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Synbiotic 365

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Synbiotic 365 is a dietary supplement that is alleged to help you address your digestive issues by combining probiotics and prebiotics. While the individual actions of these ingredients have scientific support, research confirming the benefits of synbiotics is lacking.


  • There is some research backing the individual ingredients
  • Added B vitamins are a bonus if you’re deficient
  • Favorable return policy
  • Favorable safety profile, though immunodeficient people should avoid


  • Research specific to synbiotics is needed to identify the potential role
  • Pricier compared to other synbiotic blends
  • A probiotic supplement with a high-fiber diet may be just as effective

Synbiotic 365 Review: Can It Address Your Digestive Issues?

By Anthony Dugarte, M.D., C.S.C.S

Updated on: May 9, 2020

What Is Synbiotic 365?

United Naturals claims that Synbiotic 365 will offer relief for digestive issues and bloating through a blend consisting of prebiotics, probiotics, and B vitamins.

Probiotics are the friendly bacteria that live in your gut. Prebiotics are a form of fiber that serve as a food source for probiotics and enhance their actions.

On their own, both may offer many health benefits related to digestion, immunity, weight loss, and more. Synbiotic supplements incorporate both pre- and probiotics, as their combined actions may offer even greater benefits.

In this article, we’ll review the science behind Synbiotic 365’s list of ingredients to help you determine if this supplement can help alleviate your digestive symptoms.

Synbiotic 365’s Ingredients: Do They Work?

According to the supplement facts label listed on the United Naturals website, Synbiotic 365 contains:

  • Vitamin B1 (Thiamin) 2.4 mg
  • Vitamin B2 (Riboflavin) 2.6 mg
  • Vitamin B3 (Niacin) 32 mg
  • Vitamin B6 3.4 mg
  • Vitamin B9 800 mcg (480 mcg folic acid)
  • Vitamin B12 4.8 mcg
  • Vitamin B7 (Biotin) 60 mcg
  • Vitamin B5 (Pantothenic Acid) 10 mg
  • Probiotic Blend 20 billion CFU – Lactobacillus gasseri BNR17, OPTI-BIOME Bacillus subtilis MB40, Lactobacillus paracasei Lpc-37, Bifidobacterium lactic BI-04, Lactobacillus plantarum Lp-115, Streptococcus thermophilus St-21, Lactobacillus Casei Lc-11, Lactobacillus reuteri, Lactobacillus salivarius Ls-33, Lactobacillus rhamnosus Lr-32, Lactobacillus fermentum, Bifidobacterium bifidum Db-06, Bifidobacterium longum BI-05, Saccharomyces boulardii
  • Chicory Root Inulin 315 mg

In the following section, we’ll break up these ingredients into 3 main categories and highlight the available research supporting each group.


Vitamin B deficiency is common, especially in people that live a plant-based life. Deficiency can be associated with a variety of unwanted effects like nerve issues, dry skin, fatigue, and impaired mental capacity.

There are 8 B vitamins included in Synbiotic 365; with the exception of Biotin, this supplement offers close to, or well beyond, the RDA.

The folate in Synbiotic 365 plays a crucial role in growth and development, and also for preventing birth defects.

B12 supports the development of red blood cells; deficiency is associated with anemia.


Their genus identifies probiotic bacteria (e.g., Lactobacillus), which is like an extended family; their species (e.g., acidophilus), and their strain (La-14).

These friendly bacteria impact your digestion and support your immune function. They may also work to reduce allergies, as well as improve diarrhea and constipation. Each strain behaves differently and offers strain-specific effects.

L. casei may relieve digestive symptoms.

In 70 individuals with constipation, those treated with 65 mL of a Lactobacillus casei Shirota containing beverage had reduced symptoms when compared to placebo. A 100g (97 ml) drink with L. casei, L. bulgaricus, reduced the number of antibiotic-associated diarrhea cases in hospitalized patients.

Many L. plantarum species have been studied; the Lp-115 strain has been extensively investigated.

