Yakult Benefits and Possible Side Effects

9+ Potential Yakult Benefits & Possible Side Effects

As a probiotic yogurt drink, Yakult inherently offers a slew of potential health benefits.  Some Yakult benefits include, but aren’t limited to: improved gut health, reduced symptoms of depression and anxiety, enhanced immunity, reduced inflammation, and more. 

However, on the other hand, Yakult may not necessarily be healthy for everyone, since one size never fits all.  Like all other foods, there are a few possible side effects of Yakult worth considering.

In this article we’ll unpack the pros and cons, potential benefits, and side effects of Yakult, based on a fusion of the latest research and real-life clinical experience.

Disclaimer:  This article was written for general educational purposes, not to be taken as medical or nutritional advice.  Consult with your doctor and a gut health dietitian nutritionist for custom advice tailored to your bio-individual needs!

What is Yakult?

Yakult is a 2.7-ounce fat-free yogurt drink and functional probiotic food which, at first glance, may seem very similar to kefir.

The key difference between Yakult versus “kefir” (a more broad category and spectrum of fermented yogurt drinks) is that Yakult uniquely contains the Lacticaseibacillus paracasei probiotic strain, Shirota.

This probiotic strain can withstand the harsh acidity of our stomach acid, making it a hot commodity to say the least.

Yakult was originally created by company founder Dr. Minoru Shirota in Japan in 1935, and is now sold in over 40 different countries worldwide.

Ingredients and nutrition facts

Regular Yakult

Ingredients  
  • Water
  • Sugar
  • Non-fat milk
  • Glucose
  • Natural flavors
  • Lacticaseibacillus paracasei strain Shirota
Nutrition per bottle (2.7 ounces, or 80 milliliters)
  • Calories:  50
  • Fat:  0 grams
  • Cholesterol:  0 grams
  • Sodium:  15 milligrams
  • Total carbohydrates:  12 grams
  • Total sugar:  10 grams
  • Added sugar: 9 grams
  • Protein:  1 gram
  • Calcium:  40 milligrams
  • Potassium:  50 milligrams 
  • Vitamin D:  0 micrograms
  • Iron:  0 milligrams

Yakult Light

Ingredients

  • Water
  • Non-fat milk
  • Corn dextrin
  • Sugar
  • Glucose
  • Pectin 
  • Natural flavors
  • RebA (stevia extract)
  • Lacticaseibacillus paracasei strain Shirota
Nutrition per bottle (2.7 ounces, or 80 milliliters)
  • Calories:  25
  • Fat:  0 grams
  • Cholesterol:  0 grams
  • Sodium:  15 milligrams
  • Total carbohydrates:  12 grams
  • Total sugar:  10 grams
  • Added sugar: 9 grams
  • Protein:  1 gram
  • Calcium:  40 milligrams
  • Potassium:  50 milligrams 
  • Vitamin D:  0 micrograms
  • Iron:  0 milligrams

Potential benefits and perks

Probiotics are less transient

The majority of probiotic strains and even many probiotic foods on the market could be considered “transient”  in that their benefits are fleeting, especially if you aren’t taking them alongside prebiotic foods/supplements.

What makes Yakult unique is that its probiotic Lacticaseibacillus paracasei strain Shirota seems to be able to live in our gut, withstand the harsh acidity of our stomach acid, and stay in our system for significantly longer. (1, 2, 3)  

This makes it more convenient and more effective in that you don’t need to take Yakult with food in order for its beneficial probiotic strains to reach your colon.

May help with constipation

A 2021 Nutrients study found that Yakult optimized gut microbes (feeding the good stuff, whale reducing the harmful gut pathogens) among people with depression, leading to less constipation. (4

It doesn’t stop there!  A 2023 study conducted among people with Parkinson’s disease (PD) showed very similar findings. 

  • In this study, Yakult was helpful in improving bowel regularity and reducing symptoms of constipation among participants with PD. (5)

Reduced stress-induced gut dysfunction in medical students

A 2016 study found that drinking Yakult once daily for just 8 weeks leading up to final exams was enough to significantly reduce stress-induced gastrointestinal dysfunction (upset stomach) among medical students, leading up to exams. (6)

May help reduce depression

There’s a strong gut-brain connection, which you may have heard of as the “gut-brain axis.”

That’s because the presence (or lack thereof) of certain beneficial probiotic microbes in our gut seem to be inversely correlated with symptoms of depression and other mental health conditions.

(Translation:  MORE good bacteria = LESS likelihood of developing depression… and having LESS beneficial probiotic microbes in your gut = increased risk of depression.)

