Discover more from My Bacteria
Why probiotic yogurts may not provide health benefits
When I was a teenager, the world still seemed fine: walking through the supermarket and along the milk counter showed a selection of different dairy products, butter, margarine, cheese and, of course, yogurts in every flavor imaginable, such as strawberry, raspberry, orange, and so on. It was clear that a yogurt contained sugar and fat, and that's why my health-conscious mother would occasionally choose a reduced-sugar or reduced-fat yogurt when grocery shopping. We were aware that yogurt was a sweet, a small vice in the evening in front of the TV or for the small hunger in between in the afternoon.
However, from time to time my grandmother made kefir. The production had something of a witch's kitchen, strange tubers mixed with milk for several days. Then, at the end, the mixture was strained to separate the sour-smelling tubers from the kefir.
She stood next to me, smiled and said, "Now you've done something good for your body.
I would not have been surprised if she had muttered spells in a magical language. I dreaded that moment because then I knew I was supposed to drink this sour something. Because it was so "healthy." I would much rather have had a sweet strawberry yogurt, but since I loved my grandma, I did her the favor and choked down the mixture with a contorted face. She stood next to me, smiled and said, "Now you've done something good for your body.
Today it is different. The world has changed. And yogurts have changed with it. Gone are the days of little nibbles. Everywhere I look, young women, mothers with smiling children or entire families are beaming at me. They stroke their bellies, hold hands and are happy that they are radiantly beautiful and healthy, always in a good mood, and that their lives are simply wonderful. Because they eat probiotic yogurt.
For a while, a food manufacturer showed dancing, yogurt-producing bacteria in its advertising, and it was only natural that their cheerfulness would spread to the consumer.
Today it is different. The world has changed
Probiotics seem to be the egg of Columbus. And even better: foods with probiotics promise pleasure without regret. After all, isn't it a wonderful idea that the nightly trip to the refrigerator is not punished with a guilty conscience, but with billions of bacteria that, as soon as I have gone back to sleep, freshly go to work to optimize my health and my mood until sunrise.
A perfect advertising world. If only it were that simple...
What are probiotics?
Probiotics are defined by the United Nation Food and Agricultural Organization and the WHO as "living microorganisms that, when consumed in proper amounts, produce a noticeable improvement in the health status of their host."
So probiotics are living microorganisms that you eat that are supposed to improve your health.
Furthermore, there is the concept of prebiotics. These are not bacteria but nutrients from plants that are supposed to stimulate the growth of our good microorganisms in the body, the microbiota. In addition, there is the term synbiotics, which is nothing more than a combination of pro- and prebiotics. Recently, the term postbiotics has also appeared, which refers to the substances released by probiotic microorganisms during their metabolism or decomposition.
However, as always, the devil is in the details. Let's look at the definition of probiotics:
FIRST, they must be living microorganisms. In principle, this is not a major challenge for manufacturers. After all, living cultures are added to milk during yogurt production. If these are killed at the end during a pasteurization step, living cultures must be added to the yogurt again. This procedure - as senseless as it may seem - is often the safer, because more controllable, way to go in production. Possible contaminants are killed and the yogurt is made more durable. Or there is no pasteurization. In this case, the manufacturer must always be prepared for the presence of microorganisms in the yogurt that he may not want to be there. For probiotics, however, in the vast majority of cases an artificial addition of probiotic bacteria takes place in order to be able to call the product "probiotic".
But the essential problem are the living microorganisms, which should remain viable until the product is consumed by the customer.
How much living bacteria will end up at the consumer?
This is because the moment the yogurt is created by fermentation, a decay process begins. The bacteria die because of the high pH. The conditions for the cultures are worse in the cup than they were during the production process. Bacterial cells die every minute on the way to the consumer. So the question is how much living bacteria will end up at the consumer?
Supply in proper quantities
That is the SECOND point. The microorganisms should be supplied in proper (!) quantities. But since they are constantly dying after the yogurt is made, the amount of living microorganisms is continuously decreasing. Manufacturers do not specify how many living bacteria are in their yogurts. This is for simple reasons: it is simply too expensive for producers to measure the amount of living bacteria, they also cannot manage a realistic measurement with standard methods, and they do not want to because of traceability. In addition, the measurement at the end of the production process makes little sense, because the decisive factor would be how many bacteria are still present shortly before consumption by the customer.
The probiotic bacteria therefore make up 0.00001% of the microbiota.
But let's assume an optimistic case: In Germany, one gram of yogurt must contain at least 10 million bacteria. A 150 g portion would therefore contain 1.5 billion bacteria. During the period from production to storage to customer to consumption, we assume a mortality rate of 30% (and that is still extremely optimistic). So we have 1 billion bacteria in the cup that the customer eats. Of these bacteria, up to 99% are killed in the stomach by the high acidity. The remaining 10 million bacteria, still living but damaged by the acid, meet the microbiota in the intestine, which consists of about 100 trillion bacteria. For comparison: 10,000,000 bacteria meet 100,000,000,000 cells. The probiotic bacteria therefore make up 0.00001% of the microbiota. Moreover, the bacteria of the microbiome are very stable, which means they are not easily influenced by other microorganisms because they have found their niche there.
So what happens? The bacteria cannot establish themselves, but are flushed out more or less quickly.
Furthermore, the WHO designates living microorganisms in its declaration. This brings us to the THIRD point. Which microorganisms? In what composition? Adding some probiotic microorganisms to yogurt and then hoping that they will have an effect is the same as taking a soccer player off a team and simply hoping that he will immediately have a breakthrough success in another team without training. We still know far too little about the interaction of the individual microorganisms in our microbiota. Research to date suggests at least several thousand bacterial species make up our microbiome. The interplay is complex, multi-layered and still largely unknown. Probiotic yogurts usually have very few probiotic germs, often only one. It can be virtually ruled out that this one germ has any kind of effect on the microbiota. It simply does not play a role.
Perceptible improvement in health
Bringing about a "perceptible improvement in health" is the FOURTH point that can be doubted about probiotic yogurts. In order to supply significant amounts of probiotic bacteria, large amounts of yogurt would have to be eaten every day. The question arises, however, to what extent a sugar product such as yogurt does not cause much more damage to the stomach by feeding the bad bacteria with easily digestible carbohydrates than it can bring about positive changes through the few good bacteria. There are hardly any usable and neutral (!) studies on this.
Brave new advertising world
The human microbiome is much more complex than the food industry makes it out to be. Although it would be perfectly in the spirit of the beautiful colorful advertising if a probiotic hero were to fight his way through the stomach and bring about good things in a miraculous way, but in the end this is just a fairy tale.
The food industry is struggling with three main factors: First, the microbiome is still too little researched to actually say which germs could bring about positive and verifiable changes. Second, the subject matter is too complex to be communicated quickly and effectively to customers. That is why meaningless generalizations are presented that are simply wrong. Thirdly, people's microbiome is different. What works for one person does not necessarily work for another.
Just a business opportunity.
But the most essential problem in targeting the human microbiota is the stability of microbiological populations. We know from studies that the microbiome is very stable after the age of three and hardly changes. The influencing effect of externally supplied bacteria is therefore very small and virtually non-existent in the case of probiotic foods due to the problems described above.
However, the advertising food industry is hardly swayed by this. The buzzword "functional food" is too tempting, giving the food an additional boost in the form of a health-promoting effect - including price increases. Advertising promises are not for free. The customer is unable to judge this and follows the brave new food world and its healing promises.
But it's all fake.
Just a business opportunity.
And the customer pays a higher price for it.