A groundbreaking study published on July 16, 2025, in The EMBO Journal, analyzed over 100 human eggs from 21 healthy women aged 19 to 34, revealing how these eggs maintain their viability over decades by deliberately slowing their internal waste disposal systems.

The research shows that human eggs reduce their metabolic activity as they mature, which helps minimize damage from long-term dormancy, a process crucial for preserving egg quality over potentially 50 years.

During the final hours before ovulation, eggs actively expel lysosomes and relocate mitochondria and proteasomes to the cell's outer rim, a process described as 'spring cleaning,' to lower energy consumption and reactive oxygen species (ROS) production.

While protein recycling via lysosomes and proteasomes is essential for cell health, it consumes energy and can generate harmful ROS, which can damage eggs, prompting eggs to reduce this activity intentionally.

This reduction in waste recycling activity helps eggs minimize ROS and damage, aligning with previous findings that eggs skip certain metabolic reactions to lower oxidative stress.

The study found that metabolic activity in eggs is about 50% lower than in surrounding support cells and decreases further as eggs mature, supporting the idea of a natural, low-metabolism state.

Women are born with one to two million immature eggs, but this number declines to a few hundred by menopause, making it essential to preserve egg quality over long periods.

Dr. Elvan Böke, lead author from the Centre for Genomic Regulation in Barcelona, emphasizes that this minimalist, low-metabolism strategy helps preserve egg quality during their long lifespan, which can last up to 50 years.

Instead of trying to boost egg metabolism with supplements, maintaining their natural low metabolic state may be more effective for preserving their quality over time.

The researchers hypothesize that by reducing waste recycling, eggs minimize ROS production while still performing enough housekeeping to survive decades.

Future studies aim to explore how aging and disease affect egg metabolism by examining eggs from older donors and those from failed IVF cycles.

This research, utilizing live imaging techniques, provides the largest dataset to date, offering new insights into the cellular strategies eggs use to maintain viability over extended periods.