Evidence links prebiotics to reduced appetite and increased satiety

In July this year I wrote about the link between the bacteria in the digestive system and obesity.  The human adult gut contains up to 100 trillion microbial organisms and it certainly seems sensible to ensure that these are mainly made up of ‘friendly’ good bacteria.  The type of bacteria in the digestive system seems to have an effect on the entire body and not just the health of the gut.



A recent study (1) has found that prebiotic supplementation was associated with reduced appetite sensation after a meal.  Prebiotics act as food for the good ‘friendly’ bacteria in the digestive system and previous studies (2) suggest that prebiotics in the diet may reduce our energy and food intake, increase satiety, reduce hunger and appetite and reduce total daily calorie intakes.  Prebiotics may also have positive effects on blood sugar balance in the body which can also impact appetite.  This recent research (1) was set up to see whether prebiotic supplements affected the hormones associated with satiety.  The study was very small but well designed and provided interesting results.  Prebiotic treatment was associated with a three fold reduction in hunger rates and an increase in hormones which are associated with feelings of satiety/fullness. 



In past blog posts I have mentioned many nutritional ways that can help to keep us feeling satisfied after a meal and may hence prevent over eating, or even cravings (which are often related to blood sugar imbalance).



Again, I would like to stress that obesity is a complex disease involving many factors with no miracle cure and no easy solutions – I am not about to disillusion anyone by inferring that bacterial balance is a major factor and probiotic or prebiotic supplements are the cure.  However, gut bacteria may well be having some kind of impact on the development of excess body weight in some people.  What we eat does affect the composition of the microorganisms that are present in our digestive systems and in turn these microorganisms can have an effect on the health of our body.  A review paper (2) stated that “probiotic and prebiotic supplements may be useful in order to positively change the gut bacterial balance and help prevent and treat overweight but that these manipulations should clearly not be viewed as a substitute for a healthy diet and exercise”.



Further conclusive evidence needed, however prebiotics (such as FOS) and probiotics do seem to positively change the composition of bacteria in our digestive systems and affect overall health.  Supplements are readily available but should not be seem as a quick-weight loss fix.  A healthy diet and lifestyle is of paramount importance for weight control and overweight prevention and treatment.



Another factor to mention here is fibre (since prebiotics are a form of fibre), a high fibre diet can also help with feelings of fullness and therefore prevention against over-eating.  A recent study (3) in young people (aged 11-17) at high risk of obesity found that an increase in total dietary fibre intake was associated with decreases in fat tissue.  A decrease in fibre was associated with significant increases in fat tissue, this was noted even if the decrease in fibre was small (about 3g).  The authors of the study conclude that “Small reductions in dietary fiber intake over 1–2 y can have profound effects on increasing visceral adiposity [fat mass]”. 


A diet that is high in fibre has been linked to numerous health benefits in most areas of the body from the: heart, where it seems to have positive effects on blood pressure and risk of heart disease; digestive system where it seems to be useful to sufferers of irritable bowel syndrome (IBS), constipation and diverticulitis and the immune system where there seems to be a link with reduced risk of cancer.  A high fibre diet also appears to be very useful in blood sugar control and also appetite control as it gives us the feeling of fullness and helps to control satiety.  The recommended daily intake for fibre in the UK is currently set at 18g/d, however for optimal health many experts regard at least 25g per day as necessary.  In the UK our average intake is low at only 12g/d.  Foods that are naturally high in fibre are also a really important part of a healthy diet e.g. vegetables, fruits, beans/pulses, nuts/seeds and wholegrains.


 


(1)Cani PD et al.  2009.  Gut microbiota fermentation of prebiotics increases satietogenic and incretin gut peptide production with consequences for appetite sensation and glucose response after a meal.  Am J Clin Nutr.  90:1236-1243
(2) DoBaise JK et al.  2008.  Gut microbiota and its possible relationship with obesity.  Mayo Clinical Processings.  83:460-469
(3) Davis JN et al.  2009.   Inverse relation between dietary fiber intake and visceral adiposity in overweight Latino youth.  Am J Clin Nutr.  90:1160-1166
Written by Ani Kowal

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