Glucosamine sulfate is one of the most popular supplements taken for joint support. More than 40 million Americans take this compound daily for stiff joints and pain associated with osteoarthritis. Eight percent of seniors report taking glucosamine, making people ages 60 and up the biggest market for this supplement. What does the research show about its effectiveness and potential side effects? In this article, we discuss these questions, and reveal a 2026 study that links accelerated dementia in glucosamine supplement users who already showed signs of dementia.
Glucosamine Studies
Glucosamine sulfate is primarily studied for its potential to relieve osteoarthritis (OA) symptoms, especially in the knees. Research also looks at its role as a potential cartilage-preserving agent, particularly in relation to osteoarthritis management.
Literature to date has not proven that glucosamine sulfate supplements slows disease progression or effectively decreases OA-associated pain. randomized controlled studies show conflicting results. 1 2
Some research indicates that the potential beneficial effects of supplementing with glucosamine sulfate are due to preventing glycosaminoglycan and collagen degradation by down-regulating the production of inflammatory cytokines as well as stimulating the synthesis of glycosaminoglycans and augments type II collagen expression in chondrocytes. 3 4
Does taking supplements with chondroitin and glucosamine enhance the potential benefits?
Glucosamine, hyaluronic acid, and chondroitin sulfate are important basic natural components of cartilage and synovial fluid. They are naturally formed by the body, but can also be provided in the diet. Glucosamine and chondroitin are two compounds that occur naturally in your cartilage.
Glucosamine and chondroitin, typically taken combined in a single supplement, are said to relieve arthritis pain by acting as natural anti-inflammatories and slowing down the deterioration of cartilage.
Recommended Dosage
Studies that have observed improvements in osteoarthritis symptoms routinely used dosages of 1,500 mg glucosamine sulfate and 1,200 mg chondroitin sulfate. These supplements can be purchased over–the–counter, often combined. 5 6 7
Generally, glucosamine and chondroitin are considered safe, though they may not be suitable for those with shellfish allergies, diabetes, or for those taking anticoagulant medication. Speak with a healthcare professional first.
Alarming New Safety Concerns associated with Glucosamine Sulfate Related to Brain Function
New research studies indicate that seniors with dementia, including mild cognitive related impairment, should avoid supplementing with glucosamine sulfate. This research shows a 25% faster progression from mild cognitive impairment to full- blown Alzheimer’s disease.
Even more concerning, for individuals already diagnosed with dementia, the supplement was associated with a 25% increase in mortality risk. Because glucosamine easily crosses the blood-brain barrier, scientists believe it feeds into an already overactive protein ‘sugar-tagging’ pathway in vulnerable brains, worsening metabolic dysfunction. 8
Crucially, researchers emphasize that this risk appears highly specific to individuals whose brains are already undergoing neurodegeneration. In cognitively healthy adults, previous research has actually suggested that glucosamine may have a protective effect.
Researchers cautioned that the possible risk may apply mainly to people who already have mild cognitive impairment, Alzheimer’s disease, or a related dementia. 9. 2025 May 5:2025.04.30.651461. doi: 10.1101/2025.04.30.651461. PMID: 40654813; PMCID: PMC12247771.] In contrast, earlier population studies of cognitively healthy adults have linked regular glucosamine use with a lower risk of developing some forms of dementia. However, these findings do not prove cause and effect. 10 11
Eye Disease and Inflammation
Common eye conditions that can result from chronic inflammation include: macular edema, macular degeneration, uveitis, iritis, dry eyes.
Note: For more info, see our blog at Blog Archive – Natural Eye Care.
Connective Tissue and Eye Disease
Connective tissue and collagen disorders often cause significant eye complications because collagen is a primary structural component of the cornea, sclera, and vitreous humor. Manifestations range from severe nearsightedness and retinal detachment to glaucoma and corneal thinning.
Retinal Detachment
Weakened collagen in the eye’s gel (vitreous) can pull on the retina, causing tears or detachment. Retinal tears can be corrected typically with a laser in the eye doctor’s office. Symptoms can include: flashing of light, wavy vision and/or increases in eye floaters. With a full retinal detachment, you cannot see in that eye. Emergency surgery needs to be done within 24 hours to save vision.
