MD, PhD, FMedSci, FRSB, FRCP, FRCPEd

prevention

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.

Influenza kills thousands of people every year. Immunisation could prevent many of these deaths. Those at particularly high risk, e.g. young children, individuals aged 65 and older and people with severe diseases in their medical history, are therefore encouraged to get immunised. Nova Scotia health officials have just started their annual flu shot campaign. Now they are warning about some anti-flu vaccine literature being distributed by a chiropractor.

The leaflets from local chiropractic clinics suggest that flu shots increase the risk of a child ending up in hospital and link Alzheimer’s disease to flu shots. When questioned about this, the chair of the Nova Scotia College of Chiropractors defended this misinformation and claimed the author of the pamphlet did his homework. “Chiropractic is really pro information. Look at the positive, look at the negative, look at both sides, get your information and make the appropriate decision that’s right for you,” he said.

However, Dr. Robert Strang, Nova Scotia’s chief public health officer, said the message is wrong and added that the pamphlet is not based on medicine and is confusing to the public. “It’s discouraging, but unfortunately there are a range of what I call alternative-medicine practitioners who espouse a whole bunch of views which aren’t evidence based,” he said.

The stance of many chiropractors against immunisations is well known and has long historical roots. Campbell and colleagues expressed this clearly: Although there is overwhelming evidence to show that vaccination is a highly effective method of controlling infectious diseases, a vocal element of the chiropractic profession maintains a strongly antivaccination bias… The basis seems to lie in early chiropractic philosophy, which, eschewing both the germ theory of infectious disease and vaccination, considered disease the result of spinal nerve dysfunction caused by misplaced (subluxated) vertebrae. Although rejected by medical science, this concept is still accepted by a minority of chiropractors. Although more progressive, evidence-based chiropractors have embraced the concept of vaccination, the rejection of it by conservative chiropractors continues to have a negative influence on both public acceptance of vaccination and acceptance of the chiropractic profession by orthodox medicine.

No doubt, there will be comments following this post claiming that many chiropractors have now learnt their lesson and have considerably revised their stance on vaccination. This may well be true. But far too many chiropractors still post hair-raising nonsense about vaccination. Take this guy, for instance, who concludes his article (just one example of many) on the subject with this revealing paragraph: Our original blood was good enough. What a thing to say about one of the most sublime substances in the universe. Our original professional philosophy was also good enough. What a thing to say about the most evolved healing concept since we crawled out of the ocean. Perhaps we can arrive at a position of profound gratitude if we could finally appreciate the identity, the oneness, the nobility of an uncontaminated unrestricted nervous system and an inviolate bloodstream. In such a place, is not the chiropractic position on vaccines self-evident, crystal clear, and as plain as the sun in the sky? 

As long as dangerous cranks are tolerated by the vast majority of chiropractors and their professional organisations to mislead the public, I have to agree with Dr Strang: “It’s discouraging, but unfortunately there are a range of what I call alternative-medicine practitioners who espouse a whole bunch of views which aren’t evidence based.”

For this blog, I am constantly on the lookout for ‘positive news’ about alternative medicine. Admittedly, I rarely find any.

All the more delighted I was when I found this new study aimed to analyse the association between dietary long-chain n-3 polyunsaturated fatty acids (PUFAs) and incidence of rheumatoid arthritis (RA) in middle-aged and older women.

Data on diet were collected in 1987 and 1997 via a self-administered food-frequency questionnaire (FFQ). The risk of RA associated with dietary long-chain n-3 PUFAs and fish intake was estimated using Cox proportional hazard regression models, adjusted for age, cigarette smoking, alcohol intake, use of aspirin and energy intake.

The results show that, among 32 232 women born 1914–1948, 205 RA cases were identified during a mean follow-up of 7.5 years. An intake of dietary long-chain n-3 PUFAs (FFQ1997) of more than 0.21 g/day (lowest quintile) was associated with a 35% decreased risk of developing RA compared with a lower intake. Long-term intake consistently higher than 0.21 g/day (according to both FFQ1987 and FFQ1997) was associated with a 52% decreased risk. Consistent long-term consumption (FFQ1987 and FFQ1997) of fish ≥1 serving per week compared with<1 was associated with a 29% decrease in risk.

