Shirota Probiotic Review: Gut Health, Immunity, Stress, and Sleep

The Shirota strain is one of the few single probiotic strains with a long history of food use and numerous human trials. As of August 2026, related research has covered gut microbiota, bowel movements, stress, sleep, immunity, infections, metabolism, and safety, but positive and negative results coexist, and the actual effects are not as absolute as advertisements suggest.

1. What Is the Shirota Probiotic Strain?

In Chinese, the Shirota strain is usually called:

Shirota strain / Shirota probiotic / Lactobacillus Shirota strain

The more formal current classification name is:

Lacticaseibacillus paracasei strain Shirota

The old name is:

Lactobacillus casei strain Shirota

Therefore, in older papers, L. casei Shirota, LcS, and L. casei YIT 9029 generally all refer to this strain. In Japan, Yakult is currently labeled as Lactic Acid Bacteria Shirota Strain (L. casei YIT 9029). After the reclassification of lactic acid bacteria around 2020, its official scientific name changed.

It is a strain selected and cultured by Minoru Shirota in 1930 and is also the core strain of Yakult.

First, it is necessary to clarify:

“Lactic acid bacteria” is not an active ingredient. What really matters is the "strain."

For example, Shirota, LGG, BB536, HN019, PS128, and others are completely different strains.

Effectiveness proven for a certain LGG strain cannot be inferred for Shirota; the reverse is also true. Probiotics have clear strain specificity.

2. Its Defining Feature: Surviving the Stomach and Small Intestine

One of the most mature pieces of evidence for the Shirota strain is:

It has good resistance to stomach acid and bile, allowing it to reach the intestines in an active form.

Early human trials and subsequent studies have detected large amounts of the Shirota strain in the feces of those who consumed it.

For example, a human study:

• 20 men
• Consumed Shirota fermented milk
• About 3×10¹¹ CFU/day
• For 4 consecutive weeks

The results showed a significant increase of Shirota strain in the feces during consumption, and the number of bifidobacteria also increased.

Small human studies conducted officially by Yakult have also observed that, after continuously drinking a beverage containing at least 10 billion CFU per day, live Shirota strains could be detected in feces.

But here is another important fact:

It usually does not permanently colonize

That is:

Drink → pass through the intestines → exert effects → excreted in feces.

After stopping, the number gradually decreases.

Yakult’s official FAQ also clearly states:

The Shirota strain does not permanently colonize the gut, so continuous intake is recommended.

So probiotics are not:

“Drink for a month, put good bacteria in, and you no longer need to drink.”

Rather, it is:

Exert effects continuously as they pass through the intestines.

3. Its Best-Supported Benefit: Improving the Gut Environment

This is the most solid piece of evidence in Shirota strain-related promotion.

It may include:

• Increase certain lactic acid bacteria
• Increase certain bifidobacteria
• Change the ratio of certain gut microbiota
• Reduce some potentially harmful bacteria
• Alter the intestinal metabolic environment
• Adjust stool condition

When summarizing Shirota-related research in systematic reviews, it was found that the commonly used doses in human studies range approximately from:

6.5 × 10⁹ ～ 1 × 10¹¹ CFU/day

All have been recorded in research.

In numbers that are easier to understand:

Even a single bottle of regular New Yakult in Japan contains 20 billion CFU strain.

4. Constipation: Potentially Helpful, but Far From Certain

This part is particularly interesting.

Many people would simply say:

Yakult = cures constipation.

In reality, human randomized double-blind trials are not so impressive.

One relatively important randomized, double-blind, placebo-controlled study:

• Patients with functional constipation
• Shirota group: 47 people
• Plaque group: 43 people
• Daily intake
• 4 weeks

Results:

Both groups showed improvement in bowel movement frequency and constipation severity.

However:

There was no significant difference between the Shirota group and the placebo group.

In other words, the primary endpoint did not show that Shirota was significantly better than placebo.

Systematic reviews of adult constipation also found:

After combining studies on the Shirota strain, there was no clear statistically significant improvement in hard stools.

So:

Shirota ≠ strong laxative.

It is not as direct as:

• Polyethylene glycol
• Magnesium salts
• Stimulant laxatives

.

5. Where It May Help: Supporting Stool Regularity

It does not seem to simply soften stools.

