What Is Lactic Acid?
What Do Lions Teach About Lactic Acid and Limbic
from What Do Lions Know About Stress? (1996)
Majid Ali, M.D.
"What do lions know about lactic
acid?" Choua asked me during a safari trip in Kenya
"I thought we were through with chemistry," I
"Lactic acid is the guardian angel molecule for
antelopes," he murmured.
"I thought you asked me about lions and lactic
acid. Are we on to antelopes now? Tell me, what
makes lactic acid a guardian angel molecule for
"Lactic acid is a guardian angel molecule for
lions," he mumbled.
"Will you make up your mind?" I asked, perplexed,
"Are you talking about lions or antelopes?"
"It's the same thing, isn't it?" he grinned.
"Lions are not antelopes, nor antelopes lions," I
countered. "Is lactic acid a guardian molecule for
lions or for antelopes?"
"For both," he replied calmly. "It saves
antelopes from lions and lions from themselves."
"Saves lions from lions?" I asked, irked by his
cryptic words. "What do you mean it saves lions from
"Just as it saves antelopes from lions."
"Speak plainly, will you? How does lactic acid
save antelopes from lions and lions from
"It's simple," he grinned. "Think about it. What
does lactic acid do in muscles?"
Lactic acid is an interesting molecule of human
energy pathways. It is produced from its precursor,
pyruvic acid, during the metabolism of
carbohydrates, fats and proteins. It is a cul-de-sac
molecule—once produced in tissues, it cannot be
All food substances are metabolized to release
chemical bond energy contained in them for various
body functions. After initial steps in their
breakdown are completed, partially digested fat,
protein and carbohydrate molecules enter a metabolic
cycle called Krebs cycle. Next, the enzymes of this
cycle break down those food molecules into pyruvic
acid, and finally into water and carbon dioxide.
At rest in health, sufficient oxygen is available
to completely break down pyruvic acid. Under these
conditions, pyruvic acid is anaerobically (without
oxygen) converted into lactic acid, only in minute
quantities. Whatever amounts of lactic acid are so
produced eventually get converted back into pyruvic
acid, then broken down further into water and carbon
In many states sufficient oxygen is not available
for complete metabolism of food molecules in Krebs
cycle. The metabolic steps are then arrested at the
level of pyruvic acid. Some of the excess pyruvic
acid so produced is turned into lactic acid that
accumulates into tissues, producing a condition
called lactic acidosis. Acidosis, of course, is a
condition of excess acidity that is detrimental to
many biologic processes of the body. Specifically,
it inhibits many essential energy and detoxification
When a sprinter sprints, muscle tissue burns
sugar rapidly to release the required energy for the
sprint. When oxygen in tissues has been used up,
pyruvic acid cannot be broken down further, and
instead is converted into lactic acid. Excess lactic
acid, in turn, shuts off energy and detoxification,
forcing the sprinter to break his sprint.
Thus, lactic acid may be considered a limiting
factor in intense physical activity.
But, why did Choua bring the subject of lactic
acid in a discussion about stress, I wondered? I
looked at him for clues. He was looking at the
distant horizon, deeply absorbed in his thoughts.
"How does lactic acid save an antelope from a
lion?" I pulled Choua out of his reverie.
"Lions have everything going for them, antelopes
nothing—except for lactic acid in the lions'
muscles," he replied without turning to face me.
"Ah, I get it now. Lactic acid is a fatigue
molecule. Its accumulation in the lion's muscles
turns off the energy enzymes in those muscles."
"Yes," Choua continued. "The mitochondria—those
cellular powerhouses—in lions' muscle cells need
oxygen to keep humming. Why do you think lions stop
midway in the hunts so often?" he grimaced.
"Because lactic acid build-up inactivates energy
enzymes in the lion's legs and stops the lion dead
in his ballistic charge. The poor antelope has a
chance to escape. Right?" I asked.
"Right," Choua replied.
"Lactic acid accumulation—lactic acid debt, as it
is called, switches off oxidative enzymes that
oxidize foods for release of energy—keep the
oxidative enzymes of Krebs's energy cycle humming,"
"Right!" Choua's eyes lit up. "That's what
happens in the lion muscle cells. Wouldn't it be
nice if things were that simple for humans?" he
murmured, raised his eyebrows, then turned his gaze
at the distant hills.
In physiology class I learned that the human body
spends considerable energy to maintain a state of
slight alkalinity of blood and fluid that bathes
cells at all times. Thus, accumulation of excess
lactic acid first exhausts the acid-alkali buffering
capacity of the body, then makes it difficult for
the body to maintain its normal alkaline state.
Since all enzymes (catalysts) of the energy,
detoxification and antioxidant systems of the body
require an alkaline state for optimal function,
lactic acidosis impairs all such functions.
Oxygen-starved cells produce lactic acid in large
quantities—the state of acidosis so caused is a
harbinger of some life-threatening events. When I
prepared for my examination to receive the diploma
of the fellow of the Royal College of Surgeons in
England, lactic acid was a favorite molecule of the
examiners. Surgeons are concerned about lactic
acidosis because it can trigger irregular heart
rhythm, which, unless reversed expediently, can lead
to cardiac arrest and death on operating tables.
