Enzyme-Digested Edible Bird’s Nest Boosts Nerve Growth Factor Signaling in Lab-Grown Neurons

Edible bird’s nest, the gelatinous secretion harvested from swiftlet caves and prized as a luxury tonic across Asia for more than a thousand years, has long carried a reputation for sharpening the mind. Now a team of Chinese researchers has provided one of the most detailed molecular explanations yet for why the substance might genuinely support brain health. In a study published in Food Science & Nutrition, the investigators showed that an enzyme-digested preparation of edible bird’s nest dramatically enhances the ability of nerve growth factor to drive immature cells toward a neuronal fate, and they traced the effect to a specific signaling cascade inside the cell. The work, performed in the widely used PC12 cell line, offers a mechanistic bridge between an ancient dietary tradition and modern neurobiology, and it points to a possible role for the delicacy in future strategies against neurodegenerative disease.

The research team, led by Wen Zhang and Xintong Wang, focused on a stage of brain development called neuronal differentiation, the process by which precursor cells stop dividing, extend slender projections called neurites, and mature into functional neurons. This process is central to neurogenesis, which underpins neural plasticity, brain homeostasis, and cognitive function throughout life. Adult neurogenesis is notoriously vulnerable to disruption by poor diet, alcohol, aging, oxidative stress, and neuroinflammation, and its decline has been implicated in Alzheimer’s, Huntington’s, and Parkinson’s diseases. Because recent studies suggest that enhancing adult neurogenesis may improve cognition, identifying dietary factors that promote neuronal differentiation has become an attractive strategy for delaying or preventing neurodegeneration. Edible bird’s nest, derived from the salivary secretions of swiftlets in Thailand, Indonesia, and Malaysia, was a natural candidate: it is rich in sialic acid, a nutrient linked to neuroprotection, brain development, and enhanced memory, and it also contains lactoferrin, transferrin, N-acetylgalactosamine, and epidermal growth factor, all of which have been associated with healthy brain development.

Previous work by the same group had shown that feeding edible bird’s nest to pregnant and lactating rats improved spatial learning and memory in their offspring by promoting neurogenesis in the hippocampus, the brain’s memory hub. What remained unclear was the molecular mechanism. To probe it, the researchers turned to PC12 cells, a pheochromocytoma line derived from an adrenal tumor that behaves much like a sympathetic neuron. When exposed to nerve growth factor, or NGF, PC12 cells cease proliferating, extend neurites, and acquire the characteristic appearance of neurons, which makes them a standard laboratory model for studying neuronal differentiation. The team first simulated human digestion: they soaked dried Malaysian bird’s nest, heated it, exposed it to pepsin at stomach-like acidity, then to trypsin at intestinal pH, and finally lyophilized the resulting digest, which they abbreviated EBND. This digestive preprocessing was crucial, because it converted the nest’s complex proteins into a form resembling what the gut would actually deliver to the body.

Safety came first. Using a cell viability assay, the researchers confirmed that EBND showed no toxicity toward PC12 cells across a broad concentration range from 1 to 1000 micrograms per milliliter, with a gradual rise in viability observed between 1 and 100 micrograms per milliliter. They then selected 10, 50, and 100 micrograms per milliliter for the differentiation experiments. The first result was intriguing but incomplete. When PC12 cells were treated with EBND alone for seven days, the cells did not visibly extend neurites, the classic morphological hallmark of differentiation. Yet at the biochemical level something significant was happening: all three neurofilament proteins, the structural backbone of the neuronal cytoskeleton, were upregulated. NF68 expression more than tripled, while NF160 and NF200 at least doubled at the highest dose, changes that were highly statistically significant. Because NF68 and NF160 typically appear early in neuronal differentiation and NF200 marks more mature neurons, the finding suggested that EBND was switching on the molecular program of differentiation even without producing visible neurites.

The decisive experiment came when the researchers added a whisper of NGF. At a concentration of 1.5 nanograms per milliliter, far below the 50 nanograms per milliliter used as a positive control, NGF alone failed to induce any differentiation. But when that subthreshold dose of NGF was combined with EBND, the cells responded robustly. Differentiation rates climbed in a dose-dependent fashion, reaching 22.8 percent at 10 micrograms per milliliter, 31.2 percent at 50, and 42.7 percent at 100, compared with cells given the low NGF dose alone. Mean neurite length rose in parallel, and the expression of all three neurofilament subunits increased two- to threefold at the higher EBND doses. In other words, EBND alone primed the cells for differentiation, while NGF provided the essential trophic signal that translated that priming into visible structural growth. The authors describe this as a state of differentiation priming, in which EBND raises the cell’s responsiveness to coexisting neurotrophic cues.

