Effects of oral glucosamine and chondroitin sulfate alone and in combination on the metabolism of SHR and SD rats

Crystalline glucosamine sulfate in the treatment of osteoarthritis: evidence of long-term cardiovascular safety from clinical trials

BACKGROUND AND OBJECTIVE

Glucosamine is a safe and common treatment for osteoarthritis. Even so, literature data on the cardiovascular safety of glucosamine are limited. The objective of this paper is to investigate the long-term effects of crystalline glucosamine sulfate (CGS) on key measures of cardiovascular risk in patients with osteoarthritis.

METHODS

We analyzed safety data from two long-term (6-month and 3-year, respectively) randomized controlled trials of CGS. Mean changes in blood pressure, lipids, and glucose were calculated for all patients randomized to CGS or placebo in either study and for subgroups with abnormally elevated baseline values. Shift tables were used to analyze transitions from normal to abnormal levels, or vice versa.

RESULTS

This analysis on 428 osteoarthritis patients includes data from subjects who had, on average, high normal blood pressure or high cholesterol at baseline. There were no significant changes in mean blood pressure after 6 months on CGS (systolic: -5±15 mmHg; diastolic: -5±10 mmHg) or placebo (systolic: -7±14 mmHg; diastolic: -4±10 mmHg). Subgroup analysis did not show significant effects in subjects with hypertension. Likewise, blood lipids (total/LDL cholesterol) and blood glucose did not change over 3 years and 6 months of treatment, respectively, even in hypercholesterolemic or hyperglycemic subjects. The proportions of patients whose blood pressure or cholesterol levels shifted from normal to abnormal, or vice versa, were comparable in the CGS and placebo groups.

CONCLUSIONS

Long-term use of CGS did not affect blood pressure, lipids, or glucose in patients with osteoarthritis. These findings further support the cardiovascular safety of CGS.

A comprehensive review of oral glucosamine use and effects on glucose metabolism in normal and diabetic individuals

Glucosamine (GlcN) is a widely utilized dietary supplement that is used to promote joint health. Reports that oral GlcN supplementation at usual doses adversely affects glucose metabolism in subjects with impaired glucose tolerance have raised concerns that GlcN should be contraindicated in individuals with diabetes and those at risk for developing it. This review addresses its potential, when used at typical doses, to affect glucose metabolism and insulin sensitivity in healthy individuals and those with diabetes or 'pre-diabetes'. Publicly available scientific information and data on GlcN were systematically compiled using the electronic search tool, Dialog , and reviewed with special emphasis on human studies. In long-term clinical trials, including those containing subjects with type 2 diabetes or 'pre-diabetes', GlcN produced a non-significant lowering of fasting blood glucose concentrations in all groups of subjects treated for periods of up to 3 years. Owing to limitations in study design, conclusions based on studies that report adverse affects of GlcN on insulin sensitivity and glucose tolerance in pre-diabetic subjects are suspect. However, no definitive long-term studies of GlcN use for individuals with pre-diabetes are available. Nevertheless, based on available evidence, we conclude that GlcN has no effect on fasting blood glucose levels, glucose metabolism, or insulin sensitivity at any oral dose level in healthy subjects, individuals with diabetes, or those with impaired glucose tolerance.

Improvement of experimental accelerated atherosclerosis by chondroitin sulphate

The rheumatic diseases have been associated with accelerated atherosclerosis. Rheumatoid arthritis (RA) is a systemic inflammatory disease characterized by persistent synovial inflammation which leads to disability and structural changes in joints. Epidemiological studies have demonstrated an increased cardiovascular mortality in patients with RA. In these patients, atherosclerotic plaque occurs earlier, and it has a faster evolution than in general population. Atherosclerosis (AT) is also an inflammatory disease partly mediated by cytokines, many of them involved on chronic synovitis. Our group has developed a rabbit experimental model of AT aggravated by chronic arthritis to study inflammatory mechanisms involved on the progression of vascular lesions and their response to drugs. A preliminary study using this model suggests a beneficial effect of chondroitin sulphate (CS), a drug recommended for the treatment of osteoarthritis, in controlling AT lesions. Yet clinical trials should be conducted with this compound to address the same hypothesis in human studies.