L. Plantarum N14 reduced inflammation in intestinal cells in a laboratory model. 100 mg/kg injections of L. plantarum K8 decreased enzymes associated with heart disease in mice.

  • L. Gasseri is also thought to aid digestion and reduce allergies.
  • L. Gasseri TMC0356 at 200mL decreased the level of antibodies associated with allergies in 15 subjects over 4-weeks. Subjects treated with L. gasseri OLL2716 at 109 CFU doses experienced improved indigestion symptoms over 3-months.
  • L. salivarius may offer antimicrobial effects.

In 59 children with oral disease, treatment with L. salivarius reduced bacterial and fungal levels.

In the Bifidobacteria genus, lactis may reduce inflammation and aid in the management of diabetes, bifidum shows promise for addressing constipation and lung infections, and longum may also be useful for constipation and airway infections, in addition to IBS and ulcerative colitis.

Bifidobacterium lactis strains can offer immune support and allergy relief. B. longum may provide the same benefits.

In a laboratory model, B. Longum CCUG 52486 had anti-inflammatory, especially in samples from elderly individuals. These effects were confirmed in a trial with human subjects; BB536 boosted antibody and white blood cell levels in elderly individuals.

S. boulardii is a fungal probiotic. Its potential benefits have been researched, though most of the available data is found in animal and laboratory models.


Fiber is a type of carbohydrate that can’t be digested or absorbed. Prebiotics, also classified as fiber, pass into your gut fully intact and serve as food for probiotic bacteria.

Additionally, they can absorb water and expand to make you feel full. Prebiotics may also improve blood glucose levels, promote weight loss, and enhance digestion.

The inulin in Synbiotic 365 may offer these benefits.

Inulin reduced hunger, desire to eat, and food consumption in obese adults randomized treated for 12-weeks. 12g of inulin daily for 4-weeks resulted in softer stools, increased stool frequency, and increased amounts of probiotics in constipated adults.

Side Effects and Safety

The company provides details for the total amount of ingredients in the probiotic blend, though they don’t offer amounts for each ingredient. Also, strains behave in a strain-specific manner and may provide different effects when compared to similar strains within the same family.

These factors make it challenging to compare many of these ingredients to those that have been specifically studied.

Probiotic strains are often tested at doses comparable to the probiotic blend in Synbiotic 365. These amounts are generally safe in pre-and probiotic blends, with only mild side effects reported.

Most often, these include digestive symptoms like abdominal pain, gas, bloating, and diarrhea. These can typically be relieved by lowering your dose or discontinuing use.

Lastly, Synbiotic 365 contains a fungal probiotic. While the risk for fungal infections may be small, they are not uncommon. Therefore, critically ill patients, as well as those with a compromised immune system, should avoid using Synbiotic 365.

Whether you’re considering Synbiotic 365 or another probiotic-containing supplement, have an in-depth conversation with a healthcare provider before ordering.

In addition to making recommendations that could maximize value, they can also help minimize any potential side effects based on your diagnosis.

How Much Does Synbiotic 365 Cost?

Synbiotic 365 is only available on the United Naturals website, priced as follows:

  • 1 Box: $45
  • 3 Boxes: $119 ($39.67 per box)
  • 6 Boxes: $229 ($38.17 per box)

All orders come with a 30-day refund policy, less S&H, which customers can request by calling support at 844-794-7728.

Synbiotic 365 vs. Competing Probiotic & Prebiotic Supplements

While Synbiotic 365’s exact formulation is less common, there are a number of synbiotic supplements currently available.

Syntol AMD ($40, 90 capsules), Dr. Axe Formula SBO Probiotic ($41, 60 capsules), HLC Synbiotic Intensive ($43, 7 sachets), NutriCology SymBiotics with FOS ($23, 40 servings), are a few examples.

These supplements are alike in that they’re priced competitively, and each combines a relatively similar blend of probiotics, prebiotics, vitamins, and minerals. These often include many of the same species among the Lactobacillus and Bifidobacteria genera, vitamins C and B, and various extracts like apple cider vinegar or black pepper fruit.

