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Smartphone survey data reveal the timecourse of changes in mood outcomes following vitamin C or kiwifruit intervention in adults with low vitamin C.

  • 2023-12-11
  • The British journal of nutrition 131(8)
    • Benjamin D Fletcher
    • Jillian J Haszard
    • Margreet C M Vissers
    • Tamlin S Conner

Study Design

Type
Clinical Trial
Population
Adults (n 155, 63 % female, aged 18-35 years) with low plasma vitamin C (<40 μmol/l)
Methods
three-armed placebo-controlled trial, 14-d lead-in, 28-d intervention, 14-d washout, smartphone surveys every second day, supplementation with vitamin C (250 mg tablet/d), kiwifruit (2 SunGold™ kiwifruit/d) or placebo (1 tablet/d)
Duration
28-d intervention
Funding
Unclear
Vitamin C-rich foods can improve mood; however, the timecourse of these benefits is unknown. This study utilised intensive longitudinal smartphone surveys from a three-armed placebo-controlled trial to determine mood-related changes following supplementation with vitamin C (250 mg tablet/d), kiwifruit (2 SunGold™ kiwifruit/d) or a placebo (1 tablet/d). Secondary data were analysed from the KiwiC for Vitality trial (Trial ID: ACTRN12617001031358). Adults (n 155, 63 % female, aged 18-35 years) with low plasma vitamin C (<40 μmol/l) completed a 14-d lead-in, 28-d intervention and 14-d washout. Participants self-reported vitality (SF-36), mood (POMS total mood disturbance), flourishing (flourishing scale), sleep quality, sleep quantity and physical activity every second day using smartphone surveys. Plasma vitamin C, measured fortnightly, reached saturation after 2 weeks of vitamin C or kiwifruit supplementation. Kiwifruit supplementation improved vitality and mood within 4 days, peaking around 14-16 days, and improved flourishing from day 14. Vitamin C marginally improved mood until day 12. Incremental AUC analyses revealed significant overall effects of kiwifruit consumption on vitality and mood compared with placebo, which were stronger than effects for vitamin C tablets, but attenuated when adjusting for covariates. Sensitivity analyses of participants with low baseline vitamin C status revealed improved mood (vitamin C and kiwifruit) and flourishing (kiwifruit only). This is the first study to use intensive smartphone surveys to model the day-to-day timecourse of mood-related states following vitamin C intervention and highlights the value of using smartphone surveys to reveal the temporal changes in mood-related outcomes following nutrient supplementation.

Research Insights

  • Vitamin C→Improved Flourishing

    Kiwifruit supplementation improved vitality and mood within 4 days, peaking around 14-16 days, and improved flourishing from day 14. Vitamin C marginally improved mood until day 12.

    Effect
    Neutral
    Effect size
    Small
    Dose
    250 mg tablet/d
  • Vitamin C→Improved Mood

    Vitamin C marginally improved mood until day 12.

    Effect
    Neutral
    Effect size
    Small
    Dose
    250 mg tablet/d
  • Vitamin C→Improved Vitality

    Vitamin C marginally improved mood until day 12.

    Effect
    Neutral
    Effect size
    Small
    Dose
    250 mg tablet/d
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