The accumulation of beta-amyloid proteins has long been linked to the development of brain stunting conditions including Alzheimer’s disease and other forms of dementia.
The new findings come from a Japanese trial in mice with cognitive dysfunction.
Writing in the Journal of Functional Foods, the team revealed that brain functions were ‘significantly better-preserved’ in aged mice fed green soybean than age-matched control mice with or without yellow soybean feeding.
The molecular mechanisms of these beneficial effects on brain function were examined using transcriptome analysis.
An increased expression of lipocalin-type prostaglandin D2 synthase (Ptgds) and a significant reduction in the amyloid precursor protein Aplp1 was reported by the team, led by Keiko Unno from the University of Shizuoka in Japan.
“As Ptgds binds and transports small lipophilic molecules (…) it has been proposed as the endogenous Aβ chaperone,” noted the team, adding that lower levels of the usually abundant protein “may play an important role in the development of dementia and of Alzheimer's disease (AD).”
“Furthermore, the amount of beta-amyloid 40 and 42 was reduced in the insoluble fraction of cerebral cortex,” the team noted.
Unno and colleagues noted that previous research has suggested several beneficial effects of soybean components such as so isoflavones, including previous suggestions of benefits for cognitive function and the prevention of oxidative damage.
In the current study, the isoflavones found to be present in soybean extracts were mostly the glycosides genstin and daidzin.
“The levels of genistein and daizein, aglycones of genstin and daidzin, respectively, were very low or not detected,” reported the team – adding that the content of oligo sugars, especially sucrose, was significantly higher in green soybean than in yellow.
Furthermore, the contents of saponin and carotene in green soybean were found to be slightly higher in the green than in yellow, however the contents of other components were not different between green and yellow soybeans.
“Soybean feeding did not change the weight of body, liver or cerebrum,” Unno and colleagues said – adding that the average food consumptions of each group were also not different.
Source: Journal of Functional Foods
Volume 14, Pages 345–353, doi: 10.1016/j.jff.2015.02.011
“Cognitive dysfunction and amyloid β accumulation are ameliorated by the ingestion of green soybean extract in aged mice”
Authors: Keiko Unno, et al