Dr. Rose, M.D. (researcher)

Evan Jerkunica (writer)

Lactobacillus Gasseri BNR17 for Weight Loss?

The most unique thing about L gasseri, is that it may directly improve weight loss.D L Gasseri also seems to help regulate blood sugar control hormone sensitivity, reduce belly fat and turn on more fat burning genes.C

But before we dive deep into the weight loss research studies, let’s look more generally at what L gasseri BNR17 is.

What is L Gasseri BNR17?

L. gasseri probiotic is one of 180 lactobacillus probiotic strains that live throughout our bodies. The most researched strain of lactobacillus gasseri is BNR17. This strain was found in human breast milk. It was isolated, heavily researched and eventually patented in Korea. Gasseri is now licensed as a probiotic supplement ingredient in the USA.

Recent studies have suggested positive effects of L gasseri in humans, primarily in weight lossA,B,C,D,E and in irritable bowel syndrome.F,G

This probiotic strain is safe – it’s in human breast milk after all. Probiotics.org has not heard of any serious side effects from taking this product either in research or from Probiotics.org readers.

L Gasseri BNR17 Researched Benefits

We found 7 good research studies about Lactobacillus gasseri BNR17. It looks like there is strong research evidence that gasseri helps with weight loss. There is also some research showing L gasseri helps with IBS, but it is fairly weak research.

L Gasseri Weight Loss Benefits

Yun published the results of Gasseri BNR17 in a mouse model of type 2 diabetes mellitus. The bacteria caused reductions in hyperglycemia, improved blood sugar control hormone sensitivity, and reductions in the classic symptoms of excessive hunger (polyphagia), excessive thirst (polydipsia), and excessive urination (polyuria).A

A year later, a group led by Kang used a rat model to show that Lactobacillus gasseri resulted in weight loss and reduced severe obesity (adiposity) in animal models.B

The same author released a similar follow-up study in 2013 showing that LG effectively blocked the weight gain in rats fed a high-calorie diet. It turned on more fat burning genes (upregulated fatty acid oxidation-related genes), lowered levels of leptin, and reduced blood sugar control hormone levels.C

A different group, Jung et al, led a clinical trial of LG BNR17 in humans. This was a well-designed randomized double-blind clinical trial comparing LG vs. placebo in 62 obese volunteers. The statistics were not strong, but there was a tendency towards lower weight and lower obesity in the LG-treated subjects. The changes in biometrics and laboratory studies did not reach statistical significance.D A similar study by Kim in 2017 did show statistically significant decreases in weight, belly fat and obesity.E

L Gasseri IBS Benefits

LG BNR17 has also been studied for the treatment of irritable bowel syndrome (IBS). In a study published in 2017, it was shown by Shin and colleagues that LG significantly reduced the diarrhea and improved health-related quality of life indices in diarrhea-predominant IBS.F

A similar report by Kim in 2018 showed that IBS patients taking LG supplements experienced significant improvements in symptom score. One concern to note is the marked overlap in the author lists for these articles. It appears that these IBS studies were all performed by the same group. The reader is encouraged to wait until more IBS studies are published by other research groups.G

L Gasseri Side Effects

There has not been any serious or dangerous side effects reported for any strain of Lactobacillus gasseri BNR17, or any other strain of gasseri. It comes from breast milk, so it makes sense that it’s a very safe supplement. The common probiotic side effects are:

  • diarrhea
  • gas
  • bloating
  • cramps
  • rashes
  • acne

Lactobacillus Gasseri Products

Probiotics.org is a big fan of 2 probiotic products that contain L Gasseri.

#1 – Synbiotic 365 has L gasseri BNR17

The #1 product that has L Gasseri BNR17 is Synbiotic 365. I spoke with United Naturals, and they said that Synbiotic 365 contains 20 billion CFU of L Gasseri BNR17 at the time of manufacture. That is double the 10 billion CFU used in clinical studies showing weight loss benefits.D This means that even 1 year after manufacture, you’re guaranteed to get a clinical dose of L gasseri BNR17.

We rated this product a strong 5 stars. It’s also ranked as our #1 probiotic brand overall. Probiotics.org can’t say too many good things about this product.

You should click here to read our 5 star review of Synbiotic 365

#2 – 1MD Complete Probiotics Platinum has L gasseri L22G – Not BNR17

We also rated 1MD Complete Probiotics Platinum 5 out of 5 stars. But, this product has Lactobacillus gasseri L22G, which isn’t the BNR17 that has all the research mentioned above. Also, there are 6 other strains that have higher CFU than L gasseri L22G…so L gasseri isn’t a priority of 1MD’s complete probiotic platinum.

