What is Yakult 400? An In-Depth Look at the High-Potency Probiotic Drink

November 22, 2025 •

4 min read

First launched in Japan, Yakult 400 is a high-potency probiotic drink that contains a significantly higher concentration of the beneficial Lacticaseibacillus paracasei strain Shirota compared to the original version, designed for enhanced digestive and immune support. Unlike the standard Yakult, the '400' variant was developed to provide a more intensive dose of probiotics to strengthen the gut microbiome.

Quick Summary

Yakult 400 is a fermented milk drink with a very high concentration of the unique Shirota strain bacteria, formulated to promote a balanced intestinal flora and strengthen immunity by increasing beneficial bacteria.

Key Points

High Probiotic Count: Yakult 400 contains a very high concentration (~40 billion) of the unique L. paracasei strain Shirota per bottle, significantly more than the original version.
Enhanced Digestive Support: The large number of live bacteria reaches the intestines to improve the balance of gut flora, which can aid in better bowel function and regularity.
Boosted Immunity: A healthier gut, fostered by the high probiotic count, can lead to a stronger immune system, helping the body resist infections.
Shirota Strain Survival: The specific strain used in Yakult is fortified to survive the stomach's gastric juices, ensuring a high number of beneficial bacteria reach the gut alive.
Daily Habit: For continuous health benefits, Yakult 400, like other probiotics, must be consumed daily to replenish the transient bacteria in the gut.
Variant Options: Options exist for different needs, including lower-sugar variants like Yakult 400LT and products like Y1000 in Japan, which also claim to help with stress and sleep.

Unpacking the Potency of Yakult 400

At its core, Yakult 400 is a fermented milk drink, but it is defined by its substantial quantity of live, beneficial bacteria. While the classic Yakult contains a significant number of probiotics, the '400' designation in Yakult 400 refers to its much higher concentration of the exclusive Lacticaseibacillus paracasei strain Shirota (LcS). This powerhouse version was developed to provide a more potent effect on the intestinal environment, contributing to a robust and balanced gut flora. As with all probiotic products, the effect of Yakult 400 is temporary, meaning daily consumption is required to maintain the desired levels of good bacteria in the gut.

What Makes the Shirota Strain So Special?

The LcS strain, discovered by Yakult's founder Dr. Minoru Shirota, is the central pillar of all Yakult products. This specific strain of lactic acid bacteria is uniquely formulated to be strong enough to survive the stomach's harsh digestive acids and bile, ensuring it reaches the intestines alive and in large numbers. Once in the gut, it helps to suppress harmful bacteria and increase the count of beneficial microorganisms like Bifidobacteria. By promoting a healthy balance, the Shirota strain supports overall digestive function and helps bolster the body's natural immune defenses.

The Composition: Key Ingredients

Beyond its probiotic content, Yakult 400 has a simple ingredient list, making it a functional food rather than a medicine. The core components are:

Water: The base liquid for the fermented drink.
Skim Milk Powder: Provides the nutrients for the bacteria to ferment.
Sugar/Sweeteners: A small amount of sugar is typically added for both taste and to act as a nutrient source for the live bacteria. Variants like Yakult 400LT or other 'light' versions use sweeteners like stevia to reduce calories.
Natural Flavors: Gives the drink its characteristic citrusy taste.
Lacticaseibacillus paracasei strain Shirota: The star ingredient, present in a very high concentration.

It is also fat-free and cholesterol-free, making it a suitable dietary addition for many people. However, those with severe lactose intolerance should consult a doctor, although the lactose content is low.

The Health Benefits of Daily Consumption

Consuming Yakult 400 daily is associated with several health benefits, particularly centered around the gut-immune axis. Approximately 70% of the body's immune cells reside in the digestive system, making gut health a critical component of overall well-being. The potential benefits include:

Improved Digestive Function: The live LcS bacteria help to improve the balance of intestinal flora. This can aid in better bowel movements and help alleviate symptoms of both constipation and diarrhea. Research has demonstrated that daily consumption can improve stool consistency.
Enhanced Immunity: By promoting a healthy gut environment, the Shirota strain stimulates immune cells, helping the body fight off infections. Some evidence suggests regular intake can reduce the risk of upper-respiratory tract infections.
Potential Stress Reduction and Sleep Improvement: Specific variations of the 400 series, such as Yakult Y1000 in Japan, are classified as foods with functional claims related to reducing stress and improving sleep quality under temporary mental stress. This highlights the growing research into the gut-brain connection.
Better Nutrient Absorption: A healthier gut environment can lead to more efficient absorption of nutrients from food.

How Does Yakult 400 Compare to Other Variants?

To understand what is Yakult 400, it helps to compare it with the standard Yakult and other special versions. The primary difference lies in the concentration of the Shirota strain.


Feature	Yakult Original	Yakult Light	Yakult 400	Yakult 400LT	Y1000 (Japan)
Probiotic Count (per bottle)	~6.5 billion LcS	~6.5 billion LcS	~40 billion LcS	~40 billion LcS	100 billion LcS
Bacteria Strain	L. paracasei Shirota	L. paracasei Shirota	L. paracasei Shirota	L. paracasei Shirota	L. paracasei Shirota
Calories	~60 kcal	~25 kcal	Varies by region (~70-90 kcal)	~30% less than 400	Varies by region
Sweeteners	Sugar, glucose	Stevia, sugar	Sugar, glucose	Stevia, sugar	Specific sweeteners
Key Benefit	Digestive health, immunity	Digestive health, lower calories	Enhanced digestive & immune support	Enhanced support, reduced sugar	Stress reduction, sleep improvement
Availability	Worldwide	Varies by region	Limited regions, often via delivery	Limited regions	Japan, often via delivery

Conclusion: A Targeted Probiotic Solution

In summary, what is Yakult 400 is not just a standard probiotic drink but a high-concentration, targeted functional food developed to deliver a powerful dose of the beneficial Lacticaseibacillus paracasei strain Shirota. Its purpose is to more effectively restore the balance of gut flora, thereby enhancing digestive and immune health. While the original Yakult provides solid probiotic support, Yakult 400 is for those seeking a more potent daily dose. Variants like the 'LT' version cater to individuals mindful of their sugar and calorie intake, while others, like the Y1000, target more specific health outcomes like stress and sleep. For those committed to consistent probiotic intake for maximal gut health benefits, Yakult 400 represents a scientifically-backed, high-efficacy option within the Yakult family of products. For further reading on probiotic efficacy and gut health, a clinical study on Yakult's effect on stool consistency offers compelling evidence.

Frequently Asked Questions

The main difference is the concentration of the beneficial Lacticaseibacillus paracasei strain Shirota bacteria. While the original has billions, Yakult 400 has approximately 40 billion per bottle, providing a more potent probiotic dose.

Yes, daily consumption is recommended to maintain a balanced gut flora and its associated benefits. The probiotic strain is transient and needs to be replenished regularly.

Some individuals may experience temporary bloating or gas as their digestive system adjusts to the new beneficial bacteria. People with severe lactose intolerance or compromised immune systems should consult a doctor.

While generally safe for children who have started weaning, it's best to consult a pediatrician before introducing it to infants. For older children, it can be a beneficial part of their daily diet.

Yes, studies have shown that the probiotic strain in Yakult can help improve bowel movements and stool consistency, which can provide relief from constipation.

Yes, there is a variant called Yakult 400LT (Lite) available in some markets, which has reduced sweetness and fewer calories compared to the standard Yakult 400.

Yakult 400 can be enjoyed at any time of the day as a functional food. What is most important is to consume it consistently every day, rather than the specific time of day.