Monday, April 03, 2006

Xanthone Juice: Snake oil and placebo?

Just came across an ad by Xanthone Corporation in the weekly newspaper Village Voice.1 It touts:

A Revolutionary Discovery

Some Health Benefits:

* Anti-Tumor
* Blood Pressure/Fat Lowering
* Anti-Diabetic
* Anti-Arthritic
* Anti-Allergic
* Anti-Depressant/Anti-oxidant
* Anti-Aging
* Anti-Microbial/Viral
* And more

The ad then lists Xanthone's contact numbers and their web address. Well, they certainly weren't kidding when they said "and more." The litany continues at their Complete List of Mangosteen Benefits page.

Here's how they describe their product:
Xanthone Juice™: The Power Formula is what we call it. And, unlike other rejuvenating drinks, its potency has been proven, time and time again, for countless generations. From the sun-baked nipa huts of ancient healers to the sanitized feel of modern research labs, it exerts its power on an incredibly wide range of diseases that afflict the common man. And still the list is growing.... [O]ur product goes through a special cold process and is blended with other fruit extracts to make a tonic drink that is both nutritive and curative [emphases added].... Its history is rich, its potency proven.

But after all those claims right there at the bottom their web pages they have the disclaimer:
Statements about the product efficacy have not been evaluated by the U.S. Food & Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. [emphasis added]

Now this isn't just hypocrisy. This is blatant misrepresentation. Their newspaper ad and their online claims are intentionally meant to mislead people. Their print ad does make very explicit therapeutic claims--not for the fruit mangosteen--but for Xanthone Juice, very extravagant claims at that. That's fraud.

On their site they have a link to, supposedly, research material that I presumed would back up the claims they're making for their product. But once you reach the research page all there is a link to PubMed. They neither have quotes from any scientific study whatsoever nor do they provide any citations. Instead they pass the buck to the readers, explicitly telling them to go and look for evidence themselves over at PubMed. Irresponsible is an understatement.

The best they've done is to write an article that, among other things, says:
Some of the known benefits of xanthones based on recent research are:

* Helps boost energy
* Helps prevent and reduce inflammation
* Shows signs of slowing aging
* Helps lower blood pressure
* Helps lower blood sugar
* Helps prevent infections by bacteria, viruses, and fungus
* Effectively treats a variety of diarrheal diseases
* Helps prevent dementia
* Helps prevent allergies
* Helps prevents cataracts and glaucoma
* Helps protect the heart and cardiovascular system
The article provides no references.

Are we to presume that research has shown xanthones to be effective in humans per se? Or could it be that the results are from animal studies, or that what is available to date are merely results from in vitro experiments?

Near the bottom of their Complete List of Mangosteen Benefits is a list of medical conditions one of which is cancer. Clicking on that we read that the study or studies they allude to are in vitro ones. The problem with such studies is that they don't necessarily translate into effective treatments for humans, not least because in vitro experiments don't tell us what happens to these substances when taken orally and how they would interact with a complex biochemical system such as our body in dosages that are therapeutic. "One test-tube [i.e., in vitro] study or a hundred test-tube studies can't provide strong evidence for an effective treatment in a living human." Likewise, "by themselves, animal studies can't show that a substance is safe for humans." 2

In lieu of scientific studies, what evidence do they present? What else but anecdotes and testimonials. And yet personal stories are of little use in knowing and establishing whether a treatment is efficacious or not. Drs. Stephen Barrett and Victor Herbert's explanation bears quoting in full:
We all tend to believe what others tell us about personal experiences. But separating cause and effect from coincidence can be difficult. If people tell you that product X has cured their cancer, arthritis, or whatever, be skeptical. They may not actually have had the condition. If they did, their recovery most likely would have occurred without the help of product X. Most single episodes of disease end with just the passage of time, and most chronic ailments have symptom-free periods. Establishing medical truths requires careful and repeated investigation -- with well-designed experiments, not reports of coincidences misperceived as cause-and-effect. That's why testimonial evidence is forbidden in scientific articles, is usually inadmissible in court, and is not used to evaluate whether or not drugs should be legally marketable. (Imagine what would happen if the FDA decided that clinical trials were too expensive and therefore drug approval would be based on testimonial letters or interviews with a few patients.)

Never underestimate the extent to which people can be fooled by a worthless remedy. During the early 1940s, many thousands of people became convinced that "glyoxylide" could cure cancer. Yet analysis showed that it was simply distilled water! [1] Many years before that, when arsenic was used as a "tonic," countless numbers of people swore by it even as it slowly poisoned them.

Symptoms that are psychosomatic (bodily reactions to tension) are often relieved by anything taken with a suggestion that it will work. Tiredness and other minor aches and pains may respond to any enthusiastically recommended nostrum. For these problems, even physicians may prescribe a placebo. A placebo is a substance that has no pharmacological effect on the condition for which it is used, but is given to satisfy a patient who supposes it to be a medicine. Vitamins (such as B12 shots) are commonly used in this way.

Placebos act by suggestion. Unfortunately, some doctors swallow the advertising hype or become confused by their own observations and "believe in vitamins" beyond those supplied by a good diet. Those who share such false beliefs do so because they confuse coincidence or placebo action with cause and effect. Homeopathic believers make the same error.

As I posted last year, Quackwatch, in a March 2005 monograph, reported that there is still no reliable evidence for various therapeutic claims in humans:
Mangosteen juice is becoming a popular healthful and medicinal drink. It is usually marketed with the name xango juice. Some marketers claim that xango juice can treat diarrhea, menstrual problems, urinary tract infections, tuberculosis, and a variety of other conditions. There is no reliable scientific evidence to support these claims.

And of course, even if xanthones taken orally are in fact efficacious for certain diseases and are safe in dosages that would be therapeutic, we still wouldn't know if Xanthone Juice is effective. What that particular product actually contains (both active and inert ingredients) and what it can and cannot cause is another issue.


1. EDSA-Ortigas Village Voice, Vol. XII No. 29, April 2-8, 2006, p. 3

2. Schick, Theodore, Jr. and Lewis Vaughn, How to Think About Weird Things: Critical Thinking for a New Age, 2nd ed., Mountain View, CA: Mayfield, 1999, p. 219

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