Joint and skin supplements: what the evidence says

A popular joint supplement — but the largest independent trial found no significant benefit over placebo for most people with knee osteoarthritis.

Biotin is sold everywhere for hair, skin and nails, and the evidence for that use in people without deficiency is close to nonexistent.

A cheap, remarkably safe sulfur compound with a handful of small, mostly positive joint pain trials — none large or rigorous enough to be convincing.

Oral hyaluronic acid has a modest, mostly favourable trial record for skin hydration and knee pain, but the studies are small, heavily concentrated in Japan, and usually funded by ingredient makers.

Borage oil is the richest common source of gamma-linolenic acid (GLA), roughly triple the concentration in evening primrose oil.

Sea buckthorn oil is nutritionally interesting — it is one of very few plant oils containing palmitoleic acid (omega-7) — but the human evidence is thin.

The "brain tonic" claims do not survive meta-analysis, which found no benefit in any cognitive domain.

Two small randomized trials from the early 2000s found modest pain relief in knee osteoarthritis and rheumatoid arthritis, and essentially nothing has confirmed them in the two decades since.

Bromelain, a pineapple-derived protease, shows modest anti-inflammatory and analgesic effects in small trials of osteoarthritis and post-surgical swelling, but the evidence base is fragmented, mostly low quality, and dominated by combination products.

Serrapeptase (serratiopeptidase) has a small, low-quality evidence base for reducing swelling and trismus after dental surgery, and essentially nothing supporting the sweeping claims about dissolving arterial plaque, scar tissue or mucus.

Devil's claw shows a real but small and low-confidence signal for short-term low back pain at 50-100 mg harpagoside per day.

Pooled trials show eggshell membrane produces small but statistically significant improvements in knee osteoarthritis pain and function at 500 mg/day.

Small manufacturer-run trials report modest gains in skin hydration after 6-12 weeks of oral plant-derived ceramides, but the studies are tiny, short and use soft endpoints.

Polypodium leucotomos extract raises the UV dose needed to redden skin and may reduce photodermatosis flares, but trials are small and short and the protection is weak — equivalent to a very low SPF.

Bamboo extract is the most concentrated natural silica source sold (up to 70% silica by weight), but that silica is largely insoluble phytolith silica with poor absorption — and the human hair/skin/nail trials everyone cites were run on a different, soluble form (choline-stabilized orthosilicic acid), not bamboo.

"Five types of collagen in one scoop" is a marketing construct, not a research finding — no trial has tested a multi-type blend head-to-head against a single-source peptide, and the type II and X fractions are usually present in token amounts.

These products contain no collagen — they are vitamin C, amino acids, silica and biotin sold as raw materials for your own collagen synthesis.

Oral keratin (usually solubilized wool keratin, sold as Cynatine HNS) rests on a single small manufacturer-funded trial; the intuitive idea that eating hair protein makes hair is not how protein digestion works.

These formulas are built around megadose biotin, which does nothing for hair in people who are not deficient — and which reliably corrupts common blood tests, including the troponin assay used to diagnose heart attacks.

Oregon grape cream has modest randomized evidence for mild-to-moderate plaque psoriasis, where it beats placebo but loses to standard prescription topicals.

Chinese skullcap (Scutellaria baicalensis) has one week-long trial for knee osteoarthritis using a proprietary blend, and a documented history of liver injury when its baicalin was sold as the medical food flavocoxid.

BPC-157 is an experimental peptide with impressive rat healing data, essentially no published human trials, and no legal status as a dietary supplement.

Squalene is a natural lipid your own skin makes and a well-validated vaccine adjuvant, but as an oral supplement it has almost no controlled human evidence.

Tremella fuciformis is marketed as a plant-based hyaluronic acid alternative for skin, but that claim rests on the polysaccharide's water-binding chemistry in a beaker, not on oral trials.

Oral homeopathic arnica pellets, taken for bruising and post-surgical swelling, have been tested repeatedly and the best-quality placebo-controlled trials are negative.

A waxy fatty acid ester marketed for arthritis since the 1990s on the strength of a handful of small, industry-linked trials that have never been independently replicated.

The best-tested version of this category — glucosamine plus chondroitin — failed its largest independent trial and its largest network meta-analysis.

An acetylated form of glucosamine promoted for joints and the gut lining.

A plant-style boron-carbohydrate complex studied mainly for knee discomfort.

A plant antioxidant used mainly to stabilise vitamin C and E in topical serums.

An Ayurvedic root (Rubia cordifolia) traditionally used as a blood purifier for skin complaints.

An Ayurvedic herb famous for hair growth and liver support.

The plant that gave aspirin its name, containing salicylate precursors.

Marigold flower extract with a modest evidence base for topical wound and skin care.

A marine animal rich in chondroitin-like glycosaminoglycans, sold for joint pain.

Ground pearl, used for centuries in Chinese medicine as a beauty tonic.

A popular anti-ageing supplement across parts of Asia.

A seed oil supplying gamma-linolenic acid, sold for dry skin and eczema.

An amino acid that makes up a large share of collagen, sold on that basis for skin and joints.

Fish-derived protein and mucopolysaccharide blends taken for thinning hair.

A hair supplement ingredient always paired with L-cystine, biotin and pantothenic acid.

Hydrolysed elastin from fish, marketed for skin elasticity by analogy with collagen peptides.

A proteoglycan extracted from salmon nasal cartilage, popular in Japan for joints and skin.

A ginger relative whose joint reputation comes from one large trial where it was combined with ginger.

A triterpene extract whose only well-tested use is a topical gel for wound healing in the rare skin disease epidermolysis bullosa.

A traditional East Asian and North American rhizome used for tendons and joints.

A saponin-rich desert root long sold for arthritis.

An Amazonian tree resin rich in beta-caryophyllene, marketed for inflammation and skin.

A concentrated cucumber extract sold for joint pain.

Capsules combining zinc, vitamin A and botanicals for acne-prone skin.

Oral glutathione, usually with vitamin C and other antioxidants, marketed for a lighter or more even complexion.

Enteric-coated proteases — serrapeptase, bromelain, trypsin — taken on an empty stomach for swelling and inflammation.

Dried cattle cartilage, sold as a whole-food source of collagen and glycosaminoglycans for joints.

A classical Ayurvedic decoction of ten roots, used traditionally for pain, inflammation and vata disorders.

A fern rhizome used in Chinese medicine for fractures and bone loss.

A root used in Chinese formulas for the knees and lower back, almost always as one component of a multi-herb prescription.