The trial, published in the journal Nutrition, suggests that increasing vitamin C levels in acutely hospitalized patients – who often have vitamin deficiencies – could improve mood response scores by 34 percent.
"About one in five acute-care patients in our hospital have vitamin C levels so low as to be compatible with scurvy," said lead researcher, Dr. John Hoffer, professor of medicine at McGill University, Canada.
"Patients are rarely given vitamin supplements. Most physicians are simply unaware of the problem. Subclinical deficiencies of vitamin C and D have each been linked to psychological abnormalities, so we examined that aspect in our clinical trial," added Dr. Hoffer.
The term hypovitaminosis C usually implies a deficiency in vitamin C intake. But in acutely hospitalized patients’ responses to inflammation could re-direct the vitamin away from important tissues and into immune cells - without necessarily indicating nutritional deficiency.
Previous research attempted to pinpoint the metabolic origin of hypovitaminosis C in such patients by measuring their responses to vitamin C provision.
Because psychological abnormalities are a known feature of vitamin C deficiency, previous research included assessments of mood. The results showed increased vitamin C was associated with a 35 percent reduction in mood disturbance.
Although the results from this previous research suggested a strong effect for vitamin C, the mood improvement could not be confirmed due to the set up of the study - and may have reflected a placebo response.
The new trial investigated vitamin C supplementation therapy in a double-blind clinical trial - to examine if previous observations of its effects were replicable in a new patient sample.
Vitamin D was used as an alternative treatment to vitamin C, as vitamin D deficiency is also very common in acutely hospitalized patients and has been linked to abnormal mood.
The researchers reported that vitamin C was associated with a 34 percent improvement in mood scores. The authors noted the results as comparable to previous research suggesting a 35 percent improvement in scores.
No improvement in mood was found with vitamin D supplementation, “thus making the placebo response an unlikely explanation for the effect of vitamin C,” according to the researchers.
The researchers note the well-known relationship between vitamin C deficiency and psychological state, adding that “the observation that vitamin C provision improved mood in these patients may therefore be considered surprising, but it is not implausible.”
The authors suggested that if sub-normal vitamin C concentrations in the cerebrospinal fluid adversely affect brain functions and mood, then their replenishment could improve mood.
"The lack of any effect of vitamin D on mood is good evidence we are not dealing with a placebo response," said Dr. Hoffer.
"This looks like a true biological effect. Our finding definitely requires follow up in larger studies in other centers.
"The treatment is safe, simple and cheap, and could have major clinical practice implications." he added.
Published online ahead of print, doi: 10.1016/j.nut.2010.05.016
“Vitamin C provision improves mood in acutely hospitalized patients”
Authors: M. Zhang, L. Robitaille, S. Eintracht, L. J Hoffer