A week ago, we wrote about the positive effects of sage - also known as Salvia officinalis - on the cognitive abilities of people with a mild form of dementia. Sage also improves the functioning of the brains of young people when they have to perform under stress.

Study
In 2006, psychologists from the University of Northumbria in the UK published a trial in which 30 students served as test subjects. The psychologists tested the students on three different days. They used the Defined Intensity Stress Simulator for this purpose. This is a test in which the students have to complete four different standard psychological tests in a random order.

The test subjects view the four tests continuously and simultaneously on a computer screen. The screen indicates what they need to do.

The Defined Intensity Stress Simulator is suitable for measuring mental flexibility and also generates quite a bit of stress. The test, which lasts twenty minutes, also provides insight into the ability to perform under stress.

On one test day, the students took a placebo an hour before the test began. On a second day, they received capsules containing 300 milligrams of powder from dried leaves of Salvia officinalis On a third test day, the students received 600 milligrams of powder.

The researchers obtained the powder from their sponsor, the British company MedicHerb. We cannot say anything meaningful about that company or their product range. We suspect that MedicHerb no longer exists.

Active substances
According to the analyses we have been able to find, carnosic acid and rosmarinic acid are the main active substances in dried sage leaves in terms of concentration.

Just before the supplementation period began and on the last day thereof, the researchers determined the cognitive and mental abilities of their subjects using two tests.

Results
According to in vitro research, carnosic acid and especially rosemarinic acid inhibit acetylcholinesterase, the enzyme that breaks down acetylcholine. [Plants (Basel). 2022 Feb 14;11(4):514.]

However, this occurs at high concentrations, which you will not find in the bodies of users of Salvia officinalis supplements.

When you dry saliva leaves, carnosic acid oxidizes. This produces substances such as carnosol, rosmanol, and isosorosmanol. These substances inhibit acetylcholinesterase even at low concentrations that you might find in people who consume dried sage. [Arch Pharm (Weinheim). 2025 Mar;358(3):e2400909.]

The researchers used capsules. Readers who want to experiment with sage powder from the Asian grocery store or dry sage themselves can administer a third of a teaspoon. That is approximately 600 milligrams. Coincidentally, this is exactly the effective dose according to the publication we are boring you with today.

Results
The 300 milligram dose had no positive effect, while the 600 milligram dose did.

Normally, total scores on the Defined Intensity Stress Simulator increase as subjects perform the test more frequently. This also occurred in this study.

However, as you can see in the table below, scores increase approximately twice as fast with the 600 milligram dose as under the other conditions. The effect of that dose is small to medium.

Click on the table for a larger version.

Mechanism
When test subjects perform the Defined Intensity Stress Simulator test, their alertness drops. However, after ingesting the 600-milligram dose, that alertness remained constant.

This could well be the result of increased activity of the neurotransmitter acetylcholine. After all, the dried sage leaves contained substances that inhibit the breakdown of this substance.