September 17, 2019

expert reaction to conference abstract/poster looking at vegan diet and gut microbes and body weight

A conference abstract, being presented at the Annual Meeting of the European Association for the Study of Diabetes (EASD), reports that vegan diets can increase levels of gut microbes that are related to improvements in body weight, body composition and blood sugar control.

Dr Ian Johnson, Nutrition researcher and Emeritus Fellow, Quadram Institute Bioscience, said:

“This is a very short and preliminary account of a human trial in which the participants who switched from their habitual diets to what the authors describe as a “low-fat vegan diet” lost a significant amount of weight and showed improvements in insulin sensitivity.  Unfortunately, we are told nothing about the composition of the diets, or the amounts eaten, but we can speculate that the vegan group consumed fewer calories, which would account for their weight loss.  It is also reasonable to speculate that the vegan diets provided more dietary fibre than the control diets, and that this led to the changes observed in the gut bacteria.  This general effect of fibre on gut microbes has been observed and studied for decades.  What we certainly cannot infer without further research is that the changes in gut bacteria caused the weight losses or the improvements in metabolic health.  Without other information, simple correlations cannot prove causality.”

Prof Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:

“This is an uncontrolled study as the control group did not have their calorie intake restricted.  The diet used was a low fat vegan diet whereas typical vegan diets usually contain 30-35 percent energy from fat.  The weight loss was substantial and would be expected to improve insulin sensitivity.  However, it is not possible to attribute these changes to change in the gut microbial flora (these are already well known to change on a vegan diet so it is not a novel finding).  However, it does illustrate that a calorie restricted diet high in carbohydrates (presumably unrefined) is of benefit for people with diabetes which is opposite to the misplaced public perception that high carbohydrate diets increase risk of diabetes.”

Abstract/poster title: ‘Changes in gut microbiota in response to a plant-based diet are related to changes in weight, body composition and insulin sensitivity: a 16-week randomised clinical trial’.

This is a conference abstract from the Annual Meeting of the European Association for the Study of Diabetes (EASD), and was under embargo until 00:01 UK time on Tuesday 17 September 2019.

There is no paper as this is not published work.

Declared interests

Dr Ian Johnson: “No conflicts of interest.”

Prof Tom Sanders: “Tom was one of the reviewers of this paper. Honorary Nutritional Director of HEART UK.  Scientific Governor of the British Nutrition Foundation.  He is now emeritus but when he was doing research at King’s College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks.  In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011.  This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London.  The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar.  Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.  Tom also used to work for Ajinomoto on aspartame about 8 years ago.  Tom was a member of the FAO/WHO Joint Expert Committee that recommended that trans fatty acids be removed from the human food chain.  Tom has previously acted as a member of the Global Dairy Platform Scientific Advisory Panel and Tom is a member of the Programme Advisory Committee of the Malaysian Palm Oil Board.  In the past Tom has acted as a consultant to Archer Daniel Midland Company and received honoraria for meetings sponsored by Unilever PLC.  Tom’s research on fats was funded by Public Health England/Food Standards Agency.”