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Fish diet to prevent Parkinson’s? Fishy claim more like.

Eating more fish could prevent Parkinson's disease

Our Review Summary

fish dietThe subtitle of this news release says the Chalmers University of Technology (Sweden) study “shines more light on the link between consumption of fish and better long-term neurologic health.”

But this in vitro lab study only suggests that the fish protein, parvalbumin, binds to a particular human protein called “alpha-synuclein” which has been identified as forming amyloid chains in patients with Parkinson’s disease.

The news release should have made it clear that studies of fish cannot be extrapolated to humans, and further, that no cause and effect relationship has been established between amyloid proteins and the development of any neurologic disease.


Why This Matters

Any news release touching on Parkinson’s disease — or any other of the neurodegenerative disorders that have no cure — is likely to draw a lot of attention from news organizations.

Parkinson’s disease alone affects about 1 million Americans and 10 million people worldwide.

Although this news release clearly states the disease has no cure, it is riddled with language that implies fish consumption inhibits amyloid formation and that amyloid formation “can be responsible for various diseases,” but that’s an unproven theory and not even addressed by this study.

Our concern is that this framing will be adopted by unskeptical reporters and the cause and effect language will be erroneously adopted despite absolutely no evidence to support it.


Does the news release adequately discuss the costs of the intervention?

Not Applicable

Affordability of fish varies widely around the world so we can understand not bringing up costs.

The intervention advocated is consuming a fish protein called parvalbumin, or PV for short. Some readers may be curious if this protein can be found in the fish oils that are widely marketed. Nonetheless, the issue of cost doesn’t seem entirely applicable here.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The release doesn’t include any numbers to help put the benefits claimed in context. Early in the news release a lead author is quoted as saying:

Parvalbumin collects up the ‘Parkinson’s protein’ and actually prevents it from aggregating, simply by aggregating itself first.

Lower down in the news release it says:

Increasing the amount of fish in our diet might be a simple way to fight off Parkinson’s disease

The italics are ours to emphasize that unjustified leaps of causality, and unjustified language, are used to imply benefits that can’t be supported by this study.

This study simply hypothesizes that PV, by binding with alpha-synuclein, prevents it from forming amyloid chains with other proteins. We’ve written many times about the uncertainty surrounding amyloids (of all types/subtypes) as a sign of, or contributor to, neurodegenerative diseases like Parkinson’s or Alzheimer’s.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The news release is dominated by suggestions that parvalbumin could help with Parkinson’s and perhaps other neurodegenerative diseases including Alzheimer’s, ALS and Huntington’s but only at the very end do we learn it’s been studied as a a cause of fish allergies.

Is this the only harm? We don’t know because harms aren’t included.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

A major problem with this news release is that it does not mention this was an in vitro experiment; that is, conducted in a controlled environment outside a living organism (aka a laboratory experiment).

Above all else that should be highlighted clearly and early in the news release. It should also be made clear that no cause and effect relationship between amyloid proteins and the development of any neurologic disease has ever been established.

Put another way, anything that inhibits amyloid formation — whether it be a diet, drug, or something else — does not equate with either preventing or treating any diseases of the brain.

Does the news release commit disease-mongering?

Not Satisfactory

While there is no overt disease mongering, there are subtle influences here.  For example,  the reader is told of a linkage of amyloid and a host of neurodegenerative diseases including Alzheimer’s and then an author notes: “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. So we need to follow up on anything that looks promising.” The clear take away message being conveyed is these disease are of concern and eating fish is the answer.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

The funding sources for the study and any potential conflicts among the researchers are not mentioned in the release. The published article acknowledges funding from the Knut and Alice Wallenberg Foundation, the Swedish Research Council, the Olle Engqvist Foundation and the Chalmers Foundation.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

No alternatives to preventing Parkinson’s and other neurodegenerative diseases are mentioned. On the surface this omission may seem justified since there are none.

But perhaps it would help readers to tell them this up front. The following is our suggested wording:

“Please note there are no interventions of any kind proven to prevent any neurodegenerative disease. Furthermore, no cause and effect relationship between amyloid (of any kind) and these diseases have ever been established. Finally, this is an in vitro study, so no conclusions regarding clinical efficacy in humans can be made.”

Does the news release establish the availability of the treatment/test/product/procedure?


Fish is widely available. We’re told the protein of interest, parvalbumin, is found in higher concentrations in certain species, and that this concentration is seasonal and tends to peak in late summer.

Does the news release establish the true novelty of the approach?

Not Satisfactory

This is not the first research attempting to link parvalbumin with a host of neurodegenerative diseases including Parkinson’s. And while there is no direct clear claim of novelty, “shining a light…” suggests this is a new discovery.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Not Satisfactory

There are glimpses of cautious language in this news release such as:

“It will be interesting  to study how parvalbumin distributes within human tissues in more depth.”

“The team is careful to note that no definite links (between higher fish consumption) can be established at this point.”

But this is drowned out by unjustified phrasing (italicized) like this:

“Amyloids are not necessarily a bad thing, but can be responsible for various diseases.”

“increasing the amount of fish in our diet might be a simple way to fight off Parkinson’s disease.”

“Other neurodegenerative diseases, including Alzheimer’s, ALS, and Huntington’s disease are also caused by certain amyloid structures interfering in the brain.”

Finally, the evidence here is in fish. Not humans. And even if it was in humans the language used in this news release would still be unjustified.

Total Score: 1 of 9 Satisfactory


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