Glucosamine, Chondroitin and Proteoglycan: A Guide to Japanese Joint Supplements

In a Japanese drugstore the joint-care shelf is one of the largest in the building. Glucosamine, chondroitin, type II collagen, proteoglycan, hyaluronic acid and MSM appear in dozens of combinations, most carrying a small mark that says the product has a notified health claim.

The ingredients are the same ones sold everywhere else, with one exception: Japan has built a sub-category around salmon-cartilage proteoglycan, which barely exists outside the country.

What is in the bottle

Every ingredient on the shelf is a component of articular cartilage, the smooth tissue on bone ends that thins with age, or of the fluid lubricating it.

Japanese	Reading	Ingredient	Source
グルコサミン	gurukosamin	Glucosamine	Shellfish shells, or fermentation
コンドロイチン	kondoroichin	Chondroitin sulphate	Shark, bovine or chicken cartilage
II型コラーゲン	ni-gata korāgen	Type II collagen	Chicken sternum cartilage
プロテオグリカン	puroteogurikan	Proteoglycan	Salmon nasal cartilage
ヒアルロン酸	hiaruron-san	Hyaluronic acid	Fermentation
MSM	emu-esu-emu	Methylsulfonylmethane	Synthetic sulphur compound

Whether a swallowed building block reaches the knee is the question the evidence has spent thirty years on, and the answer is a qualified maybe.

Glucosamine

Glucosamine is the base of nearly every Japanese joint product. The standard daily amount is 1,500 mg, and the trials that found any benefit used that figure, mostly as glucosamine sulphate for at least three months. Japanese products more often use the hydrochloride, which delivers more per gram but has a thinner trial record.

The honest summary: some European trials showed a modest reduction in knee osteoarthritis pain, the large American GAIT trial found none overall, and most orthopaedic guidelines do not recommend it. It is also very safe, which is why so many people try it.

Yakult's version uses fermented rather than shellfish-derived glucosamine, 1,500 mg across nine tablets with a little chondroitin and hyaluronic acid, the sensible pick for anyone with a crustacean allergy.

DHC's 2,000 mg formulation is a notified functional food with the claim worded around knee bending and straightening; six capsules a day is a commitment, so be sure of the routine before buying the 30-day box.

Chondroitin and type II collagen

Chondroitin sulphate was dosed at 800–1,200 mg a day in the trials that studied it alone, and pharmaceutical-grade material beat placebo in several European studies where lower grades did not. Japanese products tend to include tens of milligrams, so treat it as a supporting ingredient rather than the reason to buy.

Type II collagen is different. The undenatured form, at roughly 40 mg a day, is thought to work through immune tolerance rather than as a building block, and a handful of small trials have shown benefit for knee comfort. Hyaluronic acid and MSM appear at low doses as supporting ingredients; oral hyaluronic acid has only small studies behind it, and MSM trials used 1.5–6 g a day, far more than any Japanese blend contains.

DHC's chondroitin capsule adds type II collagen and royal jelly, a typical blend for people who already take glucosamine and want the other cartilage components in one product; our DHC beginner's guide explains the range.

Proteoglycan: the Japanese ingredient

Proteoglycan is a large molecule that holds water inside cartilage and gives it its cushioning. It was prohibitively expensive until researchers at Hirosaki University in Aomori found a way to extract it from salmon nasal cartilage, a by-product of the local fishery; it has since gone into hundreds of notified products.

The typical dose is 10 mg a day, and the claim is usually about knee discomfort when standing, sitting or walking. The evidence consists of small Japanese trials, some funded by manufacturers. It is plausible and not well established, roughly where glucosamine sat in the 1990s.

Rakunari layers proteoglycan and hyaluronic acid over a glucosamine and MSM base with no preservatives or artificial colours, the most complete single formula here.

FUJIFILM's Hizatect is notified for knee discomfort when walking and on stairs, and is built around supporting the body's own cartilage production rather than supplying components.

Kaiho takes the kitchen-sink route: a standardised Boswellia serrata extract, a resin with some anti-inflammatory trial data, on top of glucosamine and shark cartilage in a 720-tablet, three-month tub.

Reading the label

Japan has three tiers of health claim on food, and the mark on the box tells you how much scrutiny the claim has had.

Japanese	Reading	English	Who checks it
特定保健用食品	tokutei hoken-yō shokuhin	FOSHU, or トクホ	Government approves each product on its own clinical data
機能性表示食品	kinōsei hyōji shokuhin	Foods with function claims	Company files evidence with the Consumer Affairs Agency; no approval
栄養機能食品	eiyō kinō shokuhin	Nutrient function claims	Standard wording for vitamins and minerals; no review

Nearly every joint supplement sits in the middle tier: the maker has filed a dossier and taken responsibility, and nobody in government has tested the product. Read the claim on the front literally: "reduces knee discomfort when walking" is what was filed, and nothing broader.

How much, and for how long

1. Take the full daily dose on the box. Half-dosing to make it last is the commonest reason people see nothing.
2. Take it with a meal and trial for 12 weeks. Cartilage turns over slowly, and every positive trial ran at least that long.
3. Note how the knee feels on stairs, first thing in the morning, and after a walk. If nothing has changed at 12 weeks, stop.

Check with a doctor if

• You take warfarin or another blood thinner. Case reports link glucosamine and chondroitin to a raised INR.
• You have a shellfish allergy. Most glucosamine is made from crustacean shells; fermented products avoid the issue.
• You have diabetes, or are pregnant or breastfeeding. Data is thin.
• The knee is swollen, hot, locked or suddenly painful. Supplements are for slow mechanical discomfort, not for something that needs a diagnosis.

None of this is medical advice; a persistently painful joint deserves an examination before a supplement.

Frequently asked questions

Sulphate or hydrochloride? Sulphate has the better trial record; hydrochloride delivers more glucosamine per gram. Either is a reasonable trial at 1,500 mg.

Can I take a joint supplement with fish oil? Yes. Omega-3 has separate, modest evidence for joint stiffness, covered in our fish oil guide.

Do these help hips and hands as well as knees? The trials are almost all on knees. The biology is the same; the evidence is not.

Are there side effects? Mild stomach upset is the main one. Take the dose with food and it usually settles.

Pick one product with 1,500 mg of glucosamine, take it properly for three months, and judge honestly. Our supplement routine guide covers fitting it into a wider daily regime.