An amazing amount of research during the past decade has shown that probiotics – friendly bacteria that live in your body and support better health – are crucial for helping digestion and supporting the function of many organs.

Because there is such a wide variety of bacteria that grow in various parts of our anatomy, scientists are just beginning to grasp the functions of many of these microscopic life forms.

But recently Dr. Lorenzo Cohen, who directs the Integrative Medicine Program at the University of Texas MD Anderson Cancer Center in Houston, called into question the benefits of taking probiotic supplements. He thinks they may be a bad idea.1

So what’s the truth about probiotics? Helpful or harmful?

Before raising his objections, Dr. Cohen had been diagnosed with melanoma, a deadly form of skin cancer. Because research had shown that people with a greater diversity of probiotic bacteria in their intestines respond better to cancer treatment, he had made an effort to increase the different types of healthy bacteria in his own digestive tract.

For six months, he followed a diet he thought would improve his bacterial diversity.

As he describes his diet, he:

  • Ate more fermented foods that are rich in probiotic bacteria.
  • Stopped eating refined carbs – cutting out white rice, white flour and other processed foods.
  • Consumed fewer whole grains.

But according to Dr. Cohen, the diet backfired. An analysis of the bacteria in his digestive tract demonstrated that the diversity of the probiotic flora living there had decreased after six months.

Plus he argues that research at MD Anderson Cancer Center mirrors his experience – that taking a probiotic supplement may lower a patient’s response to being treated for cancer with immunotherapy.2 Note that Dr. Cohen did not take a supplement, he ate fermented foods.

Reasonable Conclusions?

So what are we to make of everything that Dr. Cohen has experienced and said?

First, note that one person’s experience does not establish a new scientific truth. If he was taking chemotherapy drugs or other treatments, what effect might that have had?

One expert who works in the supplement industry points out that Dr. Cohen’s diet may have failed because he cut back on prebiotics – fibrous foods that are known to provide nutrients for probiotic bacteria in the digestive tract.

It’s not unreasonable to expect that eating fewer prebiotics would mean fewer intestinal probiotics would survive in the body. Prebiotics include fruits, vegetables and whole grains that are high in fiber.3

Dr. Cohen himself endorses the prebiotic concept. He suggests that if we eat plenty of these bacteria-friendly foods, the natural microbiome in our colon will do just fine.

The idea is that even if your colon’s native bacteria have been knocked way back by overuse of antibiotics or overgrowth of yeast infection, there are still some members of the healthy strains lurking in your intestine, and they can make a comeback if you give them some encouragement.

Studies Contradict Cohen’s Slam at Probiotics

But with all due regard for prebiotics, Dr. Cohen’s experiment on himself raises more questions than answers and points to the fact that research into probiotics has only just begun. We need to know a lot more.

Meanwhile, a whole host of studies contradict his high-profile attack on probiotics:

Support the health of the liver: Studies at Emory shows that probiotics protect the liver against oxidative injury and help limit the damage from an overdose of acetaminophen (the active ingredient in Tylenol®).4

Help the immune system fight off invading pathogens: Researchers in Italy, in a review study, found there’s plenty of evidence that probiotics stimulate immune cells to prevent infections from damaging the digestive tract and other organs.5

Keep bones stronger as you age: Tests in Sweden show that women who take probiotics have bones that are stronger than the bones in women lacking probiotics. In a year-long double-blind study, the researchers at the University of Gothenburg gave probiotics to elderly women whose average age was 76 years. At the end of twelve months, women taking the probiotics had bones that were twice as strong as the women who took a placebo.6 If those results can be confirmed, they’re amazing.

Reduce the use of antibiotics: A review study at Emory shows that healthy children who receive probiotics are 29 percent less likely to need antibiotics for illness. According to researcher Andi Shane, this analysis shows that taking probiotics lowers the risk or shortens the duration of “acute respiratory tract infections, acute digestive infections, and acute ear infections.”7

Saving The Bees

I also have found evidence that probiotics might soon be used to help protect bees from extinction. You may have heard that bees are having a tough time coping with all of the pesticides we use as well as diseases that can wipe out bee colonies. But now researchers in Canada have discovered that giving bees the right probiotics can increase their survival of fungal infections by up to 40 percent.8

Research into how probiotics work in the human body (as well as in insects!) is progressing so quickly it’s hard to keep up. Yes, there have been a few studies that have questioned their reliability. Those just remind me that nothing that supports our health works all the time for everybody. But the studies that show the benefits of probiotics far outnumber the negative results.

My publishing house is actually in the midst of pulling together a new book on gastrointestinal health, and I can share a few of our preliminary findings. Scientists we’ve talked to confirm that prebiotic foods are very important. They also tend to endorse fermented foods as a more effective approach than probiotic pills. They recommend eating a little of these every day.


  1. https://www.wsj.com/articles/those-probiotics-may-actually-be-hurting-your-gut-health-11570721466?shareToken=st58225018106a4d84bfaf64a76eca8034&reflink=article_email_share
  2. https://www.aacr.org/Newsroom/Pages/News-Release-Detail.aspx?ItemID=1273&mod=article_inline
  3. https://www.nutraingredients-usa.com/Article/2019/10/18/Probiotics-under-fire-When-a-doctor-treats-himself-he-has-a-fool-for-a-patient
  4. https://www.fasebj.org/doi/abs/10.1096/fasebj.2019.33.1_supplement.369.5
  5. https://www.ncbi.nlm.nih.gov/pubmed/31632412
  6. https://www.ncbi.nlm.nih.gov/pubmed/29926979
  7. https://academic.oup.com/eurpub/article/29/3/494/5094938
  8. https://www.allaboutfeed.net/Feed-Additives/Articles/2018/5/Probiotics-reduces-antibiotic-need-in-bees-287149E/