18th June 2020 by Vera Hoermann

Teuni H Rooijackers, Marga C Ocké, Linda M Hengeveld , Marjolein Visser, Jolanda MA Boer

Public Health Nutrition 2020, 1-13. doi:10.1017/S1368980020000026

Adequate protein intake is important for the health and physical functioning of older adults. There are indications that the timing of protein intake may influence total protein intake, but evidence is limited so far. Therefore we studied the association between timing of protein intake and the total amount of protein ingested in 739 community-dwelling Dutch older adults (70+), who participated in the Dutch National Food consumption Survey 2010-2012. Participants were interviewed at home by trained dieticians twice, with a mean interval of four weeks about all food and drinks they had eaten the day before. For all foods and drinks consumed, the amount and time of consumption was recorded. For each day we calculated how much protein the participant ingested. If the participant ingested less than 0.8 g protein per kilogram of body weight, protein intake was considered to be low that day.

The results showed that protein intake differed across hours of the day with peaks between 08:30-09:29h (mostly breakfast), 12:30-13:29h (mostly lunch), and 17:30-18:29h (mostly dinner). On the 290 days that protein intake was low, for each hour of the day the average amount of protein ingested was lower compared to the 1188 days with a higher protein intake. This lower intake at either time of day may, however, just reflect a lower food consumption and does not necessarily provide information on the distribution of protein intake over the day. Therefore, we also investigated how much of the total protein was ingested in the morning, midday or in the evening. On days with a low protein intake, a larger part of the total protein intake was ingested in the morning (22%), compared to days with a higher protein intake (17%). If a larger part of total protein was consumed in the morning, there was a higher change that the total protein intake of that day was low. Weaker associations were observed for the part of protein that was ingested midday or in the evening. These results confirm results of other studies on this topic and suggest that timing of protein intake may influence total protein intake. Drawing final conclusions on the effect of timing of protein on total protein intake from our study is difficult. It is important to look in more depth into the timing of protein intake in experimental studies actively manipulating protein intake at different hours of the day, to see if timing of protein intake can be used to increase the likelihood of an adequate protein intake among older adults.

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