Proline: Food Sources & Daily Intake
Proline is one of the main building blocks of collagen — the structural protein that holds skin, tendons, ligaments, cartilage, bone and blood-vessel walls together — where it pairs with glycine and hydroxyproline. The body can make proline from glutamate, so it is classed as non-essential, but it becomes conditionally essential during rapid growth, wound healing and recovery, when demand runs high. To actually build collagen from proline the body needs vitamin C, which the enzyme that converts proline to hydroxyproline depends on. In the table below the richest source is collagen itself — gelatin — followed by hard cheeses, then organ meats, beef, seeds, nuts and beans, with poultry and fish lower down; other sources include bone broth and eggs. The table below shows grams of proline per 100 g of food; there is no U.S. Food and Drug Administration (FDA) Daily Value for individual amino acids, so amounts are absolute.
| Proline: Food Sources & Daily Intake | |||||
|---|---|---|---|---|---|
| Rank | Food (serving) | Per 100 g | Glucose | Fructose | Notes |
| 1 | Gelatin (Dry) 1 tbsp / 7 g | 🟢 12 g | 0 | 0 | By far the richest source — pure collagen protein. |
| 2 | Parmesan Cheese 1 oz / 28 g | 🟡 4.2 g | — | — | Concentrated aged-dairy protein. |
| 3 | Cheddar Cheese 1 oz / 28 g | 🟡 2.7 g | 0 | 0 | |
| 4 | Soybeans 1 cup cooked / 172 g | 🟡 2.4 g | — | — | Top whole-plant source. |
| 5 | Pork Organ Meats 3 oz / 85 g | 🟡 1.6 g | — | — | Nutrient-dense organ meat. |
| 6 | Beef Meat 3 oz / 85 g | 🟡 1.3 g | 0 | 0 | |
| 7 | Sunflower Seeds 1 oz / 28 g | 🟡 1.2 g | — | — | |
| 8 | Peanuts 1 oz / 28 g | ⚪ 1.1 g | — | — | |
| 9 | Lentils 1 cup cooked / 198 g | ⚪ 1.0 g | 0 | 0.3 | |
| 10 | White Beans 1 cup cooked / 179 g | ⚪ 1.0 g | — | — | |
| 11 | Chicken 3 oz / 85 g | ⚪ 0.9 g | 0 | 0 | |
| 12 | Pork 3 oz / 85 g | ⚪ 0.9 g | 0 | 0 | |
| 13 | Tuna 3 oz / 85 g | ⚪ 0.8 g | 0 | 0 | |
| 14 | Salmon 3 oz / 85 g | ⚪ 0.7 g | 0 | 0 | |
| 15 | Chicken Organ Meats 3 oz / 85 g | ⚪ 0.5 g | 0 | 0 | Nutrient-dense organ meat (giblets). |
| 16 | Brown Rice 1 cup / 195 g | ⚪ 0.1 g | 0 | 0 | Common staple. |
Table of Contents
How to Read These Tables
- Non-essential, but it matters during healing. The body normally makes its own proline, so there is no dietary requirement. During rapid growth or while healing a wound, demand can outpace what the body produces — that is when proline-rich food (and the vitamin C needed to use it) becomes useful.
- Grams per 100 g, not %DV. There is no U.S. Food and Drug Administration Daily Value for individual amino acids, so this table reports the absolute grams per 100 g of food and ranks foods by that. A typical serving is shown beside each food.
- Proline concentrates in collagen. The food at the top of the list is collagen itself — gelatin, made from connective tissue, skin and bone — followed by aged dairy. Ordinary muscle meat, fish, seeds, nuts and legumes supply proline too, just less densely; other sources include bone broth and eggs.
Recommended Intakes & Upper Limits
Proline has no Daily Value: the U.S. food-label rules (21 CFR 101.9) set none for it, and the green and yellow marks in the food table above only rank each food against the richest food listed. The table below summarizes its status.
| Reference | Adult value | Notes |
|---|---|---|
| Status | Non-essential (conditionally essential in growth/healing) | The body makes proline from glutamate, but demand can outstrip supply during rapid growth, wound healing or recovery. |
| Adult requirement | None set | No WHO/FAO or DRI requirement exists for proline; it is not an essential amino acid. |
| Main role | Building block of collagen | Proline and its hydroxylated form (hydroxyproline) make up much of collagen, the body’s main structural protein in skin, joints and connective tissue. |
| Richest in | Collagen-rich & dairy foods | Gelatin and bone broth (from connective tissue), then hard cheeses, meat, fish and eggs. |
Bioavailability & Absorption
Proline from food is well absorbed as part of dietary protein, and the body can also synthesize it from glutamate, so blood levels are rarely a problem in anyone eating enough total protein. What matters for connective tissue is having proline available together with the cofactors collagen synthesis needs — especially vitamin C, plus iron and oxygen — because the enzyme prolyl hydroxylase uses vitamin C to convert proline into the hydroxyproline that locks collagen’s triple helix together. Eating proline-rich food without enough vitamin C limits how much usable collagen the body can build.
Cooking & Storage
Proline is stable to ordinary cooking and is not destroyed by normal heat. In fact, the most proline-dense food of all is created by cooking: simmering bones, skin and connective tissue for hours dissolves their collagen into gelatin — this is exactly what bone broth is, and why it carries so much proline and glycine. Slow, moist heat (braising, stewing, stock-making) is the way to extract collagen-bound proline from tougher cuts and bones.
Vegetarian & Vegan Sources
Getting proline for collagen-style repair is harder on a plant-based diet, because the densest sources — gelatin and bone broth — are animal connective tissue, and plants contain no collagen at all. Plant eaters can still supply plenty of proline as an amino acid from sunflower seeds, peanuts, lentils and white beans, with a smaller amount from brown rice; other sources include fermented soy foods and vegetables such as asparagus and cabbage. The body then builds its own collagen from that proline — provided total protein is adequate and vitamin C intake is good, since vitamin C is the limiting cofactor for collagen synthesis.
Who Needs to Pay Attention
Outright proline deficiency is essentially unknown in people eating adequate protein, because the body manufactures its own. Proline becomes more relevant in situations of high connective-tissue demand — wound healing, recovery from surgery or burns, and rapid growth — where supply may not keep up with need. In those settings, collagen building depends on enough total quality protein plus sufficient vitamin C, the cofactor that lets proline be turned into collagen; proline alone, without vitamin C, cannot build sound new tissue.
Key Research Papers
- NIH MedlinePlus — Amino acids
- Linus Pauling Institute — vitamin C and collagen synthesis
- Wu G, Bazer FW, Burghardt RC, et al. (2011). Proline and hydroxyproline metabolism: implications for animal and human nutrition. Amino Acids. — PubMed PMID: 20697752
- PubMed — proline, vitamin C and collagen synthesis in wound healing. — Search PubMed