Gut health can be confusing. What should we eat? What’s the difference between good bacteria and bad? Which probiotics should we take? Here’s your cheat sheet…


GUT HEALTH IS at the center of attention these days in the wellness world – and it’s about time. There may be no more important topic to master for vital health.  

We asked Dr. Joe Alcock of Pressed Juicery’s Medical Advisory Board to break down everything we need to know about the key topic of probiotics – appropriate, since Pressed just launched it’s first line of juices with high-quality probiotics added (find ’em here). Here is Dr. Joe’s practical guide to gut health, including how to select the right probiotics…

Let’s frame the topic simply, by casting you in the role of gardener of your gut – which makes sense since you’re the only one who can make sure good stuff is growing in there and prevent the bad stuff from taking over. Gut microbes are like plants or the garden, there are good plants and not-so-good ones (weeds). But first, you have to plant these microbes by seeding – probiotics are the seeds. And you can encourage the good microbes to grow with fertilizer – by eating the right foods.

So to review: seeds = probiotics; plants = microbes (weeds = bad microbes), fertilizer = food… and bad-ass gardener = you.

Let’s take a deeper look at the history of the seeds (probiotics), the scientific evidence and the best way to be a champion gardener of your gut.

The idea of using probiotics dates to 1907, when Nobel laureate Elie Metchnikoff observed that people who drank fermented milk had longer lives. He believed that the health benefits of sour milk came from “useful” lactic acid microbes that replaced harmful bacteria in the gut. Two of these lactic acid bacteria – Lactobacillus and Bifidobacteria – were discovered to prevent gut infections in the 1910s. Since then, multiple strains of bacteria have been identified that promote health when consumed, satisfying the modern definition of probiotics.

Good Bac vs. Bad Bac

YOUR MICROBES, YOUR GARDEN: Think of the microbes in our guts as a landscape or a garden that needs fertilizer and seeds. Our earliest microbes come from our mothers during birth and breastfeeding. Breast milk contains seeds (microbes) and fertilizer (milk carbohydrates). That combination causes beneficial Lactobacillus and Bifidobacteria – the first probiotics – to populate the gut. With the transition to solid food, different kinds of microbes begin to grow in the gut. Unhealthy diets – like those high in sugar and low in fiber – overfertilize the gut and interfere with the immune system. The result: Harmful microbes grow like weeds. Weed species crowd out healthier microbes and change the ecology in the gut. In this way, poor diets pave the way for illness, chronic disease and obesity.

YOUR FOOD, YOUR FERTILIZER: Is it possible to change the landscape of the gut by changing the fertilizer – the food we eat?  The science says yes.  A change in diet has a profound effect on the community of microbes in our guts, and those changes are quick, happening within 24 hours. Healthy diets – those high in dietary fiber, fruits and vegetables – may decrease the growth of weed species, like pathogenic Proteobacteria, while boosting cooperative microbes.

A small nutritional study performed at the David Geffen School of Medicine at UCLA tested whether a fruit juice diet affects the microbiota in 20 volunteers. The fruit-juice diet caused changes in microbe groups linked with healthy metabolism, in line with findings of other researchers. The juice diet also reduced the number of Proteobacteria, a group that contains many pathogens. Molecules known as flavonones in fruit are thought to inhibit the growth of Proteobacteria and other harmful microbes. The ability to shape gut microbes is one way that dietary fruit and vegetables might protect against chronic diseases.


The strongest medical evidence supporting probiotics is their ability to prevent diarrhea and gut inflammation (though the benefits of probiotics extend beyond the gut). Should we seed the microbial landscape of the gut with probiotics? Probiotics are safe and can be beneficial, with a couple of caveats: First, the benefits of probiotics depend on the specific strain (see below), so different members of the same microbe species can have different effects. Second, a health benefits of probiotics depend on lots of factors, like age, medical conditions, and which microbes already live in the gut. When choosing a probiotic, it would be wise to take a defined probiotic strain that has been shown to be effective in human studies.

The modern study of probiotics is still pretty new. Most of what is known involves the benefits of dairy probiotics, like Metchnikoff’s lactic acid bacteria. Probiotics in non-dairy drinks often use different microbes that don’t grow until they make it into the intestine. Bacillus coagulans is one such probiotic that has been used in juice and other drinks. Like lactic acid bacteria, B. coagulans has been shown to prevent the growth of gut pathogens, boost numbers of beneficial species and lower inflammation in a variety of small trials. Are these effects long lasting and do they prevent chronic diseases? Well-designed long-term studies are needed to answer that question. Meanwhile, the existing results are promising, so keep a close eye on this space!



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