呃人的飽和脂肪, 膽固醇有害論

Hanford

http://www.abc.net.au/catalyst/stories/3876219.htm

NARRATION
For the last four decades, dietary fat and cholesterol have been the villains in heart disease.

Dr Michael Eades
You very seldom see the words 'saturated fat' in the public press when they're not associated with artery clogging. So it's like it's all one term - 'artery clogging saturated fats'.

NARRATION
But now some medical experts are coming forward to challenge this medical paradigm.

Dr Jonny Bowden
I think it's a huge misconception that saturated fat and cholesterol are the demons in the diet, and it is 100% wrong.

Dr Stephen Sinatra
Saturated fat has been vilified for years because of the cholesterol theory.

NARRATION
A multibillion dollar food industry has fuelled our phobia of fat and cholesterol and dramatically influenced our diet.

Dr Michael Eades
That's not science. That's marketing.

Dr Jonny Bowden
It's lived past its expiration date, and it's one of these hypotheses that just won't die.

NARRATION
Have we all been conned?

Dr Maryanne Demasi
In this episode, I'll follow the road which led us to believe that saturated fat and cholesterol cause heart disease, and reveal why it’s being touted as the biggest myth in medical history.

NARRATION
The food industry has shaped our ideas about heart health with TV ads like this one.

Advertising Man
So join me in the Uncle Toby's Oats cholesterol challenge!

NARRATION
Lowering our cholesterol has been a running theme with the food industry.

Dr Michael Eades
People have this fear of cholesterol because they've been bombarded with it so much in the media that it's bad and it's going to cause heart disease. That's why all these things were emblazoned with 'cholesterol free'.

NARRATION
These advertising campaigns are at the behest of our peak health authorities.

Dr Maryanne Demasi
The National Heart Foundation guidelines are pretty clear. We're told to reduce our saturated fat and cholesterol levels in order to reduce our risk of heart disease. But many doctors are now suggesting we need to radically rethink this approach.

NARRATION
One of those doctors challenging this medical dogma is California-based nutritionist, Dr Jonny Bowden.

Dr Jonny Bowden
When you look at the data, it's very clear - everything that we have been told about saturated fat and cholesterol is a bold-faced lie. It's just not so.

Dr Maryanne Demasi
But isn't there good science behind this?

Dr Jonny Bowden
If you look at the 'science' that actually the dietary guidelines were based on, the early stuff was so badly done, so filled with confirmation bias, it would never even pass muster today. And unfortunately most doctors don't know this.

NARRATION
Dr Ernest Curtis is astonished at how medicine has gilded the lily on cholesterol.

Dr Ernest Curtis
During medical school, I was taught the same thing everybody else was - the importance of cholesterol and so forth - and I saw no reason to doubt it. But once I got into the cardiology field itself, I was seeing people with heart attacks that had cholesterol all over the place - high cholesterol, low cholesterol, the middle - it didn't seem to matter.

And at first I thought, 'Well, OK, these are probabilities, so there will be exceptions.' But it turned out that, after a while, I was seeing far too many exceptions. So that motivated me to go back and look at the origins of these theories. And, quite frankly, given the certainty with which we're taught this, it surprised me to find out how poor the evidence was. It's virtually non-existent.

NARRATION
Cardiologist Dr Stephen Sinatra said he routinely ordered patients to lower their cholesterol with medications. But now admits he was wrong.

Dr Stephen Sinatra
I used to be the poster boy for the drug companies. And when I was Chief of Cardiology, I used to write for statins all the time. I really believed in the cholesterol theory of heart disease. I first became sceptical of the cholesterol theory in the mid-'80s. I was doing coronary angiograms. You know, you place a tube in the groin and it goes up into the heart, and you can see if there's blockages there.

Sometimes I would do the angiogram on a person with high cholesterol thinking I was going to find a lot of disease, and I... Many times, I didn't find disease, and the converse was true. You know, I would do somebody with low cholesterol, and expecting not to find disease, and I found disease. So I was starting to think, 'Maybe I don't have this right. Maybe cholesterol is not the enemy we think it is.'