In a 2021 study by Microorganisms, a small group of 18 participants with major depressive disorder (MDD) or bipolar disorder were given the Lacticaseibacillus paracasei strain Shirota for just 12 weeks, and reported significant improvements in depressive symptoms. (7)

Could help reduce cortisol levels among the stressed

A 2016 randomized control trial published by Neurogastroenterology and motility found that just 8 weeks of daily Yakult was effective at reducing excessive cortisol production (a stress hormone) by stimulating the vagus nerve (part of our gut-brain axis), compared to the placebo. (8)

(The mechanism is still unclear, but this benefit reminds me of what we’re seeing in adaptogenic mushrooms and other types of adaptogenic herbs which modulate or “optimize” our physiological response to stress.)

While more research is needed, these findings are groundbreaking for those dealing with physiological symptoms of chronic stress – something we see a lot of, nowadays!

May benefit oral health 

Did you know that digestion starts in the mouth, and the mouth (aka our “oral cavity” is a part of our gastrointestinal tract?

That being said, it isn’t too surprising that just 4 weeks of Yakult (taken 1x/day) helped reduce infectious bacteria and plaque among participants who started out at increased risk of plaque and dental infections, in a 2013 study. (9)

Likely supports immune system resilience 

Probiotics like the special strain in Yakult seem to have an effect similar to adaptogens in that they work synergistically with our bodies to strengthen and optimize our innate immune system response to threats.

For example, drinking Yakult just once daily for 6 weeks was shown to have a balancing and optimizing effect among participants, on the cellular level, according to a 2023 randomized, double-blind controlled clinical trial. (10)

(This isn’t too surprising, since ~70% of our immune system is intimately synced with our gut!)

May have anti-cancer properties

While more research is needed before making any claims, a few studies have alluded to the possibility that Yakult might help inhibit cancer cell growth.

The first study was done on rodents in 1998 – so while it’s got limitations, it’s still worth knowing about!  In this study by the International journal of food microbiology, orally-administered Yakult inhibited the growth of various cancer cells in mice and other rodents via altering the immune system. (11)

A more recent Molecules study from 2018, which included human participants, found that the special probiotic strain found in Yakult was able to enhance the effectiveness of a substance which inhibits oral cancer growth in humans. (12)

This is a big deal, if you ask me!  (More research is called for, but I think it warrants hope and inspiration.)

May help reduce inflammation 

Inflammation is a modern-day epidemic we’re noticing on-the-rise, in my field of holistic nutrition, as well as in functional and integrative medicine.

More specifically…

A common, yet little-known, way that we may get “inflamed” at the root-cause level is via certain pathogenic gut microbes in our gut:  they inflame us by releasing an inflammatory substance called “lipopolysaccharides” (aka “LPS”). (13, 14, 15)

These inflammatory substances (the “LPS” particles) become a huge problem when they cross a leaky gut barrier and enter into our bloodstream systemically. (15, 16, 17)

On this level, like many other probiotic foods and supplements, the probiotic Lacticaseibacillus paracasei strain Shirota (found in Yakult) was shown in a 2013 study to help prevent diet-induced hepatitis, as well as reduce inflammation in rodents by lowering LPS levels, while also protecting the colon from LPS-induced damage. (18)

Another study concluded that Yakult’s probiotic Lacticaseibacillus paracasei strain Shirota helped significantly reduce oxidative stress (cell damage) among septic (poisoned) mice by altering and optimizing their immune systems. (19)

(While I always prefer studies conducted in humans versus in rodents, this is pretty consistent with what we’ve seen in other probiotic foods and I think it’s generally very promising!)

May enhance optimal wellbeing and performance at work

As we covered earlier, Yakult and its probiotic strain clearly have a benefit on the gut-brain axis.

But what’s even more exciting is this potential benefit isn’t limited to people who are feeling depressed, anxious, stressed or lousy!

A small double-blind, randomized, crossover, placebo-controlled trial by Nutrients (published in 2023) uncovered that in just 4 weeks, 1 daily serving of Yakult significantly improved and optimized energy levels, perceived mood, sleep patterns, and heart rate variability among 12 healthy adults with sleep complaints. (20)

Again, while this sample is very small, and only one study was conducted, it’s an interesting and noteworthy pattern. 😉 

Are there any Yakult benefits for skin?

There aren’t any direct studies investigating the benefits of Yakult for skin.

However, given what I just mentioned in the above section, it’s clear Yakult can potentially help reduce inflammation and oxidative stress, while improving and optimizing our gut microbes.

Each of those factors could significantly impact our skin, since higher levels of inflammation and oxidation (cell damage) and unhealthy gut microbes could increase the likelihood of skin breakouts and even faster aging.

TLDR:  While we don’t have any formal data to confirm or deny it, Yakult most likely supports healthier skin indirectly, by supporting healthier gut microbes, reducing inflammation and protecting our liver.