The authors concluded that this prospective study of women supports the hypothesis that dietary intake of long-chain n-3 PUFAs may play a role in aetiology of RA.

These are interesting findings which originate from a good investigation and which are interpreted with the necessary caution. As all epidemiological data, this study is open to a number of confounding factors, and it is therefore impossible to make firm causal inferences. The results thus do not led themselves to clinical recommendation, but they are an indication that more definitive research is warranted, all the more so since we have plausible mechanisms to explain the observed findings.

A most encouraging development for alternative medicine, one could conclude. But is this really true? Most experts would be surprised, I think, to find that PUFA-consumption should fall under the umbrella of alternative medicine. Remember: What do we call alternative medicine that works? It is called MEDICINE!

Many experts are critical about the current craze for dietary supplements. Now a publication suggests that it is something that can save millions.

This article examines evidence suggesting that the use of selected dietary supplements can reduce overall disease treatment-related hospital utilization costs associated with coronary heart disease (CHD) in the United States among those at a high risk of experiencing a costly, disease-related event.

Results show that:

  • the potential avoided hospital utilization costs related to the use of omega-3 supplements at preventive intake levels among the target population can be as much as $2.06 billion on average per year from 2013 to 2020. The potential net savings in avoided CHD-related hospital utilization costs after accounting for the cost of omega-3 dietary supplements at preventive daily intake levels would be more than $3.88 billion in cumulative health care cost savings from 2013 to 2020.
  • the use of folic acid, B6, and B12 among the target population at preventive intake levels could yield avoided CHD-related hospital utilization costs savings of an average savings of $1.52 billion per year from 2013 to 2020. The potential net savings in avoided CHD-related health care costs after accounting for the cost of folic acid, B6, and B12 utilization at preventive daily intake levels would be more than $5.23 billion in cumulative health care cost net savings during the same period.

The authors conclude that targeted dietary supplement regimens are recommended as a means to help control rising societal health care costs, and as a means for high-risk individuals to minimize the chance of having to deal with potentially costly events and to invest in increased quality of life.

These conclusions read like a ‘carte blanche’ for marketing all sorts of useless supplements to gullible consumers. I think we should take them with more than a pinch of salt.

To generate results of this nature, it is necessary to make a number of assumptions. If the assumptions are wrong, so will be the results. Furthermore, we should consider that the choice of supplements included was extremely limited and highly selected. Finally, we need to stress that the analysis related to a very specific patient group and not to the population at large. In view of these facts, caution might be advised in taking this analysis as being generalizable.

Because of these caveats, my conclusion would have been quite different: provided that the assumptions underlying these analyses are correct, the use of a small selection of dietary supplements by patients at risk of CHD might reduce health care cost.

My 2008 evaluation of chiropractic concluded that the concepts of chiropractic are not based on solid science and its therapeutic value has not been demonstrated beyond reasonable doubt. It also pointed out that the advice of chiropractors often is dangerous and not in the best interest of the patient: many chiropractors have a very disturbed attitude towards immunisation: anti-vaccination attitudes till abound within the chiropractic profession. Despite a growing body of evidence about the safety and efficacy of vaccination, many chiropractors do not believe in vaccination, will not recommend it to their patients, and place emphasis on risk rather than benefit.

