that IH had anything to do with the result
  • the sample size was tiny,
  • the patients elected to receive IH which means that had high expectations of a positive outcome,
  • only subjective outcome measures were used,
  • there is no good previous research suggesting that IH benefits cancer patients.

On the last point, a recent systematic review showed that the studies available on this topic had mixed results either showing a significantly greater improvement in QOL in the intervention group compared to the control group, or no significant difference between groups. The authors concluded that there existed significant gaps in the evidence base for the effectiveness of CAM on QOL in cancer survivors. Further work in this field needs to adopt more rigorous methodology to help support cancer survivors to actively embrace self-management and effective CAMs, without recommending inappropriate interventions which are of no proven benefit.

All this new study might tell us is that IH did not seem to harm these patients  – but even this finding is not certain; to be sure, we would need to include many more patients. Any conclusions about the effectiveness of IH are totally unwarranted. But are there ANY generalizable conclusions that can be drawn from this article? Yes, I can think of a few:

  • Some cancer patients can be persuaded to try the most implausible treatments.
  • Some journals will publish any rubbish.
  • Some peer-reviewers fail to spot the most obvious defects.
  • Some ‘researchers’ haven’t got a clue.
  • The attempts of misleading us about the value of homeopathy are incessant.

One might argue that this whole story is too trivial for words; who cares what dodgy science is published in the NURSING TIMES? But I think it does matter – not so much because of this one silly article itself, but because similarly poor research with similarly ridiculous conclusions is currently published almost every day. Subsequently it is presented to the public as meaningful science heralding important advances in medicine. It matters because this constant drip of bogus research eventually influences public opinion and determines far-reaching health care decisions.

It has been estimated that 40 – 70% of all cancer patients use some form of alternative medicine; may do so in the hope this might cure their condition. A recent article by Turkish researchers – yet again – highlights how dangerous such behaviour can turn out to be.

The authors report the cases of two middle-aged women suffering from malignant breast masses. The patients experienced serious complications in response to self-prescribed use of alternative medicine practices to treat their condition in lieu of evidence-based medical treatments. In both cases, the use and/or inappropriate application of alternative medical approaches promoted the progression of malignant fungating lesions in the breast. The first patient sought medical assistance upon development of a fungating lesion, 7∼8 cm in diameter and involving 1/3 of the breast, with a palpable mass of 5×6 cm immediately beneath the wound. The second patient sought medical assistance after developing of a wide, bleeding, ulcerous area with patchy necrotic tissue that comprised 2/3 of the breast and had a 10×6 cm palpable mass under the affected area.

The authors argue that the use of some non-evidence-based medical treatments as complementary to evidence-based medical treatments may benefit the patient on an emotional level; however, this strategy should be used with caution, as the non-evidence-based therapies may cause physical harm or even counteract the evidence-based treatment.

Their conclusions: a malignant, fungating wound is a serious complication of advanced breast cancer. It is critical that the public is informed about the potential problems of self-treating wounds such as breast ulcers and masses. Additionally, campaigns are needed to increase awareness of the risks and life-threatening potential of using non-evidence-based medical therapies exclusively.

I have little to add to this; perhaps just a further reminder that the risk extends, of course, to all serious conditions: even a seemingly harmless but ineffective therapy can become positively life-threatening, if it is used as an alternative to an effective treatment. I am sure that some ‘alternativists’ will claim that I am alarmist; but I am also convinced that they are wrong.

Linus Carl Pauling (1901 – 1994), the American scientist, peace activist, author, and educator who won two Nobel prizes, was one of the most influential chemists in history and ranks among the most important scientists of the 20th century. Linus Pauling’s work on vitamin C, however, generated considerable controversy. Pauling wrote many papers and a popular book, Cancer and Vitamin C. Vitamin C, we know today, protects cells from oxidative DNA damage and might thereby block carcinogenesis. Pauling popularised the regular intake of vitamin C; eventually he published two studies of end-stage cancer patients; their results apparently showed that vitamin C quadrupled survival times. A re-evaluation, however, found that the vitamin C groups were less sick on entry to the study. Later clinical trials concluded that there was no benefit to high-dose vitamin C. Since then, the established opinion is that the best evidence does not support a role for high dose vitamin C in the treatment of cancer. Despite all this, high dose IV vitamin C is in unexpectedly wide use by CAM practitioners.

Yesterday, new evidence has been published in the highly respected journal ‘Nature'; does it vindicate Pauling and his followers?

Chinese oncologists conducted a meta-analysis to assess the association between vitamin C intake and the risk to acquire lung cancer. Pertinent studies were identified by a searches of several electronic databases through December of 2013. Random-effect model was used to combine the data for analysis. Publication bias was estimated using Begg’s funnel plot and Egger’s regression asymmetry test.

Eighteen articles reporting 21 studies involving 8938 lung cancer cases were included in this meta-analysis. Pooled results suggested that highest vitamin C intake level versus lowest level was significantly associated with the risk of lung cancer. The effect was largest in investigations from the United States and in prospective studies. A linear dose-response relationship was found, with the risk of lung cancer decreasing by 7% for every 100 mg/day increase in the intake of vitamin C . No publication bias was found.

The authors conclude that their analysis suggested that the higher intake of vitamin C might have a protective effect against lung cancer, especially in the United States, although this conclusion needs to be confirmed.

Does this finding vindicate Pauling’s theory? Not really.

Even though the above-quoted conclusions seem to suggest a causal link, we are, in fact, far from having established one. The meta-analysis pooled mainly epidemiological data from various studies. Such investigations are doubtlessly valuable but they are fraught with uncertainties and cannot prove causality. For instance, there could be dozens of factors that have confounded these data in such a way that they produce a misleading result. The simplest explanation of the meta-analytic results might be that people who have a very high vitamin C intake tend to have generally healthier life-styles than those who take less vitamin C. When conducting a meta-analysis, one does, of course, try to account for such factors; but in many cases the necessary information to do that is not available, and therefore uncertainty persists.

In other words, the authors were certainly correct when stating that their findings needed to be confirmed. Pauling’s theory cannot be vindicated by such reports – in fact, the authors do not even mention Pauling with one word.

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