Vitreous Tears and Detachments
Are where the vitreous partially or fully pulls away from the retina. This does not threaten vision, but can cause visual disturbances including significant increases in eye floaters.
Note: High myopia, aging, visual stress, and inflammatory conditions can contribute to the conditions above.
Glaucoma
Abnormally structured collagen in the eye’s drainage system (trabecular meshwork) can hinder fluid outflow, increasing intraocular pressure.
Keratoconus
Abnormal collagen cross-linking can cause the clear cornea to bulge outward into a cone shape, heavily distorting vision.
Nutrients That Help Support Connective Tissue in the Eyes and Body Overall
Vitamin C and Hyaluronic Acid
Vitamin C is a crucial cofactor in collagen production and helps stabilize collagen’s structure. Hyaluronic acid supports tissue hydration, cushioning, and flexibility. Both Vitamin C and hyaluronic acid are found in the vitreous. They appear to help support the integrity of the vitreous as well as the related connective tissue to the retina. Best food sources for Vitamin C include oranges, kiwi, strawberries, bell peppers and broccoli. Bone broth, citrus fruits, leafy green vegetables, soy, almonds and other nuts are high in hyaluronic acid.
Amino Acids (Glycine, Proline, Lysine, etc.)
Provide the fundamental building blocks of collagen and elastin. Best food sources include: bone broth, lean meats, poultry, and fish.
Zinc
Involved in collagen synthesis and tissue regeneration, and is also essential for retinal health. Best food sources include: lean meats, lentils, pumpkins seeds and oysters.
Copper and Manganese
They are trace minerals necessary for enzymatic reactions that cross-link collagen and strengthen tissues. Best food sources include: shellfish, nuts, seeds, and whole grains.
Omega-3 Fatty Acid
Help modulate biochemical inflammation, preventing the tissue degradation that causes joint pain. Best food sources include: salmon, mackerel, walnuts and chia seeds.
Vitamin A
Supports cell growth and the structural formation of tissues. Also essential for retinal health related to photoreceptor cell regeneration. Best food sources include: oily fish (herring, salmon, cod liver oil), dairy and eggs, sweet potatoes, winter squash, carrots, leafy greens, and broccoli.
Suggested Supplements to Consider
Dr. Grossman’s Complete Eye Formula 2oz (oral spray)
Dr. Grossman’s Complete Eye (oral Spray)/Meso Plus Combo Package
Advanced Eye & Vision Support Formula (whole food) 60 vcaps
Dr. Grossman’s Meso Plus Retinal Support and Computer Eye Strain Formula with Astaxanthin 90 vcaps
Dr. Grossman’s ReVision Formula (wild-crafted herbal formula) 2 oz – support healthy circulation and energy flow in the eyes and whole body, and supports healthy nerve function.
Dr. Grossman’s Vitamin C Supreme (Plant-Based Formula) – 60 caps – whole food, organic, GMO free formula
Wonderfeel NMN capsules 60 vegcaps
Dr. Grossman’s Advanced Eye and Dr. G’s Whole Food Superfood Multi1 20 Vcap Combo – 2 months supply
Dr. Grossman’s Blood Vessel Control Formula 2oz
OmegaGenics EPA-DHA 2400 5 fl oz
OmegaGenics™ EPA-DHA 720 Lemon 60 gels
Packages
Dr. Grossman’s Vision Wellness Package (2-month supply)
Recommended Books
Natural Eye Care: Your Guide to Healthy Vision and Healing
Natural Parkinson’s Support: Your Guide to Preventing and Managing Parkinson’s
