Neurodegeneration or nerve repair refers to the regrowth or repair of nervous tissues, cells or cell products.   Neurodegeneration differs between the peripheral nervous system (PNS) and the central nervous system (CNS).  The central nervous system consists of the brain and spinal cord and controls most functions of the body and mind.  The peripheral nervous system consists of the nerves that branch out from the brain and spinal cord and its role is to connect the CNS to the organs, limbs, and skin.  

 

While the peripheral nervous system has an intrinsic ability for repair and regeneration, the central nervous system is, for the most part, incapable of self-repair and regeneration1.  Typically, damaged nerve fibres of the central nervous system (CNS) in the brain, the optic nerve and spinal cord don't have the ability to regenerate. One of the key reasons is that nerve fibres don't produce any proteins that are necessary for their regeneration, or that they don't produce enough of those proteins.  However, under certain conditions, a protein is formed in injured nerve cells of the CNS that had previously only been described in muscle cells2.  

 

When the spinal cord is injured, the damaged nerve fibres — called axons — are normally incapable of regrowth, leading to permanent loss of function. Considerable research has been done to find ways to promote the regeneration of these nerve fibres following injury. Results of a study performed in mice and published in Cell Metabolism3 suggests that increasing energy supply within these injured spinal cord nerves could help promote nerve fibre regrowth and restore some motor functions. 

 

 

Within the brain are neurons which are information messengers and use electrical impulses and chemical signals to communicate information around the brain and between the brain and the rest of the nervous system.  Certain nutrients have been shown to support brain neuron protection and repair in neurodegenerative diseases or following traumatic injuries, with consequential improvements in mood, lifelong learning, and memory4.   

 

 

Omega 3 fatty acids 

 

Omega-3 polyunsaturated fatty acids (PUFAs) are compounds that have a structural role in the nervous system and are essential for neurodevelopment.  Acute administration of omega-3 PUFAs after injury and dietary exposure before or after injury improve neurological outcomes in experimental spine cord injury (SCI) and traumatic brain injury (TBI)5. 

The role of these PUFAs in the growth and maintenance of neurons in the brain is well documented. The omega-3 fatty acid intake could lessen the secondary effects of the trauma in brain. The beneficial effects of omega-3 FAs suggest the importance of considering their supplementation as a therapeutic option for TBI survivors. Further studies are warranted to determine the effective dose for positive effects against TBI6. 

 

The most important n-3 PUFAs for human health, that is, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), must be acquired through dietary intake, with the primary sources being fish and fish oil. n-3 PUFAs exist abundantly in the brain and play a crucial role in essential neuronal functions.  Traumatic brain injury (TBI) is one of the most disabling clinical conditions that could lead to neurocognitive disorders in survivors. Studies have reported that prophylactic enrichment of dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) markedly ameliorate cognitive deficits after TBI.  These results indicated that repetitive and prolonged n-3 PUFA treatments after TBI can enhance brain remodelling and could be developed as a potential therapy to treat TBI victims in the clinical setting7. 

 

Vitamin E 

 

Some studies have shown that supplementation with Vitamin E in patients with TBI, demonstrated a significant reduction of mortality rates and improvement of long-term functional outcomes8.  However, this data has not been translated into the clinical setting. 

 

Vitamin B1 (Thiamine)

  

This vitamin plays a key role in carbohydrate metabolism, which is the main energy supply for nerve fibres.  There are small number of animal studies which have shown that Vitamin B1 can have a neuro-regenerative function9.  However, further studies are needed. 

 

Vitamin B6 

 

Vitamin B6 helps to maintain the health of neurons in the brain and helps to balance nerve metabolism.  Evidence for the role of Vitamin B6 in neuro-regeneration is lacking but it does play a specific role in metabolism of neurotransmitters9. 

 

Vitamin B12 

 

Vitamin B12 is another important nutrient that is beneficial for people recovering from a TBI. According to a study published in April 2019 in Frontiers in Pharmacology10, B12 is beneficial for improving functional recovery and repairing nerves after a TBI.  The results showed that the neurological functional recovery was improved in the VitaminB12-treated group after TBI, which may be due to changes in the stress signalling pathway. In addition, Vitamin 12 was shown to be involved in the stabilization, remyelination and myelin (myelin is a protective layer around nerves and can aid the speed of electrical impulses) reparation of the insulating layer of the nerves in the brain and spinal cord. The study suggests that vitamin B12 may be useful as a novel neuroprotective drug for TBI. 

Dietary sources of Vitamin B12 include meat, fish, eggs, dairy foods and fortified foods. 

