You can hardly pick up a paper or turn on the radio or TV without being bombarded with advice on how to stay healthy. You should eat less, and especially less salt, sugar and saturated fat. You should drink less alcohol, and what you do drink should be red wine. You should stop smoking. You should not go out in the sun without a big hat and special sun lotions.
If you go to the doctor, not only will you get much the same advice, you will often be prescribed drugs of one kind or another, not because you are ill but because your blood pressure or your cholesterol level is too high. If you are a woman, you will be urged to undergo screening for breast or cervical cancer, or prescribed hormone replacement therapy if you are at or past menopause. If you question the doctor about this, you will probably be told that he or she is following approved guidelines based on scientific research. There may even have been pressure on your doctor to get all their patients to participate.
Malcolm Kendrick is a doctor who has come to be sceptical about this plethora of advice. Some of it is certainly correct; the evidence that smoking is bad for your health is overwhelming. But when he started to look for the evidence to back up many of the other things we’re told, he found a lot of it ranged from flimsy to non-existent. Many of the benefits, even where they appear to be real, are so small that they’re not worth the effort, especially when balanced against side effects.
The truth is that the experts don’t know as much as they would like you to think. Worse, many of them have got vested interests in getting you to follow their advice, especially about drugs. Bearing in mind that we don’t all have the same view of what is or is not an acceptable level of risk, and how much interference with our normal lives we are willing to tolerate, we’d be better off listening to what the experts say and then deciding for ourselves.
Of course we have to be able to decide whom to trust. So Kendrick provides what he calls a “truth toolkit”: ten things you should remember when you hear a story about health:
1. Association does not mean causation. If people who eat more red meat have a higher risk of heart disease, does that mean that eating red meat is bad for your heart? You might think so, because a study from Harvard  found that people who eat more red meat have a higher risk of heart disease. And that’s how the media reported it (cf. ). But the study also found that people who eat red meat consume more calories, exercise less and are more likely to smoke.
2. We are all going to die. We often read of some new drug that saves lives, when the most it can do is postpone death. So the important question is “By how much?” Kendrick describes a press release  that claimed treating 10 million people with statins would save about 50 000 lives a year. He points out that a more informative way of putting it is that if 200 people were treated for a year, it would make no difference to 199 of them and the other one would live for a few extra months. (For more on statins, see Statins for the Healthy are Harmful  and The ‘Deadly Dangers of Saturated Fat’ & the ‘Superlative Safety of Statins’ .)
3. Relative mountains are made out of absolute molehills. According to a news report on the BBC , regularly drinking two large glasses of wine or two pints of strong beer a day triples the risk of mouth cancer. That sounds alarming, but only 2.5 out of every 100 000 people in the UK die of mouth cancer. So even if this is cause and effect and not just merely association (people who drink are more likely to smoke, less likely to exercise, and so on), the number of people affected is very small. Three times a tiny number is another tiny number.
4. Things that are false are often held to be true. For a long time it was believed that women are protected against heart disease by their sex hormones. Kendrick was unable to find any research to support the idea. The origin appears to be no more than the observation that (a) men were more susceptible than women to heart disease and (b) the sex hormones are the most obvious difference between the sexes. As a result, many menopausal women were prescribed hormone replacement therapy to maintain this protection. In the US, failure to prescribe could constitute malpractice . Eventually a large controlled study was carried out to measure the effect . It turned out that the sex hormones were not providing protection. On the contrary, women who were taking HRT were at a greater risk of heart failure and strokes.
5. Reducing numbers does not equal reducing risk. High blood pressure is associated with a greater risk of heart disease. But that doesn’t mean it is the cause; in fact, there is no evidence that reducing the blood pressure reduces the risk . Yet a drug that can lower the blood pressure below a certain number is considered an effective treatment, with no further check on whether it actually does the patient any good.
