Question: Does glucosamine raise cholesterol?
Answer: In Europe, glucosamine has been used for over 20 years by tens of thousands of people. In both preliminary and follow-up studies of blood chemistries, there has been no hint of a problem with the exception of occasional biochemical sensitivity. It should be noted that many individuals who start taking glucosamine begin so in their later years, when cholesterol levels tend to creep up.
Question: Does glucosamine cause insulin resistance?
Answer: A recent study on rodents showed that supra-pharmacologic doses did result in insulin resistance. However, the rodent gastrointestinal tract does not handle glucosamine well. Furthermore, when we again look to Europe, we see no correlation between insulin resistance and those people who have been using glucosamine over the long term. Again, this does not preclude problems in a few selected individuals with metabolic difficulty with glucosamine.
Question: What are the most common side effects of glucosamine?
Answer: Glucosomine is well tolerated in most individuals. The most common side effects are digestive in nature. In a large (1,200-patient) European trial, digestive complaints, epigastric pain, heartburn and diarrhea affected 2-3 percent of patients. Other side effects that were seen at 1 percent included nausea, dyspepsia, vomiting and drowsiness. Symptoms seen in .003 to .005 percent of subjects included constipation, gastric heaviness, headache and skin reactions.
Question: Last year you mentioned a University of Maryland study on the potency of glucosamine and chondroitin products. Was that study ever published?
Answer: It was published last spring in the Journal of the American Nutraceutical Association by Dr. Natalie Eddington (3:37,2000) and was presented in a conference in San Diego. The results were very disappointing. Only five of 32 brands of chondroitin purchased in pharmacies and health food stores contained 90 percent or more of what was listed on the label. Of the 14 brands of glucosamine that were sampled, 12 tested at or above 90 percent.
Unfortunately, the University of Maryland declined to release brand names. I would like to see Consumer Reports magazine (which always lists brands) test these products.
In the meantime, if you have a patient who is taking glucosamine, chondroitin or a combination product and is not getting results, I recommend that you order products for them from one of the many companies that cater to health care professionals. The vast majority of these companies guarantee the purity and potency of their products, and will normally also provide you with testing data, if requested.
Question: Can humans digest chondroitin sulfate?
Answer: Yes. Purified chondroitin sulfate is handled well by nonspecific esterases in the GI tracts of humans.
Question: Does it matter what type of chondroitin sulfate a person uses?
Answer: Yes and no. There were early animal studies on chondroitin sulfate type four and type six. Some companies extrapolated that there is a difference in humans. However, this does not seem to be the case. What is important is purity. Wet cartilage contains about five percent chondroitin sulfate; dry cartilage has nearly 20 percent. Companies can purchase processed bovine trachea that contains around 40 percent chondroitin sulfate. This form still contains cross-links and is much cheaper than bovine trachea purified to 90 percent or more chondroitin sulfate. As you can see from question number four, finding real chondroitin sulfate is a big problem. To purify chondroitin sulfate from the 40 percent grade to the 90 percent grade, several steps of processing are required, including an enzymatic treatment to separate chondroitin from its core protein. (To learn more about the basic anatomy of chondroitin sulfate, please see my article "Glucosamine: Part One - Basic Science" from the May 18, 1998 issue of Dynamic Chiropractic. You can find the article on line at www.ChiroWeb.com by clicking on the links to the 1998 articles, or you go directly to the article http://www.chiroweb.com/archives/16/11/07.html.)
Unfortunately, the purity problem with chondroitin sulfates is not new. Dr. Luke Bucci discussed it in his book Nutrition Applied to Injury Rehabilitation and Sports Medicine. Six years after his book was published, it appears that the problem is now bigger than ever.
It's interesting to note that the French, German and Austrian medical systems prefer chondroitin sulfate to glucosamine. Real chondroitin sulfate has some impressive research. (See "Chondroitin Sulfate Update 1999," Dynamic Chiropractic, April 19, 1999, http://www.chiroweb.com/archives/17/09/04.html.)
G. Douglas Andersen, DC,DACBSP,CCN
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