A vegan diet rich in fruits, vegetables, nuts, legumes and seeds, with no or few animal products, may significantly lower the risk of developing type 2 diabetes, a study claims.
This diet is associated with improved psychological well-being, a reduction in some of the known risk factors for type 2 diabetes, and possibly some of those linked to cardiovascular disease, one of the main causes of early death in people with the condition, said researchers from the University of London in the UK.
The International Diabetes Federation estimates that 642 million people will be living with diabetes by 2040, researchers said.
Nearly 15 per cent of all global deaths are attributed to diabetes; and it killed five million people before the age of 60 in 2015, according to the study published in the journal BMJ Open Diabetes Research & Care.
It is also frequently associated with depression, which in turn affects how well blood glucose levels are controlled, the researchers said.
While a predominantly plant-based diet rich in fruits, vegetables, nuts, legumes, and seeds with no (vegan) or few animal products has been linked to a significantly lower risk of developing type 2 diabetes, it's not clear if it might also be linked to improved mood and well-being.
The researchers, including those from the University of Northampton in the UK, trawled through the available evidence and found 11 relevant English language clinical trials, published between 1999 and 2017, comparing plant-based diets with other types of diet.
The studies involved a total of 433 people in their mid-50s, on average.
Eight of the trials assessed the impact of a vegan diet and six included patients being given information on optimal nutrition to help them better understand the benefits of a plant-based diet. The trials lasted for an average of 23 weeks.
A systematic critical analysis of the results showed that the quality of life-both physical and emotional-improved only in those patients on a plant-based/vegan diet, researchers said.
Similarly, depressive symptoms improved significantly only in these groups, they said.
Nerve pain (neuropathy) eased in both the plant-based and comparator diet groups, but more so in the former, the research found.
The loss of temperature control in the feet in those on the comparator diets suggests that eating predominantly plant-based foods may have slowed the progressive nerve damage associated with diabetes, the researchers said.
Average (HbA1c) and fasting blood glucose levels fell more sharply in those who cut out or ate very few animal products and these participants lost nearly twice as much weight: 5.23 kg vs 2.83 kg.
The fall in blood fats -- a known risk factor for cardiovascular disease -- was also greater in those on plant-based/vegan diets, researchers said.
The review is the first to attempt to look at the psychological impact of a plant-based diet in people with type 2 diabetes, and it draws on research from five different countries, they said.
In six of the studies, those following a plant-based/vegan diet were able to cut down or discontinue the drugs they were taking for their diabetes and associated underlying conditions, such as high blood pressure.
Overall, the results indicated that even though the plant-based diets were more difficult to follow, at least, to begin with, participants stuck to them better than those in the comparator groups.
(With inputs from agencies.)