Probiotic-fermented soy has potential to enhance cognitive function in older adults: RCT

By Stephen Daniells

- Last updated on GMT

© Getty Images / nevarpp
© Getty Images / nevarpp
Supplements containing Lactobacillus plantarum C29-fermented soybean (DW2009) may improve cognitive function in older adults with mild cognitive impairment (MCI), according to results of a gold-standard clinical trial from Korea.

Results of a 12-week, multi-center, randomized, double-blind, placebo-controlled clinical trial with 100 people indicated that DW2009 was associated with improvements in cognitive performance, especially for attention.

In addition, there were significant associations between cognitive enhancement and change in serum BDNF levels in the DW2009 group.

Led by Yun-Ha Hwang from Dongwha Pharm Research Institute, the scientists also reported that the brain-boosting effects of DW2009 were associated with increases in brain-derived neurotrophic factor (BDNF), which has been described as an important neurotrophic factor participating in memory and learning.

“[T]he results of this study demonstrated the efficacy and safety of DW2009 supplementation in improving cognitive function in individuals with MCI,” ​wrote the scientists in the journal Nutrients​. “As its cognitive enhancement effects have been confirmed in both humans and mice, it can be considered a promising option to ameliorate cognitive deficits in MCI.”

Gut-brain axis

Intestines probiotics © Getty Images JONGHO SHIN
© Getty Images / JONGHO SHIN

The study adds to the ever growing area of research around the gut-brain axis, that bi-directional interaction between the gastrointestinal tract and the nervous system. The area is gaining increasing attention from scientists and consumers.

A 2015 review in Neuropsychiatric Disease and Treatment​by Linghong Zhou and Jane Foster from McMaster University in Canada noted that the bacteria present in the gut affects the communication between belly and brain, and the lack of healthy gut microbiota lead to dysfunction in the gut–brain axis, which in turn may lead to neuropsychological, metabolic, and gastrointestinal disorders.

Intervention trials with select strains of probiotics have revealed that supplementation may influence mood (L. casei​ Shirota), and anxiety and depression (L. helveticus​ and B. longum​).

There is also some data to support an effect with prebiotics, with improvements in stress hormone levels and attention in health volunteers taking oligosaccharides.

Study details

The new study is said to be the first to investigate if DW2009 can enhance cognitive function in humans, with earlier data from animal studies reporting improvements in memory and brain inflammation.

One hundred people aged between 55 and 85 with mild cognitive impairment (MCI) were recruited to participate in the study. They were randomly divided into one of two groups: One group received capsules containing Lactobacillus plantarum​ C29-fermented soybean (800 mg/day), and the other group received a placebo capsules.

“Consumption of soybeans was reported to enhance memory in humans and the bioactive ingredients contained in soybean, isoflavones and saponins, also exhibited memory-enhancing effects,” ​explained the researchers. “Although soybean itself is nutritional, undergoing the process of fermentation with lactic acid bacteria is expected to augment metabolic reactions resulting in increased isoflavone absorption and antioxidant capacity.”

Results showed that the DW2009 group experienced improvements in scores of both attention and working/verbal memory, and these cognitive improvements were positively correlated with increasing BDNF levels.

Looking at the gut microbiota, the researchers found that lactobacilli numbers significantly increased in the DW2009 group, but no such increases were observed in the placebo group. No significant changes were observed for other bacterial groups for either intervention, however, including bifidobacteria and clostridia.

“These results suggest that Lactobacillus plantarum C29, which was contained in DW2009, can be resistant to stomach acid, bile, digestive enzymes, and the gut microbiota barrier,”​ wrote the researchers. “As most of the lactobacillus species have a “generally regarded as safe” (GRAS) status, they have been frequently used as probiotics.

“Thus, an increase in beneficial gut bacteria, such as Lactobacillus spp. in the gastrointestinal (GI) tract, may have alleviated cognitive decline. The microbiota-gut-brain axis has been reported to mediate changes in behavior, including cognitive decline, as well as regulate neuropsychiatric diseases.

“Our study results are in line with previous studies that suggest potential effects of interactions between the gut microbiota and brain on human behavior and cognition.”

Source: Nutrients
11​(2). doi: 10.3390/nu11020305
“Efficacy and Safety of Lactobacillus Plantarum C29-Fermented Soybean (DW2009) in Individuals with Mild Cognitive Impairment: A 12-Week, Multi-Center, Randomized, Double-Blind, Placebo-Controlled Clinical Trial”
Authors: Y.H. Hwang et al.

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