One study looked at healthy adults with relatively soft stools:

• 34 people
• Randomized, double-blind, placebo-controlled
• 40 billion CFU strain/day
• 4 weeks

Results for the Shirota group:

• Decreased bowel movement frequency
• Stools became more formed
• Improved stool quality

In other words:

People with constipation may find it easier to go, while those with soft stools may actually have more formed stools.

This is also why manufacturers prefer to say:

"おなかの調子を整える" — regulate gut condition

instead of simply saying "laxative".

Therefore, a more accurate expression is:

Supporting Bowel Regularity

rather than

"Treat constipation"

which is more precise.

6. A Practical Assessment of Its Gut Benefits

Overall evaluation:

★★★★☆ 4/5

There is quite a bit of evidence.

But the actual effect generally falls into:

mild to moderate, rather than at a medicinal level.

If a normally healthy person has regular bowel movements every day and their gut microbiota does not have obvious issues:

The difference in feeling between drinking it and not drinking it may be very small.

Conversely:

• Unstable bowel movements
• Tendency for soft stools
• Occasional constipation
• Irregular diet
• Tendency to have diarrhea/constipation under stress

These people may be more likely to notice a difference.

7. Stress: One of Shirota’s More Promising Uses

This is the most famous selling point of Yakult 1000.

The main experiments were not on ordinary "daily life stress," but rather:

The Japanese medical student exam stress model.

This is a very important distinction.

Researchers had medical students preparing for important exams consume Shirota daily.

Multiple double-blind placebo studies found that as exams approached, the placebo group experienced:

• Increased anxiety
• Increased salivary cortisol
• Abdominal symptoms
• Cold-like symptoms

Some of these changes were milder in the Shirota group.

It was also observed that:

• Rise in salivary cortisol was inhibited
• Stress-related abdominal symptoms were reduced
• Decline in gut microbiota diversity was somewhat suppressed

This part of the study usually lasts:

About 8 weeks.

8. Sleep: Human Trials Include EEG Measurements

This is actually a relatively interesting study by Shirota.

A 2017 double-blind randomized placebo study:

Approximately:

• Shirota: 48 people
• Placebo: 46 people

All were medical students under exam stress.

Continuous:

8 weeks before the exam + 3 weeks after the exam.

The study used not only sleep questionnaires, but also:

EEG sleep monitoring.

Results showed that when exam stress increased:

Placebo group:

• Increased sleep latency
• Decreased proportion of N3 deep sleep

These changes were relatively suppressed in the Shirota group.

At the same time:

The delta wave power in the first sleep cycle was higher.

So this result is not simply:

"People who drink it say they sleep better."

There are some objective EEG indicator changes.

This is worth paying attention to.

9. Yakult 1000 Is Not a Sleeping Pill

This is a point that is very easily misunderstood online.

Currently, the better evidence mainly shows:

In healthy people under temporary mental stress, it helps maintain sleep quality.

This does not mean it has been proven to:

• Treat chronic insomnia
• Replace sleeping pills
• Treat sleep apnea
• Treat insomnia related to depression
• Ordinarily, people without stress will sleep deeper just by drinking it

The evidence on sleep is evaluated as follows:

★★★☆☆～★★★★☆

Belongs to:

Interesting, with clinical data, but the applicable scenario is relatively narrow.

10. Why Does Yakult 1000 Contain 100 Billion CFU?

This involves a very key dosing issue.

Yakult 1000：

100ml = 100 billion CFU Shirota strain

Y1000：

110ml = 110 billion CFU strain.

Converted concentration:

About 1 billion CFU strains per milliliter.

Yakult officially states that this is the highest bacterial concentration in the Yakult series.

One reason is that studies on stress/sleep functions mainly use:

About 1×10¹¹ CFU/day.

So it cannot be simply assumed that:

20 billion CFU and 100 billion CFU are exactly the same.

11. Research Doses Corresponding to Different Effects

This is the most practically valuable table in all the Shirota data.

So there does not exist a:

Universal dose suitable for all targets

Different targets require very different experimental doses.

12. Immunity: Possible Benefits, but Conflicting Evidence

Shirota studied NK cells very early on.

A classic small-scale experiment:

• 9 healthy subjects
• 40 billion CFU/day
• 3 weeks

NK cell activity increased significantly, especially in those whose NK activity was originally low.

Some studies in middle-aged and elderly people have also observed changes in NK activity.

