Probiotic Foods: 2008 Update
Probiotics, Prebiotics, Synbiotics & More
CAPSULE REPORT: Our first article on probiotics dealt with the background, medical treatment and other benefits of probiotics. The first article appeared at the beginning of the “probiotics movement” in the U.S. (and it is one of the most frequently viewed articles on TheNibble.com). A year later, we asked Stephanie Zonis to return to her probiotic roots and continue her discussion of this timely topic. This is Part I of a ten-part article. Use the article index below to click among the pages.
In April of 2007, the first article in this series appeared on this website. It was an introduction to the world of probiotics, probiotics in foods and supplements, health claims and research findings. One short year down the line, much has changed, but much has also remained the same. Americans have become somewhat more aware of probiotics, and these “good bugs” are appearing in more foods, more types of foods and an endless array of supplements. New study results have been published. And there’s still enough hype about probiotics to dazzle a convention of advertising executives. Let’s see if we can’t make some sense of it all.
Let’s start by reviewing the World Health Organization’s (WHO) definition of probiotics, issued in 2001: “live microorganisms which when administered in adequate amounts, confer a beneficial health effect on the host.” (And, by the way,United States Food & Drug Administration either needs to adopt any standards set by the WHO, or develop its own standards and definitions. To date it has not done so. Thus, currently, any manufacturer of a product can toss in a handful of live and active cultures and label that product “probiotic”—even if that amount of microbes is probably not going to be of any help. This leaves the door open for abuse, as more food stores have sections devoted to probiotics and more consumers seek panaceas. But today, it’s up to consumers to educate themselves and try to ignore the hype. (By the time you finish with this page, you’ll be better-educated on the issues.)
Probiotics are beneficial bugs, largely species and subspecies of bacteria, as well as one species of yeast, Saccharomyces. But not all live cultures are probiotic, and the terms “live cultures” (i.e., live bacteria cultures), “active cultures” and “probiotic” don’t necessarily mean the same thing. To be probiotic, the bacteria must not be merely live, but live and in a sufficient concentration to be pro biotic, i.e. beneficial, for the body. Here’s the catch:
No One Knows How Many Cultures Are Needed For “Probiotic” Benefits
There’s no legal definition or standard of identity for what constitutes an “adequate amount” of probiotics; the number of live microbes required has not been defined by any official body or research authority. According to probiotics expert Dr. Mary Ellen Sanders, no research yet conducted suggests any kind of required minimum level for active cultures. No general guidelines for type of microbes, quantity, or delivery system of probiotics that address particular conditions or health concerns have ever been established. As with “antioxidants,” another item that has high consumer interest but has not been quantified, probiotics probably help human health in some way. But no one knows enough about either yet, to be able to state definitively what quantities or types are necessary to help maintain health. And neither is a panacea for bad dietary habits. Many studies are necessary to determine what quantities and types of probiotics (and antioxidants) are necessary, and this data will probably change according to each individual’s situation.
What About The “Live & Active Cultures” Seal?
The National Yogurt Association (NYA) has developed a “Live & Active Cultures” seal that requires refrigerated yogurt to contain at least 100 million cultures per gram at the time of manufacture, and frozen yogurt to contain at least 10 million cultures per gram at the time of manufacture. However, this figure references the starter culture of the product, not the amount left in the finished product; and is not a definition of “probiotic” (the NYA never uses the term). Use of the NYA seal is voluntary. This can mystify consumers, because many “probiotic” yogurts with high culture counts don’t use it. And while other yogurts that have fewer than the NYA minimums can’t use the seal, they still use the words “contains live cultures” (or active cultures) on their packaging. Plus, cultures can be live, but not active. Active cultures can be active, but not probiotic. Even the phrase “made with active cultures” says nothing substantive, because every cultured product uses live cultures in the manufacturing process. However, if the food is heat-treated or pasteurized after culturing takes place, or if it contains certain preservatives (especially sodium benzoate), the cultures will likely be dead at the end of the production process. Confused yet?
