Thank you for your question!
Different sources attribute the "white film" phenomenon you describe
to a variety of causes, among them medication side effects, yeast
overgrowth, stagnated vital energy and plain old oral bacteria. As
you've no doubt gathered, these explanations come from health and
wellness camps with widely differing approaches and philosophies.
The Einstein Medical Patient Education Libraries offer quite a
straightforward explanation grounded in traditional medicine
"...saliva helps wash away the natural buildup of bacteria in the
mouth and on the tongue. Yet, when saliva sits on the back of the
tongue and is digested by bacteria, it shows up as a white film on the
tongue. This is a major source of bad breath."
An article at Yoga-Age.com concurs:
"A white film on the top of the tongue means there are millions of
bacteria living there. The practice of scraping the tongue removes the
white colour waste products from the surface of the tongue, and
enhances the functioning of taste buds. Not only that, it helps to
reduce halitosis, or bad breath and provides a clean environment for
good dental hygiene."
< http://www.yoga-age.com/asanas/tongue.html >
An article appearing on "The Health Spas Guide - South Africa" website
also attributes the film to bacterial buildup, but suggests a possible
"Furry tongue/bad breath - if not enough fluid is passing through the
mouth to wash away food particles, bacteria builds up in the throat
and mouth, and on the tongue as a white film or fur."
< http://www.healthspas.co.za/ht/article_2005_10_18_3833.php >
A white film on the tongue is a known side effect to Kepivance, a drug
used to treat some of the side effects of radiation in cancer patients
I also found claims of this reaction in response to the acid reflux
drug Prilosec <http://www.medhelp.org/forums/gastro/archive/3444.html>
and homeopathic remedy Lycopodium
Holistic practitioner Katie Murphy claims that the white film can be
one of many potential symptoms of yeast overgrowth, also known as
Candida Albicans, in the body <
In "The Link Between Nutrition and Cancer," Dr. Patrick Quillin links
a third-world nut to a particularly toxic lingual film:
"Betel nuts provide a tobacco-like chew for hundreds of millions of
people in third world countries. The effects of betel nuts includes a
pre-cancerous condition called oral leukoplakia, in which there is a
white film over the mouth surface, which can mature into full blown
< http://www.healthy.net/scr/Article.asp?Id=515 >
Other medical traditions offer alternate possibilities. In an article
titled "Menstrual Essentials," Linda Sparrowe, using concepts integral
to Ayurvedic (traditional Indian) Medicine, attributes the "mystery
film" to the presence of "ama, the sticky, icky "stuff" that
accumulates in our bodies when something is amiss." She goes on to say
that "You can see it as the white film on your tongue after a night of
eating rich, heavy foods, or when you are sick."
<http://www.yogajournal.com/health/130_5.cfm>. An article on strokes
in the context of Chinese medicine attributes the appearance of a
white film on the tongue to a stagnation of "qi," or vital energy.
< http://www.shen-nong.com/eng/shen-nong/health/stroke/symptoms.htm >
Finally, tongue piercings commonly cause a white film to appear on the tongue.
I found the following search string helpful in developing your answer:
"white film" tongue
Please feel free to request clarification if required. All the best!
Request for Answer Clarification by
21 Nov 2005 22:41 PST
Thank you for trying to take on my question. I'm afraid, however, that
the materials you've found did not contribute much to answering the
question I asked. I heard all these speculations before, and I can
even add I few more myself. But I am not looking for a diversity of
opinions on the subject but for scientific facts.
Drug side effects are relevant (and scientific), but until the
mechanism is known, they do not add much to the picture.
I'm sure that the person who wrote the article about bad breath on
einsteindental.com thinks that he knows his science (which I find
highly unlikely from what he writes). But since he provides no
references there, I have no way of verifying anything he says.