Lactic Acid gone to your head?

ataxia
D-Lactate Encephalopathy and Periodic Ataxia
Posted by Michael Twomey, Drexel MSIV, Class of 2014

Remember that pain in your side during a long hard workout? That’s the buildup of lactic acid or L-lactate which is a way for your body to burn energy when it there isn’t much oxygen around (like when you think it’s a good idea to run 5 miles). This feeling, although uncomfortable, won’t make you loopy–it’s twin brother, however, has no such qualms.

D-lactate is just like normal old lactic acid, only completely different. In fact, it is the mirror image of the molecule that causes us such grief. For those of us who have forgotten organic chemistry, or would rather walk on broken glass than take such a torturous class, think
of it like a pair of gloves. L-lactate would be your left hand glove and D-lactate the right. They look like the same darn thing from a distance (made out of the same leather and thread, and stuffing), but no matter how you rotate them, you could never get them to match up.

FIGURE 1

Our bodies happen to be finicky. Like the 7 year old fussy eater we all know and (hopefully still) love, the human body can only make and break down L-lactate. Thus, under factory settings, we all have an undetectable level of D-lactate in our blood. Bacteria, however, are wired a bit differently (shocking, I know). Some can take the same sugars that we eat, turn them into D-lactate, and when those buggers are in your intestinal system–this form of lactic acid can enter our blood stream.

Lactobacilli (the bad guys)

It just so happens that high levels of D-lactate effects the brain just as much as it does the rest of our bodies. We aren’t exactly sure the why or how this compound acts on our central nervous system, but it can cause anything from making you unbalanced to putting a patient in a delirious state. Case reports show symptoms of sleepiness, hallucinations, clumsiness, blurred vision, disorientation, dizziness, lethargy, excessive irritability, and abusive behavior. All of which can last up to a few days! The gait can be very unsteady (ataxic) during each episode, and this syndrome is one of the causes of “periodic ataxia”.

To make the diagnosis these patients also had an elevated amount of acid in their blood (something normal Lactic Acid can do as well) and high levels of D-lactate.
So can you blame the next time you trip over the doormat on bacteria? Probably not.
Fortunately the only reports of this syndrome have been found in people with extensive small intestine surgery. It turns out that the bacteria who can make D-lactate tend to live in our large intestine where they almost never see large amounts of sugar. Normally our small intestine is long enough to absorb all of those nutrients and leaving them to digest your Mexican meal instead. People with short bowel syndrome, however, should be aware of this possibility and eat appropriately. Otherwise having meals high in simple sugars could cause you to end up in the hospital with some strange behaviors and a nice long course of antibiotics!

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