Making Sense Of The Number Of Cultures (CFUs)
So, how many cultures does it take to get a “probiotic” benefit, as opposed to eating any yogurt with “live cultures?” As mentioned above, today, no one can tell you. As far as numbers go, the legitimate, science-based research studies I’ve seen all use quantities of CFUs (colony-forming units) in the billions. Not millions, not thousands, but billions. This could turn out to be wrong, but given the huge number of bacteria always present in our systems, I don't think it is. Unfortunately, the necessary billions could mean one billion, five billion or more; nobody knows.
Until scientific researchers can set suggested guidelines for probiotic intake, my only advice is to be wary and pay attention to what your body tells you. With the recognition that everyone will react differently to a product, claims of miraculous cures or super-speedy weight loss or an amazing return to “normal” digestive and elimination processes must be regarded with some skepticism. A product may come from a well-respected manufacturer, and even be based on a private research study (contact the manufacturer to see how it determined the efficacy of its product). However, this is no substitute for standards set by credentialed authorities.
The pace of probiotics research has accelerated, as well. According to the members of a probiotics task force under the auspices of the Council for Agricultural Science and Technology, more than four times the number of human clinical trials on probiotics were published during the 2001 to 2005 time frame than had been published from 1996 to 2000. The reason for the ever-expanding range of probiotic-containing products and the greater number of scientific studies? Money, of course. From being nearly a nonexistent market a mere four or so years ago, the prebiotics/probiotics sector has blossomed into a $500 million+ industry.
For all of the new research and available products, many people are still confused about probiotic types, quantities necessary and ideal form of ingestion, if any. Adding to this confusion are the claims and suggested possibilities one can find on any number of websites, whether the sites discuss one specific product or probiotics as a whole. Further clouding the issue is the lack of any legal definition or standard of identity for probiotics within the United States. The most common definition for probiotics, formulated by the United Nations FAO/WHO, specifies live microorganisms. That the cultures are “live” is critical, just as it is important to remember that not all live/active microorganisms are probiotic organisms.
While some species of friendly bacteria are common among people, the task force cited above emphasizes that each individual has a unique population of microbes. And, for all the advertising claims about products “restoring natural balance” or helping one toward what are perceived as the ideal bacteria in the gut, what truly constitutes normal, healthy populations of intestinal microflora are not presently defined. Important genera of friendly bacteria in humans include Lactobacillus, Bifidobacterium, Streptococcus and Saccharomyces. Saccharomyces boulardii, a commonly-used probiotic, is not really called that at all, as this is not a valid species name. This yeast should more properly be referred to as a strain of Saccharomyces cerevisiae.
As interest in probiotics has grown, people are beginning to pay more attention to prebiotics, as well. A prebiotic is an indigestible carbohydrate that nourishes or helps to stimulate the growth of probiotics. Perhaps the best-known example of a prebiotic is the fiber inulin.
You’ll see claims on some products that inulin can aid in the body’s absorption of calcium. However, according to Carmelle Druchniak, Senior Communications Manager of Stonyfield Farm, this is not true of all inulins. Rather, it seems to be restricted to a specific strain (or strains) of this prebiotic. Currently, it’s common to see inulin listed simply as a fiber source on products not usually thought of as containing probiotics or prebiotics (such as cereal and granola bars). My prediction is that this will change within a few years. Inulin will become more prevalent in foods, and, as more people become aware of the word “prebiotic,” packaging labels will be changed to reflect that.
No food substance escapes charges that it’s unhealthy these days, and so it is with inulin. Much of the criticism against inulin centers around claims that it may feed harmful as well as helpful bacteria in the gut. In addition, there is concern in isolated quarters that inulin is being introduced into foods in a “refined” and “highly concentrated” state, although there seems to be no more than a scattered instance or two of any adverse effects on humans to date.
So what’s a synbiotic? It refers to an effect—specifically, the combined beneficial effects of probiotics and the prebiotics that nourish them. Yogurts that contain live, active cultures, as well as inulin, produce a synbiotic effect, for instance.
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