About Collagen

Commonly found in three different forms: Type I, II, and III. Collagen is a protein found in skin, bones, and connective tissues, often used as a supplement to support skin elasticity, joint health, and muscle function.

Effectiveness Scores

Joint Health Adults with osteoarthritis: 6.0/10.
Collagen Types Used: Type II collagen
Type II collagen is the main building block of cartilage, the cushioning inside your joints. In tiny amounts, it's thought to calm the immune reaction that wears cartilage down. Hydrolyzed collagen, in larger amounts, may give your body raw material for repair.
Why this rating: Several reviews agree that collagen eases joint pain and stiffness, mostly in people with knee osteoarthritis. The improvement is real but modest. But, many of these trials were funded by the companies selling the products.
Cardiovascular Health: 6.0/10 (moderate evidence).
Collagen Types Used: Type I collagen
When your body digests collagen, some of the small protein pieces may help blood vessels relax, which can bring blood pressure down. Collagen may also lower LDL cholesterol by a small amount.
Why this rating: A 2023 review of 12 trials found collagen lowered the top blood pressure number by about 5 points, a meaningful amount. LDL cholesterol dropped too, but only slightly, and the studies disagreed with each other a lot. The trials were short, 6 to 12 weeks, and doses ranged from under a gram to 15 grams a day. Encouraging, but too early to count on for heart health.
Bone Health Postmenopausal women: 5.0/10.
Collagen Types Used: Type I collagen
Type I collagen makes up about 90% of the protein framework inside your bones. The idea is that collagen peptides may signal your bone-building cells to work harder.
Why this rating: One well-run trial of 131 postmenopausal women found that 5 grams a day raised bone density in the spine and hip after a year. But that's one study, and it was partly funded by the company that makes the product. The four-year follow-up you'll often see cited included 31 women, had no placebo group, and everyone knew they were taking collagen. Nobody has shown that it prevents broken bones.
Promote Muscle Mass Older adults: 5.0/10.
Collagen Types Used: Type I & III collagen
Collagen is a protein, and protein helps muscles rebuild after exercise. But collagen is missing one of the amino acids your body needs to build muscle, which makes it a weaker option than most other proteins.
Why this rating: In one study, older men with age-related muscle loss who took 15 grams a day and did strength training gained more muscle and strength over 12 weeks than those taking a placebo. However, without exercise, collagen hasn't shown much result. When compared to complete proteins like whey, whey has usually come out ahead. If building muscle is the goal, another protein is likely a better use of your money.
Wound Healing: 4.0/10 (moderate evidence).
Collagen Types Used: Type I collagen
Healing wounds need a lot of protein to rebuild skin and tissue, and collagen supplies some of those building blocks.
Why this rating: The research here comes from hospital settings, like burn units and nursing homes treating pressure sores, where patients are often short on protein to begin with. Some trials found faster healing, including one burn study reporting healing 3.7 times faster. But there are only a handful of trials; the patients were very sick, and it's hard to separate collagen's effect from simply getting more protein. There's no research on everyday cuts and scrapes.
Skin Health: 3.0/10 (moderate evidence).
Collagen Types Used: Type I
As you age, your skin makes less collagen, which leads to wrinkles and less firmness. The idea is that eating collagen gives your skin more to work with.
Why this rating: This is one of the most popular reasons people take collagen, and the evidence depends entirely on who paid for it. A 2025 review of 23 trials found that studies funded by collagen companies showed better hydration, elasticity, and fewer wrinkles. But studies without that funding bias, along with the highest-quality studies, found no effect at all. The researchers concluded there's no clinical evidence that collagen helps aging skin. Many positive studies exist, but they don't hold up when you check who ran them and how well.

Understanding Effectiveness Scores

What does this mean?

Our effectiveness scoring system is based on scientific research and evidence. Each health outcome is rated on a scale of 1-10, with higher scores indicating stronger scientific support for the supplement's effectiveness.

1/10: Scientific evidence concludes that supplement is ineffective for purpose
2/10: No scientific evidence supports effectiveness
3/10: Inconclusive results regarding effectiveness
4/10: Minimal research on effectiveness
5/10: Limited evidence of effectiveness; may have potential benefits, but more research is needed
6/10: Some evidence supports the supplement's effectiveness, but research is mixed
7/10: Moderate evidence shows the supplement is effective for certain purposes, with limited population studies
8/10: Solid evidence suggests the supplement is effective, but research is not as extensive as higher levels
9/10: Strong scientific evidence supports the supplement's effectiveness, but some minor gaps in research remain (e.g., limited long-term studies or specific populations).
10/10: Ample scientific research demonstrates that the supplement is both highly effective and safe for long-term use.

Form Variations

Hydrolyzed peptide
Collagen is broken down into small pieces so it dissolves in water and absorbs easily. Usually from cows (types I and III) or fish (type I). This is what most studies used and what most powders are.
Best for: skin, bone, joint, blood pressure, and muscle
Undenatured type II
Type II collagen from chicken cartilage, left intact rather than broken down. It works differently from hydrolyzed collagen and is taken in very small amounts.
Best for: joint pain

Dosage & Timeline

Standard Dosages

Standard range: 2.5-15 grams daily
Joint Health: 10 grams daily
Bone Health: 5 grams daily
Muscle, with strength training: 15 grams daily

Results Timeline

Joint pain: 12 to 24 weeks
Bone density: measured after 12 months
Blood pressure: trials ran 6 to 12 weeks
Muscle: trials ran 12 weeks, alongside strength training

All other outcomes may be noticed after extended use or lack enough studies to establish an effectiveness timeline.

Safety Information

Pregnancy and breastfeeding: Generally considered safe, since it's a food protein. Heavy metal contamination is the bigger concern, so choose a third-party tested product.
Allergies: Collagen comes from fish, shellfish, cows, pigs, or chickens. If you're allergic to the source, avoid it. Check the label.
Kidney or liver conditions: Your body turns part of collagen into oxalate, the main ingredient in most kidney stones. If you've had kidney stones or have kidney disease, check with your doctor before taking large daily doses.
The biggest safety concern with collagen isn't collagen itself; it's what else ends up in the tub. A 2020 analysis of 30 popular collagen brands found 64% contained arsenic, 37% lead, 34% mercury, and 17% cadmium. Look for products tested by a third party, like NSF Certified for Sport or USP Verified.

Side Effects

Common side effects:

Mild stomach discomfort, like bloating or feeling full
Unpleasant aftertaste, mostly with powders and liquids

Rare side effects:

Allergic reactions in people allergic to the source animal, like fish, shellfish, or beef
Skin irritation or rash

Most side effects are mild and resolve quickly after discontinuing the supplement.

Usage Information

Most people take collagen for their skin, hair, and nails, even though that's where the evidence is weakest. The better-supported uses are joint pain and, to a lesser degree, bone density and blood pressure.

Collagen is a helper, not a treatment. It shouldn't replace medication for osteoporosis, arthritis, or high blood pressure.

User Experience

Gathered from reviews and forum posts, not from studies. What people report tells you what to expect. It does not tell you whether something works.

Most people take collagen for hair, skin, and nails, even though joints are where the evidence is strongest. Marketing tends to focus on beauty, and it shows in what people buy it for.

Reviews are mixed. Some people notice smoother skin, less joint pain, or stronger nails after about four weeks, though the changes are usually subtle. Plenty of others notice nothing. Because collagen is often sold as "science-backed," many people expect more than they get and end up disappointed.

Collagen