FK-23 increases sperm number and motility
Bisphenol A, a chemical found in plastics, harms sperm by reducing their number and movement. After treatment with FK-23, sperm numbers and activity improved. Light-colored sperm represent normal sperm; dark-colored sperm represent dysfunctional sperm.
Image Credit: Osaka Metropolitan University
Scientific Frontline: Extended "At a Glance" Summary: Paraprobiotic Protection Against BPA Toxicity
The Core Concept: Bisphenol A (BPA), a ubiquitous chemical in plastics, impairs male reproductive function through oxidative stress, but paraprobiotics like heat-treated Enterococcus faecalis (FK-23) can successfully counteract this damage and restore sperm motility.
Key Distinction/Mechanism: Unlike standard live probiotics, paraprobiotics are heat-treated bacterial cells that cannot reproduce but retain intact cell structures. These structures stimulate the gut-immune system axis safely, neutralizing the highly reactive oxygen species (oxidative stress) generated by BPA.
Major Frameworks/Components:
- Reactive Oxygen Species (ROS): Highly reactive molecules increased by BPA exposure that damage cellular components and impair sperm.
- Paraprobiotics: A new class of biologically active, non-viable (heat-treated) bacterial supplements.
- Enterococcus faecalis FK-23: A specific lactic acid bacterium strain proven to exert protective effects against reproductive toxicity.
- The Gut-Immune System Axis: The physiological pathway through which gut-based FK-23 influences systemic conditions and suppresses whole-body oxidative stress.
Branch of Science: Reproductive Biology, Toxicology, Microbiology, and Medicine.
Future Application: The development of targeted, food-derived dietary supplements and functional foods designed to mitigate the toxicological impacts of environmental chemicals and maintain human reproductive health.
Why It Matters: With widespread human exposure to endocrine-disrupting plastics like BPA, identifying safe, accessible countermeasures is critical for combating declining male fertility rates and preventing cellular damage from environmental pollutants.
Bisphenol A (BPA) is widely used in the production of plastic materials. However, recent concerns regarding its toxicity in humans have led the European Union to ban its use in food containers.
BPA has been shown to impair sperm function, in part through the increased generation of reactive oxygen species—highly reactive molecules that can damage cellular components. Because this reactive oxygen can be neutralized with antioxidants, researchers at Osaka Metropolitan University (OMU) have been investigating specific compounds that counteract oxidative stress.
A promising source is paraprobiotics, a new class of supplements based on heat-treated bacterial cells. The heat renders the bacteria unable to reproduce but does not destroy the cell structures that stimulate the immune system and the gut, making them biologically active yet safe to consume.
A research team led by Visiting Professor Yukiko Minamiyama of the Graduate School of Medicine at OMU investigated whether a paraprobiotic material derived from the lactic acid bacterium Enterococcus faecalis (known as FK-23) protects against the sperm toxicity caused by BPA. FK-23 primarily acts in the gut, influencing the gut–immune system axis, which in turn affects whole-body conditions such as oxidative stress.
The team confirmed the risks of BPA in rats: rodents exposed to the substance exhibited a significant reduction in sperm motility and an increase in markers indicative of oxidative stress. When the rats received FK-23, they exhibited improved sperm motility despite BPA exposure, and the expression of these markers was markedly reduced.
“These findings suggest that components derived from lactic acid bacteria exert protective effects against reproductive toxicity caused by environmental chemicals,” Professor Minamiyama stated. “Future studies aimed at elucidating the underlying mechanisms mediated by the gut environment, as well as validating these effects in humans, are expected to pave the way for the application of food-derived components in maintaining reproductive health.”
Funding: JSPS KAKENHI (21K05426) (Japan), Grants-in-Aid from Nichinichi Pharmaceutical Co. Industry, Ltd. (Mie, Japan)
Published in journal: Journal of Functional Foods
Title: Preventive effect of paraprobiotic Enterococcus faecalis FK-23 on bisphenol A-induced sperm toxicity
Authors: Yukiko Minamiyama, Shigekazu Takemura, Kanako Nakagawa, Hiroshi Ichikawa, Takeaki Ishizawa, and Toshikazu Yoshikawa
Source/Credit: Osaka Metropolitan University
Reference Number: bio051526_01
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