Can lion's mane repair nerve damage?

The story the mushroom pages never tell: nerve growth factor itself was given to people with nerve damage in the 1990s, and it did not repair their nerves and did cause pain

Can lion's mane repair nerve damage rests on a single chain of reasoning that every lion's mane page repeats and none completes: the mushroom's hericenones and erinacines stimulate cells to make nerve growth factor, nerve growth factor supports the survival and growth of neurons, therefore more of it repairs nerves. The honest page completes the chain by telling the story the others leave out, which is that the hypothesis has already been tested in the most direct way possible, not with a mushroom compound that nudges cells to make a little more of the protein, but with the protein itself. In the 1990s recombinant human nerve growth factor was manufactured and taken into clinical trials as a nerve repair drug, on exactly the reasoning above, for people with diabetic peripheral neuropathy and for people with HIV-associated neuropathy, conditions in which small sensory nerves are dying and a growth factor for sensory neurons was the obvious candidate. Early small trials were encouraging, as early small trials often are. The large phase three trial in diabetic neuropathy, with over a thousand participants receiving nerve growth factor by injection for a year, failed to show a benefit over placebo on the nerve measures it was designed to move, and the programme was stopped. The protein's characteristic effects, consistent across the trials, were pain at the injection site and hyperalgesia, a heightened sensitivity to pain around the dose, which was not an accident of formulation but a property of the molecule: nerve growth factor is, among its other roles, a pain-sensitising signal, released in inflamed tissue and acting on the nerves that carry pain, which is why a later generation of drugs was developed to block it for arthritis pain rather than to supply it. So the most direct test of the lion's mane hypothesis, give a person more nerve growth factor and watch the damaged nerve repair, has been run with the actual protein at pharmacological doses by injection, and the nerves did not repair and the people hurt. A mushroom compound that raises nerve growth factor synthesis in a dish sits upstream of that failed drug, by a step whose size in a human nobody has measured, and a reader who has been told that lion's mane repairs nerves because it raises nerve growth factor has been told half a story whose second half is a negative trial.

Repair as a surgeon's word: what actually happens when a nerve regrows, the interventions that change the outcome, where a growth factor sits in that process, and the honest buy

Repair is a surgeon's word, and the biology of what a surgeon is repairing explains why a growth factor, even the real one, was never going to be the answer on its own. When a peripheral nerve is cut or crushed, the part of each axon beyond the injury degenerates over days, a process called Wallerian degeneration, and the cells that wrapped it, the Schwann cells, clear the debris and line up into tubes along the old path; the part of the axon still connected to its cell body then sprouts and regrows along those tubes towards the target at about a millimetre a day, guided by the Schwann cells and by a cocktail of signals of which nerve growth factor is one among many, until it reaches the muscle or skin it once supplied, if the path is intact and the distance is not too great. The interventions that change the outcome of that process are mechanical and temporal. For a cut nerve, surgical coaptation, aligning the two ends under magnification and stitching them so the regrowing axons find the right tubes, since axons that regrow into the wrong tube or into scar never reach their target. For a gap too wide to join directly, a nerve graft taken from elsewhere or a synthetic conduit to bridge it. For a trapped nerve, decompression, removing the pressure so the nerve can recover without needing to regrow at all. And for every kind, time measured in millimetres a day and rehabilitation to keep the joints mobile and the muscles from wasting while the axons travel, so that there is something working to reconnect to when they arrive. A growth factor sits inside that process as one signal among several that the Schwann cells and the injured neuron already produce in response to the injury, and the failed human trials suggest that adding more from outside does not speed the millimetre a day or improve the destination, which is what the surgeon's needle and the calendar actually determine. Lion's mane cannot be said to repair nerve damage on any evidence: its cell-culture and rodent crush findings are real and sit upstream of a human drug that already failed, no human study of the mushroom in any nerve injury exists, and no authorised UK health claim exists for it, so no tub may print repair, regenerate or nerve. A person with a damaged nerve wants a surgeon to assess whether the nerve is cut, compressed or intact, a millimetre a day of patience once the path is secured, and a physiotherapist to keep the limb ready, and a lifter whose nerve symptom is the compressive kind, as most are, wants the pressure off it and nothing swallowed. This site describes the mushroom's two small cognitive studies as studies. Upstream of a failed drug and sold without the sentence: a stated 5:1 fruiting body extract labelled 1500mg mushroom equivalent, 120 capsules for £15.49, 120 days at 13p, vegan shell, UK made under GMP and BRC, independently lab tested, bought for what it has studies for and not for a repair that the protein itself could not deliver.

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