The differences between Synbiotic and competing supplements mostly relate to the quantities of each ingredient they contain, as well as the form in which they’re available (e.g., capsules vs. loose powder).

Alternatively, you can opt for a diet rich in both pre- and probiotics. A diet would include adding fermented foods like yogurt, sauerkraut, or kimchi, as well as fiber-rich whole grains and vegetables to your daily meal plan.

The Bottom Line

While pre- and probiotic blends both seem to offer many desirable health benefits, more research is needed to determine the role of synbiotics. Also, the added vitamins might not provide much value unless you’re deficient.

Additionally, Ultra Naturals does not provide specific quantities for the ingredient offered in their blend. This makes a comparison to the available literature challenging.

Nonetheless, similar blends are generally safe to use though individuals with impaired immune function should use fungus containing supplements with caution.

Given the need for more research regarding synbiotic supplements, you may be better off opting for a more cost-effective option. You can also choose an effective probiotic supplement and increase the fiber-rich foods in your diet.

Lastly, be sure to seek the opinion of a medical professional before use. Symptoms that you’re experiencing may be related to a more serious cause that should be cared for by a physician.

Customer Reviews

4.7 Stars out of 1236 Reviews
5 Star:79% 4 Star:14% 3 Star:2% 2 Star:1% 1 Star:2%
95% Recommend This Product
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Posted on May 16, 2022

Does it actually contain what is on the label?

By Charles M., Denver, CO, Verified Reviewer

Reviews like this are useless unless there is an independent lab analysis cited showing the product actually contains what the label indicates! I have used it for a couple of months with no observable effect.

I wrote the company about this with no reply. Another company now seems to be producing this besides United Naturals. I wrote ConsumerLab to ask them to add this to their next review, which includes lab testing for ingredients. Why write a review based upon an unconfirmed ingredient list?

Length of Use: Less than 3 months

Bottom Line: No, I would not recommend this to a friend

Pros and Cons

No “pros” were specified in this review

No verification of product contents

Helpful Review? 2 People Have Voted

Posted on Feb 21, 2022

Really works

By Jessica H., Wisconsin, Verified Reviewer

Both my mom and I have consistently taken these for a couple of months after my mom was severely ill with Covid and we both had been on antibiotics. We noticed it really helped us feel less bloated and much more regular. Highly recommended!

Length of Use: 3–6 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

Each capsule is sealed

It also contains lots of B vitamins

It works

No “cons” were specified in this review

Helpful Review? 2 People Have Voted

Posted on Aug 27, 2021

Better results than any other probiotic I've tried

By James R., Stillwater, MN, Verified Reviewer

As a nutritionally oriented health care provider for 34 years, I've tried and recommended many probiotic products over the years. I have to say that I have personally had better results with Synbiotic 365 than anything else I have tried.

Length of Use: 1–2 years

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

Fast significant improvement in GI function

Modest dosage/frequency required to obtain results

Convenient product availability and prompt shipping

More expensive than some available probiotics

Helpful Review? 2 People Have Voted

Posted on Aug 20, 2021

Great product

By Songpol E., Santa Clarita, CA, Verified Reviewer

It's the best probiotic based on the ingredients and no other probiotic can compare. Been using it for almost a year and found great results.

Length of Use: 6–12 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons



Ease of use

No “cons” were specified in this review

Helpful Review? 2 People Have Voted

Posted on May 10, 2021

I can’t live without this

By Joy P., Clinton, CT, Verified Reviewer

I have been using Synbiotic 365 for many years now. It helps with digestion, bloating, and weight gain. I ran out for a few weeks and I was shocked how lethargic I felt without it. I highly recommend this product. In fact, I have recommended it to several people and they are all using it now too.

Length of Use: 2+ years

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

It helps with digestion

No “cons” were specified in this review

Helpful Review? 2 People Have Voted

Posted on Feb 10, 2021

We love it!