Development of Improved Nanoparticulate Polyelectrolyte Complex Physicochemistry by Nonstoichiometric Mixing of Polyions with Similar Molecular Weights

Water-based, biodegradable polyelectrolyte complex dispersions (PECs) prepared by mixing oppositely charged polyions are advantageous drug delivery systems due to constituent biocompatibility and nanoparticulate architectures. Reaction phase environmental parameters dictate PEC physicochemical properties, and specifically, complexation between polyelectrolytes having significantly different molecular weights leads to formation of water-insoluble aggregates. Starting with this fact, four-component similar and dissimilar molecular weight PEC chemistries were applied and compared with and without frequency-induced dispergation. The goal was to define nanoparticulate PEC systems with desirable characteristics for use in biological systems. Results show PEC formulations from precursors with similar low molecular weights yielded dispersions with suitable physicochemical characteristics, as verified by photon correlation spectroscopy and TEM, presumably due to efficient ion pairing. Similar low molecular weight PECs fabricated with dispergation exhibited pH-independent stability, as validated by charge and size measurements. These physicochemical advantages lead to an ideal delivery platform.

Effect of glucosamine on glucose control

OBJECTIVE

To review the literature regarding the effect of glucosamine on glucose control.

DATA SOURCES

English-language articles on the effects of administration of exogenous glucosamine on glucose control were identified through a search of MEDLINE (1966-March 2006), EMBASE (1988-March 2006), and International Pharmaceutical Abstracts (1970-March 2006) databases using the search terms glucosamine, blood glucose, and diabetes mellitus. Abstracts of articles were then reviewed to determine relevance to the topic. Bibliographies of selected articles were screened for other pertinent references.

DATA SYNTHESIS

Theoretically, glucosamine may alter glucose metabolism. Insulin resistance has been noted following intravenous administration of glucosamine in animal studies; however, these findings have not been confirmed in humans. Alterations in glucose control have not been documented in long-term efficacy studies using oral glucosamine for osteoarthritis or in trials of short duration conducted in healthy or diabetic subjects. The long-term effects of glucosamine in patients with diabetes have yet to be established in well-controlled trials.

CONCLUSIONS

Small, short-term studies suggest that glucosamine may be used in selected patients without affecting glucose control; however, data in patients with diabetes mellitus are limited, and close monitoring for potential changes in glucose control is recommended.

Nutraceutical Therapies for Degenerative Joint Diseases: A Critical Review

There is growing recognition of the importance of nutritional factors in the maintenance of bone and joint health, and that nutritional imbalance combined with endocrine abnormalities may be involved in the pathogenesis of osteoarthritis (OA) and osteochondritis dissecans (OCD). Despite this, dietary programs have played a secondary role in the management of these connective tissue disorders. Articular cartilage is critically dependent upon the regular provision of nutrients (glucose and amino acids), vitamins (particularly vitamin C), and essential trace elements (zinc, magnesium, and copper). Therefore, dietary supplementation programs and nutraceuticals used in conjunction with non-steroidal, anti-inflammatory drugs (NSAIDs) may offer significant benefits to patients with joint disorders, such as OA and OCD. This article examines the available clinical evidence for the efficacy of nutraceuticals, antioxidant vitamin C, polyphenols, essential fatty acids, and mineral cofactors in the treatment of OA and related joint disorders in humans and veterinary species. This article also attempts to clarify the current state of knowledge. It also highlights the need for additional targeted research to elucidate the changes in nutritional status and potential alterations to the expression of plasma membrane transport systems in synovial structures in pathophysiological states, so that current therapy and future treatments may be better focused.

