Does cucumber water prevent dementia or Alzheimer's disease because it contains a specific component called fisetin? No, that's not true: No scientific evidence suggests that cucumber and cucumber water can prevent dementia and Alzheimer's disease.
The claim originated from a TikTok video (archived here) which was published on August 28, 2024.
It opened, as translated from Korean to English by Lead Stories staff:
Eating cucumbers like this will prevent dementia. Fisetin, a type of flavonoid abundant in cucumbers, helps prevent Alzheimer's dementia. This is because this component inhibits the formation of amyloid plaques by preventing the accumulation of specific proteins in the brain. The easiest way to consume fisetin, which helps brain health and prevents dementia, is to immerse cucumbers in water and drink it as 'cucumber water.'
This is what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Fri Aug 30 14:02:43 2024 UTC)
According to the TikTok video, since cucumbers contain fisetin, which, it claims, prevents the accumulation of amyloid plaques in the brain, cucumber and cucumber water will prevent degenerative diseases such as dementia or Alzheimer's.
Fisetin is a flavonoid: flavonoids are a group of natural substances often found in fruits and vegetables. In particular, fisetin is a bioactive flavonol that contains naturally occurring polyphenols. A study on fisetin (archived here) noted that the highest concentrations of fisetin among fruits and vegetables were found in strawberries (160 micrograms per gram), followed by apples (26.9 micrograms per gram) and persimmon (10.6 micrograms per gram), not cucumbers, which, still according to the study, contained 0.1 micrograms per gram of fisetin.
Amyloid plaques (archived here) are considered one of the distinct characteristics of Alzheimer's disease, as abnormal levels of this protein clump together to form plaques that disrupt cell function. The Salk Institute for Biological Studies (archived here) found that fisetin administered in mice prevented progressive memory and learning impairments but did not affect the formation of amyloid plaques.
According to the Alzheimer's Drug Discovery Foundation (archived here), several preclinical fisetin studies (archived here and here and here) in mice reported improved cognition but stated that this might not necessarily translate into human studies as no human research has been conducted to suggest that fisetin prevents dementia.
