Published on 22 February 2018

Plant-based diet study results report lost weight and improvements in insulin-producing cells.

A study carried out by researchers in the US has looked at the health benefits of a vegan diet in overweight people.

A group of 75 people were split into two random groups for the 16-week trial – with one instructed to follow a low-fat vegan diet and the other to carry on eating as normal.

The risk of developing type 2 diabetes can increase when beta cells are less effective - beta cells play a key role in regulating blood insulin levels.

The study was led by researchers from the Physicians Committee for Responsible Medicine (PCRM) in Washington DC, and researchers from four other international institutions in the Czech Republic, Italy and the US and the results were recently published in Nutrients.

Researchers said: “The aim of this study was to test the effect of a plant-based dietary intervention on beta-cell function in overweight adults with no history of diabetes.”

The study included both men and women aged 25 to 75 years with a BMI (body mass index) of between 28 and 40.

A BMI score of 25 to 30 is classed as being overweight in adults, and 30 or above as obese. The study did not include people already diagnosed with type 2 diabetes, or who smoked, abused alcohol or drugs, were pregnant, or were already eating a vegan diet.

Researchers concluded: “Beta-cell function and insulin sensitivity were significantly improved through a low-fat plant-based diet in overweight adults.”

An NHS Behind the Headlines report on the study said: “The study's strength lies in its method. It was a randomised trial, which is the best way to assess the effectiveness of an intervention.

“Further research is also needed to see whether improvements in beta-cell function require a 100%-vegan diet or if the beneficial effects can be achieved with smaller changes.

“Finally, it is important to note that non-vegan diets that include low-fat dairy products and oily fish, among other recommendations, can also aid weight loss and help control or prevent type 2 diabetes.”

Fish and vegetables.

Vegan diets and health
By Pam Dyson, Research Dietitian, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Oxford:

“Vegan diets are completely plant-based and contain only plants including grains, fruit, vegetables, pulses and legumes, seeds and nuts. All food derived from animal sources, including meat, fish, poultry, dairy products and eggs are avoided. Studies have shown that vegetarians (including vegans) have lower rates of overweight and obesity and are at lower risk of type 2 diabetes, ischaemic heart disease, diverticular disease and eye cataract than meat-eaters, although there is little difference in the rates of risk of death, stroke and cancer. However, most of these studies include both vegetarians and vegans and there are few data available for vegans alone.

“For people already diagnosed with diabetes, a review of six studies (five of which involved vegan diets) reported improved glycaemic control in those adopting vegan diets when compared with conventional diabetes diets. The available evidence suggests that there are health benefits associated with vegan diets for both those at risk of and those with diagnosed type 2 diabetes.

“The question is – should everyone adopt a vegan diet? Although some concern has been expressed about the nutritional adequacy of vegan diets and particularly about low intakes of iron, vitamin B12, vitamin D calcium and omega-3 fatty acids, well-balanced vegan diets are attainable. However, the way individuals choose to eat depends on many factors other than health, including food preferences, budget, past experiences of diets and cultural and social norms. For some, vegan diets will fit easily into their lifestyle, but for others they may well be as step too far.

"Generally, plant-based diets are recommended for health and most authorities agree that a reduction in meat and meat products can only benefit health, so even those who cannot do without meat have the potential to improve health by reducing the amount that they eat.”

Read the report in Nutrients
Find out your BMI
Find out more about type 2 diabetes
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