I’ll start with the bad news: There are no vegetarian collagen sources. Every collagen supplement you see on the shelf came from a living organism. Though somewhere down the line someone will probably grow legitimate collagen in a lab setting, it’s not available today or for the foreseeable future.
Now, some good news: Vegans and vegetarians probably need less dietary collagen than the average meat eater or Primal eater because a major reason omnivores need collagen is to balance out all the muscle meat we eat. When we metabolize methionine, an amino acid found abundantly in muscle meat, we burn through glycine, an amino acid found abundantly in collagen. If you’re not eating muscle meat, you don’t need as much glycine to balance out your diet, but it’s still a dietary necessity.
Collagen  isn’t just about “balancing out meat intake.” It’s the best source of a conditionally essential amino acid known as glycine. The human body requires at least 16 grams per day for basic metabolic processes , yet we can only make 3 grams, and the typical omnivorous diet provides just 2-3 grams per day, so we’re looking at an average daily deficit of 10 grams that we need to make up for through diet. And in disease states that disrupt glycine synthesis, like rheumatoid arthritis , or on plant-based diets that provide little to no dietary glycine, we need even more.
What About Marine Collagen?
Okay, but eating a product made from a cuddly cow or an intelligent pig is off limits for most vegetarians. What about marine collagen—collagen derived from fish bones, scales, and skin?
Back about twenty years ago, “vegetarians” often ate fish. A number of them still exist out in the wild, people who for one reason or another avoid eating land animals (including birds) but do regularly consume marine animals. If it jibes with your ethics, marine collagen is a legitimate source of collagen for vegetarians. The constituent amino acids are nearly identical to the amino acids of mammalian collagen with very similar proportions and properties.
It’s highly bioavailable, with the collagen peptides often showing up intact in the body and ready to work their magic—just like bovine or porcine collagen. In fact, if you ask many marine collagen purveyors, it’s even more bioavailable than mammalian collagen owing to its lower molecular weight.
I’m not sure that’s actually accurate, though.
According to some sources, marine collagen comes in smaller particles and is thus more bioavailable than mammalian collagen, but I haven’t seen solid evidence.
There’s this paper , which mentions increased bioavailability in a bullet point off-hand, almost as an assumption or common knowledge.
This analysis  found low molecular weights in collagen derived from fish waste. Mammalian collagen generally has higher molecular weights, so that appears to be correct.
However, a very recent pro-marine collagen paper  that makes a strong case for the use of marine collagen in wound repair, oral supplementation, and other medical applications does not mention increased bioavailability. It may be slightly more bioavailable—the lower the molecular weight, the more true that is—but I don’t think the effect is very meaningful. Mammalian collagen is plenty bioavailable (most efficacious studies use collagen from cows or pigs), even if it’s a few dozen kilodaltons heavier.
But even if marine collagen isn’t particularly superior to mammal collagen, it is equally beneficial.
For skin health: Fish collagen improves hydration, elasticity, and wrinkling in humans who eat it . And again .
For metabolism: Fish collagen improves glucose and lipid metabolism in type 2 diabetics . HDL and insulin sensitivity go up, triglycerides and LDL go down.
And although fish collagen hasn’t been studied in the treatment of joint pain, if it’s anything like other types of collagen, it will help there too.
What Are Strict Vegetarian Options?
What if you absolutely won’t eat collagen from marine sources? Is there anything you can do as a vegetarian to make up for it?
Make Your Own
You could cobble together your own facsimile of collagen by making an amino acid mixture. Glycine , proline , and arginine  don’t cover all the amino acids present in collagen, but they’re widely available and hit the major ones.
Still, eating the amino acids that make up collagen separately doesn’t have the same effect on those collagenous tissues as eating them together in a collagenous matrix. One reason is that the collagen matrix can survive digestion more or less intact, giving it different biological properties and effects.
In one study , rats with osteoporosis ate collagen hydrolysate that scientists had marked with a radioactive signature to allow them to track its course through the body. It survived the digestive tract intact, made it into the blood, and accumulate in the kidneys. By day 14, the rats’ thigh bones had gotten stronger and denser with more organic matter and less water content.
Another study  found similar results, this time for cartilage of the knee. Mice who ate radioactive collagen hydrolysate showed increased radioactivity in the knee joint.
In both cases, the collagen remained more or less intact. A blend of the isolated amino acids would not. The fact is that collagen is more than glycine. When you feed people collagen derived from pork skin, chicken feet, and cartilage, many different collagenous peptides appear in the blood . You don’t get any of those from isolated glycine.
That’s not to say it’s pointless. Pure glycine can be a helpful supplement, used in several studies to improve multiple markers of sleep quality . Just don’t expect it to have the same effect as full-blown collagen.
Get Adequate Vitamin C
Acute scurvy, caused by absolute vitamin C deficiency, triggers the dissolution of your connective tissue throughout the body. Teeth fall out, no longer held in by gums. Wounds don’t heal, your body unable to lay down new collagen.
Vegetarians usually don’t have any issues getting adequate vitamin C.
Get Adequate Copper
Copper is a necessary cofactor in the production of collagen. Studies show  that you can control the production of collagen simply by providing or withholding copper.
The best vegetarian source of copper is probably dark chocolate , the darker and more bitter the better.
Get Adequate Lysine
Lysine is another amino acid that’s necessary for the production of collagen.
True vegetarian collagen doesn’t exist. Strict vegetarians will balk. But if you can bend the rules a bit, realize that making marine collagen out of fins and scales and bones is far less wasteful than just throwing it away, and look at the benefits with an objective eye, you’ll be pleasantly surprised. Even if you don’t end up using marine collagen, at least you have a few tools for getting many of the benefits with quick shortcuts and optimizing your own production of collagen.
Have you ever tried marine collagen? If you’re a vegetarian, would you consider it?
Thanks for reading, everyone. Take care and be well.