Possible side effects

Gas and bloating

Introducing a new probiotic strain into your gut is beneficial for the majority of people, but not for everyone.  (That’s why I can never emphasize biochemical individuality enough!)

For example, many of my clients have reported feeling gassy and bloated after trying a new probiotic.  This is generally more likely to happen if you have an underlying case of small intestinal bacterial overgrowth (SIBO).  

  • In my clinical experience, many types of probiotic foods and supplements on the market (which are generally beneficial) can actually make SIBO symptoms like gas and bloating worse.

When in doubt, listen to your body and consult a qualified practitioner!

Lactose intolerance

Yakult is made with cow’s milk, and contains small amounts of lactose (milk sugar).

While this isn’t inherently bad, and there’s only about 1 gram of lactose per bottle of regular Yakult (based on subtracting the total 9.5 of added sugar from the 10.5 grams of total sugar), I’ve noticed not all, but many of my clients with irritable bowel syndrome (IBS) and/or small intestinal bacterial overgrowth (SIBO) tend to be lactose intolerant- on a spectrum.

(The small quantities of lactose in Yakult are most likely easier to digest for most people compared to the 12 grams of lactose in a glass of milk, but this isn’t always the case.)

TLDR:  if you have issues with lactose, you may or may not tolerate the lactose in Yakult.  If not, consider checking out my fave low FODMAP (lactose free) yogurts on the market!

Casein intolerance

Yakult contains casein, a type of dairy protein.  Again, this isn’t inherently bad.  However…

If you’re someone who notices that low FODMAP, lactose free dairy products still don’t sit well, it’s possible your body might not tolerate the casein in Yakult.

(Note that the majority of milk nowadays is made with A1 versus A2 milk; many people are intolerant to the casein in A1 milk but can still drink A2 milk without any issues.  Read more about A1 versus A2 milk here!)

If you have an intolerance to the casein in A1 cow’s milk (found in Yakult), consider trying a kefir made with goat milk, sheep milk, A2 milk, or a dairy free milk alternative. 

Dairy sensitivity

A dairy sensitivity is different from a lactose intolerance and a casein intolerance in that it’s your immune system (versus your gut) reacting to certain constituents in cow’s milk.

Symptoms of a sensitivity to cow’s milk / dairy constituents may include, but aren’t limited to:

  • Diarrhea
  • Skin rashes
  • Headaches/migraines
  • Fibromyalgia
  • Extreme fatigue
  • Depression/anxiety

(Read more about the difference between lactose intolerance versus dairy sensitivity here!)

TLDR:  If you’ve confirmed or suspected a sensitivity to dairy (i.e. even low FODMAP, very low casein forms of dairy like butter and ghee seem to be triggering symptoms of inflammation), you may be better off with a dairy free kefir.

Added sugar

As noted earlier, regular Yakult contains ~9.5 grams of added sugar per 2.7 ounce bottle, in the form of glucose and sucrose (table sugar).  

There are a few reasons why this isn’t ideal, from a gut health nutrition standpoint. 

Glycemic index

If you have a medical condition impacted by blood sugar levels, you may want to opt for Yakult Light, which has only 3 grams of total sugar and 1 gram of added sugar per bottle.

Candida and dysbiosis

Significant quantities of added refined sugar in the diet have been shown to be generally detrimental for our gut microbes, from a functional nutrition standpoint.  

That’s because a diet high in refined sugar may potentially feed “bad” gut microbes… aka, the kind linked with IBS and dysbiosis. (21)

This may be another reason to opt for Yakult Light, versus the regular version of Yakult.

Sucrose intolerance

Many people with IBS symptoms interested in trying out Yakult to help with their chronic diarrhea and upset stomach may not yet be aware that the underlying cause of their IBS symptoms is actually a sucrase-isomaltase deficiency.

If that applies to you, it means your gut is missing the digestive enzyme that breaks down sucrose (sugar) in food. 

Recommended reading:

TLDR:  Both versions of Yakult contain at least some sucrose.  If you have or suspect a sucrose intolerance, Yakult will likely trigger unwanted sucrose intolerance symptoms. 

If that’s the case, consider consulting your treatment team about trying Yakult Light in combination with enzyme replacement therapy (such as Sucraid® or Starchway), or you could also try a sucrose-free alternative to Yakult such as plain kefir/yogurt as tolerated.

Corn allergy/sensitivity 

It’s worth mentioning that a certain percentage of my private practice clients have uncovered via the Mediator Release Test (MRT) that they have a sensitivity to corn. 

This is relevant because Yakult Light contains ingredients derived from corn – specifically in the form of corn dextrin and pectin.