Glucosamine effects in humans: a review of effects on glucose metabolism, side effects, safety considerations and efficacy

Glucosamine is widely used to relieve symptoms from osteoarthritis. Its safety and effects on glucose metabolism are critically evaluated in this review. The LD50 of oral glucosamine in animals is approximately 8000 mg/kg with no adverse effects at 2700 mg/kg for 12 months. Because altered glucose metabolism can be associated with parenteral administration of large doses of glucosamine in animals and with high concentrations in in vitro studies, we critically evaluated the clinical importance of these effects. Oral administration of large doses of glucosamine in animals has no documented effects on glucose metabolism. In vitro studies demonstrating effects of glucosamine on glucose metabolism have used concentrations that are 100-200 times higher than tissue levels expected with oral glucosamine administration in humans. We reviewed clinical trial data for 3063 human subjects. Fasting plasma glucose values decreased slightly for subjects after oral glucosamine for approximately 66 weeks. There were no adverse effects of oral glucosamine administration on blood, urine or fecal parameters. Side effects were significantly less common with glucosamine than placebo or non-steroidal anti-inflammatory drugs (NSAID). In contrast to NSAID, no serious or fatal side effects have been reported for glucosamine. Our critical evaluation indicates that glucosamine is safe under current conditions of use and does not affect glucose metabolism.

Balancing fact and fiction of novel ingredients: definitions, regulations and evaluation

Veterinarians have an opportunity to help educate their clients regarding the safety and efficacy of novel ingredients used by their clients. This is no small task because of the lack of acceptable information. Clients should be counseled regarding the lack of scientific evidence and be encouraged to discriminate fact from fiction, including many testimonials. Safety should be of primary concern, and clients should be encouraged not to neglect traditional therapies in lieu of novel ingredients unless clinical evidence of efficacy exists. Quality assurance is equally important and cannot be underestimated. Clients are likely to resort to less expensive products. Clients should be directed to the advice offered by the Arthritis Foundation as follows: "When a supplement has been studied with good results, find out which brand was used and buy that." Although skepticism is encouraged regarding any unknown product with medicinal indications, open mindedness should also guide the veterinarian as these products are considered. Indeed, veterinarians should take actions to ensure that the use of these compounds is accomplished within the confines of the veterinary-client-patient relationship, thus ensuring the role of the veterinarian in the health and well-being of animals, regardless of the modality of therapy. The veterinary profession should support the development of standards that might guide manufacturers of novel ingredients to meet criteria that protect the consumer. Likewise, we should encourage manufacturers and agencies to fund veterinary clinical trials to provide evidence for the use of these potentially exciting compounds. Above all else, the veterinarian needs to become a credible resource of information about the possible role of these products. The lack of a regulatory mechanism that establishes the safety and efficacy of these products is not justification for ignoring the potential therapeutic benefit of some of these products. Veterinarians should follow the advice of the Arthritis Foundation, which notes: "Since glucosamine is self-prescribed ... health care professionals are not regarded [to have] objective advice. This situation must change. It is time for the profession to accommodate the possibility that many nutritional products may have valuable therapeutic effects" [61].

Subchronic toxicity study of dietary N-acetylglucosamine in F344 rats

A subchronic toxicity study of N-acetylglucosamine (GlcNAc), a monomeric form of chitin, was conducted in groups of 10 male and 10 female F344 rats fed pelleted diets containing 0, 0.625, 1.25, 2.5 or 5% concentrations for 13 weeks. All animals survived until the end of the experiment. Slight, non-significant increase in body weights was observed in males receiving 0.625, 1.25 or 2.5% from week 4 until the end of the experiment, when significant elevation was found for the males receiving 0.625, 1.25 or 2.5% at the terminal sacrifice to result in decreased relative weights of many organs in these cases. However, there were no obvious indications of toxicity in any group receiving GlcNAc in terms of clinical signs, food intake, hematology, serum biochemistry, and histopathological findings. Thus, it was concluded that orally administered GlcNAc exerts no obvious toxicity to F344 rats at concentrations up to 5% in the diet for 13 weeks. Based on the present toxicity data, > or =5% was determined to be a no-observed-adverse-effect level, translated into 2476 and 2834 mg/kg/day for male and female rats, respectively.

