The findings, published in the British Journal of Nutrition, are “altogether relevant for the prevention of obesity and the metabolic syndrome,” write the authors from the University of Lund.
Individuals who ate barley bread made using 85% boiled barley kernels and wheat flour, had an improved metabolism for up to 14 hours after the final day of the intervention compared with those given white bread.
The barley promoted increased gut fermentation, indicated by increased hydrogen in the breath, as the dietary fibre provided by the barley stimulated the activity of good bacteria, notably Prevotella copri, known to regulate metabolism and appetite, whilst the activity of harmful bacteroides was reduced.
'Surprising yet promising'
Blood sugar and insulin levels decreased while insulin sensitivity increased and appetite control was improved.
“It is surprising yet promising that choosing the right blend of dietary fibres can - in a short period of time - generate such remarkable health benefits”, said Anne Nilsson, associate professor at the Food for Health Science Centre and study co-author. “In time this could help prevent the occurrence of both cardiovascular disease and diabetes”, she added.
Previous epidemiological studies have also shown that diets rich in whole grain may protect against cardiovascular disease, type 2 diabetes and certain types of cancer.
“The results are timely, as rates of and type 2 diabetes have significantly increased in the past few years,” said the researchers adding they hope that more knowledge about the impact of specific dietary fibres on people’s health will result in stores keeping more food products with healthy properties such as barley kernels in stores.
“The ambition is also to get more people to use barley in meals for example in salads, soups, stews, or as an alternative to rice or potatoes.”
In the randomised, cross-over study, 20 middle-aged participants (three men and 17 women aged between 50 and 70 years old with a normal BMI) were given either barley kernel-based bread or white bread for three consecutive days.
Participants had equal portions of either the barley bread or white bread for breakfast, lunch and dinner and portions were standardised to provide 100 g of potentially available starch per day.
Following a standardised breakfast on day four, the scientists took blood samples to analyse glucose levels, gut hormones and inflammation markers.
For the barley group, beta-glucose and insulin responses fell by 22% and 17% respectively for the subjects on the barley diet, while insulin sensitivity improved by 25%.
“No significant differences in appetite sensations (satiety, hunger and desire to eat) were observed at the standardised breakfast meal depending on previous interventions (data not shown). However, a tendency for a main effect appeared for desire to eat with less desire to eat in the case of the three day intervention period with barley bread.”
Source: British Journal of Nutrition
Appeared in print September 2015, issue 114, pp. 899-907. doi: 10.1017/S0007114515002524
"Increased gut hormones and insulin sensitivity index following a 3-d intervention with a barley kernel-based product: a randomised cross-over study in healthy middle-aged subjects."
Authors: Anne C. Nilsson, Elin V. Johansson-Boll and Inger M. E. Björck.