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D-Lactate Acidosis: when bugs affect your brain.

If you have SIBO, Leaky Gut/Intestinal Permeability, Cognitive Problems like Chronic Fatigue Syndrome, Alzheimer’s disease, Dementia, or Parkinson’s disease, it’s important to be prevent from getting excessive D-lactate exposure.

Its exposure, can lead to worsening of the cognitive symptoms seen in these conditions like “brain fog”. More if you have “Brain Fog” symptoms it’s important to be evaluated for SIBO, Leaky Gut, or Gut Dysbiosis.

What is D-lactate? To understand it you must understand a little about carbohydrate metabolism. Lactate, the anion that results from dissociation of lactic acid, is an intracellular metabolite of glucose (carbohydrate); specifically it is the end product of anaerobic glycolysis, the final step of which is conversion of pyruvate to lactate by the enzyme lactate dehydrogenase. In other words it’s a byproduct of carbohydrate metabolism


Key point right here:

Lactate that is metabolized in mammals is only produced only in the L-lactate form. Yet in certain bacteria Lactate is metabolized the D-lactate form. When we say bacteria this includes opportunistic bacteria and also even some probiotics (more later). D-lactate and L-lactate are different forms of the same molecular substrate. They look a lot different to the body even though they are made up of similar components.

We are equipped to deal with the L-form but not so much the D-form. The enzyme that processes lactate in humans and bacteria is called Lactate Dehydrogenase (LDH). Humans only have L-form LDH and not D-form LDH. So in humans the only known way to process D-Lactate is through an alternative pathway that metabolizes D-lactate to pyruvate by the action of the mitochondrial enzyme D-2-hydroxyacid-dehydroganse.

Another Key point:

This system can easily get overwhelmed causing D-lactate levels to build causing a physiologic state of acidosis called D-lactic acidosis.

People with leaky gut or sibo will often complain of "Brain Fog" which is worse after consuming a higher carbohydrate meal.

In one study on brain fog , a mild form of D-lactic acidosis was more prevalent in patients with brain fog then without brain fog (77 vs. 25%) (Rao, Rehman, Yu, & De Andino, 2018).

A great majority of these patients accordingly had SIBO and were trying probiotics to help. Interesting getting rid of there probiotic and taking an antibiotic improved there brain fog.

Other symptoms can exist but likely as the D-lactic acidosis worsens into severe acidosis. In conditions like short bowel syndrome, Diabetes Mellitus, and with propylene glycol intoxication (yep Miralax) we can see severe acidosis symptoms.

The Symptoms of D-lactic Acidosis can include:

  • lack of muscle coordination (ataxia)

  • balance and gait issues

  • slurred speech

  • personality changes and irritability

  • Shortness of Breath.

  • memory loss (and brain fog, spaciness)

  • fatigue (chronic fatigue syndrome-like symptoms, tired, lack of energy)

  • again gas, bloating, distension, GI symptoms. (unclear whether this is an effect or cause of acidosis)

Take home message:

You have to be individualized if selecting your probiotic.

Look closely at the label of your probiotic.

Bifidobacterium species

Most Bifidobacterium species favor Acetate production rather then D-Lactate but they do produce a little bit of lactate due to some carbohydrate metabolism. (Quigley, Pot, & Sanders, 2018)

  • B. Bifidum, B. Infantis, B. Longum and most commercially used Bifidobacterium species should be D-lactate free.

  • I have identified some resources stating b.breve does produce D-lacate but most report that it produces L-lacate primarily (Quigley et al., 2018) (Takahashi et. al. 2013)

Many Lactobacillus species produces D-Lactate

  • Including Lactobacillus acidophilus , Lactobacillus bulgaricus, Lactobacillus lactis , Lactobacillus buchneri, Lactobacillus delbrueckii subsp. delbrueckii, Lactobacillus delbrueckii subsp. lactis, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus jensenii, Lactobacillus vitulinus

Some Lactobacillus species do not favor D-lactate and rather favorite L-lactate and should be better tolerated including:

  • L.Rhamnosus

  • Lactobacillus GG only produce L-lactate

  • L.salivarius (favors L-lactate but may produce some D-lactate, likely safe)

  • Lactobacillus plantarum appears to produce both but is considered to favor L-lactate.

Streptococcus species

  • It is understood that streptococcus species in probiotics produce D-lacate.


  • Some exogenous fermented foods such as sour milk, yogurt, and pickles also produce D-lactate.

Opportunistic pathogens

These species are known to produce D-lactate :

  • Enterococcus faecalis,

  • Streptococcus sanguinis

  • E. coli

  • Klebsiella pneumoniae,

  • Streptococcus bovis

  • Bacteroides fragilis

  • Candida freundii ca

These should be identified and removed if you have symptoms of intestinal permeability.

I use PCR testing of stool samples to identify these pathogens. We have integrative approaches to remove these bacteria if harmfully overgrown.

Final Key Point

Please don’t jump to the conclusion that the D-lactate producing species are bad for everyone;(Rao et al., 2018) It's only relevant if you have a chronic neurologic /brain condition and diagnosed intestinal permeability or bacterial overgrowth condition. Please don’t throw the probiotics out with the coconut water (sorry).

Reducing exposure of your body to D-lactate by healing the gut lining and clearing sibo and dysbiosis can lead to improved symptom in conditions that seem to be effected by the brain gut axis.

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