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.

What Happens in an Aging Mouth?

The human mouth, site of so much intense sensual pleasure (and occasionally pain) is at once delicate and tough - able to appreciate the endless variety of taste and tactile sensations from the food and beverages we ingest (and the people we kiss), yet also able to withstand the daily barrage of physical, chemical, and bacteriological assaults that are visited upon it, usually without our even knowing about them.

It is commonly, but mistakenly, believed that the oral mucosa of the elderly typically becomes pale, thin, dry, and readily susceptible to injury. There is little evidence to support this misconception, however. True, there is some atrophy (wasting or deterioration) of the epithelium - the mucosa's thin layer of surface cells - but this does not appear to be clinically significant. By and large, the oral mucosa's critical function as a barrier against the external environment is well maintained in all healthy people, regardless of age.

An occasional symptom of aging is the appearance of varicosities in the floor of the mouth, the underside of the tongue, and the pharynx (the back of the mouth, before the larynx), but they rarely bleed and are not clinically significant. Other benign conditions include oral candidiasis (a common fungal infection in the elderly) and a variety of skin disorders with oral manifestations.

Xerostomia, or dry mouth, is common in the elderly. Although dysfunction of the salivary glands is the primary natural cause of this annoying disorder (which is usually mild), it is a common side effect of prescription drugs - more than 400 drugs are implicated, in fact - and of certain anticancer therapies.

A more serious problem with aging mouths is what doctors call gustatory dysfunction (a fancy term for disturbances of taste), meaning a decreased ability to taste things or, less commonly, a persistent bad taste in the mouth. These conditions usually develop slowly and insidiously as we age, but they can also be brought on by countless prescription drugs in many different categories.

Actually, the pure sensation of taste is seldom significantly impaired in the elderly. What does decrease greatly with age (even in otherwise healthy people) is the olfactory sense, our sense of smell. The vast majority of what seem to us to be taste sensations are in reality complex mixtures of olfactory cues, which add enormous variety and richness to the rather primitive sense of taste itself (think of how poorly you can taste your food when your nose is stopped up by a cold).

The problem with this disorder, whatever you want to call it, is that it often leads to poor eating habits in the elderly, which can make any nutritional deficiencies even worse than they already were. This can be particularly detrimental in regard to vitamins B6 and B12 and folic acid, deficiencies of which are common in the elderly owing to the body's declining ability to absorb them via the digestive tract. For good health, it's vital to ensure an intake of these vitamins that's sufficiently great to compensate for that problem.

But What If I Don't Have BMS?

If you don't have BMS, be grateful! But what if you, like millions of Americans, are at risk for the disease it may be related to - diabetes? It makes sense to take whatever precautions you can to minimize that risk, because diabetes is a dreadful - yet largely preventable - disease. In European medical practice, lipoic acid has been used for over two decades to prevent and alleviate the symptoms of diabetes. Although it does not cure the disease itself, "it is highly likely that lipoic acid supplements may help prevent the onset of type 2 diabetes in the first place," in the words of a renowned authority on antioxidants, Dr. Lester Packer, a professor of molecular and cell biology at the University of California, Berkeley.11


In European medical practice,
lipoic acid has been used for
over two decades to
prevent and alleviate the
symptoms of diabetes.


Dr. Packer goes on to say, "Much of the destruction that is inflicted by this disease is caused either directly or indirectly by free radicals. . . . Diabetes is very much an oxidative stress disease - that is, people who are diabetic have significantly lower levels of antioxidants than normal."

Make Sure You Get Your Lipoic Acid

Thus it would be a good idea to ensure that your levels of antioxidants, especially lipoic acid, are suitably high, in accord with the knowledge gained through research studies such as those discussed above. Its protective function for many organs and systems throughout the human body make it one of the most valuable nutritional supplements in nature's larder.

Fighting Fire with Fire

The chronic pain of burning mouth syndrome can be so debilitating and depressing that some patients, and their doctors, are willing to try just about anything to alleviate it. The list of therapies that have been tried - most without notable success except in a small percentage of cases - is long and varied. Probably the most unusual of them all, however, involves the topical application of a most unlikely chemical compound: capsaicin.1

Capsaicin, you see, is notorious as the wickedly irritating molecule that gives hot peppers their fiery effect! Sounds crazy, doesn't it? Crazy like a fox, because there's something to it. If you can get through the initial pain, capsaicin acts as a desensitizing agent, so it can provide some measure of relief for awhile. The same tactic is sometimes used to ease the pain of other hard-to-treat nerve disorders, such as trigeminal neuralgia and diabetic neuropathy.

Useful tip: If your mouth is ever on fire from a hot pepper, don't bother to drink cold water - it won't help, because capsaicin is insoluble in water. Instead, take some milk or yogurt; they contain proteins that have a chemical affinity for capsaicin and will scarf it up, giving your poor mouth some blessed relief.

  1. Epstein JB, Marcoe JH. Topical application of capsaicin for treatment of oral neuropathic pain and trigeminal neuralgia. Oral Surg Oral Med Oral Pathol 1994;77:135-40.

References

  1. Ship JA, Grushka M, Lipton JA, et al. Burning mouth syndrome: an update. J Am Dent Assoc 1995;126:843-53.
  2. Grushka M, Epstein JB, Gorsky M. Burning mouth syndrome. Am Fam Physician 2002 Feb 15;65(4):615-20.
  3. Beers MH, Berkow R, eds. The Merck Manual of Geriatrics, 3rd ed. Merck Research Laboratories, Whitehouse Station, NJ, 2000.
  4. Miyamoto SA, Ziccardi VB. Burning mouth syndrome. Mount Sinai J Med 1998 Oct/Nov;65(5&6):343-7.
  5. Basker RM, Sturdee DW, Davenport JC. Patients with burning mouths. A clinical investigation of causative factors, including the climacteric and diabetes. Br Dent J 1978;145:9-16.
  6. Reljanovic M, Reichel G, Rett K, Lobisch M, Schuette K, Moller W, et al. Treatment of diabetic polyneuropathy with the antioxidant thioctic acid (alpha-lipoic acid): a two-year multicenter randomized double-blind placebo-controlled trial (ALADIN II). Alpha-Lipoic Acid in Diabetic Neuropathy. Free Radic Res 1999;31:171-9.
  7. Ziegler D, Hanefeld M, Ruhnau KJ, Hasche H, Lobisch M, Schuette K, et al. Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: a 7-month multicenter randomized controlled trial (ALADIN III Study). ALADIN III Study Group. Alpha-Lipoic Acid in Diabetic Neuropathy. Diabetes Care 1999;22:1296-1301.
  8. Ziegler D, Reljanovic M, Mehnert H, Gries FA. Alpha-lipoic acid in the treatment of diabetic polyneuropathy in Germany: current evidence from clinical trials. Exp Clin Endocrinol Diabetes 1999;107:421-30.
  9. Femiano F, Gombos F, Scully C, Busciolano M, De Luca P. Burning mouth syndrome (BMS): controlled open trial of the efficacy of alpha-lipoic acid (thioctic acid) on symptomatology. Oral Diseases 2000;6:274-7.
  10. Femiano F, Scully C. Burning mouth syndrome (BMS): double-blind controlled study of alpha-lipoic acid (thioctic acid) therapy. J Oral Pathol Med 2002;31:267-9.
  11. Packer L, Colman C. The Antioxidant Miracle. John Wiley & Sons, New York, 1999.


Will Block is the publisher and editorial director of Life Enhancement magazine.

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