Higher Vitamin C intake linked to lower sleep disorder risk: Study
According to the National Institute for Health and Clinical Excellence (NICE), around a third of adults in Western countries experience sleep problems at least once a week, and insomnia is highly unreported, with only 30% of those affected seeking medical advice.
Lifestyle factors and rising stress levels are driving consumer demand for sleep supplements, with the global market projected to reach $11.8 billion by 2034.
Published in the journal Nutrients, the new study is reportedly the first sizable longitudinal analysis to expand previous research suggesting the potential for vitamin C supplementation to support sleep, the researchers from China noted.
Vitamin C and sleep disorders
The current UK recommendation for vitamin C intake is 40 mg/d for adults, which is lower than the National Institutes of Health recommendation of 90 mg/d and 75 mg/d for adult men and 75 women, respectively, and the European Food Safety Authority's adult recommendation of 95 mg/d average requirement (AR) and 110 mg/d population reference intake (PRI).
However, higher doses of vitamin C have been linked to beneficial health effects, and upper limits of 2,000 mg/d are considered safe, although they may cause side effects in some people.
The researchers on the current study noted that vitamin C may reduce the incidence of sleep disorders due to its anti-inflammatory and antioxidant effects, citing previous animal studies that indicate this mechanism.
According to a 2020 review of the literature, sleep disorders are very likely connected to elevated inflammation, oxidative stress and reduced antioxidant levels. The review noted that sleep changes the prooxidant-antioxidant balance in the body, restoring the body’s endogenous antioxidant mechanisms and removing free radicals.
Study details
The study used data from the UK Biobank prospective study, which collected information and samples during the initial survey between 2006 and 2010 and included ongoing follow-ups to present.
The researchers analyzed the relationship between dietary vitamin C intake and sleep disorders classified by ICD-10 codes among 68,221 participants who met the inclusion criteria.
They found that higher dietary vitamin C, ranging between approximately 125 mg/day and 200 mg/day, was associated with a reduced risk of sleep disorders, including sleep apnea.
Further stratified analysis revealed the effects were especially associated with males, individuals aged 60 years or younger, and those with hypertension.
“This protective effect persisted in patients with sleep apnea but was not observed in cases of insomnia or other sleep disorders,” the researchers wrote.
They study also found that C-reactive protein (CRP) was a significant indicator and mediator of inflammatory responses associated with sleep disorders, aligning with previous research suggesting high levels of inflammation in insomnia and extremes of sleep duration. It also noted that vitamin C can enhance vascular function in sleep apnea and help to balance hormones that determine sleep quality.
The researchers acknowledged several limitations, including dietary recall bias and not taking into account the effects of cooking on vitamin C levels, calling for further analysis of vitamin C as a sleep supplement.
Source: Nutrients 2024, 16(21), 3661;
doi: 10.3390/nu16213661
“The association between dietary vitamin C and sleep disorders: a cohort study based on UK Biobank.”
Authors: Q. Zhang et al.
