The above is based on findings from a 3.5-year pilot study in Japan.
Writing in Frontiers in Nutrition, the researchers highlighted that the study was the first-of-its-kind to investigate the long-term effects of glucoraphanin in individuals at higher risk of developing dementia.
Glucoraphanin (GLR) is a precursor of sulforaphane, and the latter has shown to improve age-related cognitive decline in healthy elderly individuals in a 12-week study.
Study method
During the 42-month trial, 26 seniors aged 63 to 90 with memory impairment were randomized to take either three capsules each containing 10mg of GLR or a placebo daily.
The GLR supplement, which contains the GLR ingredient trademarked Braphanin, was provided by Japanese firm Kagome, known for its vegetable juice products. Kagome also funded the trial.
Each GLR capsule also contains mustard powder as a source of exogenous active myrosinase to enhance the enzymatic conversion of GLR to sulforaphane (SFN).
To assess GLR’s impact on cognitive function, the MCI-Screen (MCIS) test - a tool developed to detect MCI and measure the memory performance index (MPI) score - was performed on the participants at the 3rd, 6th, 18th, 30th and 42nd months of the trial. Higher MPI scores indicate better cognitive performance.
After 18 months of supplementation, urine samples were also collected to measure the levels of Sulforaphane-N-acetyl-cysteine (SFN-NAC), which is a major metabolite of SFN.
Measuring SFN-NAC is an indicator of the amount of SFN absorbed into the body.
Improvements in MPI scores
Both the intervention group and placebo group reported significant improvements in their cognitive function, as measured by the memory performance index (MPI), by the end of the trial.
However, when comparing the extent of improvements, the intervention group had a significantly greater improvement than the placebo group.
Specifically, the mean MPI score in the intervention group increased from the mean value of 53.8 at baseline to 66.0 at the 42nd month of the trial.
As for the placebo group, the mean MPI score went up from 49.3 to 54.7 by the end of the trial.
Based on this finding, the researchers noted a significant group-by-time-point interaction for the change in MPI score.
“Multivariate analysis using an LMM (Linear Mixed Model) applied to the FAS (Full Analysis Set) revealed a significant group by time-point interaction for the change in MPI score from baseline over the entire 42-month period,” the researchers wrote. “This indicates that the change in MPI scores from baseline in the GLR group was significantly greater compared to the placebo group over time.”
Further analysis showed that significant group differences in MPI scores were not observed in the early phase of the trial, but only became more pronounced and statistically significant by the 30th month of the trial.
Specific improvements
Analysis of the MCIS test components showed that the intervention group showed significantly better results than the placebo group at immediate recall and delayed free recall tests.
In the immediate recall test, participants were given three trials to memorize 10 words by repeating them aloud, followed by immediate recall.
This task assesses attention, working memory and comprehension.
Delayed free recall tests, on the other hand, require participants to freely recall the same 10-word list. The task assesses short-term memory capacity.
“These present and previous findings suggest that glucoraphanin contributes to the maintenance and improvement of memory,” the researchers wrote.
Analysis of urinary samples at the 18th month of trial also showed that SFN-NAC levels were significantly higher in the intervention group than in the placebo group.
Effects more pronounced in seniors with MCI
Subgroup analysis showed that GLR’s benefits for cognitive function were more significant in participants diagnosed with MCI as compared to those without MCI.
Participants diagnosed with MCI and taking the supplement had significantly greater improvement in their MPI scores as compared to participants who also had MCI but were from the placebo group.
“Among participants diagnosed with MCI at baseline, the change in MPI score from baseline was significantly greater than that of the placebo group, both over the entire study period and at the 42-month endpoint,” the researchers wrote.
Although cognitively normal participants also reported an increase in their MPI scores after taking the supplement, the extent of increase was not statistically significant when compared to similarly cognitively normal participants from the placebo group.
“These findings suggest that GLR intake may help maintain cognitive function not only in healthy people but also in those diagnosed with MCI,” the researchers wrote.
Source: Frontiers in Nutrition. doi: 10.3389/fnut.2026.1740494. “Efficacy of 42-month oral administration of glucoraphanin in preventing cognitive decline in individuals at elevated risk of dementia, including those with mild cognitive impairment: a randomized, double-blind, placebo-controlled pilot study.” Authors: S. Shimizu, et al.