Mechanistic experiments found that Shirota may stimulate:

• Monocytes
• IL-12
• IFN-γ
• NK cells
• T cells

and other immune pathways.

Sounds very promising.

But here comes the problem.

13. A more formal trial did not find NK cell improvement

In 2011:

• 68 healthy men
• All pre-screened for low NK activity
• Randomized
• Double-blind
• Placebo-controlled
• 19.5 billion CFU/day
• 4 weeks

Results:

Shirota had no significant effect on:

• NK cell count
• NK cell activity
• Phagocytic function
• Respiratory burst
• Various cytokines

None showed significant improvement.

So:

"Shirota can increase NK cells" cannot be considered a fully established conclusion.

Dose, population, and experimental conditions may all affect the results.

14. A New Immunity Trial Published in 2025

This item is worth mentioning separately.

In 2025, a study was published:

• Randomized
• Double-blind
• Controlled
• 200 participants
• Healthy Japanese office workers
• Aged 23–59
• During winter
• 40 billion CFU/day
• 28 days

Results in the Shirota group:

Lower incidence and severity of upper respiratory tract infections.

The study also found:

Conventional dendritic cells (cDC) of:

• HLA-DR
• CD86

Wait until the activation indicators have improved.

This is also why Japan now has:

"Yakult 400 Immune Gut Health"

One bottle:

40 billion CFU Shirota strain

The official functional claims include:

Acts on conventional dendritic cells (cDC), helping to maintain the immune function of healthy people.

This can be considered one of Shirota's relatively important new research directions recently.

15. Can it reduce colds?

The data here is very interesting, because:

There are positive results as well as negative results.

For example, an experiment with healthy middle-aged office men:

• 96 people
• Winter
• 100 billion CFU/day
• 12 weeks

Incidence of upper respiratory tract infections:

Shirota：

22.4%

Reference:

53.2%

The difference is very large.

But in elderly trials:

Number of people who developed upper respiratory tract infections:

No significant decrease.

However, the average duration after one infection:

Shirota：

3.71 days

placebo：

5.40 days

Relatively short.

However, in a randomized double-blind trial of 243 athletes over 20 consecutive weeks:

The incidence, duration, and severity of upper respiratory symptoms showed no significant improvement.

Overall:

★★★☆☆

Yes:

"May reduce the risk/severity of infection in some populations"

Not:

"Prevention of colds has been confirmed."

16. Childhood Diarrhea: Evidence from a Large Study

This is a relatively valuable study on Shirota.

Kolkata, India:

3758 children aged 1–5

Randomized double-blind field trial.

Continuous:

12 weeks of drinking + 12 weeks of follow-up.

Outcomes of diarrhea:

Shirota group: 608 people

Control: 674 people

Calculated as:

Protection efficacy approximately 14%.

95% CI：4%～23%。

So the effect is not:

"Drink it and you basically won't have diarrhea."

It's more like:

The risk slightly decreases.

This is also quite typical of the actual effect of probiotics.

17. Antibiotic-Associated Diarrhea: A Large Trial Found No Benefit

A relatively convincing trial in 2021:

• 359 spinal cord injury patients
• Multi-center
• Randomized
• Double-blind
• Placebo
• At least 6.5 billion CFU Shirota/day

Main endpoint:

Antibiotic-associated diarrhea (AAD).

Results:

Shirota：

About 45%

placebo：

42.1%

No significant differences.

So the main conclusions:

Shirota has not been proven to universally prevent antibiotic-associated diarrhea.

Certain subgroups taking PPIs showed positive signals, but more trials are needed to confirm.

This is also a good example:

Just because it is a “probiotic” does not mean it is effective for all types of diarrhea by default.

18. Irritable Bowel Syndrome (IBS)

As of the latest strain-level systematic reviews/meta-analyses in 2026, Shirota has two IBS-related studies.

Overall:

For:

• Abdominal pain
• Bloating
• Gas
• Overall IBS symptoms

There is no sufficient and consistent evidence of improvement.

So for IBS:

★★☆☆☆

Shirota is not suitable as the first-choice strain specifically for treating IBS.

19. How are stress and the gut-brain axis explained?

The current hypothesis is not:

Lactic acid bacteria running to the brain.

