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Reduced nitric oxide synthesis in winter: A potential contributing factor to increased cardiovascular risk

Liddle, Luke; Monaghan, Christopher; Burleigh, Mia C.; Baczynska, Katarzyna A.; Muggeridge, David J.; Easton, Chris


Luke Liddle

Christopher Monaghan

Mia C. Burleigh

Katarzyna A. Baczynska

Chris Easton


Nitric oxide is a key signalling molecule that elicits a range of biological functions to maintain vascular homeostasis. A reduced availability of nitric oxide is implicated in the progression of cardiovascular diseases and increases the risk of pathogenic events.

To compare the concentration of nitric oxide metabolites in healthy adults between winter and summer months.

An observational study of healthy adults (age 32 ± 9 years) living in central Scotland.

Thirty-four healthy adults (13 females) were monitored for 7 days in summer and winter to record sunlight exposure (ultraviolet-A (UV-A) radiation), diet, and physical activity. At the end of each phase, blood pressure was measured, and samples of blood and saliva collected. The samples were analysed to determine the concentrations of plasma and salivary nitrate and nitrite and serum 25-hydroxyvitamin D (25(OH)D).

The participants maintained similar diets in each measurement phase but were exposed to more UV-A radiation (550%) and undertook more moderate-vigorous physical activity (23%) in the summer than in winter. Plasma nitrite (46%) and serum 25(OH)D (59%) were higher and blood pressure was lower in the summer compared to winter months. Plasma nitrite concentration was negatively associated with systolic, diastolic, and mean arterial blood pressure.

Plasma nitrite, an established marker of nitric oxide synthesis, is higher in healthy adults during the summer than in winter. This may be mediated by a greater exposure to UV-A which stimulates the release of nitric oxide metabolites from skin stores. While it is possible that seasonal variation in nitric oxide availability may contribute to an increased blood pressure in the winter months, the overall impact on cardiovascular health remains to be determined.

Journal Article Type Article
Acceptance Date Jun 29, 2022
Online Publication Date Jul 2, 2022
Publication Date 2022-10
Deposit Date Aug 9, 2022
Publicly Available Date Aug 9, 2022
Journal Nitric Oxide
Print ISSN 1089-8603
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 127
Pages 1-9
Keywords Ultra-violet, Plasma nitrate, Plasma nitrite, Vitamin D, Physical activity
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