To uncover the pathway responsible, the team examined the TrkA receptor, the high-affinity docking site through which NGF commands neurons to differentiate. In cells receiving only the trace dose of NGF, TrkA phosphorylation was minimal. Co-treatment with EBND more than doubled TrkA phosphorylation, and purified sialic acid produced a smaller but significant 1.5-fold increase. Downstream, the effects amplified: phosphorylation of ERK1/2, a kinase that relays signals from the receptor toward the nucleus, tripled, and phosphorylation of CREB, a transcription factor that activates neurotrophic genes, doubled. Consistent with this, brain-derived neurotrophic factor, or BDNF, a protein critical for neurogenesis and neuronal survival that CREB helps regulate, rose by nearly 45 percent in the co-treated cells. The cascade traced a coherent line from receptor to nucleus: NGF signal potentiated at TrkA, relayed through ERK1/2, consolidated by CREB, and ultimately expressed as more BDNF.

The most convincing piece of evidence came from a pharmacological blockade. When the researchers pre-treated cells with GW441756, a selective inhibitor of the TrkA receptor, the neurofilament increases driven by EBND and NGF collapsed, with significant reductions in NF68, NF160, and NF200. That loss-of-function experiment confirmed that EBND does not act through some unrelated route but specifically by amplifying signaling at TrkA, thereby making cells far more sensitive to otherwise insufficient amounts of NGF. The finding echoes earlier reports that natural products such as lignans, pterostilbene, and luteolin can bind NGF or potentiate its receptor signaling, suggesting that edible bird’s nest joins a growing family of dietary compounds capable of enhancing neurotrophic pathways.

Notably, the study also revealed that sialic acid alone cannot explain the effect. Although purified sialic acid activated the same TrkA-ERK1/2-CREB-BDNF cascade, it was markedly less potent than the full enzymatic digest at equivalent amounts. This points to a synergistic contribution from other bioactive constituents, possibly epidermal growth factor-like molecules or specific peptides released during enzymatic digestion. The authors are candid about the limitations of their work. The conclusions rest entirely on a single cell line and will need validation in other neuronal models. The boiling step used to terminate enzymatic hydrolysis may have degraded heat-sensitive components, potentially understating the digest’s true activity. And the dissociation between molecular priming and morphological outgrowth under EBND alone remains incompletely understood, leaving open questions about the temporal dynamics of the priming effect and the identity of the key active factors.

Even with those caveats, the study carries real weight. It provides a plausible molecular mechanism for cognitive benefits previously observed in animal studies, and it reframes a centuries-old delicacy as a candidate functional food for brain health. Because deficiencies in NGF and BDNF have been closely linked to depression and Alzheimer’s disease, a safe dietary substance that potentiates NGF signaling could, in principle, support the development of supplements aimed at neurodegenerative conditions related to neurotrophic factor deficiency. The researchers emphasize that much remains to be done: identifying the specific bioactive components within the digest, clarifying exactly how they enhance NGF signaling, and testing whether the priming effect translates from cell culture to living brain. For now, the Caviar of the East has earned something rarer than its culinary price: a testable, receptor-level explanation for its legendary reputation, written in the language of phosphorylated kinases and growing neurites.

Subject of Research: Effects of enzyme-digested edible bird's nest on neuronal differentiation via the TrkA-ERK1/2-CREB-BDNF signaling pathway in PC12 cells

Article Title: Enzyme‐Digested Edible Bird's Nest Promotes NGF‐Induced Differentiation of PC12 Cells by Activating the TrkA‐ERK1/2‐CREB‐BDNF Signaling Pathway

Article References: Zhang, W., Wang, X., Zhu, H., Lin, X., Li, R., Yuan, M., Xu, B., Wang, D., Xiong, W., & Li, Y. (2026). Enzyme‐Digested Edible Bird's Nest Promotes NGF‐Induced Differentiation of PC12 Cells by Activating the TrkA‐ERK1/2‐CREB‐BDNF Signaling Pathway. Food Science & Nutrition, 14(10), Article e72419. https://doi.org/10.1002/fsn3.72419

Image Credits: AI Generated

DOI: 10.1002/fsn3.72419

Keywords: edible bird's nest, neuronal differentiation, PC12 cells, nerve growth factor, TrkA, ERK1/2, CREB, BDNF, sialic acid, neurogenesis, neurofilaments, neurodegenerative disease