Sourdough fermented bread has been suggested to have beneficial health effects, in part mediated by increased satiety after a meal. However, only limited research has been conducted to verify this under conditions typically found in commercial breads. The current study aimed to investigate the effect of different amounts of sourdough and rye in soft bread on subsequent appetite.
On six occasions, 23 healthy volunteers consumed five different test breads, with varying amount of rye and sourdough, and a yeast-fermented refined wheat control bread as part of a breakfast meal. The sourdough ranged between nine to 51 percent of dough weight. Rye content varied between 35 to 48 percent of flour weight. A lunch with no limits of food intake was served four hours after the breakfast meal, from which the voluntary energy intake was measured.
Some of the test breads, including those medium or high rye content, resulted in lower hunger ratings and increased sense of fullness compared to the refined wheat bread. None of the “low rye content breads” were significantly different from the wheat breads, irrespective of sourdough content. However, there were no differences between the different sourdough-rye breads, despite different rye content. This might be explained by the small difference in rye content (35-48%) among the different rye breads.
Microstructural examination of the test breads showed an increased aggregation of proteins in the breads with high content of sourdough, indicating additional changes to the breads, beyond change in pH, which may counteract the potential effect of decreased pH in the bread on appetite.
In conclusion, the study does not support an effect of sourdough on appetite and unlimited food intake. However, there are many different types of sour doughs and here only one type was tested.
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Scientists from the University of Eastern Finland have discovered new compounds that may help explain the benefits from a whole grain rich diet.
The researchers investigated effects in mice fed bran-rich fodder, and in humans following a diet rich in whole grain products during 12 weeks. A whole grain-rich diet increased the levels of betaine compounds in both mice and humans - the first time many of these betaine compounds were observed in the human body in the first place. At the end of the 12-week follow-up, the researchers also observed a correlation between improved glucose metabolism and increased presence of betaine compounds in the body.
“Whole grains are one of the healthiest foods there is and a high intake protects against type 2 diabetes and cardiovascular diseases. However, up until now we haven’t understood the cellular mechanisms through which a whole grain-rich diet impacts our body,” says Dr Kati Hanhineva, Principal Investigator of the study at the University of Eastern Finland.
Further studies in cell models showed that one of the betaine compounds discovered reduces the use of fatty acids as a source of energy by heart cells, an effect similar to that of certain drugs used for cardiovascular diseases. Further research are needed to verify the effect in the human body.
Read more at the website of University of Eastern Finland.
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A new comprehensive study from researchers at Chalmers University of Technology and the Danish Cancer Society Research Center strongly confirms previous research findings on the importance of whole grains for prevention of type 2 diabetes. The link has been known for a long time but the role of different cereals and cereal products remain unclear.
The study was large, comprising 55,000 participants, with a long median follow-up time of 15 years. The main finding was that it made no difference which type of whole grain product or cereal the participants ate - ryebread, oatmeal, and muesli, for example. All seem to offer similar protection against type 2 diabetes. More important is the amount of whole grain that is consumed each day and the study provides important clarification when it comes to daily intakes associated with lowered risk of developing type 2 diabetes. The participants were divided into 4 different groups, based on how much whole grain they reported eating. Those with the highest intak reported that they ate at least 50 grams of whole grain each day. The development of type 2 diabetes was lowest in this group. In the group with the highest whole grain intake, the diabetes risk was 34 percent lower for men, and 22 percent lower for women, than in the group with the lowest wholegrain intake.
The researchers were surprised that the diabetes risk did not appear to differ between whole grains.
'We hypothesized that whole grain rye and oats would show larger risk reduction compared to whole grain wheat', Professor Rikard Landberg says. 'Rye is the cereal with the highest amount of dietary fibre and it also contains a mixture of fibres with different functionalities compared to wheat and whole gain oats contains dietary fibre that have been shown to beneficially affect blood lipids and glucose levels after a meal. One reason could be that questionnaires used for participants to report their intakes are not precise enough to estimate specific grain intakes', says Landberg.
The study design did not allow the researchers to investigate why whole grain foods appears to lower the risk of developing type 2 diabetes.
'We need more mechanistic studies on the physiological effects of whole grain foods where we use modern techniques and also take gut microbiota and the fact that individuals may respond differently to specific food intakes', Landberg concludes.
Read more in the press release from Chalmers University of Technology and in the full text article in the Journal of Nutrition.