Benefits
Studied for episodic memory in older adults
In the only human trial, 300 mg a day for 12 weeks was tested in older adults with self-reported memory complaints. Errors on a visual paired associates learning task fell further on the extract than on placebo at weeks 6 and 12, but only in exploratory comparisons made after the main statistical model found no group difference.
Primary endpoint did not separate from placebo
The trial was registered and sized around spatial working memory errors. That measure did not differ between groups at either visit, and neither did the multitasking test of executive function, fatigue or self-rated memory difficulties. The authors describe the positive signals as hypothesis-generating rather than confirmatory.
What the headline 18 percent figure actually measures
Seppic's figures of 18 percent fewer errors and an 11 percent higher memory score at week 6 are the extract group's change from its own baseline, not the gap versus placebo. The extract group also started with more errors (24.0 versus 19.8, a gap the authors report as not statistically significant), and by week 12 both groups scored almost the same (18.5 versus 18.8), a pattern that can reflect regression toward the average.
Verbal recall gains limited to a younger subgroup
Across the whole trial, verbal word recall and recognition did not differ between groups. After spotting an age interaction, the researchers split participants at age 70; those aged 60 to 69 on the extract recalled about 1.4 more words at week 12, versus 0.2 on placebo. The authors call the size of this change modest and of unclear clinical relevance.
Perceived stress, sleep and fatigue outcomes
Perceived stress fell by about 1.7 points on a 40-point scale in the extract group, and in an exploratory comparison the difference from placebo was statistically significant at week 6 only, not at week 12. The extract group also began with higher stress scores. Insomnia scores improved similarly in both groups, and fatigue did not change in either.
Small daily polyphenol and ellagitannin dose
Each 300 mg daily dose supplied about 20 mg of total polyphenols, including roughly 4 mg of ellagitannins and 3 mg of salidroside. Diet questionnaires showed participants in both groups already took in about 5 to 9 mg of ellagitannins a day from food, so the extract adds a modest amount on top of an ordinary diet rather than a concentrated load.
Mechanism of action
Ellagitannins are converted to urolithins by gut bacteria
Ellagitannins and ellagic acid are poorly absorbed as such. Gut bacteria turn them into urolithins, which are absorbed much better than their precursors. Depending on their microbial make-up, people fall into urolithin metabotypes A, B or 0, so the same dose can lead to very different urolithin exposure from person to person.
Urolithin A brain effects shown only in animals and cells
Urolithin A restores mitophagy and dampens neuroinflammation in rodent and cell models, and reviewers suggest it may be a final driver of ellagitannin neuroprotection. In people it circulates mostly as glucuronide and sulfate conjugates, the forms reaching the brain are unknown, and no completed trial has tested it on cognitive outcomes.
Nrf2 antioxidant signaling in animal studies
In diabetic rats, four weeks of a water extract of strawberry leaves improved water maze performance and lowered hippocampal oxidative and inflammatory markers alongside Nrf2/HO-1 activation. A separate cell and mouse study linked an ethanol leaf extract to Nrf2 activation and protection of dopaminergic neurons. Neither tested Sepibright.
Salidroside as a second marker compound
The extract also supplies about 3 mg a day of salidroside, the phenylpropanoid glycoside best known from rhodiola. The trial authors propose it may contribute to the stress result, citing animal work, but the trial measured no blood levels of salidroside, urolithins or cortisol, so any mechanism in people remains untested.
Leaves are richer in polyphenols than the fruit
Strawberry leaves are a cultivation by-product; one analysis of the Festival cultivar found about 122-fold higher total polyphenol content and 13-fold higher antioxidant capacity in leaf extracts than in the fruit. That difference is why strawberry fruit trials cannot simply be read across to a leaf extract.
Clinical trials
Randomized, double-blind, placebo-controlled, single-center trial of strawberry leaf extract (Sepibright) 300 mg/day for 12 weeks, registered as NCT06819163, funded by Seppic, with four Seppic employees among the authors (Dormal V, Dudonné S, Gombert C, Laurençon L, Fouilland J, Buchet M, Zacharias I, Copine S, Simar L, Deldicque L 2026, J Nutr Health Aging 30(9):100929, PMID 42508219).
109 adults aged 60 to 80 in Belgium with self-reported memory complaints and preserved global cognition (MMSE above 24); 98 analysed per protocol (50 extract, 48 placebo).
The primary mixed-effects analysis found no significant group-by-time interaction for the registered primary outcome (spatial working memory errors) or any secondary outcome. Exploratory change-from-baseline comparisons favored the extract for paired associates learning errors at weeks 6 and 12 (p = 0.016 and p = 0.048), perceived stress at week 6 only (p = 0.043) and verbal recall in a post hoc subgroup under age 70. Registered secondary outcomes on emotional state (PANAS), self-rated health and self-perceived memory, concentration and attention are not reported in the paper. Possibly related adverse events: 7 on the extract, 9 on placebo, none serious. The sponsor holds the data, which are not publicly available.
Randomized, double-blind, placebo-controlled trial of 24 g/day freeze-dried strawberry powder for 90 days (Miller MG, Thangthaeng N, Rutledge GA, Scott TM, Shukitt-Hale B 2021, Br J Nutr 126(2):253-263, PMID 33468271). Class evidence: whole fruit, not a leaf extract; it did not test Sepibright.
37 healthy adults aged 60 to 75 (22 men, 15 women).
Group-by-visit interactions favored strawberry on a virtual spatial navigation task and on word recognition in the California Verbal Learning Test, while gait and balance did not improve. The authors called for larger, longer trials. It shows some human cognitive signal for strawberry fruit, but the fruit is a different material from the leaf extract sold as Sepibright.