TLDR:  If you’re finding that Yakult triggers food sensitivity symptoms like migraines, sudden fatigue, diarrhea, skin rashes, etc… you may want to opt for a plain kefir (or possibly regular Yakult).

Frequently asked questions (FAQ’s)

When is the best time to drink Yakult?

According to Yakult’s FAQ page, it’s best to find a time of day that works well for you practically, so you can be consistent.  

Since Yakult, unlike other probiotic foods, has a unique strain of bacteria that can endure and withstand our stomach acid pH, it doesn’t necessarily need to be taken with food.  It just needs to be taken consistently.

(Think: 1x daily!)

Is Yakult low FODMAP?

No; technically, Yakult doesn’t make the cut.

According to the Monash University FODMAP App, up to 0.5 gram of lactose or less per serving is considered low in FODMAPs.

But if you look at the Yakult nutrition fact label, there’s ~1 gram of lactose per serving of Yakult. (I calculate this by subtracting the number of grams of added sugar from the number of grams of total sugar, per serving.)

However, this doesn’t necessarily mean you won’t be able to tolerate Yakult.  It just means you can’t include it in the initial phase of a low FODMAP elimination diet.

Remember a low FODMAP diet shouldn’t be followed long-term but rather for ~6 weeks, so you can get your IBS symptoms under control and then test/re-introduce higher FODMAP foods one at a time, by category – to determine what you can and can’t tolerate.

TLDR:  Yakult is not low FODMAP, but it may still be IBS-friendly.

Is Yakult good for anemia?

No; Yakult won’t benefit iron deficiency anemia.  (This may seem confusing, since probiotics may sometimes help to enhance iron absorption as noted in my article all about iron supplements and probiotics!)

How it works:  Yakult is high in calcium from the milk.  Calcium  reduces iron absorption because calcium and iron compete for the same absorption sites in the gut.)

However, this  doesn’t make Yakult inherently bad for iron deficiency anemia, as long as you’re drinking it at least a few hours apart from iron supplements or herbs high in iron.

Is Yakult good for GERD and heartburn?

There aren’t any formal research studies specifically investigating the benefits of Yakult for heartburn and gastroesophageal reflux disease (GERD).

However, generally, research does show us that probiotic-rich foods like yogurt and kefir can potentially benefit our gut microbiome in ways that could support GERD/heartburn.

It could be worth giving Yakult a try to see for yourself!  (Consult your treatment team if you’re unsure.)

When is Yakult good for diarrhea, and when does it make diarrhea worse?

Yakult could potentially help or worsen your symptoms of diarrhea, depending on your biochemical individuality.

People with simple cases of IBS caused by dysbiosis (unbalanced gut flora) are more likely to benefit from Yakult compared to people with severe intolerance/sensitivity to some or multiple ingredients in Yakult like milk proteins, lactose, added sugar, or even the corn which is in Yakult Light.

Everyone’s situation is unique so consult with your treatment team (a doctor and a gut health dietitian) for help and guidance pinpointing any potential adverse food reactions (food allergies, sensitivities, and/or intolerances).

Is Yakult good for candida?

Based on the research, the probiotic benefits of Yakult seem to outweigh the added sugar, which can potentially feed candida overgrowth if consumed in excess.

But all in all, I believe this really depends on your bio-individuality.  

At the end of the day, the best data and feedback we can get comes directly from our own body.

If you notice you’re among the many who feel better drinking Yakult, chances are it’s helping to balance out your candida levels. 

On the other hand, if you feel worse, you may want to consider other options for addressing candida overgrowth.

More resources and related articles

Final verdict

Yakult offers LOTS of potential research-backed benefits!

These include but certainly aren’t limited to:

  • Improved digestion (reduced constipation)
  • Improved mental health
  • Enhanced wellbeing
  • Reduced inflammation
  • More resilient immunity

…when consumed consistently, in moderation (i.e. once daily).

On the other hand, it’s always possible to experience an adverse reaction.

I’ve found adverse reactions and side effects of Yakult may be more likely to occur if you have:

  • Small intestinal bacterial overgrowth (SIBO)
  • Severe lactose intolerance/dairy sensitivity
  • Casein intolerance/allergy
  • Blood sugar imbalance
  • Acne
  • Corn sensitivity

Yakult Light may be a healthier choice, if you’re noticeably impacted by lots of added refined sugar.

The best way to know for sure if Yakult is right for you is to listen to your body. 

And as always, remember to consult with your treatment team 1-1 as needed.

Next steps

If you’d like to learn more about nutrition for gut health, make sure to download a copy of my free gut health nutrition guide: 5 Diet Mistakes to Avoid When Healing Your Gut!

Free Download - 5 Diet Mistakes to Avoid When Healing Your Gut - by Jenna Volpe RDN LD CLT

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