Dr John Beaney



Fibre in our diet

Dogma: a principle or set of principles laid down by an authority as incontrovertibly true

Fibre became popular when Dr Denis Burkitt, who was an accomplished physician working in Uganda in the 1960s, noticed that the rural population passed copious amounts of faeces and didn’t get cancer or heart disease. He formed the conclusion that constipation caused these conditions. To quote the great man: “America is a constipated nation.... If you pass small stools, you have to have large hospitals”. He failed to do any studies to prove his hypothesis. Nevertheless, the medical profession and the public accepted his word.

Studies have been done since and have failed to support the hypothesis. A 2005 study of 8,081 patients with colorectal cancer concluded: “a high dietary fiber intake was not associated with a reduced risk of colorectal cancer”. The latest Cochrane Collaboration report in January 2017 entitled: “Does dietary fibre prevent the recurrence of colorectal adenomas and carcinomas?” concluded that not only was there was no reduction in cancer over eight years, there was, in fact, a small increase.

A well conducted 2012 study of 63 people who all complained of either constipation, bloating, bleeding or abdominal pain found that they all improved on a diet devoid of fibre.

But advocating fibre fitted in well with the promotion of plant-based food that appeared in the USA in the 70s.

Vegetables contain a significant amount of fibre, a form of carbohydrate which is difficult for humans to digest. Other carbohydrates are readily converted to sugar and absorbed in the small bowel to be used directly as fuel, but fibre has to pass through to the large bowel where some of it is digested by the gut bacteria into a form of fat known as a short chain fatty acid, mainly butyrate.

The current dogma, laid down by those promoting plant-based food, is that we need fibre
• to keep our gut microbiome healthy,
• to prevent constipation
• to prevent bowel cancer
• to keep us feeling full longer
• to prevent heart disease and diabetes.

To that end we are encouraged to eat nuts, seeds, bran, psyllium husks, beans and lentils and vegetables in general.

Plant-eating animals and meat-eating animals have each developed a very different anatomy and physiology to deal with the dietary differences. To summarise very briefly, meat-eating animals developed large brains and small guts and move fast when they need to hunt, while plant-eaters have small brains and large guts and sit surrounded by food whenever possible.

The energy and nutrient density in plants is low. Plant-eating animals need to conserve energy to digest their food using their large capacity gut. The food is fermented by bacteria in the gut and this is a long slow process. Cows eat grass and have 4 stomachs and must vomit the food repeatedly in order to digest it completely. Rabbits also eat grass and only have one stomach. A good deal of rabbit faeces is half digested. The rabbit eats the faeces repeatedly until all the nutrients are extracted.

Meat on the other hand is very energy dense. It is rapidly and completely digested in the small bowel and, being free of fibre, doesn’t require fermentation. Man used his larger brain and intellect to discover how to cook the meat which renders it even more easy to digest. During the process of switching from plants to cooked meats, the brain of the carnivore apes grew from 350ml to 1,500ml with intelligence to match.

The short chain fatty acid, mainly butyrate, formed in the large bowel from the fermentation of fibre is regarded by plant food advocates as an important source of nourishment mainly if it contacts the cells that line the large bowel. Carnivores use fat as their main energy source throughout the body, converting it to ketones, mainly beta-hydroxybutyrate. The whole carnivore body is bathed in the same beneficial nourishment that, in vegetarians is of limited benefit to the large bowel.

I would be among the first to agree that much of the animal food industry requires a major overhaul. But the enormous pressure on the world’s population to convert to being vegetarian of vegan is inappropriate for human metabolism and for the environment.

Human metabolism has evolved from our ancestral past and is what it is. A tiger doesn’t consider animal rights or ethics when it brings down the slowest antelope, kills and eats it.

We must return the world to the natural order that existed before we caused so much damage. Man must combine superior intellect with the will to care for our environment instead of destroying it. Our oceans could be rehabilitated. Proper animal husbandry, particularly of ruminants grazing the grasslands of the world, as they did for millions of years, together with reforestation, could provide an ethical solution to global warming, population feeding and the desertification of our landscapes.