Lipoic Acid Helps Quench the Fire of Burning Mouth Syndrome

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Lipoic Acid Helps Quench the Fire of Burning Mouth Syndrome

Its antioxidant action on a symptom of diabetes may be the reason it works
By Will Block

aeeeiiii! You probably screamed something like that (or something less printable) the last time you unsuspectingly bit into one of those small, superhot peppers that make a blowtorch seem like a cool breeze. Oh, the pain! It's so exquisite, so beyond ordinary pain, that some people actually seem to enjoy it, and they eat those little red devils with gusto. Whew! Just thinking about it brings on the hot sweats.

Count yourself lucky if your mouth has never been seared like that. You're definitely unlucky, however, if you have stomatopyrosis, unpopularly known as burning mouth syndrome (BMS). Chances are you've never even heard of BMS, let alone known anyone who's had it, even though it's been estimated to affect over one million Americans.1 BMS is a chronic burning or stinging sensation in the mouth, in the absence of visible lesions or any other obvious cause. It's not as acute as hot-pepper pain, but it can still be very painful (as bad as a toothache in some cases) and it disrupts its victims' lives.

And who are its victims? By a large margin, BMS afflicts mainly postmenopausal women. (This has led to the suspicion that hormonal factors may be involved, yet there is little convincing evidence that hormone replacement therapy is effective in treating the disorder.) The statistics may be skewed, however, by the fact that women are far more likely to seek medical help for what ails them than men are, so BMS may be more common in men than appears to be the case.

BMS Is a Mystery

BMS can affect any part of the mouth, including the lips, but it occurs most often on the tongue, along with various other areas. (There's a special type of BMS that affects only the tongue; it's cleverly called burning tongue, or glossopyrosis in medical jargon). Most studies have found that it's often accompanied by other symptoms, notably xerostomia (dry mouth) and altered taste sensations (typically a persistent bitter or metallic taste).2

The disorder is poorly understood, to put it mildly. There is much speculation on what may cause it and how best to treat it, but it remains largely a mystery. Treatment strategies vary all over the map, from the mundane to the exotic, and they are notable for being highly unreliable.

Can Lipoic Acid Shed Light on BMS?

Naturally, researchers are always looking for something new and better to try, and recently they hit upon a familiar nutritional supplement, lipoic acid. This natural substance (our bodies make it in tiny quantities) is a powerful, versatile antioxidant with remarkable properties, not the least of which is that it's soluble in both water and fat. It is the linchpin in the body's "antioxidant network" and has well-documented health benefits in many areas. (See "Lipoic Acid, the 'Antioxidant's Antioxidant'" and "Lipoic Acid Helps Heart Health" in Life Enhancement, July and September 2001, respectively.) We'll get back to lipoic acid shortly.

BMS Appears to Have Multiple Causes

BMS often occurs for no apparent reason, although a number of possible causes have been suggested: ill-fitting dentures, which can injure the oral mucosae (the sensitive mucous membranes lining the mouth); dysfunction of the salivary glands, which can cause dry mouth; psychiatric disorders, especially anxiety and depression; nutritional deficiencies, especially of vitamins B1, B2, B6, or B12, or of folic acid (which is also a B-vitamin, but without a number); gastrointestinal disorders; food allergies; type 2 (age-related) diabetes; and certain drugs, notably antihypertensives such as ACE inhibitors.3,4 Many cases turn out to have multiple causes - when causes can be determined in the first place.

97% of the subjects on lipoic acid
(600 mg/day for 2 months) showed
some improvement (73% had
"decided" improvement).

Diagnosing BMS is by a process of elimination - ruling out anything else that could cause pain in the mouth, such as canker sores or other kinds of lesions, benign or malignant.* Basically, if the patient's mouth looks fine and tests fine but burns anyway, it's BMS. The burning sensation may be sporadic or constant. In the latter case, the condition is typically mild in the morning and gets worse throughout the day (it tends to disappear during the night, though). This is not only painful but also depressing to the patient.

