http://news.bbc.co.uk/1/hi/scotland...ast/6764169.stm
Monday, 18 June 2007



Low-carb diet 'cancer risk' claim


Low-carbohydrate diets may increase the risk of people suffering bowel cancer, scientists have claimed.

Researchers from Aberdeen's Rowett Research Institute believe there is a link between eating less carbohydrate and reducing cancer-fighting bacteria.

The Rowett study saw 19 overweight men given three diets containing different levels of carbohydrate.

Low-carbohydrate diets, such as Atkins, have their critics, however supporters say studies have show effectiveness.


In the long run, it is possible that such diets could contribute to colorectal cancer
Prof Harry Flint
Rowett Research Institute

The researchers said they had discovered a link between consuming carbohydrate and the production of a fatty acid in the gut that protects against colorectal cancer.

The acid, called butyrate, is produced by bacteria and helps kill off cancerous cells.

The researchers said they found low-carbohydrate regimes could cause a four-fold reduction in the cancer-fighting bacteria.

'Preventable disease'

The diets start by reducing carbohydrate intake, including foods such as potatoes and bread.

The researchers say the danger comes if dieters are tempted to keep the level low.

They said the study showed a low carbohydrate group consuming only 24g a day - behind the high intake group at 400g - saw a four-fold drop in the level of the cancer-fighting bacteria.

Prof Harry Flint, who led the research, said: "In the long run, it is possible that such diets could contribute to colorectal cancer.

"It is a preventable disease, and there is evidence that poor diet can increase your risk."

He said it was likely the results would be the same in women.

Note how many times weasel words are used:

Could: 3
Possible: 2

I.e. It's a hypothesis.

I know - it's just SO frigging annoying -

"In the long run, it is possible that such diets could contribute to colorectal cancer."

yes it's POSSIBLE - but what about all the benefits of following a low carb diet?

Makes you want to bash some heads together.

A. This is a wild-ass guess. No one has ANY idea if lowered butyrate -- if in fact that is what will occur over time -- will have any effect whatsoever on bowel cancer. They didn't study bowel cancer here.

B. Butyrate is found in butter. That's where the name came from.

ahh, then the inuit and masai must be droppin like flies from colorectal cancer, eh?

Cancer must have been really common before potatoes and bread were added to the food supply.

Well years ago it was some other diet or some other food or some other drink that caused cancer. I'm sure at some point we will be told sex causes cancer!
Leah

I thought that had been established already; Nuns, with a lifetime of celibacy, have very little cancer.

think there could be other lifestyle factors that lead to reduced cancer rates in nuns?

ya, we don't often see them going through drive throughs, now do we.

Cervical cancer is caused by a sexually trasmitted virus.

My mother's sister is a nun and many of her colleagues suffered and/or died from cancer.

As KWalt said, butyrate is found plentifully in butter, and some is also found in coconut/coconut oil. Both of which fats having been replaced by partially hydrogenated oils in the food supply thanks to the efforts of the anti-saturated fat zealots.

Wow a whole 19 people for this statistically significant study.

Give me a break.

Maybe the "low carb" group didn't eat enough butter.

ScienceDaily Online
20 June, 2007


Very Low Carbohydrate Diets May Disrupt Long-term Gut Health

Scientists at Aberdeen’s Rowett Research Institute have shown that a very low carbohydrate weight-loss diet results in a four-fold reduction in the numbers of certain types of bacteria in the gut of obese men.

This is a significant finding because these gut bacteria produce a substance called butyrate, which has been shown to be important for keeping the gut healthy including helping to prevent colorectal cancer. The study raises questions about the impact of the prolonged use of very low-carbohydrate weight-loss diets on gut health.

Very low-carbohydrate weight-loss diets (such as the so-called ‘Atkins-type diets) are popular with people struggling to lose weight and are used in some weight-loss clinics. Nutritionists have raised concerns about the low fruit and vegetable content of such diets as these contain nutrients that help protect against a number of diseases and cancers within the body. Less attention has been paid to the consequences of the low carbohydrate intake on the bacteria within the gut and how this might alter the release of either beneficial or harmful compounds from the food.

In this study, 19 healthy, obese men were given three diets containing different levels of carbohydrate (high, medium and low). Two of the diets also contained a high proportion of protein, as this is known to help reduce appetite and is used in a number of diets that help produce weight loss. Indeed, the volunteers lost similar amounts of weight and body fat on these two diets. Stool samples were analysed for the amount and type of bacteria, and for butyrate.

“The changes in butyrate production that we observed in this study are the largest ever reported in a human dietary trial. The results provide strong evidence that butyrate production is largely determined by the content of a particular type of carbohydrate in the diet that the bacteria in our guts can utilise,” said Professor Harry Flint who led the research at the Rowett Institute.

“We can’t be sure from this study about the impact of butyrate production on gut health, but there has been quite a lot of work done which shows that butyrate stops cancer cells from growing, and so helps prevent colorectal cancer.

“If low carbohydrate diets are to be consumed for long periods of time, it may be important to ensure that there is enough of the right sort of carbohydrate in the diet which can be used by the bacteria to produce compounds such as butyrate, which are beneficial for human health. This means making sure you continue to eat plenty of sources of fibre – such as fruit and vegetables,” said Professor Harry Flint.

What is butyrate?

Butyrate is what is known as a short chain fatty acid, and is produced in the gut when the bacteria ferment the carbohydrate present in food. It can be used by the bacteria as a source of energy and also is used by the cells which line the gut wall. Studies have shown that butyrate can prevent cancer cells in the gut from continuing to grow and so reduce the risk of colorectal cancer.

The composition of the three diets was as follows:

Normal (maintenance) diet: 13% protein, 52% carbohydrate, 35% fat, as calories;

Medium carbohydrate diet: 30% protein, 35% carbohydrate, 35% fat. as calories

Low carbohydrate diet: 30% protein, 4% carbohydrate, 66% fat, as calories.

The work is published in Applied and Environmental Microbiology, 73:1073-8.



http://www.sciencedaily.com/release...70619173537.htm