Seasonal variation in plasma lipids and lipases in young healthy humans

ABSTRACT

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year.

In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am.

Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude).

Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter.

These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.

KEYWORDS:

• Lipases
• lipids
• seasonal rhythm
• seasonal variation

Acknowledgements

We would especially like to thank the students and teachers from University of Barcelona who participated in the study. Special thanks also to the Blood Bank of the Hospital Clínic de Barcelona (Spain) and to its Hemotherapy and Hemostasis Service, which facilitated and helped us collect the samples. This work was supported by the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III (ISCIII) (PI11/01159 and PI15/00190 to JP-O PI15/00332 to JAB-F) and the FEDER Funds of the EU (Fondo Europeo de Desarrollo Regional: “Una manera de hacer Europa”).

The authors have declared that no conflict of interest exists. The authors who have taken part in this study do not have a relationship with the manufacturers of the drugs involved either in the past or present and did not receive funding from the manufacturers to carry out their research. English grammar and language have been corrected by American Journal Experts (www.journalexperts.com).

Conflict of interest

All authors fully declare no financial or other potential conflict of interest.

Funding

This work was supported by the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III (ISCIII) (PI11/01159 and PI15/00190 to JP-O PI15/00332 to JAB-F) and the FEDER Funds of the EU (Fondo Europeo de Desarrollo Regional: “Una manera de hacer Europa”).

Ethics committee approval

I certify that a statement confirming that appropriate institutional and/or ethics committee approval has been obtained and is stated in the Methods section of the manuscript.

Abbreviations used

LPL, lipoprotein lipase; HL: hepatic lipase; FFA, free fatty acids; TAG: triacylglycerides.

Additional information

Funding

This work was supported by the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III (ISCIII) (PI11/01159 and PI15/00190 to JP-O PI15/00332 to JAB-F) and the FEDER Funds of the EU (Fondo Europeo de Desarrollo Regional: “Una manera de hacer Europa”).