But rather the so-called:

Gut–Brain Axis

Gut-Brain Axis

May involve:

Gut microbiota ↓ microbial metabolites ↓ gut barrier / immune cells ↓ vagus nerve / immune signals / endocrine ↓ HPA axis ↓ cortisol ↓ stress and sleep

Studies on exam stress have indeed observed:

• cortisol
• tryptophan
• serotonin-related indicators
• gut microbiota
• EEG

changes.

However:

The mechanism still cannot be simply said to be fully established.

20. Can it improve attention and cognitive ability?

We need to be particularly cautious here.

There was an interesting study in 2023:

• Only 12 healthy office workers
• Had sleep complaints
• Double-blind
• Randomized
• Crossover
• Placebo
• 100 billion CFU/day
• 4 weeks

Results showed better subjective attention scores in the afternoon, along with changes in EEG theta power.

However:

n=12 is really too small.

So we cannot currently conclude:

"Shirota improves cognitive ability."

Even less can we say:

• Enhances memory
• Increases IQ
• Prevents dementia
• Boosts learning ability

The more reasonable statement at present is:

In people with poor sleep, it may indirectly affect daytime state and attention through sleep/stress improvement, but the evidence is very preliminary.

Evidence evaluation:

★★☆☆☆

21. Depression and Anxiety

There are some experiments.

For example, in patients with chronic fatigue syndrome:

• 39 people
• Randomized placebo
• 24 billion CFU/day
• 2 months

The Shirota group showed a decrease in anxiety scores.

Another single-arm study with only 18 patients with depression/bipolar disorder:

• 80 billion CFU/day
• 12 weeks

Depression scores decreased.

But:

There was no placebo control.

So we cannot rule out:

• Placebo effect
• Natural disease course
• Other treatments

and other factors.

In another RCT on constipated depressed patients:

Depression scores decreased in both groups,

but:

There was no significant difference between Shirota and placebo.

So it cannot be used to treat depression.

22. Blood Sugar and Diabetes

There are some studies, but the effects are not strong.

100 obese Japanese men with prediabetes:

• Double-blind
• Placebo
• 8 weeks

Results:

Main postprandial blood sugar indicators showed no obvious difference between groups;

However:

• Glycoalbumin
• Some cholesterol indicators

showed some improvement. The researchers' own conclusion was also:

Improvement in glucose metabolism may be limited.

In addition, in metabolic syndrome studies:

• Insulin sensitivity did not show stable improvement
• TMAO did not improve
• Intestinal barrier indicators did not show significant recovery

Therefore:

It should not be treated as a blood sugar-lowering product.

23. What about weight loss?

Currently, there is not enough human evidence to support:

Shirota can significantly reduce fat or weight.

Animal experiments have shown that rats on a high-fat diet had reduced body fat, but:

Animal experiments cannot be directly used as evidence for weight loss effects.

Overall, studies on human metabolic syndrome have not proven significant:

• BMI reduction
• Waist circumference reduction
• Body fat reduction

Therefore, for weight loss:

★☆☆☆☆～★★☆☆☆

Not worth drinking specifically for weight loss.

24. Older, Intriguing Studies on Cancer

This part is often greatly exaggerated in health supplement articles.

Early studies in Japan were conducted:

Bladder cancer recurrence

1995:

138 patients with superficial bladder cancer underwent a postoperative randomized double-blind trial.

Some subgroups of patients taking oral Lactobacillus casei preparation had a lower risk of recurrence.

Later, in 2008:

About 200 patients.

Intravesical epirubicin:

vs

epirubicin + oral Lactobacillus casei.

3-year recurrence-free survival rate:

74.6% vs 59.9%。

Sounds impressive.

But there are issues with the research:

• Limitations such as open-label design
• Dropout issues
• Special treatment environment
• Use of special bacterial preparations
• Not ordinary healthy people
• Also, not using Yakult to prevent cancer

Later reviews also clearly pointed out these issues.

25. Colorectal Tumor Study

A randomized study was conducted on 398 patients who had previously had multiple colorectal tumors removed.

Observation groups:

• Wheat bran
• Lactobacillus casei
• Both
• Control

After 4 years:

Overall incidence of new tumors:

No significant reduction.

But the occurrence of moderate or higher grade dysplastic tumors was lower in the lactic acid bacteria group.

So this belongs to:

"A signal worth further research."

It should absolutely not become:

"Shirota prevents colorectal cancer."

Currently, there is no evidence at this level.

26. Strength of Human Evidence for Various Effects

If we only look at human evidence, the strength of various effects can be ranked as follows:

27. How Much Do You Actually Need?

Based on existing research, different usage goals can be understood as follows.

