Which Probiotics Produce D-Lactate?

December 10, 2025 •

4 min read

An estimated 3.9 million people in the U.S. alone consume probiotics daily, yet many are unaware that certain strains can produce D-lactate. Understanding which probiotics produce D-lactate is crucial for individuals with specific health conditions, such as SIBO or mitochondrial dysfunction, to avoid potential adverse effects like neurological symptoms.

Quick Summary

Certain probiotic species, predominantly in the Lactobacillus genus, produce D-lactic acid as a byproduct of fermentation. This can lead to issues like brain fog in sensitive individuals or those with short bowel syndrome. Some Bifidobacterium strains are considered D-lactate-free.

Key Points

Lactobacillus is a primary producer: Many Lactobacillus species, such as L. acidophilus, L. plantarum, and L. delbrueckii, are known to produce D-lactate.
Bifidobacterium is generally D-lactate free: The Bifidobacterium genus does not typically produce D-lactate as a metabolic end product, making certain strains a safer choice for sensitive individuals.
D-lactate accumulation affects sensitive individuals: While harmless to most, D-lactate can build up in those with short bowel syndrome, SIBO, or compromised detoxification, causing symptoms like 'brain fog'.
Strain-specificity is important: The level of D-lactate production can vary significantly between individual strains, even within the same species.
Always check the label: For those sensitive to D-lactate, it is crucial to select brands that explicitly market themselves as 'D-lactate free' and list the specific strains used.
Consult a healthcare provider: Due to the complexities of gut health and individual tolerances, seeking professional medical advice before changing probiotic intake is essential.

Understanding D-Lactate Production

Lactic acid bacteria (LAB) are a group of microorganisms known for producing lactic acid through carbohydrate fermentation. This acid exists in two isomeric forms: L-lactate and D-lactate. While the human body efficiently metabolizes L-lactate, some individuals, particularly those with conditions affecting gut motility or metabolism, may struggle to process D-lactate efficiently. The inability to clear D-lactate from the system can lead to its accumulation in the bloodstream, resulting in a condition known as D-lactic acidosis.

Lactobacillus: A Common D-Lactate Producer

The Lactobacillus genus is one of the most prominent groups of probiotics associated with D-lactate production. A wide range of species within this genus produce D-lactic acid, as well as L-lactic acid or a mix of both. Some of the most common Lactobacillus species that produce D-lactate include:

Lactobacillus acidophilus: A staple in many probiotic supplements, L. acidophilus can produce D-lactic acid.
Lactobacillus plantarum: This strain produces both L- and D-lactate. Research has shown that deleting the gene for L-lactate production results in L. plantarum producing D-lactate exclusively.
Lactobacillus delbrueckii subsp. bulgaricus: One of the traditional bacteria used in yogurt, this subspecies is also known to produce D-lactate.
Lactobacillus brevis: This species can produce both D- and DL-lactate.
Lactobacillus reuteri: Often included in multi-strain formulas, L. reuteri is another known D-lactate producer.
Lactobacillus fermentum: Several sources confirm this species' ability to produce D-lactate.

The Case of Bifidobacterium

In contrast to many Lactobacillus strains, the Bifidobacterium genus does not typically produce D-lactate as a metabolic byproduct. This is a key distinction for individuals seeking probiotics without D-lactate. Brands like Custom Probiotics use specific Bifidobacterium strains, alongside selected Lactobacillus strains, that are formulated to be D-lactate-free. The safety of D-lactate-producing strains, even within the Lactobacillus genus, is often strain-specific and varies among individuals. While Bifidobacterium species generally don't produce D-lactate, it is essential to be aware that some species, such as Bifidobacterium longum subsp. infantis, can produce both isomers, albeit in lower amounts than many Lactobacillus species.

