Keeping on top of the rights and wrongs of a healthy diet sometimes takes a fair bit of concentration. But some old favorites never seem to go out of fashion. A good dose of fiber, for example, is always your friend. New research published this week in the journal Diabetologia indicates that consuming greater quantities of dietary fiber can even reduce the risk of developing type 2 diabetes.
The wide-ranging new study looked at data previously gathered by the EPIC-InterAct, the world's largest investigation into new-onset type 2 diabetes, which was coordinated by Cambridge University in the U.K. The authors of the new study looked at the 12,403 cases of type 2 diabetes from EPIC-InterAct and compared them to a representative group of 16,835 individuals from the European Prospective Investigation into Cancer and Nutrition (EPIC) study, which included 350,000 participants.
The authors divided the cases they studied into four equal groups and rated them from the lowest to the highest for intake of fiber. To get an idea of the long-term prognosis for each group, they then assessed the risk of those involved developing type 2 diabetes over an average of 11 years.
According to the Juvenile Diabetes Research Foundation (JDRF), more than 370 million people worldwide are affected by diabetes, and some suggest that this figure will increase to more than 550 million by 2030. According to the Centers for Disease Control (CDC), the current figure includes 29 million Americans — or 1 in 11 people. This clearly has serious consequences for the health and economy of both developed and developing countries.
According to the Mayo Clinic, type 2 diabetes, the most common form of the disease in adults, is caused by the body's inability to metabolize correctly the glucose it gets from food. With type 2 diabetes, they say, "your body either resists the effects of insulin — a hormone that regulates the movement of sugar into your cells — or doesn't produce enough insulin to maintain a normal glucose level."
Type 2 diabetes usually affects adults but the number of children being diagnosed with it is rising as childhood obesity increases. Although, as yet, there is no cure, the condition is manageable by maintaining a healthy regime of diet and exercise in addition to any medications prescribed to keep blood sugar in check. We've previously reported on the increasing risk of diabetes posed by unhealthy modern lifestyles and the ways in which you can rethink your diet following a diagnosis.
The new study found that participants with the highest total fiber intake — more than 26 g per day — had an 18 percent lower risk of developing diabetes compared to those with the lowest total fiber intake — less than 19g per day — after adjusting the figures for the effects of other lifestyle and dietary factors. When the results were adjusted for body mass index (BMI) as a marker of obesity, higher total fiber intake was found to be no longer associated with a lower risk of developing diabetes, suggesting that the beneficial association with fiber intake may be mediated at least in part by BMI. In other words, fiber intake won't help people avoid diabetes regardless of their weight. Rather, dietary fiber may help people maintain a healthy weight, which in turn reduces the chances of developing type 2 diabetes.
The authors of the study evaluated the associations between total fiber as well as that from other sources such as cereal, fruit and vegetables. They found that cereal fiber was the most effective — those with the highest levels of cereal and vegetable fiber consumption had a 19 percent and 16 percent lower risk of developing diabetes respectively, compared with those with the lowest consumption of these types of fiber. These associations, of course, disappeared when the results were adjusted for BMI. Fruit fiber, however, was not associated with a reduction in diabetes risk.
The authors of the study also combined their results with those of 18 other independent studies from across the globe. Overall, they found that the risk of diabetes fell by 9 percent for each 10g per day increase in total fiber intake, and by 25 percent for each 10g per day increase in cereal fiber intake. At the same time, they found no significant benefit in increasing either fruit or vegetable fiber and reducing diabetes risk.
One of the researchers, Dagfinn Aune, says that though a direct relationship between the intake of some types of fiber and protection from diabetes does seem to exist, the reasons are not completely clear. "We are not certain why this might be," Aune says, "but potential mechanisms could include feeling physically full for longer, prolonged release of hormonal signals, slowed down nutrient absorption, or altered fermentation in the large intestine. All these mechanisms could lead to a lower BMI and reduced risk of developing type 2 diabetes. As well as helping keep weight down, dietary fiber may also affect diabetes risk by other mechanisms — for instance improving control of blood sugar and decreasing insulin peaks after meals, and increasing the body's sensitivity to insulin."
Professor Nick Wareham, senior author on the paper and director of the MRC Epidemiology Unit, University of Cambridge, added: "This work adds to the growing evidence of the health benefits of diets rich in fiber, in particular cereal fiber. Public health measures globally to increase fiber consumption are therefore likely to play an important part in halting the epidemics of obesity and of type 2 diabetes."