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.

  • 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’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

Start your review of Synbiotic 365:
  • 1227 Customer Reviews
  • 96% Recommend This Product
4.7 out of 5
5 star: 79% 4 star: 14% 3 star: 2% 2 star: 1% 1 star: 2%

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  • Wonderful product

    • By Lenora P.,
    • San Leandro, CA,
    • Nov 24, 2020
    • Verified Reviewer
    • Length of Use: 3–6 months
    Overall Experience:

    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.

    Pros and Cons:

    • It really does as it says
    • Product works
    • No side effects
    • No “cons” were specified in this review

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

  • Full of energy

    • By Georgina R.,
    • Riverside, CA,
    • Nov 3, 2020
    • Verified Reviewer
    • Length of Use: Less than 3 months
    Overall Experience:

    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.

    Pros and Cons:

    • Improve metabolism
    • Improve digestive system
    • More energy
    • No “cons” were specified in this review

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

  • Great Synbiotic, it works

    • By Diana M.,
    • Martinez, CA,
    • Oct 26, 2020
    • Verified Reviewer
    • Length of Use: 1–2 years
    Overall Experience:

    I have been using Synbiotic 365 for a little over 1 year. It has helped with my overall gut health, this product works! Thank you United Naturals.

    Pros and Cons:

    • It does what it says it will do
    • Easy to take, 1 capsule/day
    • Don't have to refrigerate
    • My auto ship was early this month, I still have 1 box and it shipped yesterday, I faithfully take 1/day, not sure why that happened

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

  • Best probiotic

    • By Jolene E.,
    • New Britain, CT,
    • Oct 26, 2020
    • Verified Reviewer
    • Length of Use: 1–2 years
    Overall Experience:

    Easy to swallow, convenient packaging, especially when traveling - just pops out and never needs refrigeration. Reasonably priced, convenient delivery every three months.

    Pros and Cons:

    • It works
    • Price
    • Convenience
    • No “cons” were specified in this review

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

  • Product is very good

    • By Scott D.,
    • Boca Raton, FL,
    • Oct 23, 2020
    • Verified Reviewer
    • Length of Use: 1–2 years
    Overall Experience:

    Enjoy the product, have taken a few various probiotics in the past and this is by far the best I have taken. The three stars are due to the website user login, very poor and difficult to navigate/update. Did send an email and they respond fast.

    Pros and Cons:

    • The way it makes me feel
    • Price

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

    • Nov 2, 2020

      Company Response from United Naturals

      Hey Scott, we're glad you're enjoying Synbiotic 365! We're sorry that our website wasn't intuitive for you, I'll pass that feedback on for you :)

  • Feel better in a general way

    • By Lynnette A.,
    • Ukiah, CA,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: 3–6 months
    Overall Experience:

    Since I started taking this product I have more energy, I spend less time in the bathroom, and just feel better. I have less pain in my intestines and less gas.

    Pros and Cons:

    • Feeling better
    • Less bathroom time
    • Balances my system
    • Having to take pills

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

  • Synbiotic 365

    • By Dana F.,
    • Claremore, OK,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: Less than 3 months
    Overall Experience:

    I have taken it for 1 month. My overall digestion improved and I have felt much better. As a real plus, I have started to lose weight also. I am looking forward to seeing the results of my continued relationship with this product.

    Pros and Cons:

    • Improved digestion
    • Just feel better
    • Started to lose weight
    • No “cons” were specified in this review

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

  • Synbiotic 365 gives rewarding health benefits

    • By Abram F.,
    • Winkler, Manitoba, Canada,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: 3–6 months
    Overall Experience:

    Great for bowel movements, energy, and stomach health. I always take one before breakfast with a cup of water. It gives me a boost for the day.

    Pros and Cons:

    • Energy
    • Bowel movements
    • Stomach health
    • No “cons” were specified in this review

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

  • Stopped my hot flashes!

    • By Patricia H.,
    • Montreal, Canada,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: 3–6 months
    Overall Experience:

    I have always taken probiotics but clearly not the right ones! This year at 50 I was catapulted into menopause and was suffering through hot flashes, relentless insomnia, debilitating fatigue, and felt like I was losing my mind. My GP recommended anti-anxiety medication and sleeping pills to quell the insomnia and we started looking at hormone therapy. I felt even worse after starting to follow my doctor's plan. In addition to feeling like a zombie, I was starving all the time. I started to put on weight and that made me feel even lousier. My ex-husband introduced me to Synbiotic 365. He had started taking it to combat weight gain he was struggling with...and I noticed that the midsection he had put on was no more. So I decided to give it a try and to my complete amazement, my hot flashes disappeared and I started sleeping through the night. No hormones, no anti-anxiety meds, and no further sleeping pills required. During my first two weeks in Synbiotic, I noticed discomfort in my colon so I started taking the pills with two full glasses of water and that solved the problem. I also did some Acupuncture for the first two weeks to help reset my system. I swear by Synbiotic 365. I had no idea it would help with menopause symptoms to the extent that it has. More women need to give this a try!

    Pros and Cons:

    • Eliminated my hot flashes
    • Improved my sleep
    • Gained energy
    • It took a while for my colon to adjust
    • I need to take on an empty stomach with lots of water
    • It takes a long time to arrive in Canada

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

  • Happy

    • By Melody Y.,
    • Barnstead, NH,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: Less than 3 months
    Overall Experience:

    I feel so much healthier and have more energy!

    Not sure if it helps blood levels but when I donated this past Friday it was 14! Never has it been that high!

    Pros and Cons:

    • No more bloated feeling
    • No more hard belly
    • Blood level was better for donating to the Red Cross
    • Price

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

  • Relief

    • By Randy W.,
    • Grand Blanc, MI,
    • Oct 22, 2020
    • Verified Reviewer
    • Length of Use: 3–6 months
    Overall Experience:

    I have been having gastrointestinal issues for some time. Since taking Synbiotic 365 I do not have to worry about having a problem when I leave home. Previously, I was barely able to prevent bowel movements when a bathroom wasn’t immediately available.

    Pros and Cons:

    • Easy to swallow
    • Only needed once a day
    • No side effects
    • The cost

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

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