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Sebastian Rushworth MD: Does a high fibre diet prevent disease?
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Real science is never settled, and anyone who has certainty on such things is not qualified to discuss it.
Yet another nutritional myth appears to have very poor if any evidence.
Does a high fibre diet prevent disease?
by Sebastian Rushworth M.D.., 8 August 2021. Emphasis added.
...Burkitt came to believe instead that it was the absence of dietary fibre that was responsible. Since refined carbohydrates are by definition low in dietary fibre, the two things track together perfectly, and it becomes almost impossible to say from observational data which is the causative factor and which is the confounder.
There was a big fly in the ointment of Burkitt’s hypothesis from the start, however, and that was the fact that the Maasai tribespeople in Kenya and Tanzania, who lived on a diet consisting almost entirely of meat, milk, and blood, showed none of the diseases of modern civilization, even though they had virtually no fibre in their diet. Burkitt, who spent much of his career in Africa, was well aware of this fact, but seemingly chose to ignore it because it didn’t fit his hypothesis.
The world of nutrition was at this time (the late 1970’s) focusing increasingly on dietary fat as the cause of modern diseases (based on atrociously low quality evidence and forceful lobbying by diet-heart hypothesis originator Ancel Keys), and Cleave’s hypothesis was inconvenient, because telling people to cut down on both fats and carbohydrates wouldn’t work – people had to eat something. Burkitt’s fibre hypothesis could however be made to fit together with the diet-heart hypothesis without too much trouble. The two were thus wedded and came to dominate dietary advice for the next couple of decades.
That is how breakfast cereals came to be considered a health food, and why we’ve all been told to increase our intake of dietary fibre. Anyway, it’s now a couple of decades later. One would think that by now there would be plenty of data from actual randomized trials to tell us whether we should be eating more dietary fibre or not. Unfortunately we’re still to a large extent stuck with crappy and confounder-riddled observational studies that cannot separate the presence of refined carbohydrates from the absence of dietary fibre, and that therefore cannot actually say anything about what causes what.
...In these two studies, participants in the high fibre group were 170% more likely to develop colon cancer than participants in the control group. Yes, more. Not less. That difference was statistically significant. So… that’s strange. Admittedly, this result is based on a few thousand participants followed for a few years. It could be wrong. But what it means is that the highest quality evidence currently available suggests that a high fibre diet might actually increase your risk of colon cancer, not decrease it.
...
So, what can we conclude from all this? Does fibre prevent the so-called “diseases of civilization”?
Well, maybe. That is certainly the impression you would get if you look at the observational data, which find a correlation between a low fibre diet and pretty much any chronic disease you care to look at. The randomized trials that have been done have however for the most part failed to show evidence of a benefit of increasing intake of dietary fibre.
WIND: “dominant dietary advice”based on... pet theories.
The modern medical establishment remains stunningly free of evidence about nutrition and diet. Here we are 80 years or so later with a debunked cholesterol hypothesis and still no credible data on diet.
Eat whole unprocessed food, all of the time. All processed food is an unknown risk, but if your body looks and feels good with what you are eating of whole unprocessed foods, you’re surely on the right path.