By Rhonda P., Terrebonne, OR, Verified Reviewer

My partner and I both take it. It is easy to remember to take our pill first thing in the morning. My doctor read the content and approved my taking it.

Length of Use: Less than 3 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

No more "messy" poos.

Saving on toilet paper.

No longer buy B Vitamins.

Doctor approved.

No “cons” were specified in this review

Helpful Review? 2 People Have Voted

Posted on Jan 10, 2021

My journey with autoimmune issues

By Cathy L., Ohio, Verified Reviewer

I saw Synbiotic 354 V7 on my Facebook feed. I normally don't pay attention to ads, but I felt I needed to watch and "pay attention" to this probiotic. I deal with autoimmune issues that are constantly giving me gut issues. I had tried several probiotics with not much luck since I am lactose intolerant which leaves me limited. I ordered the product and saw WONDERFUL results the first 2 weeks.

I am feeling great and my gut integrity has improved a lot!

Thank you!

Length of Use: 3–6 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

Easy once a day regimen

Easy open packaging


Company Response from United Naturals

Jan 12, 2021

Hey Cathy, that is wonderful! We love hearing success stories like yours :) Thanks for sharing.

Helpful Review? 2 People Have Voted

Posted on Dec 21, 2020

Synbiotic 365

By Brenda C., Waynesville, NC, Verified Reviewer

I am a 67-year-old woman with stomach issues. I have taken various over-the-counter probiotics through the years with minimal relief. As a last result I decided to try Synbiotic 365, thank God. My stomach and I are doing great! I would say to everyone who has stomach issues, take a leap of faith and try it, you will be completely satisfied as I am.

Length of Use: 3–6 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

It works for my stomach issues

Took care of my constipation

A little bit expensive

Company Response from United Naturals

Dec 23, 2020

We're so happy to hear that Brenda! Thanks for letting us know! :)

Helpful Review? 2 People Have Voted

Posted on Dec 8, 2020

The only probiotic that works for me and my daughter!

By Cynthia B., Las Vegas, NV, Verified Reviewer

This is THE ONLY probiotic that works for me and my daughter! We've tried others, but now have to stick to United Naturals. I lost 15 pounds taking these, and after 2 weeks without having gained 10 pounds, I won't do without these again!

Length of Use: 3–6 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

Doesn't upset my stomach

Lost weight

Feel better and more regulated

Higher price than others

Company Response from United Naturals

Dec 9, 2020

That's awesome to hear! Thanks for letting us know :)

Helpful Review? 2 People Have Voted

Posted on Nov 24, 2020

Wonderful product

By Lenora P., San Leandro, CA, Verified Reviewer

I have used Synbiotic 365 for several months and have given it to my 95-year-old mother who was having some issues with her stomach and digestion. After a few weeks, I have noticed a remarkable difference in her having very few issues that she was having prior to my giving her Synbiotic 365.

Length of Use: 3–6 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

It really does as it says

Product works

No side effects

No “cons” were specified in this review

Company Response from United Naturals

Nov 25, 2020

That's awesome to hear Lenora! Thanks for letting us know :)

Helpful Review? 2 People Have Voted

Posted on Nov 3, 2020

Full of energy

By Georgina R., Riverside, CA, Verified Reviewer

After many years of trying so many things to help my digestive system and improve my energy levels, I finally found this great product that was recommended by a great friend. Before I would always be taking energy pills to have energy throughout the day. Now this pill has improved my digestive system which helps my energy levels and gets me full rested nights. It has also decreased my sugar cravings. Now I don’t take any other pills besides my Synbiotic 365. Give it a try, you won’t regret it.

Length of Use: Less than 3 months

Bottom Line: Yes, I would recommend this to a friend

Pros and Cons

Improve metabolism

Improve digestive system

More energy

No “cons” were specified in this review

Company Response from United Naturals

Nov 25, 2020

Wow! It sounds like Synbiotic 365 has been incredible for you, thanks for letting us know!

Helpful Review? 2 People Have Voted
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