6. Challenges to the status quo are crushed. When Marshall and Warren argued that ulcers were caused not by stress but by a bacterial infection, they were met with ridicule and hostility – until they were awarded a Nobel Prize. Kendrick suggests three points to bear in mind. First, most experts are only experts in a relatively narrow field. Second, the angrier they are, the more likely it is that they suspect they are wrong. Third, because their reputation, status and income may all be at stake, it is very difficult for experts to change their minds.
7. Games are played. He who pays the piper calls the tune, and the pharmaceutical industry carries out or funds an ever-increasing proportion of the research and pays, in one way or another, most of the so-called key opinion leaders.
8. Doctors can seriously damage your health. For a number of reasons, doctors tend to be inclined towards more intervention rather than less.
9. Never believe that something is impossible. Many people died because the experts claimed cholera could not possibly be communicated by water or puerperal fever by doctors’ unwashed hands. Today we are assured that vaccination cannot possibly be a cause of autism. (See MMR Controversy Reignites  for an update.)
10. ‘Facts’ can be, and often are, plucked out of the air. It may sound very scientific to be told we should aim for a body mass index (BMI) between 18.5 and 25 but these are arbitrary figures. What is more, the evidence is that those who are considered overweight (BMI between 25 and 30) live longer than those who are ‘normal’, and even those classed as obese (BMI between 30 and 35) do as well .
(If you find it hard to believe that you should take so much of what you are being told with a very large grain of salt, you should read a classic paper published ten years ago with the title “Why most published research findings are false” .)
After you have read this book, you will be better placed to judge what you’re told. But it’s still not going to be easy. Kendrick has been working on the problem for a long time and besides, as a doctor he had a lot of background knowledge to begin with. He also knows his way around the medical journals, whereas most people don’t even have access to them except at extortionate cost.
As lay people we may not be able to evaluate scientific or statistical papers ourselves, but where experts disagree we have the right to hear both sides and judge between them. This is, after all, what juries are expected to do in a trial when there is disagreement between expert witnesses. For that to happen, the relevant papers must be publicly available, not hidden behind pay walls nor concealed on the grounds of “commercial confidentiality”. And the details of the research, if not included in the published papers, must be in accessible repositories. This might come about if the Transparency and Openness Promotion Guidelines, recently published in Science , were to be adopted, but if this progresses as slowly as the registration of Phase 1 clinical trials, it will be a long time before we see any effect.
Article first published 06/07/15
Got something to say about this page? Comment
There are 3 comments on this article so far. Add your comment above.
David Packham Comment left 6th July 2015 18:06:22
Malcolm Kendrick is surely right, but only a specialist in the particular field can stand any chance of cutting through the conflicting reports and half-truths. Traditionally the government has appointed such experts to do this for the public. But successive governments have corrupted the boundary between vested interest and disinterested experts in the Scientific Civil Service and the universities, so that reliable, expert knowledge is very difficult to find. Adam Smith in the Wealth of Nations [Bk 1. xi. para.10] warned of laws and regulations coming from commercial interests "who have generally an interest to deceive and even to oppress the publick, and who accordingly have, upon many occasions, both deceived and oppressed it". Kendrick's article shows this!
Elaine S Comment left 7th July 2015 20:08:31
This is why all data should be freely available from all medical trials. If there is nothing to hide, why not release the data? If there is something to hide, then keep as Cara away from it as you can, and take any outcomes with a pinch of salt!
Todd Millions Comment left 8th July 2015 15:03:45
Point 2- Even the most skilled and compassionate medical personnel have too live with the fact that they can never win in the end. The occasional draw bout,with squaw wrestling the crone is the best they can hope for. Unfortunately this fact too often ends up camouflaging the aims and designs of psychopaths. Points 3 thru 10-A book on trade in the Caribbean that I've not being able too track down(notes destroyed deliberately),had an Italian banking family starting a rumour that -the Lignium viate lumber they happened too have a monopoly on could cure the-'French Pox'. Paracelsus inquired for evidence for this claim-and found it didn't exist. But for a century the medical establishment of Europe found this treatment efficacious and profitable. What they found when the doctors picked up a dose is less clear. This may be why the staffs of Mercury and Aspeculious, became confused .