Similar risks are encountered in congestive heart
failure. The failing heart fails to pump enough
blood—and oxygen—to tissues for oxidative
metabolism. Tissues struggle to function in a
nonoxygen-utilizing mode, or anaerobic
metabolism—the opposite of the commonly known
aerobic type of activity. Such metabolic
insufficiency is diagnosed in clinical practice by
measuring blood levels of lactic acid or lactate-pyruvate
ratio. The higher the values in these tests, the
more severe the heart failure.
I learned all those things about lactic acid in
medical school, and again during my surgical and
pathology training. But I found little use of such
knowledge once I began my pathology and clinical
work. With time, lactic acid faded away from my
working knowledge of clinical medicine. And then, in
the Serengeti Plains, Choua fired all those
questions at me. Why? I wondered. And what did he
mean by things about lactic acid not being as simple
for humans as they are for lions?
"Why aren't these things about lactic acid as
simple for humans as they are for lions?" I finally
"Because you humans are humans, and lions are
lions. That's why?" he glowered. "You can't let go.
You brood and sulk, and keep the oxidative coals
simmering even when the metabolic digestive fires
are out. The cortical monkey simply doesn't let up."
"What does the cortical monkey have to do with
lactic acid?" I asked, baffled.
"What would happen if you inject lactic acid into
the veins of these lions?" he asked, without
acknowledging my question.
"I am not about to try that," I replied quickly.
"Why don't you try that? Tell me, what will happen
"Some lions will suffer from anxiety attacks," he
"Really?" I was taken aback. "Has that ever been
done, or are you just making it up?"
Choua grinned but didn't say anything. I didn't
follow through. We rode in silence for a while.
"Exercise requires energy," Choua spoke finally.
"Where does such energy come from?"
"From oxidative metabolism of food substances
that releases the chemical bond energy," I replied.
"Didn't we just cover that subject?"
"So, the increased demands of tissues for energy
during exercise can only be met by increased
oxidative activity in them? In other words,
metabolically tissue in exercise comes under greater
oxidative stress. Right?" He asked.
"Right," I replied, not knowing where that might
"You would expect that many toxic oxidative
species—free radicals, as you call them in common
language—will be produced in much larger quantities
"What kinds of toxic oxidative species might
"Hydrogen peroxide, superoxide radicals, singlet
oxygen, hydroperoxides, hydroxyl radicals, and
aldehyde, such as malonaldehyde," I named some
commonly known oxidants.
"How does the body cope with such toxic
molecules?" he asked.
"By neutralizing them with antioxidants," I
"What would happen if there were an excesses of
lactic acid in tissues when there were also excess
of toxic oxidative species in them?"
"The body's antioxidant systems will be
overwhelmed. Indeed, that's the reason I recommend
the use of antioxidants, such as vitamin E, C and
pycnogenol for my patients who engage in endurance
"Now, tell me, what will happen if you inject
lactic acid into lions?"
"I don't know."
"Didn't you cite the lactic acid study of Pitts
and McLure in The Cortical Monkey and
"The one published in the New England Journal of
Medicine in 1967?"
"But, Choua, that wasn't about injecting lactic
acid into lions' veins. It was about people who
suffered from anxiety."
"What happened to anxiety sufferers when they
were injected with lactic acid?" he asked.
"About one half of the subjects with anxiety
developed acute anxiety reactions, while one out of
five of volunteers who served as control subjects
also suffered similar symptoms," I replied, then
asked, "Are you saying injections of lactic acid can
cause anxiety reactions in lions as well?"
"Yeah. Some lions will suffer anxiety attacks
just as some people do."
"You're just guessing, aren't you?" I expressed
"Lactic acid doesn't differentiate between the
oxidative energy enzymes of humans and lions. If
there are differences between the lactic
biochemistry of humans and lions, they are
quantitative, not qualitative."
"There must be species differences," I countered.
"When enough lactic acid accumulates in the
tissues, its effects are the same," he went on,
ignoring my objection. "Lions, of course, may
express their anxiety somewhat differently." "Do
lions suffer anxiety attacks the way my patients
do?" I asked. "Do they also develop sweating,
jitteryness, hyperventilation and heart
"They would if they carried cortical monkeys on
their backs as you do," Choua snapped.
"Okay, let's agree that lactic acid plays the
same role in lions as it does in humans. So what?"
"Lions are straight shooters. Their charge is
ballistic in speed. Once begun, it has no strategy.
A lions' prey can often outrun him. If the prey
escapes the charge, a lion stops but doesn't dwell
on his failure. When a lion breaks his sprint, it
soon settles down. His lactic acid-producing
chemistry returns rapidly to a pyruvic-burning
"And the accumulated lactic acid is converted
back into pyruvic acid, then pulled back into
Krebs's oxidative cycle and oxidized," I completed
"Right. When the opportunity arises again, the
lion strikes again, fresh and without any lactic
acid debt. Lions don't sulk the way people do. You
know how it is with humans, don't you?"