 

Gut health 

 

Gut health is an important and often overlooked factor when it comes to recovering from a traumatic brain injury. Research shows that a brain injury can lead to an imbalance of gut microbes (an imbalance of microbes in the gut can cause bacteria to multiply rapidly) microbes and increase inflammation in the gut.   

TBI also causes increased intestinal permeability. The disruption of the anatomic and functional integrity of the gut can result in systemic inflammation, bacterial translocation, (bacteria seeps through the gut lining and creates diseases in other organs) and sepsis. In addition, it has been shown that TBI affects the composition of gut microbiota in the caecum and drew a link between TBI severity and changes in the microbiome, specifically, in the composition of Bacteroidetes, Porphyromonadaceae, Firmicutes, and Proteobacteria11 (types of bacteria).   

 

Summary 

 

Our understanding of nutrients in the recovery of traumatic brain injury is ever evolving and individual nutrients have been identified as having a neuro- regenerative role.  However, due to the complexity and individuality of brain injuries, no studies have been conducted to draw clear conclusions on the best combination of nutrients to support with neuro-regeneration.  It is recommended to eat a healthy, well-balanced diet to achieve an adequate intake of vitamins and minerals and to prevent deficiencies. 

 

  1. References: 
  2. Moattari M, Moattari F, Kaka G, Kouchesfahani HM, Sadraie SH, et al. (2018) Comparison of neuroregeneration in central nervous system and peripheral nervous system. Otorhinolaryngol Head Neck Surg 3: doi: 10.15761/OHNS.1000180 
  3. Evgeny Levin, Marco Leibinger, Philipp Gobrecht, Alexander Hilla, Anastasia Andreadaki, Dietmar Fischer. Muscle LIM Protein is expressed in the injured adult CNS and promotes Axon Regeneration. Cell Reports, 2019 DOI: 10.1016/j.celrep.2018.12.026 
  4. Han Q. et al. “Restoring cellular energetics promotes axon regeneration and functional recovery after spinal cord injury.” Cell Metabolism March 3, 2020 
  5. Dennis A Steindler, Brent A Reynolds, Perspective: Neuroregenerative Nutrition, Advances in Nutrition, Volume 8, Issue 4, July 2017, Pages 546–557, https://doi.org/10.3945/an.117.015388 
  6. Michael-Titus AT, Priestley JV. Omega-3 fatty acids and traumatic neurological injury: from neuroprotection to neuroplasticity? Trends Neurosci. 2014 Jan;37(1):30-8. doi: 10.1016/j.tins.2013.10.005. Epub 2013 Nov 22 
  7. Kumar PR, Essa MM, Al-Adawi S, et al. Omega-3 Fatty acids could alleviate the risks of traumatic brain injury - a mini review. J Tradit Complement Med. 2014;4(2):89-92. doi:10.4103/2225-4110.130374 
  8. Pu H, Jiang X, Wei Z, et al. Repetitive and Prolonged Omega-3 Fatty Acid Treatment After Traumatic Brain Injury Enhances Long-Term Tissue Restoration and Cognitive Recovery. Cell Transplant. 2017;26(4):555-569. doi:10.3727/096368916X693842 
  9. Di Pietro V, Yakoub KM, Caruso G, Lazzarino G, Signoretti S, Barbey AK, Tavazzi B, Lazzarino G, Belli A, Amorini AM. Antioxidant Therapies in Traumatic Brain Injury. Antioxidants (Basel). 2020 Mar 22;9(3):260. doi: 10.3390/antiox9030260. PMID: 32235799; PMCID: PMC7139349. 
  10. Baltrusch S. "The Role of Neurotropic B Vitamins in Nerve Regeneration", BioMed Research International, vol. 2021, Article ID 9968228, 9 pages, 2021. https://doi.org/10.1155/2021/9968228 
  11. Wu F, Xu K, Liu L, et al. Vitamin B12 Enhances Nerve Repair and Improves Functional Recovery After Traumatic Brain Injury by Inhibiting ER Stress-Induced Neuron Injury [published correction appears in Front Pharmacol. 2021 Apr 12;12:598335]. Front Pharmacol. 2019;10:406. Published 2019 Apr 24. doi:10.3389/fphar.2019.00406 
  12. Zhu CS, Grandhi R, Patterson TT, Nicholson SE. A Review of Traumatic Brain Injury and the Gut Microbiome: Insights into Novel Mechanisms of Secondary Brain Injury and Promising Targets for Neuroprotection. Brain Sci. 2018;8(6):113. Published 2018 Jun 19. doi:10.3390/brainsci8060113