Dr Maryanne Demasi
We've become so paranoid about cholesterol, we've actually forgotten it's essential for life. It's a major component of brain and nerve tissue, and central for the production of hormones. In fact, it's so important that virtually every single cell in the body makes it.

NARRATION
Aside from people with a genetic condition, like familial hypercholesterolemia, diet has long been the focus of how we can lower our cholesterol. The idea that saturated fat clogs your arteries by raising cholesterol first gained traction in the '50s. American nutritionist Ancel Keys became intrigued with the soaring rates of heart disease after World War II.

Ancel Keys
The facts are simple. You know the chief killer of Americans is cardiovascular disease.

NARRATION
He compared the rates of heart disease and fat consumption in six countries. It was almost a perfect correlation - the more fat people ate, the higher the rates of heart disease. Except, there was just one problem. Keys withheld data for 16 other countries. Later, when researchers plotted all 22 countries, the correlation wasn't so perfect. Dr Michael Eades is critical of the way Ancel Keys excluded countries that didn't fit his hypothesis.

Dr Michael Eades
He more or less cherrypicked countries. You could show just the opposite. You could show that the more saturated fat people ate, the less heart disease they had, if you cherrypicked the right countries.

NARRATION
Dr Eades says that even if fat consumption trends in the same direction as heart disease, it doesn't prove anything.

Dr Michael Eades
Just because there's a correlation, doesn't mean that there's causation. It's like people who are fat have big belts, but that doesn't mean that if you buy smaller belts, you won't be fat. I mean, that's not the causation. That's what these observational studies show - it's just a correlation.

Dr Ernest Curtis
The classic study by Ancel Keys is a textbook example of fudging the data to get the result that you want out of a study. And, unfortunately, there's a lot of that that goes on.

NARRATION
Science writer Gary Taubes says it's all very well to have a theory, but in science you have to prove it. And they tried.

Gary Taubes
And over the next 15 years, researchers did trial after trial. There were probably a half a dozen of them between 1960 and 1975. All refuted or failed to confirm the idea that you could live longer by either reducing the saturated fat in your diet or reducing the total fat in your diet.

NARRATION
The American Heart Association was also reluctant to lend credence to Keys' theory. But then he managed to score a position on the Association's advisory panel, where he pushed for the acceptance of his ideas, and it wasn't long before they had a change of heart.

Gary Taubes
Instead of the data not being good enough to claim that dietary fat was a cause of heart disease, they concluded that the data were good enough, and, therefore, all Americans over the age of two should go on low-fat diets.

NARRATION
As the idea gained widespread acceptance with the public, science was left to catch up. Two ambitious trials, costing over $250 million, involving hundreds of thousands of patients, both failed to prove that lowering saturated fat could lower your risk of dying from heart attack.

Gary Taubes
The way the authorities responded to this was to claim that they must have done the study wrong. Instead of saying, 'Hey, look, eating a low-fat diet doesn't apparently do anything for people, or certainly not women,' instead they respond by putting out press releases saying, 'Look, we don't know why this trial failed to confirm our hypothesis, but it doesn't mean the advice we've been giving you is wrong, and it doesn't mean that the hypothesis that dietary fat causes heart disease is wrong.'

NARRATION
The National Heart Foundation of Australia defends these failures, saying that nutrition trials are just too complex.

Dr Robert Grenfell
When you ask that question of 'Do dietary fats increase heart disease?', you're sort of trying to negate all the other risk factors that, in fact, actually also cause heart disease. So, to imagine creating a study that would prove that conclusively is virtually impossible.

Dr Maryanne Demasi
So, if they can't prove it, on what basis have they decided that saturated fat is bad for us?

Presenter, in advertisement
Eat too much fatty food and you risk a high level of blood cholesterol building up in your arteries. Eat sensibly.