Potential Risks and Underlying Conditions

For most healthy individuals, the D-lactate produced by probiotics is not an issue, as the body can clear it effectively. However, in people with underlying health conditions, D-lactate can accumulate to problematic levels. The primary risk is D-lactic acidosis, a metabolic condition that can cause neurological symptoms. People most at risk include those with:

Short Bowel Syndrome (SBS): Due to extensive small intestine resection, undigested carbohydrates reach the colon, fueling an overgrowth of D-lactate-producing bacteria.
Small Intestinal Bacterial Overgrowth (SIBO): SIBO can involve an overgrowth of bacteria, including lactobacilli, in the small intestine, leading to increased D-lactate production and associated symptoms like brain fog.
Leaky Gut and Compromised Detox Pathways: For these individuals, even minor amounts of D-lactate can cause adverse neurological symptoms, as their body's ability to clear the substance is impaired.

Comparison of D-Lactate Producing vs. Non-Producing Probiotics


Feature	D-Lactate Producing Probiotics	D-Lactate Free Probiotics
Common Species	Lactobacillus acidophilus, L. plantarum, L. delbrueckii subsp. bulgaricus, L. reuteri	Bifidobacterium lactis, Bifidobacterium longum (often D-lactate free strains), L. salivarius, L. rhamnosus GG (note: L. rhamnosus can produce D-lactate, but specific strains may be D-lactate-free)
Production	Produces D-lactic acid as a metabolic byproduct	Specific strains are engineered or selected to produce little to no D-lactic acid
Potential Concern	Can contribute to D-lactic acidosis and neurological symptoms in susceptible individuals	Generally safer for individuals sensitive to D-lactate, including those with SIBO or SBS
Best For	Generally healthy individuals with no history of D-lactate sensitivity or related conditions	Individuals with SIBO, SBS, brain fog, or compromised detoxification systems

Choosing the Right Probiotic

Selecting the right probiotic requires understanding your health status and any potential sensitivities. For those with a history of SIBO, short bowel syndrome, or unexplained brain fog after taking probiotics, choosing a D-lactate-free formula is recommended. Always consult with a healthcare provider before starting a new supplement regimen, especially if you have an underlying medical condition.

Conclusion

The question of which probiotics produce D-lactate is critical for targeted health supplementation. Many species within the Lactobacillus genus are known producers, including L. acidophilus and L. plantarum. In contrast, the Bifidobacterium genus, with exceptions, is generally considered D-lactate-free. While most healthy people tolerate D-lactate without issue, it can be problematic for those with short bowel syndrome or SIBO, potentially leading to D-lactic acidosis and neurological symptoms. Therefore, careful selection of strain-specific probiotics is essential for those with sensitivities or underlying conditions. Individuals experiencing adverse effects should consider switching to a D-lactate-free alternative and consulting a healthcare professional for guidance. The key is to prioritize individual needs and select probiotics with transparency about their strain characteristics.

Frequently Asked Questions

D-lactic acidosis is a rare metabolic condition characterized by the accumulation of D-lactic acid in the blood, leading to neurological symptoms. It is most commonly seen in patients with Short Bowel Syndrome (SBS), who have a large portion of their small intestine removed, allowing undigested carbohydrates to reach the colon and be fermented by D-lactate-producing bacteria.

For some sensitive individuals, yes. People with SIBO or leaky gut may experience neurological symptoms like 'brain fog' and fatigue after taking probiotics that produce D-lactate, as their body struggles to clear the compound.

No, not all Lactobacillus strains produce D-lactate. However, many common probiotic species, including L. acidophilus and L. plantarum, are known to produce it. Production can also be strain-dependent, with some strains producing less D-lactate than others.

Symptoms can include confusion, slurred speech, ataxia (poor coordination), and other neurocognitive issues. The condition is rare and usually associated with underlying gut disorders rather than probiotic use in healthy individuals.

You should check the product label for specific strains. Strains from the Lactobacillus genus are more likely to produce D-lactate. If you are sensitive, look for products explicitly labeled 'D-lactate free' and ask your healthcare provider or a knowledgeable pharmacist for guidance.

L-lactate is the form of lactic acid most readily produced and metabolized by the human body during normal metabolism. D-lactate is less common in humans and primarily produced by certain bacteria. In healthy individuals, both are cleared efficiently, but metabolism of D-lactate can be compromised in certain health conditions.

For healthy people with a functional digestive system, the risk is generally considered negligible. Their bodies can effectively clear any D-lactate produced. Issues typically arise only in those with pre-existing conditions that impair D-lactate metabolism.