So even though 1MD’s probiotic is strong overall, Synbiotic 365 has clinical doses of BNR17 which is the most researched backed strain of L gasseri.

If you’re interested in getting clinical doses of L gasseri BNR17 proved in these research studies, you should read our 5 star review of Synbiotic 365.


Lactobacillus gasseri BNR17 appears to be effective as an adjunct in the treatment of obesity, type 2 diabetes mellitus, and irritable bowel syndrome. It is well-tolerated with very mild side effects.

If you have any questions about L gasseri, please ask in a comment below.

Full Reference List

  1. Jung SP, Lee KM, Kang JH, Yun SI, Park HO, Moon Y, Kim JY. Effect of Lactobacillus gasseri BNR17 on overweight and obese adults: a randomized, double-blind clinical trial. Korean journal of family medicine. 2013 Mar;34(2):80.
  2. Kang JH, Yun SI, Park HO. Effects of Lactobacillus gasseri BNR17 on body weight and adipose tissue mass in diet-induced overweight rats. The Journal of Microbiology. 2010 Oct 1;48(5):712-4.
  3. Kang JH, Yun SI, Park MH, Park JH, Jeong SY, Park HO. Anti-obesity effect of Lactobacillus gasseri BNR17 in high-sucrose diet-induced obese mice. PloS one. 2013 Jan 30;8(1):e54617.
  4. Kim J, Yun JM, Kim MK, Kwon O, Cho B. Lactobacillus gasseri BNR17 Supplementation Reduces the Visceral Fat Accumulation and Waist Circumference in Obese Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of medicinal food. 2018 May 1;21(5):454-61.
  5. Yun SI, Park HO, Kang JH. Effect of Lactobacillus gasseri BNR17 on blood glucose levels and body weight in a mouse model of type 2 diabetes. Journal of applied microbiology. 2009 Nov;107(5):1681-6.
  6. Shin SP, Choi YM, Kim WH, Hong SP, Park JM, Kim J, Kwon O, Lee EH, Hahm KB. A double blind, placebo-controlled, randomized clinical trial that breast milk derived-Lactobacillus gasseri BNR17 mitigated diarrhea-dominant irritable bowel syndrome. Journal of clinical biochemistry and nutrition. 2018;62(2):179-86.
  7. Kim JY, Park YJ, Lee HJ, Park MY, Kwon O. Effect of Lactobacillus gasseri BNR17 on irritable bowel syndrome: a randomized, double-blind, placebo-controlled, dose-finding trial. Food science and biotechnology. 2018 Jun 1:1-5.

7 comments on “Lactobacillus Gasseri BNR17 – Weight Loss Probiotic?” - Click here to write your comment

  1. Charles Woods says:

    How can Synbiotic claim there’s 20bil Gasseri when the total probiotic blend of the entire capsule is 20bil?

    • evan says:

      Hi Charles,

      That is a good question!

      When they manufacture the product, they put 20 billion CFU of L gasseri BNR17. They do this because they think that up to 50% of the CFU could die off after 1 year. This is called “overfilling”, and it’s because some bacteria will die over the course of the year. They told me they are positive there will be at least 10 billion CFU L gasseri BNR17 a year after manufacture.

      Less reputable companies will only guarantee CFU’s at the time of manufacture, and just pretend that the freeze dried bacteria don’t slowly die over time.

      The 20 billion CFU is guaranteed to be in the product at the time of consumption, for all strains. That amount is guaranteed up to 1 year after they manufacture it.

      Very good question – I apologize for not being more clear.

      To your health,
      Evan Jerkunica

  2. Angela says:

    Where do I purchase this

  3. David Vega says:

    theres no way they have 20billion L. Gasseri the total blend have 30billion mixed with a lot of strains, maybe 2 billion gasseri but is totally imposible to have 20 billion just gasseri

    • evan says:

      Hi David,

      At time of manufacture, they put 20 billion CFU L gasseri BNR17 in Synbiotic 365. They “overfill” the amount inside each capsule so that if the product gets too hot, then there will still likely be at least 10 billion CFU L gasseri.

      The 20 billion total CFU for all the strains on the box is the “worst case scenario”…meaning that if you take the product 2 years after you bought it, there will still be 10 billion L gasser, and 10 billion of the other strains…for a total of 20 billion CFU.

      Does that make sense? Please write another comment or email me if it doesn’t.

      Evan Jerkunica

  4. Aimee says:

    Do not buy Synbiotic 365. The seller has sleazy sales practices and a sleazy website!!!!

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