Taking soy protein before bed may improve sleep quality
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Key takeaways:
- Higher soy protein intake showed a significant impact on sleep quality from baseline to week 8.
- The association was no longer significant after 16 weeks.
CHICAGO — A higher intake of protein, particularly soy, a half-hour before bed was tied to improved sleep quality in older adults, according to the results of a study presented at NUTRITION.
“As you get older, your sleep quality actually decreases over time,” Clarinda N. Sutanto, PhD, an instructor at the National University of Singapore, told Healio. “If you have lower sleep quality, there are so many risks that come with it, like a higher risk for CVD. So, [we wondered] how we can improve the quality of sleep in this older population.”
According to Sutanto and colleagues, preliminary results have found that plant-based protein intake may promote better sleep quality, but more randomized clinical trials assessing the effect of protein intake on sleep were needed.
In the single-blinded, 16-week, randomized controlled trial, Sutanto and colleagues randomly assigned older Singapore adults (mean age, 66 years) to a control group with normal protein intake (n = 14) or to one of two higher protein groups. Those assigned to a protein group were asked to consume 30 g of soy protein (n = 16) or casein protein (n = 12) 30 minutes before bed. The participants were also asked to follow Singapore’s healthy eating pattern.
Both soy and casein protein were in the form of protein isolate powders, Sutanto noted.
The researchers collected sleep quality data every 4 weeks with the Pittsburg Sleep Quality Index questionnaire and an actigraphy watch. They used the questionnaire to estimate global sleep scores (GSS), with lower scores representing better sleep quality.
The researchers observed a significant time and protein intake effect on GSS at 8 weeks. Decreases in GSS occurred in both the casein protein and soy protein groups, while GSS increased in the control group. However, only the soy protein group showed a significant GSS reduction from baseline, and this effect no longer existed at 16 weeks.
Sutanto explained that it is not fully understood why the effect of soy protein did not last beyond that point.
“We haven't started analyzing the sleep-related biomarkers yet (eg, melatonin levels),” she said.
No other sleep components were affected by protein intake.
The fact that soy protein had an effect on sleep but casein protein did not could be due to the different amino acid compositions of the protein sources, Sutanto and colleagues noted.
Sutanto added that the findings could contribute to “more personalized nutrition.”
“Making big changes in a patient’s lifestyle and diet is not going to be easy, but by knowing this, we could find ways to tweak their diets to cater to their specific conditions,” she said.
Perspective
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This study is of interest because improving sleep quality in older adults can have many positive health benefits. The use of protein before bed is an affordable and easy way for people to potentially improve sleep without using medications that can have unwanted side effects. Increased protein intake can also have other health benefits including improved immunity, muscle maintenance and improved physical function. This study shows promise for a non-pharmacologic way to improve sleep. However, this study leaves more questions than answers. Why was the protein administered 30 minutes prior to bedtime as opposed to a different length of time? More research needs to be done to determine what, if any long-term benefits specifically on sleep in older adults come from protein intake before bedtime.
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Sutanto C, et al. Abstract P03-050-24. Presented at: NUTRITION; June 29-July 2, 2024
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