Posted on May 26, 2020, 3 p.m.
Two recent studies from the University of Otago have shown that consuming more dietary fiber can help to improve life expectancy, especially for those with type 2 diabetes, but food processing may be removing these benefits.
Type 2 diabetes is associated with serious medical complications, and according to researchers this disease has reached epidemic proportions around the globe. Plos Medicine published one study using data collected from 8300 adults with type 1 or 2 diabetes to show that those with a higher fiber intake experienced a significant reduction in premature mortality.
Those consuming 35g of fiber per day have a 35% decreased risk of dying early compared to those consuming only 19g according to lead author Dr. Andrew Reynolds. He advises to increase fiber by consuming more whole vegetables, fruits, legumes and whole grains.
"Try a few different ways to increase your fibre intake, see what works best for you.If you eat white refined bread or rolls, try changing to whole grain bread or rolls. Try brown rice, try brown pasta, try adding half a tin of legumes to meals you already make.Try an extra veggie with your main meal -- fresh, frozen, or canned without sodium are all good choices,” says Reynolds.
42 trials were also analyzed that involved 1789 adult participants with prediabetes, or type 1 or 2 diabetes who were given more fiber and whole grains for at least 6 weeks. Consistent improvements were observed in cholesterol levels, blood glucose control and reductions in body weight when the participants increased their fiber intake.
"When our controlled studies confirmed the benefits of dietary fibre four decades ago, we never suspected that they would be quite so impressive," says senior author Professor Jim Mann. "It has taken forty years of research and these meta analyses to be able to show that this dietary treatment can have an effect as striking as that produced by medications."
Not all foods that contain fiber are created equally according to the second study; while whole grains can be an important source of fiber the benefits may be diluted when they are heavily processed. In this study participants consumed minimally processed whole grains for two weeks, then more processed whole grain foods for another two weeks.
"Wholegrain foods are now widely perceived to be beneficial, but increasingly products available on the supermarket shelves are ultra-processed," says Professor Mann.
Glucose monitors were used to record blood glucose levels throughout the day and during the night during the study periods, finding showed improved blood glucose levels after meals and reduced level variability when the participants were consuming minimally processed whole grains with the results being the most striking after breakfast when most of the whole grains were consumed.
Additionally although the participants were not asked to lose any weight by eating less during the study the results showed that the participant's average weight increased following the two weeks of consuming processed whole grains and average weight decreased following the two weeks of consuming minimally processed whole grains.
When taken together these two studies along with previous research indicates that high fiber food choices including whole grains, whole fruits, legumes, and dark leafy green vegetables promote good health for everyone, and they are an important part in managing diseases including type 1 and 2 diabetes, according to Reynolds.
"However we are now beginning to understand that how foods are processed is also important, and for whole grains when you finely mill them you can remove their benefits," he concludes.
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