Researchers at the Vetmeduni, Vienna have established that the composition of human cell membranes is subject to daily rhythms, such as variations in the time of day, changes in seasons and temperature, etc. The results of the study published in the Journal of Biological Rhythms, suggest that these cyclic changes in membrane structure could play an important role in health and disease.

Natural Life: The Study

Thomas Ruf and Walter Arnold of the Research Institute of Wildlife Ecology at the University of Veterinary Medicine, Vienna explained that most physiological processes, such as heart rate and body temperature, exhibited fluctuations with daily rhythms. They aimed to determine whether an association existed between these natural rhythms and variations in cell membrane composition.

Researchers observed the buccal mucosa cells on 20 study participants over a year. These participants collected samples of their buccal cells every month on a pre-decided day, at three-hour intervals. Samples were collected by vigorously rinsing the mouth with water and freezing the samples in specialized flasks.

Results – Differences in Fatty Acid Composition

Fatty acids are an integral component of the cell membrane. They perform many vital functions, including signaling within the cells and regulating metabolic activities of the entire body. Analysis of the samples revealed changes in eleven fatty acids on account of daily rhythms. Many fatty acids were observed in higher concentrations during the night, while others were abundant during daytime.

“The cellular changes have one thing in common: they always occurred at about the same time in all participants. This shows that a clear rhythm is present”, highlighted first author Ruf. He further added that animal physiology explains how fatty acid composition of cell membrane is altered due to environmental conditions, especially seasonal changes. However, effects due to the latter were seen in only a few participants.

Why Isn’t There A Clear Pattern?

As compared to wildlife, the results showed no apparent annual rhythms in fatty acid patterns. About half of the participants exhibited yearly rhythms, but these were also not synchronous. Peaks in fatty acids were seen to vary between the seasons as well.

Ruf explained that seasonal influences were playing a smaller impact on the body in western countries. He attributed this to the prevalence of artificial light, which makes days seem longer, and the prolonged heating season, which reduces fluctuations in temperature. He stated that annual rhythms did exist within human populations as well, but due to modernization, they are no longer coherent with seasonal changes.

Significance Of The Findings

The cyclic variations in cell membrane structure observed, could be medically significant. It is a known fact that omega-3 fatty acids protect against diseases and help in brain development. Similarly, other fatty acids, if taken in excess, can be potentially harmful. Thus, fatty acid composition can have various health-related consequences.

“This phenomenon might also explain why certain diseases, and even death, occur at certain times of the day. Statistically, heart attacks occur more often in the morning than in the evening, and blood pressure is usually elevated before noon”, said Ruf.

Presently, the exact reason behind these compositional variations is not known. Further research into associations with food types and the appropriate time for intake is required.