Glucosamine is one of the major building blocks utilized in the body's synthesis of the lubricants and shock absorbing mechanisms necessary to maintain and restore healthy joint performance. Glucosamine HCL supplementation enhances the body's ability to manufacture collagen and proteoglycans, which are essential for rebuilding joints, as well as synovial fluid which lubricate your joints.

What form of Glucosamine Should I take?

Pure glucosamine is very "hygroscopic" and degrades (breaks down) rapidly when exposed to moisture or air. To avoid this, glucosamine needs to be bound to a stabilizer to be sold commercially. The sulfate and the HCL forms are two of the most common "agents" that glucosamine is bound to to ensure its stability. After glucosamine is bound, it is stable and will not degrade before it can get to the store shelf. This is why you never find "just" glucosamine and instead find Glucosamine Sulfate or Glucosamine HCL. However some manufacturers play a trick on you. They replace up to 30% of a "1500 mg" mixture and replace it with plain table salt. This means you are only taking 1050 mg of "actual" glucosamine! What's worse is that this is entirely legal because they put the ingredients on the label and the product DOES contain 1,500 mg of glucosamine sulfate (NaCl or 2KCL). It's just that the NaCl and 2KCL that is added on is just filler.

These manufacturers take glucosamine sulfate and add potassium (KCl) or ordinary table salt (NaCl). They then co-crystallize the resulting mixture and wind up with the same weight of "total" glucosamine but stiff you on the actual glucosamine dosage! As usual, you get what you pay for as these are commonly found in "no frills" glucosamine brands, in a low priced pill form with no other synergistic ingredients. In our opinion, they are simply a waste of money.

Some Glucosamine Sulfate preparations even claim to be salt free when in fact they are actually just sodium free. They still contain up to 30% potassium chloride (KCl). Finally, an mg-to-mg comparison shows that the hydrochloride may provide more Glucosamine than the Sulphate salt, and this may be the reason why some people prefer to choose Glucosamine HCL. The jury is still out however as to which benefits you more and an easy fix is to just take both HCL and Sulfate forms.

When searching for products, you may wish to look for products that contain both glucosamine HCL and glucosamine sulfate, as people sometimes respond quicker to one form over another. While most of the clinical studies were done with glucosamine sulfate, this is because the early glucosamine sulfate for the studies was provided by a manufacturer that did not make glucosamine HCL. Since then, HCL has increased in popularity. Look for a supplement that contains both for maximum benefit but be sure to look out for any that contain the less effective NaCl or KCl forms.
Source: http://www.glucosamine-osteoarthritis.org/...samine-hcl.html

There is discussion over which of the two glucosamine salts, hydrochloride or sulfate, is preferred for the treatment of osteoarthritis. The answer is straightforward - both salts, in the pure form, deliver equally effective amounts of the desired glucosamine to joint cartilage. If there is a preference, it should be based on relative purity and economics - not on the specific salt.

Historically, the sulfate was used for the initial European clinical studies because it was made available for that purpose by an Italian pharmaceutical company which had a proprietary position on the sulfate. Thus, it was to their marketing advantage to supply only the sulfate and ignore the hydrochloride.

The original researchers, however, clearly relate all of the observed benefits relative to osteoarthritis to "glucosamine" not to the sulfate. When ingested, glucosamine sulfate is fully ionized in the stomach by the relative strong concentration of hydrochloric acid (pH 1- 3) naturally present. As a result, glucosamine ions and sulfate ions are thoroughly mixed with an overwhelming number of chloride and hydrogen ions from the hydrochloric acid. If you could stop at this point and recover the glucosamine salt, you would get 99+ % glucosamine hydrochloride as the sulfate is essentially lost due to its very low concentration relative to the large amount of hydrochloric acid present.

As reported by Setnikar, 54% of glucosamine that moves into the small intestines (pH 6.8) exists in its unionized, amine form (not a salt at all) while 46% is ionized (the amine group is protenated and positively charged). In the blood at pH 7.4, 75% of the glucosamine is present as the neutral amine while only 25% is ionized. Since ionization or high polarity is usually an obstacle in the crossing of cellular membranes, the ability of glucosamine to exist predominantly in its less polar, unionized form in the small intestines and, even more so, in the blood contributes directly to its bio-availability. The specific salt form is relevant only as a convenient delivery vehicle with the proviso that the salt must readily dissolve (ionize) in stomach acid when ingested - the hydrochloride and the sulfate equally meet this requirement.

The real issue, therefore, become one of purity (and stability). Our highly stable Glucosamine Hydrochloride is domestically manufactured in an FDA approved, GMP plant and is 99+ present pure with less than 0.1% ash on ignition. Glucosamine sulfate, on the other hand, must be prepared with a co-mixture of sodium or potassium chloride in order to prevent the glucosamine sulfate from decomposing and turning brown. For this reason, virtually all of the glucosamine sulfate imported into the US is only 74% pure with the remainder being sodium or potassium chloride (this account for the high percentage of ash found in the sulfate on ignition). In a dietary supplement market that is under constant government and media scrutiny, purity and stability are key elements for success.

There is also the additional question of economics. Because glucosamine sulfate is made from glucosamine hydrochloride, it is significantly more expensive - approximately twice the price of the hydrochloride. The necessary addition of 26% sodium chloride to maintain stability further dilutes the sulfate and significantly adds to the cost of the sulfate on an active glucosamine basis. Conversely, Glucosamine HCI provides a high purity, stable source of glucosamine that is readily absorbed by the body and is economically priced. It is the most cost effective form of glucosamine available.
Source: http://www.healingedge.net/store/page172.html