① General daily gut health

10–20 billion CFU/day

This already falls within a dosage range supported by human studies.

New Yakult：

20 billion CFU/bottle

Just fits this level.

② If you want to focus on improving bowel/intestinal status

The more appropriate range is:

20–40 billion CFU/day

And continuously:

At least 2–4 weeks.

There are multiple human studies with a dose of 40 billion CFU.

③ If you want to see "immune maintenance"

The most direct current clinical evidence is:

40 billion CFU/day.

The 2025 RCT used:

4×10¹⁰ CFU/day.

So Japan's current:

Yakult 400 Immune Intestinal Care

It is 40 billion CFU.

28. Stress and Sleep Require a Different Dose

If the goal is what Yakult 1000 claims:

• Stress
• Sleep quality

The research-supported dose is mainly close to:

Study dose: 100 billion CFU/day

Not 20 billion CFU.

Yakult 1000：

100 billion CFU

Y1000：

110 billion CFU.

Therefore:

Regular Yakult and Yakult 1000 are not just different in packaging.

The difference in the number of bacteria is:

5 times.

20 billion CFU → 100 billion CFU.

29. Is More Always Better?

No.

This is also a problem that many health supplement consumers easily misunderstand.

For example:

20 billion CFU effective → 100 billion CFU may be effective for another endpoint

Does not mean:

500 billion CFU is better.

Currently, there is no evidence to prove this unlimited dose relationship:

More bacteria = stronger effect.

Yakult itself also clearly states:

Consuming more will not treat diseases, nor will it infinitely increase health benefits.

30. When Is the Best Time to Drink It?

This point is actually very simple:

There is no reliable evidence proving that evening is better than morning.

The official statement is also:

It is a food, not a medicine, so it can basically be consumed at any time; choose a time convenient for daily consistency.

So:

After breakfast ✓ After lunch ✓ After dinner ✓ Before bed ✓

What is truly more important is:

The key is to drink it daily

Not:

The exact time of day is not the key.

31. How Long Should You Try It Before Judging the Results?

Based on clinical trial designs, the following time frames can be used to judge:

Digestive system / bowel movements

Try first:

2–4 weeks.

Immune-related

At least:

About 4 weeks.

Stress / sleep

Studies usually take longer:

4–8 weeks, many key trials are about 8 weeks.

So if you drink for 3 days and think:

“Why do I feel nothing at all?”

It is actually normal.

It is not like caffeine or melatonin, which produce noticeable effects in a few hours.

32. Do the Effects Fade After You Stop?

Most likely, it will gradually weaken.

Because, as mentioned earlier:

Shirota is usually not a permanently colonizing bacterium.

After stopping continuous intake:

The amount of Shirota in the feces will decrease.

Therefore, if it really works for you, continuous intake is generally required.

33. How Safe Is It?

For:

Healthy adults

The overall safety record is very good.

This strain has a very long history of use in food, and severe adverse reactions are very rare in large clinical trials.

For example, in a large RCT on antibiotic-associated diarrhea with 359 participants:

No intervention-related adverse events were found.

Small safety studies in critically ill children also did not find Shirota bacteremia.

34. Probiotics Are Not Completely Incapable of Causing Infection

It should be noted that as of 2026, new safety signals have emerged.

In 2026, a case was published:

A 71-year-old patient with advanced lung cancer, whose tumor invaded and perforated the esophagus, with malnutrition and very poor immune status.

The blood ultimately confirmed the presence of the bacteria from what they drank:

L. paracasei Shirota

Consistent strain.

This is considered the second confirmed case of Shirota strain bacteremia in the literature.

That is to say:

Normal people have an extremely low risk.

But for the following groups, one cannot simply assume "the more live bacteria, the better":

• Severe immunosuppression
• Severe cancer
• Severe malnutrition
• Intestinal perforation
• Severe intestinal mucosal damage
• After major gastrointestinal surgery
• Central venous catheter
• Severe condition in ICU

In these situations, you should consult a doctor first.

35. Another Practical Issue: Sugar

This may actually be more worth considering for many healthy people than the lactic acid bacteria themselves.

For example, in Japan now:

New Yakult

65ml：

20 billion CFU Shirota

Approx:

50 kcal

Carbohydrates:

About 11.5g.

