Amino acids

L-proline

An amino acid the body makes itself and also gets from meat, eggs and dairy. It is one of the main building blocks of collagen, the protein in skin, tendons and bones.

16 products from US online stores, sorted by what 500 mg of proline costs – not by the price per pack.

2.8¢Lowest cost
per 500 mg proline

Prices checked Nov 1, 2026, US
No paid placements

What does 500 mg mean?

proline per serving in most of the products we checked: 1,000–2,000 mgproline per serving in most of the products we checked

500 mg is a fixed amount to compare by: half of the 16 products we checked have up to 2,000 mg per serving, the other half more.
There’s no official daily amount for proline.

We compare by 500 mg only so products line up – it’s not a recommendation. Not medical advice.

Where products miss quality points

How the 16 products score

Very good 90+: 0
Good 75+: 16
Fair 60+: 0
Low under 60: 0

have no seal from an independent testing program: 16 of 16have no seal from an independent testing program10 of 30 testing points for GMP, 15 for the 3 whose label says “third-party tested”

The full 30 testing points need an independent test. Every supplement sold in the US is made under the FDA’s GMP rules – the maker checks its own products, which gives 10 points. A seal from a testing program like NSF, USP or Informed Choice means a lab outside the company checks that what’s inside matches the label. Most brands don’t take part. That doesn’t make a product bad – without a seal, a clean product still gets up to 80.

We find seals on the label and in NSF’s public lists. USP and Informed Choice don’t let us search their lists automatically, so a seal that’s only in their lists can be missing. How the score works

Good to know

Fact: 317%more per 500 mg for the most expensive product than for the cheapest.
Fact: 197%more per 500 mg for the cheapest capsules than for the cheapest powder.

How we checked: one-time price for each size in the store’s US online shop, before sales tax and shipping, without subscriptions or coupons. Prices change often, so check the store before you buy. More on how we check

The amount we compare by only makes products comparable – it is not a dosage recommendation. Not medical advice.

How we calculate

Cost per dose = price ÷ (servings × amount per serving) × comparison amount. Example: $119.99 for 74 servings with 24 g of protein each is 1,776 g of protein. $119.99 ÷ 1,776 g × 30 g = $2.03 per 30 g of protein.

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L-proline

What does 500 mg mean?

Where products miss quality points

Pack size

L-Proline Powder

L-Proline, Unflavored

L-Proline Powder

L-Proline Powder

L-Proline Powder

Amazing Formulas L-Proline - 100 Grams

L-Proline Powder

L-Proline

Amazing Formulas L-Proline - 500 Mg

L-Proline

L-Proline 500 mg

L-Proline Capsules

L-Proline

L-Proline Capsules

L-Proline Powder

L-Proline

Good to know