The Effect of a Fortified Date Bar on Perceived Stress and Morning Salivary Cortisol in Female Students: A Pilot Randomized Controlled Trial.

Background/

Objectives

Chronic stress poses a serious threat to public health and is associated with the rising global burden of mental disorders, including anxiety and depression. University students, particularly young women, represent a highly vulnerable group due to the combination of academic pressure, social adaptation challenges, and gender-specific stress reactivity. This pilot randomized controlled parallel-group trial aimed to evaluate the effect of a 4-week daily consumption of a date bar fortified with magnesium (240 mg), vitamin C (300 mg), inulin (1000 mg), and grape seed extract (100 mg) on perceived stress and morning salivary cortisol in healthy female university students under natural academic load.

Methods

Thirty healthy female students (aged 18-28 years) were randomized in a 1:1 ratio to either the intervention group (fortified date bar) or the control group (placebo bar) for 4 weeks. The primary outcome was the change in morning salivary cortisol levels (measured 30-60 min after awakening), and the secondary outcome was the change in perceived stress assessed by the Perceived Stress Scale (PSS-14). Measurements were performed at baseline and within 24-48 h after the intervention. Adherence was monitored via daily digital reports and weekly in-person meetings. Statistical analysis was performed using non-parametric tests (Mann-Whitney U test, Wilcoxon test) with effect sizes (rank-biserial correlation, r). Per-protocol analysis was applied for the primary outcome (n = 28) and available-case analysis for the secondary outcome (n = 29). Participants and outcome assessors were blinded to group allocation throughout the study.

Results

No adverse events were reported. Median adherence was 100% in both groups, with all participants demonstrating ≥ 90% compliance. No statistically significant changes in morning salivary cortisol were observed within or between groups (within-group: p = 0.173 in the intervention group, p = 0.326 in the control group; between-group: p = 0.104), although a consistent trend toward a reduction was observed in the intervention group (median Δ = -0.64 ng/mL) with a moderate effect size (r = 0.43 within-group; r = -0.37 between-group). For perceived stress, a statistically significant reduction in PSS-14 scores was observed within the intervention group (median Δ = -4.0 points; p = 0.009) with a large effect size (r = 0.80), while no significant change occurred in the control group (p = 0.624). Between-group comparison for PSS-14 changes did not reach statistical significance (p = 0.073), although the effect size was moderate (r = -0.40). No significant correlation was found between changes in cortisol and changes in PSS-14 scores (ρ = -0.134; p = 0.496).

Conclusions

In this pilot randomized controlled trial, four-week consumption of a fortified date bar was associated with a reduction in perceived stress among healthy female university students, as reflected by a large within-group effect size on PSS-14 scores. However, given the exploratory nature of the study, the small sample size, and the absence of an a priori power calculation, this finding should be regarded as preliminary and hypothesis-generating rather than as evidence of established efficacy. A consistent, albeit non-significant, trend toward reduced morning cortisol was also observed, suggesting a possible modulatory effect on the HPA axis that requires confirmation in larger, longer-term studies with optimized dosages. The dissociation between subjective and objective stress measures underscores the multidimensional nature of the stress response and supports the use of complementary assessment approaches in future research. The fortified date bar may warrant further investigation as a potentially feasible, acceptable, and economically accessible component of primary stress prevention strategies in young populations, although this possibility remains to be tested in adequately powered confirmatory trials.