A User's Guide to Hosting Beneficial Foreign Lifeforms

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Does the idea of playing host to foreign lifeforms freak you out? It shouldn't — everybody does it. And you probably already know that your body is full of bacteria — many of which actually help keep you alive. You wouldn't survive for long without all the foreign life forms that your body is playing host to right now.

What exactly are probiotics, and why do they help you stay healthy? And how are changes to the enviornment reducing their effectiveness? Find out below.


Your body as host
Elie Metchnikoff, 1908 Nobel prize winner for his work in the field of immunity, posed the idea of intentionally consuming additional bacteria to populate the human body with bacteria helpful in digestion. The vast majority of bacteria are "good" and aid in the body's everyday routine and defensive measures, with only about 10% of all bacteria pathogenic.


Foods claiming to supplement the good bacteria in your body are divided into three categories – probiotic, prebiotic, or a combination of the two, labeled synbiotic. Probiotics contain the good bacteria within the food, while prebiotics only contain nutrients for the bacteria. Prebiotics are a little of a misnomer, as almost every food contains some sort of nutrients that are useful to bacteria.

The U.S. Food and Drug Administration does not currently approve any probiotics for their health claims, nor is FDA approval necessary prior to their sale — as probiotic containing items often come under the guidelines of dietary supplements. Europe's equivalent, the European Food Safety Authority, goes one step further and publicly disputes claims made by several probiotic products.


Probiotics come in many forms – foods with live cultures like some varieties of yogurt and cottage cheese, sweet acidophilus milk, powdered diet supplements, capsules, and even suppositories. Regardless of FDA or EFSA acceptance, probiotics are used for a variety of gastrointestinal issues, including antibiotic associated diarrhea, the stomach flu, irritable bowel syndrome, and Crohn's disease. Preliminary research exists to give reason for their use combatting the stomach flu, and decrease the duration and frequency of infectious diarrhea.

Gain of function for the host
If you are lactose intolerant, ingestion of Lactobacillus delbrueckii subsp. bulgaricus, (LAB), and Streptococcus thermophilus via yogurt can help you metabolize lactose by allowing the the added bacteria to use it as a precursor in creating lactic acid. This is a really neat use of taking on bacteria into your host system, as the bacteria gives your body a function it previously didn't have. LAB may also play a role in preventing mutations caused by binding heterocyclic amines digested when eating barbecued or charred meat.


Another member of the Lactobacillus genus, Lactobacillus acidophilus could enhance the action of a vaccine for rotavirus infection. Rotavirus is the most common cause of infectious diarrhea in children worldwide, a virus killing two million children each year.


Maintaining the activity of probiotics in your food
Temperature, the amount of water present, and pH all pose challenges for food products containing probiotics, as these are organisms accustomed to living within a certain environment — and changing this environment can kill the bacteria or decrease their activity.

Most probiotic organisms need to stay in a situation where the pH is above 4.6 – this is a large problem as the pH of yogurt is often in the 3.7 to 4.3 range, limiting the types of bacteria able to be added to even slightly acidic foods.


Exposure of probiotic-containing food to temperatures above 113 °F (45 °C) can kill off the beneficial bacteria, leading manufacturers to add bacteria and supplements after pasteurization and other manufacturing processes. This also poses a problem while transporting the food, as a sharp jump in temperature can severely decrease the positive effects of probiotic containing foods.

Water, interestingly, causes problems for probiotic additions to food, leading manufacturers to freeze or freeze dry of bacteria stocks in order to increase their lifespan and decrease their exposure to water. When freeze dried, the bacteria enter an inactive state, awaiting activation months later and still retain their beneficial attributes.


You are not going to cure anything out of the ordinary with probiotics
While data suggests probiotics aid in digestive disorders, these beneficial colonies of bacteria are not a replacement for conventional medical care or paying a visit to your physician in the case of an acute medical problem.

Also, if you are in poor health, the use of probiotics might make your condition worse. A mixture of six probiotics posed deadly problems in patients suffering from pancreatitis in a recent clinical trial. Lactobacillus septicaemia is also possible consequence for immunocompromised or severely ill individuals consuming large amount of probiotics. Probiotics can help, but please don't use them as your sole line of medical defense.


The top image displays a particularly scary example of the human body playing host to a foreign lifeform from the movie Aliens. Images courtesy of Lancashire Farm and Robert Hutkins at the University of Nebraska. Sources linked within the article.