Macronutrient intake and alertness during night shifts - the time interval matters

Mariëlle G de Rijk; Alexander P J van Eekelen; Sanne Boesveldt; Elly Kaldenberg; Tineke Holwerda; Ceciel J M Lansink; Edith J M Feskens; Jeanne H M de Vries

doi:10.3389/fnut.2023.1245420

Macronutrient intake and alertness during night shifts - the time interval matters

Front Nutr. 2023 Nov 9:10:1245420. doi: 10.3389/fnut.2023.1245420. eCollection 2023.

Authors

Mariëlle G de Rijk¹, Alexander P J van Eekelen², Sanne Boesveldt¹, Elly Kaldenberg³, Tineke Holwerda⁴, Ceciel J M Lansink⁵, Edith J M Feskens¹, Jeanne H M de Vries¹

Affiliations

¹ Division of Human Nutrition and Health, Wageningen University and Research, Wageningen, Netherlands.
² Circadian NL, Amsterdam, Netherlands.
³ Sanavis, Spijk, Netherlands.
⁴ Hospital Gelderse Vallei, Ede, Netherlands.
⁵ Deventer Hospital, Deventer, Netherlands.

Abstract

Background: Working night shifts is associated with higher safety risks due to shift work-related fatigue. Nutrition, especially certain (macro) nutrient compositions, has been suggested to reduce fatigue, however, results of studies are contradictory. This could be explained by differences in the time interval investigated between the consumption of a meal and measurement of cognitive performance. Therefore, this observational study investigated the association between macronutrient intake and objective alertness at different time intervals during the night shift in nurses.

Methods: 128 nurses, aged 20-61 years, completed an alertness test (Psychomotor Vigilance Task) during the night shift and a 24-h dietary recall after the night shift. This was repeated three times, always on the first night shift in a night shift series. The associations between macronutrient intake 0 to 1, 1 to 2, and 2 to 3 h before the PVT with alertness during the night shift were analyzed through Linear Mixed Models. The basic model was adjusted for age and gender and the adjusted model additionally for BMI, start time of PVT and energy and caffeine intake during the relevant time interval.

Results: Protein intake was not associated with objective alertness levels, while fat and carbohydrates intake had opposite associations with objective alertness levels over similar time intervals. Fat intake up to 1 h prior to the PVT was borderline associated with a longer median reaction time (RT) (ß = 9.00 ms/10 g fat, 95% CI: -0.21, 18.20), while a higher carbohydrate intake up to 1 h prior to the PVT was borderline associated with shorter median RTs (ß = -3.89, 95% CI: -7.85, 0.06). A higher fat intake 2 to 3 h prior to the PVT was associated with less lapses (log transformed ß = -0.16; 95% CI: -0.31, -0.02), while a higher carbohydrate intake 2 to 3 h prior to the PVT was associated with more lapses (ß = 0.06, 95% CI: 0.01, 0.12).

Conclusion: Our results contribute to understanding the association between macronutrient intake, as part of a mixed meal, and alertness levels. Conflicting results from previous studies may probably be due to time differences between macronutrient intake and alertness testing.

Keywords: diet; fatigue; nutrients; occupational health; shift work; sustained attention; timing.

Grants and funding

The author (s) declare financial support was received for the research, authorship, and/or publication of this article. This work was carried out as part of a public-private partnership funded by the Netherlands Organization for Scientific Research (NWO, grant 057-14-040).