- Reichenbach S, Sterchi R, Scherer M, Trelle S, Bürgi E, Bürgi U, Dieppe PA, Jüni P. Meta-analysis: chondroitin for osteoarthritis of the knee or hip. Ann Intern Med. 2007 Apr 17;146(8):580-90 ↩
- Vlad SC, LaValley MP, McAlindon TE, Felson DT. Glucosamine for pain in osteoarthritis: why do trial results differ? Arthritis Rheum. 2007 Jul;56(7):2267-77. ↩
- Yoshimura M, Sakamoto K, Tsuruta A, Yamamoto T, Ishida K, Yamaguchi H, Nagaoka I. Evaluation of the effect of glucosamine administration on biomarkers for cartilage and bone metabolism in soccer players. Int J Mol Med. 2009 Oct;24(4):487-94 ↩
- Henrotin Y, Chevalier X, Herrero-Beaumont G, McAlindon T, Mobasheri A, Pavelka K, Schön C, Weinans H, Biesalski H., Participants at the Hohenheim Consensus Conference in August 29th 2011. Physiological effects of oral glucosamine on joint health: current status and consensus on future research priorities. BMC Res Notes. 2013 Mar 26;6:115. ↩
- Ogata T, Ideno Y, Akai M, Seichi A, Hagino H, Iwaya T, Doi T, Yamada K, Chen AZ, Li Y, Hayashi K. Effects of glucosamine in patients with osteoarthritis of the knee: a systematic review and meta-analysis. Clin Rheumatol. 2018 Sep;37(9):2479-2487. doi: 10.1007/s10067-018-4106-2. Epub 2018 Apr 30. PMID: 29713967; PMCID: PMC6097075. ↩
- Hochberg MC, Martel-Pelletier J, Monfort J, Möller I, Castillo JR, Arden N, Berenbaum F, Blanco FJ, Conaghan PG, Doménech G, Henrotin Y, Pap T, Richette P, Sawitzke A, du Souich P, Pelletier JP; MOVES Investigation Group. Combined chondroitin sulfate and glucosamine for painful knee osteoarthritis: a multicentre, randomised, double-blind, non-inferiority trial versus celecoxib. Ann Rheum Dis. 2016 Jan;75(1):37-44. doi: 10.1136/annrheumdis-2014-206792. Epub 2015 Jan 14. PMID: 25589511; PMCID: PMC4717399. ↩
- Zeng C, Wei J, Li H, Wang YL, Xie DX, Yang T, Gao SG, Li YS, Luo W, Lei GH. Effectiveness and safety of Glucosamine, chondroitin, the two in combination, or celecoxib in the treatment of osteoarthritis of the knee. Sci Rep. 2015 Nov 18;5:16827. doi: 10.1038/srep16827. PMID: 26576862; PMCID: PMC4649492. ↩
- Source: Hawkinson, T. R., Gentry, M. S., & Sun, R. (2026). Hyperglycosylation is a metabolic driver of Alzheimer’s disease. Nature Metabolism. ↩
- Hawkinson TR, Liu Z, Ribas RA, Medina T, Nielsen RS, Clarke HA, Ma X, Mueller AC, Plasencia AF, Shear AL, Simpson ST, Soto CM, Sudderth J, Cai F, Cantrell AR, Colpert MG, Shedlock CJ, Wu L, Young LEA, Kooser DD, Chen L, Ryan AM, Ribas RA, Azadi P, Deberardinis RJ, Prokop S, Allison D, Huang Y, He X, Bian J, Vander Kooi CW, Gentry MS, Sun RC. Hyper-Glycosylation as a Central Metabolic Driver of Alzheimer’s Disease. bioRxiv [Preprint ↩
- Zheng J, Ni C, Zhang Y, Huang J, Hukportie DN, Liang B, Tang S. Association of regular glucosamine use with incident dementia: evidence from a longitudinal cohort and Mendelian randomization study. BMC Med. 2023 Mar 29;21(1):114. doi: 10.1186/s12916-023-02816-8. Erratum in: BMC Med. 2023 May 8;21(1):175. doi: 10.1186/s12916-023-02892-w. PMID: 36978077; PMCID: PMC10052856. ↩
- Zhou C, Zhang Y, Yang S, Ye Z, Wu Q, Liu M, He P, Zhang Y, Qin X. Habitual glucosamine use, APOE genotypes, and risk of incident cause-specific dementia in the older population. Alzheimers Res Ther. 2023 Sep 9;15(1):152. doi: 10.1186/s13195-023-01295-6. PMID: 37689747; PMCID: PMC10492372. ↩
