December 9, 2022

Can probiotics and prebiotics restore your gut after antibiotics?


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Antibiotics treat infections caused by bacteria. But they can also destroy the good bacteria in your gut. For some people, this results in an upset stomach and diarrhea.

A UK review of research looked at changes in gut bacteria after antibiotics commonly prescribed for respiratory and urinary tract infections found that after treatment, the number and diversity of bacteria types rapidly decline.

He also found that some types of “bad” microorganisms increased while some “good” decreased.

For most people, after the antibiotic treatment is stopped, the bacteria in the gut recover to some extent. But other studies suggest that some antibiotics may have lasting effects on the balance of microorganisms.

It is important to use antibiotics only when needed, and certainly not for viral infections, as antibiotics cannot kill viruses such as the common cold or COVID-19.

So what should you eat after a course of antibiotics? You may have heard of probiotics and prebiotics, but what are they and what evidence is there to show that they are beneficial?

Probiotics contain “good gut bacteria”

Probiotics are foods, typically yogurt and yogurt drinks, that contain “good gut bacteria”: living microorganisms that can recolonize the gut or improve your gut health.

To be called probiotics, they must be able to resist gastric acidity and digestive processes, and then be able to adhere to the intestinal walls and grow, without causing problems for the intestinal wall. They should also be tested for safety and efficacy in controlled trials.

To qualify as a probiotic, the dose of microorganisms must be sufficient to help restore “good” bacteria, by eliminating “bad bacteria”.

Most yogurts contain “good bacteria”, but not all of them can survive the acidity of stomach acid or the bacteria do not thrive in the gut, so there is no probiotic benefit.

For probiotics to exert these beneficial effects, they not only have to reach the large intestine, but once there they need the right fuel to grow well. This is where prebiotics come in, but we’ll get to that shortly.

What does science say about probiotics?

Probiotics are widely promoted as being good for your overall health. The science on this has been mixed, but it suggests that people at risk of getting diarrhea after antibiotics might benefit from their consumption.

A review of the evidence found that probiotics may be helpful for people at high risk for antibiotic-associated diarrhea, such as the elderly and those in hospital.

The review found that side effects were common when taking antibiotics and included taste disturbance, nausea, abdominal cramps, loose stools, fever, and gas.

But people taking probiotics have reported fewer side effects, suggesting they may be helpful in countering some of the side effects.

So what are prebiotics?

Prebiotics are compounds that help beneficial gut microorganisms grow and survive.

Prebiotic foods contain complex carbohydrates that cannot be digested and dietary fiber that is resistant to digestive processes in the stomach and small intestine.

They pass undigested into the large intestine where they are fermented by “good” healthy bacteria.

To be called prebiotics, they must undergo the above processes and be shown in clinical trials to selectively improve the composition of microorganisms in the gut.

Not all dietary fiber is prebiotic. The most common include the complex carbohydrates called fructooligosaccharides, inulin, and resistant starch.

You can find foods in the supermarket with prebiotics added, but indigestible carbohydrates are naturally present in many everyday foods, including:

  • cereals: barley, rye bread, rye crackers, pasta, gnocchi, couscous, wheat bran, wheat bread, oats
  • legumes: chickpeas, lentils, red beans, baked beans, soybeans
  • vegetables: artichokes, asparagus, beetroot, chicory, fennel bulb, garlic, green peas, leek, onion, shallots, spring onion, snow peas, sweet corn, savoy cabbage
  • fruit: nectarines, white peaches, persimmon, tamarillo, watermelon, rambutan, grapefruit, pomegranate, dates, figs
  • nuts: cashew nuts, pistachios.

Additional sources of resistant starch include unripe bananas, cooked and cooled rice, cornmeal, cooked and cooled potatoes.

For babies, breast milk is naturally rich in oligosaccharides.

So who should have them?

Prebiotic foods are good for everyone, contain a range of nutrients, and help promote a healthy bacterial intestinal environment.

The advantages of probiotics for a range of health issues are unclear – they are likely to be small and depend on what is being taken and the underlying health issues.

But people at high risk of diarrhea after antibiotics may benefit from consuming probiotic and prebiotic foods on a daily basis.

There is also new evidence that the combination of specific probiotics and prebiotics may increase the beneficial effects of both. Probiotics and prebiotics could be added to a single food, called a “symbiotic,” or they could come from separate sources but be eaten together.

When it comes to antibiotics, the main thing is to take them only when prescribed for bacterial infections. Take them according to the directions of the manufacturer, your pharmacist and your doctor.

As fermented foods rise in popularity, here’s what the experts are saying

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