Sorting Out Medical Advice from Medical Nonsense

Story at-a-glance

  • A basic tenet of science is that correlation does not imply or prove causation
  • Some health recommendations are completely made up and have no scientific basis. This includes the linear model for blood pressure, healthy alcohol consumption levels, and recommended cholesterol levels
  • Absolute risk versus relative risk can be used to make something sound far worse than it really is, or conversely, make something appear better than it is


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

By Dr. Mercola

There’s so much confusion regarding health information in the media. How do you determine which advice to follow and what to take with a grain of salt? Dr. Malcolm Kendrick wrote the book Doctoring Data: How to Sort Out Medical Advice from Medical Nonsense to help you answer that question.

His fabulous book will teach you how to identify common research flaws and help you sift through misleading and meaningless data. An important resource if you are a serious student of health.

Dr. Kendrick has also written The Great Cholesterol Con: The Truth about What Really Causes Heart Disease and How to Avoid It, which is another great book. Like me, he’s a trained family doctor whose journey led him to abandon much of what’s promoted in conventional medicine.

“The first time it really hit home, I was at a conference in Gleneagles... At that meeting the results of the first ever trial on treating mild to moderate hypertension came out.

Prior to that, no one has done a study. It was done in the UK under the Medical Research Council. When the results came out, there was great fanfare.

But once I teased out all the figures... it worked out that the total number of deaths from stroke and heart disease in the placebo group was 124, and in the treatment group, it was 124. I thought, ‘Well, nothing happened. This was a complete waste of time...’

I realized that basically, research, data, facts, and figures seem to have no effect on some people. I think that was when I suddenly thought, ‘Hold on, this is nonsense.’”

Quite often, this kind of “nonsense” is a manipulation effect designed by the people who funded or put these studies together. Over the past decade, Dr. Kendrick has developed 10 tools the average person can use to help identify the truth in any given study.

The book is an important tool that teaches you how to tear apart any study promoted in the media as a breakthrough. The reality is most of the time it isn’t, and the book will explain how you can make that determination yourself.

Correlation Does Not Prove Causation

A basic tenet of science is that correlation does not imply or prove causation. This is one of Dr. Kendrick’s 10 principles. It’s a common mistake to get excited about associations that in reality frequently amount to nothing.

“People will look at a group of people, studying what they eat and do over many years. Then they say, ‘Oh, look, they drink red wine and they don’t get heart disease.’ They immediately come out and say, 'Red wine protects you against heart disease.’

I always go, ‘No. It could mean that. But what it probably means is that people who drink red wine may be better off; maybe they’re more educated, maybe they exercise, maybe they eat vegetables as well, maybe they don’t smoke, or maybe they do a hundred of other things.’

Even though it’s something highly correlated... it doesn’t mean it is [causative].”

On the other side of this coin, lack of association disproves causation.

“We have studies like that,” Dr. Kendrick says. “There’s a huge study in Austria of 150,000 people, which showed that the higher your cholesterol level was, the longer you lived. And the lower your cholesterol level was, the shorter you lived. These [findings] don’t see the light of day. They are published, but silenced...”

Many Times They Just Make Stuff Up

While it’s hard to comprehend, some health recommendations are completely fabricated and are not based in any science. Dr. Kendrick wrote about this in a recent article for The Independent:1

“If you are a man, it has virtually become gospel that drinking more than 21 units of alcohol a week is damaging to your health. But where did the evidence to support this well-known ‘fact’ come from?

The answer may surprise you. According to Richard Smith, a former editor of the British Medical Journal, the level for safe drinking was ‘plucked out of the air.’

He was on a Royal College of Physicians team that helped produce the guidelines in 1987. He told The Times newspaper that the committee's epidemiologist had conceded that there was no data about safe limits available and that ‘it's impossible to say what's safe and what isn't.’

Smith said the drinking limits were ‘not based on any firm evidence at all,’ but were an ‘intelligent guess.’ In time, the intelligent guess becomes an undisputed fact.”

According to Dr. Kendrick, the linear model for blood pressure—which states the higher your blood pressure is, in a linear fashion, the greater your risk of dying—was also made up.

Ditto for recommended cholesterol levels, and healthy versus unhealthy obesity levels. Believe it or not, none of these are based on real data. The recommendation to eat five portions of fruit and vegetables is equally made up, yet recommendations such as these become set in stone.

People believe it must be based on solid evidence and therefore true. One of the most impressive comments he made in the interview is: “Don’t believe it. They just made it up.”

Absolute Risk versus Relative Risk, and Number Needed to Treat

Absolute risk versus relative risk can be used to make something sound far worse than it really is, or conversely, make something appear better than it is. Most doctors even struggle to understand what these two terms actually mean. Dr. Kendrick explains absolute versus relative risk with the following example:

“You get 100 people and you put them on a blood pressure-lowering medication, and you get 100 people and put them on a placebo. After a year, two people have died in the placebo group; one person has died in the blood pressure-lowering group.

That’s an absolute difference of one percent [one out of 100], and a relative difference of one death versus two; that’s 50 percent.

Now, take 1,000 people and do the same. In the thousand-people group, one person dies in the blood pressure arm and two people die in the placebo arm. The difference is absolute: It’s 0.1 percent. The relative risk difference is one versus two—it’s 50 percent...

When it comes to things like statins, which they say reduces the risk of heart disease by 40 percent, you say, ‘What was the underlying risk? Was it one in 10,000, one in two, one in a million?’ Unless you know that, the statistic is meaningless. I think relative risk should never be mentioned in any clinical study. It should be absolute risk all the time. [Relative risk] is the standard, and it shouldn’t be because it’s just ridiculous.”

