A biphasic response to blueberry supplementation on depressive symptoms in emerging adults: a double-blind randomized controlled trial.

2024-02-01
European journal of nutrition 63(4)
- Martin Velichkov
- Zsofia Bezur
- Carien M van Reekum
- Claire M Williams

PubMed: 38300292
DOI: 10.1007/s00394-023-03311-9

Study Design

Type: Randomized Controlled Trial (RCT)
Population: 60 emerging adults (M_age = 20.0 years, 32% male) with self-reported depressive symptoms
Methods: Double-blind trial, randomly assigned to receive a single blueberry drink (acute phase), followed by 6 weeks of daily blueberry supplementation (chronic phase), or a matched placebo drink
Blinding: Double-blind
Duration: 6 weeks

Rigorous Journal

Purpose

The aim of the present study was to examine the acute and chronic effects of wild blueberry supplementation on mood, executive function, and serum biomarkers of neuroplasticity, inflammation, and oxidative stress in emerging adults with moderate-to-severe depressive symptoms.

Methods

In this double-blind trial, 60 emerging adults (M_age = 20.0 years, 32% male) with self-reported depressive symptoms were randomly assigned to receive a single blueberry drink (acute phase), followed by 6 weeks of daily blueberry supplementation (chronic phase), or a matched placebo drink. The primary outcome was Beck Depression Inventory-II (BDI-II) scores at 6-week follow-up. Further measures included momentary affect (PANAS-X) and accuracy on an executive function task. The data were analyzed using ANCOVAs adjusted for baseline values, sex, and habitual fruit and vegetable intake. Estimated marginal means were calculated to compare the treatment arms.

Results

The blueberry drink significantly improved positive affect (p = 0.026) and executive function (p = 0.025) at 2 h post-ingestion, with change scores being positively correlated in the blueberry group (r = 0.424, p = 0.017). However, after six weeks of supplementation the reduction in BDI-II scores was greater in the placebo group by 5.8 points (95% CI: 0.8-10.7, p = 0.023). Generalized anxiety and anhedonia also decreased significantly more in the placebo group. No significant differences were found for any of the biomarkers.

Conclusions

Six weeks of wild blueberry supplementation were inferior to placebo in reducing depressive symptoms. Nevertheless, the correlated improvements in positive affect and executive function after a single dose of blueberries point to a beneficial, albeit transient, psychological effect. These contrasting results suggest a biphasic, hormetic-like response that warrants further investigation.

Trial registration

NCT04647019, dated 30 November, 2020.

Research Insights

Wild Blueberry→Improved Cognitive Function
The blueberry drink significantly improved positive affect (p=0.026) and executive function (p=0.025) at 2 h post-ingestion
Effect
Beneficial
Effect size
Small
Dose
single blueberry drink
Wild Blueberry→Improved Neuroplasticity Biomarkers
No significant differences were found for any of the biomarkers
Effect
Neutral
Effect size
Small
Dose
daily blueberry supplementation for 6 weeks
Wild Blueberry→Improved Positive Affect
The blueberry drink significantly improved positive affect (p=0.026) and executive function (p=0.025) at 2 h post-ingestion
Effect
Beneficial
Effect size
Small
Dose
single blueberry drink
Wild Blueberry→Reduced Anhedonia
Generalized anxiety and anhedonia also decreased significantly more in the placebo group
Effect
Harmful
Effect size
Small
Dose
daily blueberry supplementation for 6 weeks
Wild Blueberry→Reduced Anxiety
Generalized anxiety and anhedonia also decreased significantly more in the placebo group
Effect
Harmful
Effect size
Small
Dose
daily blueberry supplementation for 6 weeks
Wild Blueberry→Reduced Depression Symptoms
the reduction in BDI-II scores was greater in the placebo group by 5.8 points (95% CI: 0.8-10.7, p=0.023)
Effect
Harmful
Effect size
Large
Dose
daily blueberry supplementation for 6 weeks
Wild Blueberry→Reduced Inflammation Markers
No significant differences were found for any of the biomarkers
Effect
Neutral
Effect size
Small
Dose
daily blueberry supplementation for 6 weeks
Wild Blueberry→Reduced Oxidative Stress
No significant differences were found for any of the biomarkers
Effect
Neutral
Effect size
Small
Dose
daily blueberry supplementation for 6 weeks