*Most sores in the mouth, however painful they may be, are relatively benign and will probably heal in a few days to a few weeks. Any sore that lasts for more than 2 weeks should be examined by a physician or dentist, especially if it's not painful - these can be more serious than the ones that hurt. Sores that are cancerous or precancerous may or may not hurt, so don't take any chances.

Treating BMS Is a Challenge

Also depressing is the fact that treatment is difficult and often unsuccessful. It may require the expertise of several different kinds of specialists, including those whose entire focus is on chronic pain. One of the things they prescribe (in addition to painkillers and all kinds of other things) is low-dose antidepressants; taken at bedtime, these have often been found to be beneficial.

Whether treated or not, it is not uncommon for BMS to disappear as mysteriously as it arose (spontaneous remission), but it can also spontaneously worsen. Worst of all, it often lasts for years - even for the rest of the patient's life. They just learn to live with it.

The goal of life enhancement, of course, is not to live with things but to live for things - for all the good things in life - and to live better and longer through wise lifestyle choices, including the judicious use of nutritional supplements.

Is There a BMS-Diabetes Connection?

A collaboration of researchers from universities in Naples and London decided to investigate the possibility that lipoic acid (technically, alpha-lipoic acid, and also known as thioctic acid) might be good for treating BMS, because of an intriguing link that may exist between BMS and diabetes, for which lipoic acid is known to be helpful.

It had been noted long ago that many patients with BMS have high blood glucose levels, although no consistent or causal relationship has been documented.5 More recent studies of various kinds have led to the suspicion that BMS, despite its maddeningly ambiguous and seemingly numerous origins, is a kind of peripheral neuropathy, a common symptom of long-term, poorly controlled diabetes (it can also occur independently of diabetes).

In medicine, peripheral means far from the center of the body, which usually means the extremities, but in this case it means the mouth (far enough). Neuropathy means nerve damage, and there are different causes, including high glucose levels, although how glucose damages nerves is not clear. Neuropathy generally manifests either as severe pain or as a loss of feeling - an all-or-nothing deal.

Lipoic Acid Works Well on BMS

So what we have is an apparent peripheral neuropathy with a possible connection to diabetes - and it's known that lipoic acid is effective in treating neuronal (nerve-cell) damage, especially in diabetic neuropathy.6-8 You connect the dots. The Italian-British research team certainly did, and the initial result was a randomized, placebo-controlled - but open (not blinded) - clinical trial of the efficacy of lipoic acid on the one symptom of burning mouth syndrome: pain.9 The study involved 42 patients (two age- and sex-matched groups of 21 each), all with classic cases of BMS and no other conditions that might confound the results.

The results were highly positive: 76% of the test subjects taking lipoic acid (600 mg/day for 20 days, followed by 200 mg/day for 10 days) showed some improvement, with 43% showing "decided" improvement. By contrast, only 14% of the control subjects taking placebo showed some improvement (0% had decided improvement). When the controls were then switched over to lipoic acid for 30 days, their improvement rate increased to 67% (52% had decided improvement). No side effects were reported, which is consistent with lipoic acid's excellent reputation for safety.

Lipoic Acid Works Really Well on BMS

Encouraged by these results - which bolstered their belief that BMS may be a form of peripheral neuropathy - the same research team undertook a more rigorous study (randomized, placebo-controlled, and double-blind) with the same objective.10 This time, 60 patients were involved (two groups of 30 each).

This time the results were even better: 97% of the subjects on lipoic acid (600 mg/day for 2 months) showed some improvement (73% had decided improvement), whereas 40% of the controls showed some improvement (0% had decided improvement). In the lipoic acid group, four patients (13%) showed "resolution," i.e., a complete cessation of pain, which amounts to a cure; this did not occur in any of the controls. None of the patients on lipoic acid got worse during the course of the study, whereas six (20%) of the controls did. Again, there were no side effects.

In the lipoic acid group, four
patients (13%) showed a
complete cessation of pain,
which amounts to a cure.

In a follow-up examination conducted one year later, it was found that any improvement achieved with lipoic acid had been maintained completely in 72% of the test subjects, whereas all the controls who had improved during the study had deteriorated to some extent in the interim.

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