You've probably heard that we have more "bacterial" cells than we have human cells, or some variation of this statement (Link), and this seems to have a decent amount of evidence to back that up. What we are still learning about, however, is how disruptions in what is termed the "microbiome" can impact our health and health indicators like weight. In my news feed I came across one particular article that indicated that pre-biotics could help in the "battle" against obesity. But what are prebiotics?
Those of you who have been following this blog for a while probably remember an earlier post on probiotics, and the basic message was that taking probiotics does not change your gut microbiome for the better because your body sees them as foreign objects and tries to get rid of them as fast as possible (the exception being that it does seem to help anti-biotic related diarrhea if probiotics are started at the same time as the anti-biotics). Pre-biotics, on the other hand, actually help the growth of beneficial bacteria that is already there. Think of the beneficial bacteria in your gut as potted plants and pre-biotics as a type of "plant food" such as Miracle Grow. We don't know yet if changing your gut flora will actually help you lose weight (i.e. change the way you absorb nutrition/calories from food), but it certainly doesn't seem to hurt to keep growing the good stuff.
Now, one of the problems that I have whenever prebiotics are mentioned is that someone is usually trying to sell me a supplement of some kind, similar to the way people try to sell me other vitamin supplements. There are foods that have prebiotics in them, and they are usually plant based. (I liked this quote from, oddly enough, Wikipedia, which states "Referring to a food as "a prebiotic" is no more accurate than calling a food 'a vitamin'.") Usually if you try to eat a variety of vegetables (aim for as many different kinds of vegetables as you can) you will increase your pre-biotic intake, and these particular vegetables (jerusalem artichokes, asparagus, jicama, red and white onions, leeks, garlic, spinach, dandelion greens and tomatoes) have a somewhat higher content.
For people who tolerate grains and legumes you can also get pre-biotics from these foods as well, but I would really rather people concentrated on vegetables first. In my experience/in the population I work with (anecdote alert!), people do not check carefully enough to make sure that the bread, etc really is whole grain and they get essentially empty calories and no fermentable fiber. The other problem that I have (and remember, my specialty is diabetes) is that people wind up way overdoing their carbohydrate intake through the use of bread, pasta, cereal, etc even if they were careful to get the whole grain. Same thing with legumes--if you have diabetes or any other insulin-resistant conditions you will carefully have to watch the amount to keep your blood glucose/insulin levels in check. Remember, more at one time is not usually better even if you are eating the "double fiber" bread.
There's one other consideration when it comes to pre-biotics, particularly if you are taking a pre-biotic supplement or eating an pre-biotic supplemented food (Inulin is usually the pre-biotic of choice for supplementation). Pre-biotics are also called "fermentable fibers" and guess what fermentation produces? That's right, it produces flatulence, more commonly called "gas." The internet does have some fairly entertaining stories about the so-called "Jerusalem Fartichokes", but if you don't have pets to blame it on you could be in deep trouble. Even if you can stand the smell (and the noise), if you have IBS, like yours truly, you might find the "gas pains" rather hard to cope with. So, if you are choosing to use a supplement, a high inulin food, or a pre-biotic supplement food, start with very small amounts to see how you tolerate it and/or cook the food well.
Take home message--eating more vegetables and fermentable fiber foods could help change your gut microbiome. Probiotics are of limited use only.