Overall Mortality versus Specific Cause of Death

Another way medical findings can be twisted is by focusing on the prevention of specific causes of death. For example, a study might claim that a cholesterol-lowering drug reduces the risk of dying from heart disease, but the people in the study may have died in greater numbers from other health problems instead. Naturally, you cannot die from heart disease if you die from another disease first. As a result, some research ends up forming the basis for health recommendations that actually do more harm than good.

“It’s the overall mortality you have to look at—ALL causes of possible death. What was the impact? When you look at, say, alcohol consumption, it increases the risk of mouth cancer, esophageal cancer, stomach cancer... But when you look at the overall figures, it reduces the overall mortality risk. So you can take all of these things, add them together, and basically ignore them on the basis that you’re going to have to die of something,” Dr. Kendrick says.

Another perfect example is sun exposure.

“Dermatologists have taken over the world on sun exposure and said, ‘Oh, people are getting skin cancer so you must never allow a photon go straight to your skin.’ To which I say, I’ve seen studies where women who have higher sun exposure are 50 percent less likely to get breast cancer.

Men who have higher rates of sun exposure have are 50 percent less likely to get aggressive prostate cancer. Men and women who have higher rates of sun exposure are 75 percent less likely to get colorectal cancer... Frankly, the research I’ve looked at says sun exposure protects against malignant melanoma; it doesn’t cause it. Therefore the whole thing is a crock.”

Sun exposure also protects against heart disease, improves bone strength, reduces osteoporosis, and reduces your chance of developing multiple sclerosis and Parkinson’s disease. Does it raise your risk of deadly skin cancer? If you get burned, yes, it may, but the overall health benefits FAR outweigh the potentially elevated risk of melanoma. Part of the problem is you cannot see that which does not happen.

If you tan and get melanoma, your dermatologist will tell you it’s your fault for not following his recommendations to stay out of the sun. But if you never come down with colorectal cancer, no one will pat you on the back and say, “Great job! You successfully avoided cancer because you spent so much time in the sun.”

Longest Running Study in the World Refutes Conventional ‘Facts’

One of the examples in Dr. Kendrick’s book is the Framingham Study, which was one of the longest studies ever done in the world. It has been going on for about seven decades. One of the conclusions reached was that people whose cholesterol was reduced by one millimole per liter, which equates to about 40 milligram per deciliter, raised their risk of dying of heart disease in the next 14 years by 500 percent.

Falling cholesterol was determined to be the most important risk factor for heart disease mortality in this study, yet this finding has received virtually no publicity, as it runs contrary to conventional recommendations to lower your cholesterol to prevent heart disease. They also discovered that the more saturated fat people ate, the lower their cholesterol level was during the length of the study. This too is completely contrary to conventional recommendations to avoid saturated fat because it raises your cholesterol.

Mammography is another area where science and “conventional wisdom” is often at odds. Dr. Peter C. Gotzsche, a professor of Clinical Research Design and Analysis, and director of the Nordic Cochrane Centre, wrote an excellent book on this subject called Mammography Screening: Truth, Lies, and Controversy. After studying it for years, he came to the conclusion that mammography probably does more harm than good.

The Cochrane Collaboration, by the way, is a worldwide effort of researchers who have no industry connections, who collaborate to review and evaluate available evidence on any given topic and then come to a conclusion. The Cochrane Database the gold standard for objective, impartial, non-biased meta-reviews.

Non-Disclosure of Negative Data and Other Shenanigans

Other common tactics of misdirection include the non-disclosure of negative studies and good old-fashioned conflicts of interest. As noted by Dr. Kendrick: “In the States, they have the non-disclosure of negative data on antidepressants. They only publish positive studies, and the negative ones aren’t published. You then have a bias of infinity. There are hundreds of these things that go on.”

His book also addresses the now infamous revolving door between the government and the drug industry. One classic example is Julie Gerberding, who headed up the Centers for Disease Control and Prevention (CDC)—an agency charged with overseeing vaccines and drug companies—for a number of years before becoming the president of Merck’s vaccine division.

If you don't see the enormity of the influence her former high-level ties to the CDC can have, just consider the fact that Merck makes 14 of the 17 pediatric vaccines recommended by the CDC, and 9 of the 10 recommended for adults, and while vaccine safety advocates are trying to rein in the number of vaccines given to babies, safety concerns keep falling on deaf ears.

“You should be banned forever from working with the industry if you’re in the position of authority making decisions about drugs and medications,” Dr. Kendrick says. “If we have to get opinion leaders and experts, people running studies, that’s fine. You can do that if you like. But you cannot then sit on the guideline committee.

You cannot be the person who says, ‘This is how we’ll be treating X.’ Look at the cholesterol-lowering guidelines. How many conflicts of interest are there? Last time I looked at the guidelines made in 2004, there were 107 conflicts of interest, 70 directly with statin manufacturing companies. How can this be? This is nonsense.”

More Information

Anyone who’s a serious student of health needs a copy of Dr. Kendrick’s book, Doctoring Data: How to Sort Out Medical Advice from Medical Nonsense, in their library. It goes into far more details than we’ve covered in this interview. It’s definitively eye-opening, and will empower you to make sounder choices for you and your family when it comes to your health and lifestyle.

It is an important tool to help you take control of your health and avoid deception by the media and drug companies. You don’t have to be fooled by drug industry manipulation once you know some of the tricks they use. Dr. Kendrick also has a blog,, where he discusses this and other health-related topics.

+ Sources and References

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