In case you wonder where this odd behaviour comes from, you best look into the history of chiropractic. D. D. Palmer, the magnetic healer who ‘invented’ chiropractic about 120 years ago, left no doubt about his profound disgust for immunisation: “It is the very height of absurdity to strive to ‘protect’ any person from smallpox and other malady by inoculating them with a filthy animal poison… No one will ever pollute the blood of any member of my family unless he cares to walk over my dead body… ” (D. D. Palmer, 1910)

D. D. Palmer’s son, B. J. Palmer (after literally walking [actually it was driving] over his father’s body)  provided a much more detailed explanation for chiropractors’ rejection of immunisation: “Chiropractors have found in every disease that is supposed to be contagious, a cause in the spine. In the spinal column we will find a subluxation that corresponds to every type of disease… If we had one hundred cases of small-pox, I can prove to you, in one, you will find a subluxation and you will find the same condition in the other ninety-nine. I adjust one and return his function to normal… There is no contagious disease… There is no infection…The idea of poisoning healthy people with vaccine virus… is irrational. People make a great ado if exposed to a contagious disease, but they submit to being inoculated with rotten pus, which if it takes, is warranted to give them a disease” (B. J. Palmer, 1909)

Such sentiments and opinions are still prevalent in the chiropractic profession – but today they are expressed in a far less abrupt, more politically correct language: The International Chiropractors Association recognizes that the use of vaccines is not without risk. The ICA supports each individual’s right to select his or her own health care and to be made aware of the possible adverse effects of vaccines upon a human body. In accordance with such principles and based upon the individual’s right to freedom of choice, the ICA is opposed to compulsory programs which infringe upon such rights. The International Chiropractors Association is supportive of a conscience clause or waiver in compulsory vaccination laws, providing an elective course of action for all regarding immunization, thereby allowing patients freedom of choice in matters affecting their bodies and health.

Not all chiropractors share such opinions. The chiropractic profession is currently divided over the issue of immunisation. Some chiropractors now realise that immunisations have been one of the most successful interventions ever for public health. Many others, however, do still vehemently adhere to the gospel of the Palmers.  Statements like the following abound:

Vaccines. What are we taught? That vaccines came on the scene just in time to save civilization from the ravages of infectious diseases. That vaccines are scientifically formulated to confer immunity to certain diseases; that they are safe and effective. That if we stop vaccinating, epidemics will return…And then one day you’ll be shocked to discover that … your “medical” point of view is unscientific, according to many of the world’s top researchers and scientists. That many state and national legislatures all over the world are now passing laws to exclude compulsory vaccines….

Our original blood was good enough. What a thing to say about one of the most sublime substances in the universe. Our original professional philosophy was also good enough. What a thing to say about the most evolved healing concept since we crawled out of the ocean. Perhaps we can arrive at a position of profound gratitude if we could finally appreciate the identity, the oneness, the nobility of an uncontaminated unrestricted nervous system and an inviolate bloodstream. In such a place, is not the chiropractic position on vaccines self-evident, crystal clear, and as plain as the sun in the sky?

Yes, I do agree: the position of far too many chiropractors is ‘crystal clear’ – unfortunately it is also dangerously wrong.

Yoga, it is often claimed, might be a unique method for disease prevention. One website, for instance, states that numerous studies show how yoga can help prevent these diseases: Heart disease, Alzheimer’s, Osteoporosis and Type II Diabetes. 

Cardiovascular diseases (CVD) are responsible for more deaths than any other disease category. Preventing CVD is therefore of prime importance. But are the claims made for yoga really true? What does the reliable evidence tell us?

The aim of our systematic review was to determine the effects of yoga on the primary prevention of CVD. Extensive literature searches were performed to identify all RCTs lasting at least three months, involving healthy adults or people at high risk of CVD. Trials examined any type of yoga and the comparison groups received no intervention or minimal interventions. Outcomes of interest were clinical CVD events and major CVD risk factors. Trials that involved multifactorial lifestyle interventions or weight loss programmes were excluded.

We identified 11 RCTs with a total of just 800 participants. Style and duration of yoga differed between trials. About half of all the trial participants were at high risk of CVD. Most of the studies were at risk of performance bias, with inadequate details reported in many of them to judge the risk of selection bias. None of the studies reported cardiovascular mortality, all-cause mortality or non-fatal events, and most studies were small and short-term.

