The Swedish study investigated a potential link between fish consumption and better long-term neurological health – finding that a specific protein known as parvalbumin could help prevent the formation of protein structures closely associated with Parkinson’s disease.
Writing in the journal Scientific Reports the team noted that while fish has long been considered a healthy food, linked to improved long-term cognitive health, the reasons for this have been unclear.
“From a scientific point of view, studies imply that diets rich in fish correlates with better health and less neurodegeneration. But what are the underlying reasons?” said the team – led by Professor Pernilla Wittung-Stafshede of Chalmers University of Technology, Sweden.
While omega-3 and omega-6 essential fatty acids are often assumed to be responsible – and are commonly marketed in this respect – studies investigating the effects of fish and fish oils have shown mixed results, noted the Swedish team.
The new data, however, suggests the protein parvalbumin (PV), which is very common in many fish species, may be contributing to this effect. The team report that the fish protein blocks the formation of alpha-synuclein plaques that are a hallmark of Parkinson’s disease by effectively ‘scavenging’ the protein for itself.
"Parvalbumin collects up the 'Parkinson's protein' and actually prevents it from aggregating, simply by aggregating itself first," said Wittung-Stafshede.
- One of the hallmarks of Parkinson's disease is amyloid formation of a protein, called alpha-synuclein
- Alpha-synuclein is sometimes referred to as the 'Parkinson's protein'
- Parvalbumin can form amyloid structures that bind together with the alpha-synuclein protein
- Parvalbumin 'scavenges' alpha-synuclein proteins, using them for its own purposes, therefore preventing them from forming their own potentially harmful amyloids
The team used a set of in vitro biophysical methods, to show that beta-parvalbumin ‘readily inhibits’ amyloid formation of alpha-synuclein.
“The underlying mechanism was found to involve alpha-synuclein binding to the surface of beta-parvalbumin amyloid fibres,” said the team.
“Thus, in addition to omega-3 fatty acids, PV from fish may be responsible for favourable health effects with respect to age-related dementia and cognition decline,” they said.
Linking fish to neurological health
A link between higher consumption of fish and better long-term brain health for the brain has been long established. Indeed, several observational and population studies have shown a correlation between certain diets and decreased rates of Parkinson's disease - as well as other neurodegenerative conditions.
"Among those who follow a Mediterranean diet, with more fish, one sees lower rates of Parkinson's and Alzheimer's," commented Tony Werner, first author on the study.
Furthermore, links have also been observed in Japan, where seafood forms a central part of the diet, noted the team.
However, the Swedish authors were also careful to note that no definitive links can be established on the basis of previous evidence and that provided by the new study.
“Based on our in vitro results of inhibition of alpha-synuclein S amyloid formation, which clearly must be followed by many in vivo studies, we speculate that eating PV-rich fish is a dietary recommendation that may prevent or delay Parkinson’s disease,” said the authors.
The team is keen to research this topic further, to see if the discovery relating to Parkinson's disease could have implications for other neurodegenerative disorders as well.
"These diseases come with age, and people are living longer and longer. There's going to be an explosion of these diseases in the future - and the scary part is that we currently have no cures,” said Wittung-Stafshede. “So we need to follow up on anything that looks promising."
The team are now planning a follow up study looking at parvalbumin from another angle – where the team will investigate parvalbumin from herring, and its transport in human tissues.
"It will be very interesting to study how parvalbumin distributes within human tissues in more depth. There could be some really exciting results."
Source: Scientific Reports
Volume 8, Article number: 5465, doi: 10.1038/s41598-018-23850-0
“Abundant fish protein inhibits α-synuclein amyloid formation”
Authors: Tony Werner, et al