Before the 1970s, only extremely health-conscious Americans ate yogurt. But thanks to its purported association with an especially long-lived people of the Caucasus Mountains, yogurt was heralded as a miracle health food and thrust into ubiquity. Some three decades later, the popularity of yogurt has grown like the bacteria that multiply in it. The presence of those microorganisms is also primarily what is thought to be healthful about yogurt.
In recent years, those yogurt bacteria, along with yeast and other organisms thought to be health-promoting—called probiotics—are being widely sold as supplements. As for the benefits, probiotics are seen as useful in many regards. They are believed to lower cholesterol and blood pressure, prevent colon cancer and infection, improve immune function and reduce gas and constipation.
Simply put, the idea is that adding bacterial flora—most often Lactobacillus and Bifidobacterium, many of which naturally live in our digestive tracts and aid in digestion—to our diets will be beneficial. But some pretty weighty health claims—not to mention a hefty price tag—rest on the backs of these itty-bitty bugs.
Probiotic product lines are beginning to cover supermarket shelves like yeast on damp rice. In one survey at a local Whole Foods Market, there were over 45 products in capsule, liquid and nutrition bar form advertised as probiotic. (Most of these products are refrigerated to preserve the bacterial colonies, though increasingly probiotics are showing up in dry cereals and non-refrigerated items like soy milk.) Many of the products are marketed specifically to a target demographic—infants, children, adults, seniors, women and pets—with claims that the bacterial strains they offer are beneficial for that group.
There's nothing new about using bacteria for our benefit. Microorganisms have been responsible for innumerable fermented foods in countless cultures, perhaps since we've been keeping food longer than it takes a gathering hand to bring it to the mouth. Likewise, there is nothing new about fermented foods being valued for their health-giving properties. Many cultures have attributed their longevity to one fermented product or another, or used them outright as medicine.
We owe thanks to bacteria for sauerkraut, kim chi, sour cream, soy sauce, miso and tempeh. And let's not forget beer, wine, cheese and spirits. Besides lending a unique flavor—and that popular byproduct, alcohol—to our fermented foods, microbial metabolism does a number of important and desirable things. First, it stabilizes our foods, which in centuries past allowed us to make use of a food source long after harvest. Also, these bacteria break down components of our food that are difficult or impossible for us to digest, thus creating a kind of auxiliary stomach. Because they predigest foods rich in cellulose (plant fiber or dietary fiber) such as leafy greens and cabbage, we are able to make use of nutrients sequestered in the food.
Probiotic supplements have cruised to town on the same wave that yogurt rode in on, and like yogurt, they seem to be here to stay. The good news is that they may have some salutary health effect. With a host of products on the shelves, the object is to be an educated consumer and choose wisely.
Since yogurt's rise to prominence three decades ago, the lag time between health-food fad and the science to support it has had time to elapse. So what do we know for sure about the effect of yogurt on health? Not much, really. Can we attribute the impressive longevity of yogurt-eating peoples of the Caucasus Mountains to the Lactobacilli that make their milk sour? The answer is unknown.
Here's what we can say: in the event of prolonged diarrhea or antibiotic use, which disturb the colonies of Lactobacillus in the intestines, eating yogurt will replace them and restore normal digestion. That's where supporting evidence for probiotic health claims fizzles out into the kind of unsubstantiated information or disinformation that gets self-respecting scientists surly. (An ovation goes to anyone who is wondering who is paying for the science behind probiotic health claims. In many cases it's the dairy industry.)
Now, all this is not to say that probiotics don't have a favorable effect on our overall wellbeing. There may well be credibility to the conventional wisdom-of-the-ages that says that foods rich in certain microorganisms are healthful. But science can't say for sure. We know little about yogurt probiotics and even less about probiotics found in other fermented foods.
But if a lack of science doesn't stop marketers from touting probiotics as health-promoting, it certainly doesn't stop Americans from spending like crazy on them. One industry estimate holds that Americans will spend over $4.5 billion on probiotics by 2010 (and the European market is even bigger). This probably has something to do with the high cost of probiotic supplements. One product sold by Whole Foods Market—a bottled liquid with a recommended dose of half to a whole bottle daily—sells for over $4. Another product, a bottle containing 30 capsules, has a dose of one capsule per day and sells for $25. Still another product recommends a dose of two capsules two to four times daily. At present, however, there is no scientific evidence that eating any probiotic regularly will maintain proper digestive functioning. This seems like an awful lot of money to spend given that probiotic science is still in its infancy.
What will science reveal about probiotics once the post-fad lag time has elapsed? Already it appears that benefits from probiotic use will be specific not just to the genus or species, but to distinct strains. That is to say, simply eating probiotic bacteria may not have any benefit unless they are the right kind for a given ailment—but we don't yet know what that means. Perhaps probiotics will turn out to be the miracle foods that we all want them to be. Then again, maybe they have been all along and we owe more than we realize to probiotic bacteria.
There is, however, reason to doubt that simply eating fermented foods (as opposed to taking supplements) will deliver enough of the probiotic microorganisms to have the desired effect. Bacterial counts in fermented foods are relatively low compared to supplements. It turns out that one would have to eat quite a mound of sauerkraut to ingest a sufficient number of probiotics. After being swallowed, the organisms must still survive digestion and multiply to impart benefits.
In any case, fermented foods are delicious and experience tells us they're safe to eat. At best, they're a little understood yet powerful health-promoting agent. At worst, they're probably harmless. But for now these pricey supplements with their boastful claims are quite a pill to swallow. "