"When humans fail, they brood and sulk and..."
"The cortical monkey doesn't let up, does it?" he
interrupted me. "It loves to recycle misery. And
when that's not enough, it pre-cycles feared, future
misery. Those are your words, right?"
"Right," I replied, irritated.
"The monkey keeps the blood and tissue lactic
acid levels raised—tightening muscles everywhere in
the body and raising blood pressure."
"Do lions suffer from high blood pressure?" I
"Who knows?" he shrugged, then continued, "But
the cortical monkey stays revved up, keeping
arteries clamped, hands and feet cold."
Bricks in the Neck
"How often do you see patients with stiff necks?"
"That's not uncommon at all," I replied. "Why do
"Sometimes their neck and shoulder muscles are
hard like bricks."
"Where do those bricks come from?"
"Obviously what makes neck and shoulder tissues
hard are spastic muscles. Why do you ask?"
"What causes a muscle spasm?" he pressed.
"Muscles go into spasm when they are injured," I
offered the standard answer.
"More often than that muscles go into spasm to
protect the injured ligaments and tendons that lie
beneath them, don't they?" he asked.
"Well, that's true." As usual Choua was closer to
the truth than I. "So?" I asked, a bit flustered.
"Why don't injured ligaments and tendons heal as
fast as other soft tissues?"
"Because those tissues are not rich in blood
"Right! What else?"
"Spastic muscles that protect injured ligaments
make things worse."
"Spastic muscle clamp down on the injured
ligaments and further reduce their limited blood
"Why don't the spastic muscles relax? What is the
biochemical explanation for that?" he went on.
"Spastic muscles produce excess lactic acid, and
increased acidity of the spastic muscles further
irritates the muscles, perpetuating the muscle
"Lactic acid, again, eh?" he grinned, then looked
Cancer Cell: an Oxygen
"How does a cancer cell differ from a
noncancerous cell?" Choua asked.
"That's a schizophrenic flight of ideas, isn't
it?" I chided. "What does lactic acid accumulation
in spastic muscles have to do with cancer cells?"
"How does a cancer cell differ from a
noncancerous cell?" he repeated.
"A cancer cell continues to multiply. Its
multiplication serves no useful function, but robs
healthy cells of their nutrition," I answered.
"How does it differ from a healthy cell in its
energy utilization patterns?"
"Oh, that!" I saw where he was leading me. "A
cancer cell is an oxyphobe—it abhors oxygen."
"It does its dirty work without oxygen," he
"Yes," I agreed, then continued, "Metabolism in a
cancer cell is anaerobic."
"What are the chemical consequences of that?"
"A cancer cell accumulates lactic acid."
"Lactic acid, again," he grinned broadly.
Lions like the Limbic, Not
"Humans sulk, lions don't," Choua continued.
"Lions don't have much to sulk about," I replied.
"Humans carry bricks in their shoulders, lions
"Lions don't have to report to work on time, nor
do they have to pay real estate taxes."
"Quite right," he smiled, then added, "Humans
love to recycle past misery, lions don't."
"How do we know lions don't remember past
misery?" I asked.
"Humans thrive on precycling feared future pain,"
he continued, without answering my question.
"I don't think lions have any feared future
pain," I countered.
"Humans nurse their resentments for a long time,
"How do you know?" I asked.
"When lion-hearted lionesses return to their
chicken-hearted sisters after fighting off invaders,
they're limbic about the whole thing. You would
think they would hold grudges, but they don't."
"What do you make of that?" I asked.
"There is no lactic acidosis in their limbs," he
grinned, baring his teeth.
"How do you know?" I asked, a trifle annoyed.
"Nor any bricks in their haunches."
"Are you saying holding grudges causes lactic
acidosis in shoulder muscles?"
"How else do you think folks bake those bricks in
their neck and shoulder muscles?" he laughed out
loud and walked away.
What Do Lions Teach Us
About the Anxiety-Lactic Acid Connection?
In 1967, The New England Journal of Medicine
published a landmark paper linking lactic acid to
anxiety attacks and neurosis. The authors (Drs.
Pitts and McLure) administered lactic acid and salt
solution intravenously to a group of patients with
anxiety neurosis and to a control group. Lactic acid
induced an anxiety attack in about half of the
patients with neurosis, and interestingly in 20 % of
the control subjects. They interrogated these
control subjects and
found out that many of them had histories of
previous problems. Salt solution used as a control
did not cause significant anxiety in either group.
So, what do lions teach us about the
anxiety-lactic acid connection? We can our muscles
loose, let them breathe freely, and save them from
lactic acid burn out. Or we can keep them tight,
acidic, oxygen starved, and tired. Lions say"
Breathe Limbically and keep lactic acid low.
Near 80% Reduction in
Blood Lactic Acid With Limbic Breathing
information about the above experiment, which I
performed on myself in 1990, see Reproduced
From The Cortical Monkey and Healing (1991)