For today’s edition of Dear Mark, I’m answering one question from a reader. It’s all about synthetic peptides, small chains of amino acids with potentially huge effects on your health and physiological function. In most cases, these synthetic peptides are based on naturally-occurring compounds found in the human body. Scientists isolate the “active component” of the compound and whip it up in a lab by stringing together the right amino acids. Many of these peptides are available for purchase online, strictly “for research purposes.” But people are using them.
Are these safe for humans? Are they effective?
Mark, I would love if you did a write-up on BPC-157 and LL-37 with regards to gut health. I’m surprised with all your articles on collagen peptides you haven’t written once about “synthetic” peptides. Thanks!
Let Me Cover PBC-157 First….
BPC-157 is a partial reconstruction of a string of 15 amino acids that’s already found in Body Protection Compound, a naturally occurring healing compound the body produces. Its creators took the natural BPC and figured out the most “biologically active” section of its amino acid chain, then synthesized that section alone. You can find the real thing in human stomach juice (and presumably throughout the body doing its job). You can buy the synthetic version online.
What Does BPC-157 Allegedly Do?
It enhances healing and recovery from injury. In one study , BPC-157-treated Achilles’ tendon tissues were more resistant to injury, spread more quickly on a petri dish, and recovered faster than untreated tendon tissues.
In another rat study , their cecums—the beginning of the large intestine—were perforated. Applying BPC-157 enhanced healing, stopped bleeding, and sped up recovery.
It counteracts NSAID toxicity . BPC-157 blocks aspirin-induced bleeding and improves healing of NSAID-mediated lesions in the gut, brain, and liver.
Another rat study  even used BPC-157 to improve healing from a spinal cord injury. BPC rats regained functional autonomy, had better control over their tails, and were less spastic.
It can treat periodontal disease , reversing inflammation and reducing bone loss.
It can treat colitis , reducing gut inflammation and restoring mucosal integrity.
Briefly looking through all the anecdotes online, most people are using this peptide to heal joint or tissue injuries, which seems to be the best use. Ben Greenfield swears  it healed his tennis elbow and hamstring damage. I even saw one person who used it to improve brain health and function after years of stimulant abuse. Some research does show that BPC-157 can restore dopaminergic function in the brain. Some are even reporting restored sensitivity to stimulants (although using a healing peptide just to restore your ability to get high off Adderall again seems counterproductive).
What Are the Downsides?
It must be subcutaneously injected for maximal efficacy. This isn’t as hard as it looks (millions of diabetics do it every day) but some people are really nervous around needles. Orally-active BPC-157 is available, but I’m not sure how it compares.
There is the small problem of the total lack of published human studies. If there are any, I didn’t see them. The animal studies are impressive, though, and the fact that the peptide chain does naturally occur in our bodies suggests it’s relatively safe, but we don’t know for sure.
A big problem is that you can’t verify the purity of the products available online. You have to read reviews, know the right people, and do the research. These aren’t legally intended for human consumption, so there’s no testing authority regulating the safety and content of these products.
Now For LL-37….
LL-37 is an anti-microbial peptide found naturally in people. It’s heavily involved in the immune response, and its role in health isn’t very clear. It isn’t consistently “good” or “bad.” For instance, its presence can suppress tumor growth in colon and gastric cancer, but it’s been shown  to promote tumor growth in ovarian, lung, and breast cancers. But it’s also able to bind to and negate the effects of lipopolysaccharide, the bacterial endotoxin secreted by many gut pathogens, and selectively target apoptotic white blood cells while leaving viable ones unaffected .
Why Are People Using It?
There are online forums populated by people who are using this peptide to heal gut issues, deal with inflammatory diseases, and treat autoimmunity—or, they’re at least buying the peptide, injecting it, and hoping that it works and not always following up with the results. I’m skeptical about using these as justification to experiment. As one recent paper  put it, LL-37 is a tiny peptide with huge effects:
Some of the functions of LL-37 are anti-inflammatory, particularly those involved in blocking Gram-negative signaling pathways through TLR4. However, in the context of the inflammatory response, this peptide may also provide proinflammatory signals that can propagate inflammation, stimulate type I IFN production, and result in induction of autoimmune diseases. Further research is needed to fully understand the big effects of this little peptide on immune system function so that potential therapeutic uses can be explored.
Sticking Points With LL-37
Much of this could be a guilt by association situation: LL-37 is often found elevated at disease sites and in diseases states because it’s part of the inflammatory response. It isn’t necessarily causing the disease. But the immune response is a delicate one with huge ramifications. I’d be very careful with injecting a peptide that the body normally produces in times of acute inflammation. That sounds a lot like trying to attempt top-down regulation of innate immunity—a decidedly bottoms-up process. Probably better to wait for human trials rather than rely on positive anecdotes from unsourced forum posts. I’m not saying these people aren’t helping themselves with this compound. I’m saying the risk of complications or unwanted effects would be too high for me.
That’s it for today, folks. Thanks for reading and be sure to comment down below. Do you have any experience using these synthetic peptides? How about any others?