It is an old recipe that our grandmothers and mothers have given us all our lives: if you can’t sleep, have a glass of hot milk . Have they ever told you, right? The tryptophan in milk is the reason behind the popular advice, or at least it is what has been believed to date. Now a group of researchers has discovered that the peptides in milk could also be helping us sleep better.
Until now it was thought that the power of a glass of hot milk before sleeping to fall asleep was due to the fact that it contains tryptophan, an essential amino acid that we obtain from food and that helps, among other things, to produce melatonin and serotonin , which intervene in dream. The reason milk is hot and not cold is that warm drinks help the body to relax and provide a feeling of comfort that facilitates and improves sleep. Well, the study just published in the Journal of Agricultural and Food Chemistry concludes that a mixture of peptides present in milk and known as tryptic casein hydrolyzate (CTH) relieves stress and improves sleep . Researchers have identified specific peptides in HTC that could one day be used in new natural remedies to combat insomnia.
According to the Centers for Disease Control and Prevention (CDC), one-third of American adults don’t get enough sleep. Sedatives, such as benzodiazepines and zolpidem (analog of these), are commonly prescribed to combat insomnia, but they can cause side effects and addiction. Many sedatives work by activating the GABA receptor, a protein in the brain that suppresses nerve signaling . Scientists have also discovered several naturally occurring peptides, or small pieces of protein, that bind to the GABA receptor and have anxiolytic and sleep-enhancing effects. For example, treating casein, a protein in cow’s milk, with the digestive enzyme trypsin produces the peptide mixture CTH, which improves sleep. Within this mixture, a specific peptide known as alpha-Casozepine has been identified that could be responsible for some of these effects. Lin Zheng, Mouming Zhao and the rest of the researchers wondered if they could find other peptides, perhaps more powerful, to improve sleep in HTC.
The researchers first compared the effects of HTC and alpha-Casozepine in mouse sleep tests, and found that HTC showed better sleep-enhancing properties than alpha-Casozepine alone. This result suggested that in HTC there are other peptides that promote sleep in addition to alpha-Casozepine . The team then used mass spectrometry to identify the bioactive peptides released by HTC during simulated gastric digestion, and virtually examined these peptides for their binding to the GABA receptor and their ability to cross the blood-brain barrier (the main barrier to the transport of drugs in the brain, which also acts as an immune and metabolic barrier). When the strongest candidates were tested in mice, the best one, YPVEPF, increased the number of mice that fell asleep rapidly by about 25% and the duration of sleep by more than 400% compared to a control group.
In addition to this promising peptide, others from HTC should be explored that could improve sleep through other avenues, the researchers say.
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Fuente: Jingjing Qian, Lin Zheng, Guowan Su, Mingtao Huang, Donghui Luo, Mouming Zhao. Identification and Screening of Potential Bioactive Peptides with Sleep-Enhancing Effects in Bovine Milk Casein Hydrolysate. Journal of Agricultural and Food Chemistry, 2021; 69 (38): 11246 DOI: 10.1021/acs.jafc.1c03937