Glucosamine and chondroitin sulfate supplementation to treat symptomatic disc degeneration: biochemical rationale and case report

BACKGROUND

Glucosamine and chondroitin sulfate preparations are widely used as food supplements against osteoarthritis, but critics are skeptical about their efficacy, because of the lack of convincing clinical trials and a reasonable scientific rationale for the use of these nutraceuticals. Most trials were on osteoarthritis of the knee, while virtually no documentation exists on spinal disc degeneration. The purpose of this article is to highlight the potential of these food additives against cartilage degeneration in general, and against symptomatic spinal disc degeneration in particular, as is illustrated by a case report. The water content of the intervertebral disc is a reliable measure of its degeneration/ regeneration status, and can be objectively determined by Magnetic Resonance Imaging (MRI) signals.

CASE PRESENTATION

Oral intake of glucosamine and chondroitin sulfate for two years associated with disk recovery (brightening of MRI signal) in a case of symptomatic spinal disc degeneration. We provide a biochemical explanation for the possible efficacy of these nutraceuticals. They are bioavailable to cartilage chondrocytes, may stimulate the biosynthesis and inhibit the breakdown of their extracellular matrix proteoglycans.

CONCLUSION

The case suggests that long-term glucosamine and chondroitin sulfate intake may counteract symptomatic spinal disc degeneration, particularly at an early stage. However, definite proof requires well-conducted clinical trials with these food supplements, in which disc de-/regeneration can be objectively determined by MRI. A number of biochemical reasons (that mechanistically need to be further resolved) explain why these agents may have cartilage structure- and symptom-modifying effects, suggesting their therapeutic efficacy against osteoarthritis in general.

Chondroprotective agents: glucosamine and chondroitin

The near universal finding of the safety of glucosamine and chondroitin combined with some compelling evidence of their efficacy should spur further research into their mechanism of action, optimal dosing, long-term effects on disease modification, and clinical applicability. When recommending a supplement to patients, the clinician should take into account the purity of the ingredients, reputation of the manufacturer, and the molecular weight of chondroitin supplied.

Antihypertensive and metabolic effects of whole Maitake mushroom powder and its fractions in two rat strains

Maitake mushroom has been reported to favorably influence hypertension and diabetes mellitus. The purpose of this study was to compare the effects of whole Maitake mushroom powder and two extracts designated as ether soluble (ES) and water soluble (WS) on Zucker fatty rats (ZFR), a model of insulin resistance, and on spontaneously hypertensive rats (SHR), a model of genetic hypertension. In the initial study, we followed four groups of eight ZFR and SHR receiving special diets: a baseline diet (BD), BD + whole Maitake mushroom powder (20% w/w), BD + fraction ES (0.10% w/w), and BD + WS (0.22% w/w). Different effects of these dietary regimens on the 2 rat strains were found. At 35 days, only consumption of the ES diet significantly decreased systolic BP (SBP) in SHR (average 197 vs. 176 mm Hg, p < 0.001), while in ZFR only the groups consuming the whole Maitake and WS diets showed significantly decreased SBP (138 vs. 120-125 mm Hg, p < 0.001). A challenge test with losartan (an angiotensin II receptor blocker) indicates that angiotensin II does not play a major role in SBP regulation of ZFR, but does in SHR where consumption of ES relative to other groups significantly lowered activity of this system. In SHR, glucose, cholesterol, circulating insulin and HbA1C were virtually similar among all dietary groups; but whole Maitake (-22%), ES (-120%) and WS (-80%) diets were associated with decreased triglycerides, and the ES diet with lowered serum creatinine (-29%). In ZFR, circulating insulin and HbA1C were significantly decreased in the whole Maitake powder and ES groups, and tended to be lower in the WS group compared to control. In the ensuing studies, we gavaged ZFR once daily with water (control), 44 mg fraction WS, or 44 mg fraction WS plus 100 microg niacin-bound chromium (NBC). Oral gavage of WS clearly lowered SBP and circulating glucose concentrations, more so with the addition of chromium. We conclude that the examined forms of Maitake mushroom have antihypertensive and antidiabetic potential which differ among rat strains. The ES fraction may decrease SBP in SHR via alteration in the renin-angiotensin system.