Enzyme-treated asparagus extract, stress hormones and sleep in healthy men
What it found
In two small trials of healthy men, enzyme-treated asparagus extract kept stress hormone levels steady and improved some measures of the nervous system.
It also adjusted sleep time in men who slept too much or too little.
What they found
Studies in people
Stress hormone levels
During the dummy capsule period, cortisol levels in blood and saliva rose compared to the start of the trial. When men took the asparagus extract, those cortisol levels stayed about the same. Another stress marker in saliva fell after taking the extract.
Nervous system balance
Men taking the asparagus extract showed better readings on several measures of the autonomic nervous system, which controls automatic body functions like heart rate. These readings worsened in the group taking dummy capsules.
Sleep time changes
Overall sleep time was about the same for both groups. But when men were split by how well they slept, the extract shortened sleep for those sleeping over 395 minutes a night and tended to lengthen it for those with poor sleep efficiency.
Cell protection protein
Blood levels of a messenger molecule for the protective protein HSP70 tended to be higher in men taking the asparagus extract. However, this rise was not large enough to rule out chance in this small group.
Other findings
How the extract is made
The ingredient is made from asparagus stems grown in Hokkaido, Japan. The stems are boiled in water at 121 degrees C for 45 minutes, treated with enzymes for 24 hours, then concentrated and dried into a powder.
What the authors conclude
- They suggest that enzyme-treated asparagus extract may help balance the nervous system and improve sleep quality, possibly by raising levels of a protective protein and lowering stress hormones.
- They call for larger, longer trials that include women and older people to confirm these early findings.
How it was done
Chronic stress is linked to depression, poor sleep and nerve problems, and current treatments only target symptoms. The authors wanted to see if an extract made from asparagus could boost a natural cell-protecting protein called HSP70 to help manage stress.
The researchers ran two trials in healthy adult men. In the first, 20 men took either asparagus extract capsules or dummy capsules for 7 days. In the second, 18 men took each type of capsule for 7 days with a 2-week break in between, while their sleep and stress hormones were measured.
What it can’t tell you
- Both trials included only healthy men, so the results might not apply to women, children or older adults.
- The studies lasted just 7 days each, so scientists do not yet know what happens with longer use.
- The groups were very small, meaning some trends seen might have happened by chance.
The paper
- Title
- Effects of enzyme-treated asparagus extract on heat shock protein 70, stress indices, and sleep in healthy adult men
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Ito T, Goto K, Takanari J, et al (2014). Effects of enzyme-treated asparagus extract on heat shock protein 70, stress indices, and sleep in healthy adult men. Journal of nutritional science and vitaminology. doi:10.3177/jnsv.60.283Free full textPubMed 25297618DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error