Yoga was found to produce an average reduction in diastolic blood pressure of 2.90 mmHg. The effect that was small but stable on sensitivity analysis. Triglycerides (-0.27 mmol/l) and high-density lipoprotein (HDL) cholesterol (0.08 mmol/l) were also positively affected. However, these findings were based on small, short-term studies at unclear or high risk of bias. There was no clear evidence of an effect on low-density lipoprotein (LDL) cholesterol. Adverse events, occurrence of type 2 diabetes and costs were not reported in any of the included studies. Quality of life was measured in three trials but the results were inconclusive.

Our conclusion: The limited evidence comes from small, short-term, low-quality studies. There is some evidence that yoga has favourable effects on diastolic blood pressure, HDL cholesterol and triglycerides, and uncertain effects on LDL cholesterol. These results should be considered as exploratory and interpreted with caution.

This systematic review thus offers both good and bad news. The good news is that yoga seems to hold some promise in the prevention of CVD. The bad news, however, is diverse:

  • We cannot be sure what type of yoga is best; yoga can entail anything from regular exercise, to breathing techniques, to a complete and comprehensive change of life style.
  • The effect sizes are far from remarkable.
  • The quality of the research tends to be poor.
  • Once again, we have to note that, by not reporting on adverse effects, alt med researchers are violating fundamental research ethics.

Many systematic reviews conclude by stating that more and better research is required – in the case of yoga, this platitude might actually be true.

In China (and increasingly elsewhere too), the gentle, meditative exercise of tai chi is being promoted and used for disease prevention, particularly for the prevention of cardiovascular disease (CVD). But are these exercises effective? We carried out a Cochrane review to find out.

We searched both English language and Asian electronic databases as well as trial registers and reference lists for relevant studies. No language restrictions were applied. We considered randomised clinical trials (RCTs) of tai chi lasting at least three months and involving healthy adults or adults at high risk of CVD. The comparison groups received no or only minimal interventions. Our outcome measures were CVD clinical events and CVD risk factors. We excluded trials involving multifactorial lifestyle interventions or focusing on weight loss. Two reviewers independently selected trials for inclusion, abstracted the data and assessed the risk of bias of each included study.

We identified 13 trials with a total of 1520 participants and three on-going studies. All of them had at least one domain with unclear risk of bias, and some were at high risk of bias. Duration and style of tai chi differed between trials. Seven studies recruited 903 healthy participants, the other studies recruited people with hypertension, elderly people at high risk of falling, and people with ‘liver or kidney yin deficiency syndromes’.

No studies reported on cardiovascular mortality, all-cause mortality or non-fatal events as most studies were short-term. There was also considerable heterogeneity between studies, which meant that it was not possible to combine studies statistically for cardiovascular risk. Nine trials measured systolic blood pressure (SBP), and 6 of them found reductions in SBP. Two trials found no clear evidence of a difference, and one trial found an increase in SBP with tai chi. A similar pattern was seen for diastolic blood pressure (DBP): three trials found a reduction in DBP, while three found no clear evidence of a difference.

Three trials reported lipid levels and two found reductions in total cholesterol, LDL-C and triglycerides, while the third study found no clear evidence of a difference between groups on lipid levels. Quality of life was measured in only one trial: tai chi improved quality of life at three months. None of the included trials reported on adverse events, costs or occurrence of type 2 diabetes.

From these findings, we drew the following conclusions: “There are currently no long-term trials examining tai chi for the primary prevention of CVD. Due to the limited evidence available currently no conclusions can be drawn as to the effectiveness of tai chi on CVD risk factors. There was some suggestion of beneficial effects of tai chi on CVD risk factors but this was not consistent across all studies. There was considerable heterogeneity between the studies included in this review and studies were small and at some risk of bias. Results of the ongoing trials will add to the evidence base but additional longer-term, high-quality trials are needed.”

These findings are somewhat disappointing. Tai chi might convey many health benefits, but whether a reduction of cardiovascular risk is amongst them seems doubtful. Even if a risk reduction were established beyond doubt, one would need to ask whether its effect size is larger than that achievable through regular conventional exercise. In my view, this is unlikely.

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