Benefits
Attention accuracy and speed in healthy older adults
In a randomized placebo-controlled trial in 155 adults aged 50 to 70, a standardized extract at 950 mg a day produced fewer false alarms on a rapid visual attention task after 28 days and helped hold picture-recognition accuracy steady, while speed of attention trended faster than a ginkgo comparison. The effects were specific and mostly at the higher dose.
Blood flow in the front of the brain during mental tasks
Using near-infrared spectroscopy in a subset of the same trial, both extract doses raised oxygenated hemoglobin and oxygen saturation in the prefrontal cortex while volunteers performed demanding tasks on the first day of use. This blood-flow change was seen acutely and was not found again after 28 days of daily use.
State anxiety and calm in healthy older adults
In the same trial, 950 mg a day of the extract lowered self-rated state anxiety after 28 days compared with both placebo and the ginkgo comparison. This was one outcome in one small trial that was funded by an extract maker, so it needs to be confirmed by independent groups before much is made of it.
Memory and learning in laboratory and animal studies
In aged mice and in mice bred to model amyloid build-up, daily oral extract improved memory and learning tests and reduced amyloid in brain tissue in a maker-linked study. These are animal findings used to explore how the herb might act and have not been shown as memory benefits in healthy people.
Antioxidant capacity and redox markers in healthy adults
In a 4-week randomized placebo-controlled trial in 28 healthy adults, a standardized extract raised total antioxidant capacity in blood and lowered a marker of lipid peroxidation. The researchers also recorded lower resting blood pressure and heart rate and small falls in two liver enzymes over the same period.
Traditional use as a mountain tea for everyday wellness
Across the Balkans and Greece the dried flowering tops have long been brewed as a daily tea and used in folk practice for coughs, colds and digestive upset. This is traditional and cultural use, recorded in ethnobotanical reviews rather than shown in controlled trials, and is offered here only as background.
Mechanism of action
Polyphenols that reach the bloodstream after drinking the tea
After people drink the tea, flavonoid and phenolic-acid breakdown products appear in urine, showing the polyphenols are absorbed, though only a small share is recovered. Metabolites of flavonoids such as isoscutellarein and apigenin dominate. This confirms the body is exposed to the compounds, not any specific brain effect.
Monoamine reuptake inhibition in laboratory tests
In test-tube studies using brain tissue preparations and human cells, alcohol and water extracts slowed the reuptake of serotonin, noradrenaline and dopamine, the messengers targeted by some mood medicines. This is a laboratory finding that offers a possible explanation for the mood signal but has not been measured in people.
Antioxidant and amyloid-clearing actions in preclinical models
In cell and animal studies, Sideritis polyphenols scavenged free radicals and, in mouse models, were linked to clearance of amyloid protein through increased activity of the ADAM10 enzyme and immune cells in the brain. These mechanisms come from laboratory and animal work, not from people.
Clinical trials
Randomized, double-blind, placebo-controlled parallel-groups trial of a Sideritis scardica extract at 475 or 950 mg a day, with a 240 mg ginkgo comparison, tested after a single dose and after 28 days in healthy older adults; several authors were employees of the extract maker. (Wightman et al. 2018, Nutrients)
155 men and women aged 50 to 70; cognition measured in 140, mood in 142, blood pressure in 133 and cerebral blood flow in 57.
At 950 mg a day the extract gave fewer false alarms on a rapid visual attention task at day 28, lower state anxiety at day 28, and better held picture-recognition accuracy; speed of attention only trended faster. Both doses raised prefrontal blood-flow markers on day 1 but not at day 28. Primary outcomes were mixed and most effects appeared only at the higher dose.
Randomized, double-blind, placebo-controlled trial of a standardized Sideritis scardica extract (SidTea+) at 1,500 mg a day for 4 weeks in healthy adults. (Papanikolaou et al. 2024, Molecules)
28 healthy adults.
The extract raised total antioxidant capacity and lowered a plasma lipid-peroxidation marker versus placebo, and was followed by lower resting systolic blood pressure, mean arterial pressure and heart rate and small falls in two liver enzymes. It did not measure cognition or mood. A small, short trial.
Open-label human study measuring several Phase I and II drug-metabolizing enzymes before and after 6 days of Sideritis scardica tea, using caffeine and paracetamol marker ratios. (Begas et al. 2018, Food Chem Toxicol)
14 healthy volunteers.
Usual tea drinking did not meaningfully change most enzymes (CYP1A2, xanthine oxidase, NAT2, UGT1A1/1A6). CYP2A6 activity fell significantly in men only, hinting at a possible herb-drug interaction for that enzyme. There was no placebo group.
Human feeding study measuring flavonoid and phenolic-acid metabolites in urine over 24 hours after drinking a characterized Sideritis scardica decoction. (Petreska Stanoeva and Stefova 2013, J Agric Food Chem)
10 healthy volunteers.
Many flavonoid and phenolic-acid metabolites appeared in urine, confirming the tea's polyphenols are absorbed; recovery in urine was about 5% of intake, with flavonoid metabolites making up most of it. A bioavailability study, not a health-outcome trial.
Controlled animal study of daily oral Sideritis euboea and Sideritis scardica extracts on cognition and brain amyloid in aged normal mice and in amyloid-model mice; two authors were from the extract maker. (Hofrichter et al. 2016, J Alzheimers Dis)
Aged normal mice and amyloid precursor protein transgenic mice (an animal study).
Daily extract improved memory and learning tests in both aged and amyloid-model mice, most strongly when the two species were combined, and lowered brain amyloid with signs of increased clearance. An animal study; it does not show a memory benefit in people.
Experimental study recording quantitative EEG from implanted electrodes in freely moving rats and matching the pattern of several herbal extracts against those of known drugs. (Dimpfel 2013, J Ethnopharmacol)
Freely moving rats (an animal study).
The Sideritis scardica extract, like Rhodiola, produced an EEG pattern resembling those of a psychostimulant and an antidepressant drug. This is an animal brain-activity signature used to classify extracts, not a measure of symptoms or behavior in people.
Laboratory study of Sideritis scardica extracts on serotonin, noradrenaline and dopamine reuptake in rat brain synaptosomes and on serotonin reuptake in human cells. (Knorle 2012, J Neural Transm)
Rat brain synaptosomes and human JAR cells (a laboratory study).
All extracts slowed reuptake of all three monoamines, with alcohol extracts stronger than water extracts and the strongest effect on the human serotonin transporter. A test-tube mechanism the author linked to possible mood uses; no people were studied.