In this post, I reviewed the various ways that probiotics are thought to support optimal health. But what supports the optimal performance of probiotics? Answer—Prebiotics!
What are prebiotics?
Prebiotics are non-digestible carbohydrates (fiber!) that provide fuel for probiotics and selectively ferment ingredients that leads to specific changes in the composition and or activity of the GI microbiota, providing benefits to the host. One important note: although all prebiotics are fiber, not all fiber is a prebiotic. So what are the criteria for classification as a prebiotic?
It must be resistant to digestion
It must be fermented by the gut microflora
It must selectively stimulate or support beneficial intestinal bacteria
Examples of prebiotics include: fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), sugar alcohols such as sorbitol
Reasons to include prebiotics in the diet:
Some of the reported benefits of prebiotic foods are outlined below:
Both prebiotic and non-prebiotic fibers have been shown to optimize transit time through GI tract.
Prebiotic fiber may increase insulin sensitivity, improve pancreatic β cell function and increase insulin secretion.
Improved satiety is thought to be a function of several different mechanisms including greater chewing time, a sense of increased abdominal fullness and slower gastric emptying. Some studies suggest that increased fiber intake can reduce calorie intake and contribute to weight loss.
Short Chain Fatty Acid (SCFA) Production
SCFAs perform several important functions in the gut. They are the preferred fuel for cells lining the colon. They regulate water and electrolyte absorption in the colon. They also acidify the gut, which may improve the uptake and absorption of minerals like calcium, magnesium and iron. SCFA’s have also been shown to have an anti-inflammatory effect and stimulate the immune system.
Do I need prebiotic supplements?
Supplement forms of prebiotics are available but it is easy to get the benefits from including prebiotic foods in your diet. Because prebiotic foods work by a diverse set of beneficial mechanisms, it is best to eat a variety of these functional foods. If you decide to use a supplement be sure to check the label for prebiotic content as products can vary widely.
A word about FODMAPS:
FODMAPS are a group of short-chain carbohydrates and sugar alcohols which are poorly absorbed in the gastrointestinal tract called FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) that can cause abdominal symptoms such as bloating, pain and nausea in some people including those struggling with irritable bowel syndrome (IBS). Many people with this intolerance have found relief with the low FODMAP diet– which is intended to be a learning diet- not a long term diet. It is intended to help you find and eliminate foods that trigger symptoms. You can read more about the FODMAP diet here, here and here . It is possible to get a the healthy benefits of prebiotics by opting for low FODMAP food sources. And as I mentioned before, make sure to check the labels of any supplements for FODMAP content.
If you are just beginning to add fiber and prebiotic foods to your diet, you may want to add them slowly by making small changes over time to avoid any GI upset associated with increased fiber. This applies to everyone (even if you do not have IBS or other GI issues). Remember, drink plenty of fluids as you add fiber to your diet.
What are synbiotics?
Probiotic bacteria and yeasts consumed together with prebiotics that support their growth are called synbiotics. The thought is that they work together in a synergistic and efficient way to promote health. In addition to all of the benefits of probiotics and prebiotics outlined already, synbiotics may reduce triglycerides and fasting insulin levels as well as improve inflammatory markers in overweight and obese individuals. One study found that synbiotics may reduce the symptoms associated with acute proctitis and improve quality of life during radiation treatment for prostate cancer. The research into the specific benefits of synbiotics is ongoing.
For the Tastebuds:
Beserra BT, et al. A systematic review and meta-analysis of the prebiotics and synbiotics effects on glycaemia, insulin concentrations and lipid parameters in adult patients with overweight or obesity. Clin Nutr. 2014 Oct 20. pii: S0261-5614(14)00256-8.
Brownawell AM, et al. Prebiotics and the health benefits of fiber: current regulatory status, future research, and goals. J Nutr. 2012 May;142(5):962-74.
Fedewa A, Rao SS. Dietary fructose intolerance, fructan intolerance and FODMAPs. Curr Gastroenterol Rep 2014;16:370.
Gibson GR, et al. Dietary modulation of the human colonic microbiota: updating the concept of prebiotics. Nutr Res Rev. 2004 Dec;17(2):259-75.
Mirmiran P, Bahadoran Z, Azizi F. Functional foods-based diet as a novel dietary approach for management of type 2 diabetes and its complications: A review. World J Diabetes. 2014 Jun 15;5(3):267-81.
Nascimento M, et al. Efficacy of synbiotics to reduce acute radiation proctitis symptoms and improve quality of life: a randomized, double-blind, placebo-controlled pilot trial. Int J Radiat Oncol Biol Phys. 2014 Oct 1;90(2):289-95.
Slavin J. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013 Apr 22;5(4):1417-35.
Thomas JR, Nanda R, Shu LN. A FODMAP Diet Update: Craze or Credible? Practical Gastroenterology, Nutrition Issues In Gastroenterology Series #112. December 2012, 37-46.