Vitamin C & Mental Vitality
Vitamin C supplementation promotes
mental vitality in healthy young adults:
results from a cross-sectional analysis and a randomized,
double-blind, placebo-controlled trial
Vitamin C (ʟ-ascorbic acid or ascorbate) is an essential nutrient in humans that functions as an indispensable electron donor and a cofactor in various biological reactions such as hydroxylation of collagen, biosynthesis of carnitine, and tyrosine metabolism.
Interestingly, vitamin C presents its highest concentrations in the brain, and animal model and in vitro studies have reported that vitamin C performs a critical role in brain functions.
Vitamin C protects neurons from oxidative stress, induces differentiation and maturation of neurons, and regulates the synthesis or release of neuro-modulating factors including serotonin, catecholamines, and glutamate. Accordingly, vitamin C is inferred to be important for maintaining normal mental health.
Humans rely on dietary supply to obtain vitamin C due to the absence of a gene encoding ʟ-gluconolactone oxidase, which is critical for vitamin C synthesis from glucose. The poor vitamin C status in the young can be attributed to external factors such as smoking, excessive drinking, and unhealthy eating habits that fail to provide a fresh and balanced diet rich in vitamin C.
Thus, even healthy young individuals can be at risk of vitamin C deficiency, and consequently, poor body functions due to these lifestyle-related factors. However, compared to the elderly, inadequate vitamin C status in the young is liable to remain undiagnosed or be considered as being of little importance.
Vitality is defined as a subjective feeling of energy and aliveness, which highlights the psychological aspects.
Feeling vital is suggested as a key component in healthy psychological functioning, the ability of self-regulation, work performance, and goal achievement.
Classically, vitality decline is known as the earliest sign of scurvy, a clinical symptom of severe vitamin C deficiency; it manifests in fatigue, decreases in arousal and motivation, and cognitive impairment.
Considering that professional and social engagement is highest in the young population, it is necessary to investigate whether improvement of vitamin C status helps to promote their vitality and work performance. However, the link of vitamin C status with vitality-related psychological and cognitive functions at a young age is equivocal and their causal relationship has rarely been examined.
Hence, we first investigated the associations between vitamin C status and subjective vitality in a healthy young population. Next, using a randomized, double-blind, placebo-controlled trial, we further explored the effects of vitamin C supplementation on vitality, such as work motivation and self-regulatory resources, and cognitive performance in young adults with inadequate vitamin C status.
Purpose
We aimed to investigate the link of vitamin C status with vitality and psychological functions in a cross-sectional study and examine their causal relationship through a randomized controlled trial (RCT).
Methods
We first conducted a population-based cross-sectional investigation of healthy young adults (n = 214, 20–39 years), and analyzed the associations of serum vitamin C concentrations with vitality (fatigue and attention) and mood status (stress, depression, and positive and negative affect) using Pearson’s correlation and multiple linear regression analyses.
Next, we performed a double-blind RCT in healthy subjects whose serum vitamin C concentrations were inadequate (< 50 μmol/L). Subjects were randomly allocated to receive 500 mg of vitamin C twice a day for 4 weeks (n = 24) or a placebo (n = 22).
We assessed vitality, which included fatigue, attention, work engagement, and self-control resources, and measured mood status, including stress, depression, positive and negative affect, and anxiety. ELISA determined serum brain-derived neurotrophic factor (BDNF), and a Stroop color–word test evaluated attention capacity and processing speed.
Results
In the cross-sectional data, the serum vitamin C concentration was positively associated with the level of attention (r = 0.16, p = 0.02; standardized β = 0.21, p = 0.003), while no significant associations with the levels of fatigue and mood variables being found.
In the RCT, compared to the placebo, the vitamin C supplementation significantly increased attention (p = 0.03) and work absorption (p = 0.03) with distinct tendency of improvement on fatigue (p = 0.06) and comprehensive work engagement (p = 0.07).
The vitamin C supplementation did not affect mood and serum concentrations of BDNF. However, in the Stroop color–word test, the subjects supplemented with vitamin C showed better performance than those in the placebo group (p = 0.04).
- Serum vitamin C concentration was associated with the level of attention
- Vitamin C supplementation successfully increased the serum concentration of vitamin C
- Vitamin C supplementation increased attention and absorption in work
- Vitamin C supplementation boosted cognitive performance
Conclusion
Inadequate vitamin C status is related to a low level of mental vitality. Vitamin C supplementation effectively increased work motivation and attentional focus and contributed to better performance on cognitive tasks requiring sustained attention.
Story Source:
Vitamin C supplementation promotes mental vitality in healthy young adults: results from a cross-sectional analysis and a randomized, double-blind, placebo-controlled trial [Minju Sim, Sehwa Hong, Sungwoong Jung, Jin-Soo Kim, Young-Tae Goo, Woo Young Chun & Dong-Mi Shin] European Journal of Nutrition volume 61, pages447–459 (2022) https://doi.org/10.1007/s00394-021-02656-3