Yakult 1000

100ml：

100 billion CFU

Regular version approximately:

• 63 kcal
• Carbohydrates 14.1g

Y1000

110ml：

110 billion CFU

Approximately:

• 70 kcal
• Carbohydrates 15.6g

If you drink it every day:

In a year, that would be 365 bottles.

So for:

• Blood sugar control
• Fat reduction
• High total sugar intake

It is more suitable to choose:

Lower-sugar version

For example, Yakult 1000 Sugar Off:

It still has:

100 billion CFU Shirota

But only:

• 43 kcal
• 9.4g sugar

Having less sugar does not mean 80% fewer bacteria.

36. Is Shirota the Best Probiotic?

It can't be said that way.

The correct question should be:

“For what purpose, which strain has the best evidence?”

For example:

Constipation → Certain Bifidobacterium strains may have more advantages

Antibiotic-associated diarrhea → Shirota is not the strain with the strongest evidence

Acute childhood diarrhea → Other strains/yeasts have stronger data

Stress and sleep → Shirota actually has relatively more research

General gut health → Shirota has quite good evidence and safety records.

This is the correct way to understand probiotics.

37. An Important Limitation of the Research

Although there are many studies on Shirota, there is a very obvious problem:

A considerable number of core studies are directly related to Yakult.

For example, many authors of stress, sleep, and immunity studies come from:

• Yakult Central Institute
• Yakult Honsha

The latest 2025 immune RCT is the same.

Large antibiotic-diarrhea RCTs also clearly disclose:

The study received funding from Yakult Honsha and the products and placebo were provided by Yakult.

This does not mean:

"The experiment is fake."

Randomized double-blind placebo trials are still valid scientific evidence.

But when evaluating evidence, you should consider:

The number of independent studies that have been repeatedly verified is still very important.

Therefore, you cannot evaluate it as a "magic bacteria" based on just a few positive papers.

38. The Evidence in One Sentence

After removing corporate promotion, the overall evaluation of Shirota is:

It is a mature probiotic strain with a very long safety record and a considerable number of human studies; its most reliable effect is reaching the intestines alive and regulating the intestinal environment and bowel movements. The 40 billion CFU level has human immune research support, and the 100 billion CFU level shows good results in stress and sleep quality studies for temporarily stressed populations; however, results for constipation, colds, NK cells, metabolism, and emotions show significant population differences and some negative studies, so it cannot be considered a drug.

If you just ask:

Is it purely a marketing concept?

The conclusion is:

No.

Shirota is a probiotic with real human RCT data.

But if you ask:

Will drinking Yakult 1000 every day necessarily lead to significant improvement?

The answer is also:

Not that strong.

39. How Healthy Adults Can Choose

If you just:

Want to maintain intestinal health long-term

→ 20 billion CFU/day is already reasonable.

Regular New Yakult is enough.

If the focus is:

Bowel + Immunity

→ A more suitable choice is:

Around 40 billion CFU/day.

If the focus is:

High mental stress + sleep easily affected by stress

→ Only then is there reason to consider:

100 billion CFU/day.

This does not mean:

Everyone needs to buy the much more expensive Yakult 1000.

For someone with normal bowel movements, normal sleep, and low stress:

20 billion CFU → 100 billion CFU

May not bring additional benefits that can be actually felt.

Conversely, if you are currently in a period of:

• Exams
• High-intensity work
• Long-term overtime
• Obvious stress periods

This dose of 100 billion CFU is closer to the conditions of existing stress/sleep experiments.

Shirota Comprehensive Rating

Scientific research volume: 9/10

Safety: 9/10 (for healthy people)

Gut evidence: 8/10

Bowel movement improvement: 7/10

Immune evidence: 6–7/10

Stress evidence: 7/10

Sleep evidence: 7/10

Cognition/Memory: 3/10

Metabolism/Weight loss: 2–3/10

Cancer prevention: Currently cannot be recommended for health purposes

Overall practical value: 7.5/10

Among the health ingredients that are "currently sold in Japan, suitable for long-term consumption, relatively safe, and have undergone substantial human research," the Shirota strain is indeed one worth keeping, rather than just a marketing concept.

Among health ingredients suitable for long-term consumption, Shirota can be listed as a top candidate for gut health and probiotics; claims regarding cognition, anti-aging, weight loss, and cancer prevention lack sufficient evidence and should not be mixed into its core value.