The research team, in particular, looked at earlier studies that highlight the ACE-inhibiting properties of certain milk proteins. ACE – short for angiotensin I-converting enzyme – transforms angiotensin I to angiotensin II, a protein hormone known to increase blood pressure, body water, and sodium content. Having too much angiotensin II in the body can cause high blood pressure (hypertension). It can also lead to heart failure, as the protein is thought to affect the growth of the size of the heart.
To counter the adverse effects of ACE, most doctors prescribe ACE inhibitors, which slow down the enzyme's activity, but also decrease the production of angiotensin. These drugs, however, come with side effects, including increased uric acid levels, high blood potassium levels, swelling of tissues (angioedema), liver dysfunction, and kidney failure. ACE inhibitors and other drugs for treating hypertension are also expensive, the researchers pointed out, making the need for easily available, natural, and food-derived ACE inhibitors that much more important.
Multiple studies show that milk proteins have anti-hypertensive properties. This has led to their inclusion in milk-derived nutraceutical drinks. YGLF, a derivative of alpha-lactalbumin, was shown to reduce both systolic and diastolic blood pressure in vivo. In the current study, the researchers used in silico methods to further explore the mechanisms behind this biological activity. They also looked to build a comparative molecular field analysis model (CoMFA) to predict which peptide sequences would be released from enzymatic digestion without the need for experimental data. CoMFA is an approach that looks at the relationship between a chemical's molecular structure and its activity in 3D – aptly called 3D quantitative structure-relationship (QSAR). While milk peptides that have ACE inhibitory activity have been reported using 3D QSAR, researchers noted that these are insufficient.
Based on the results of molecular docking simulation, the researchers found that peptides that contain hydrophobic amino acids have the most potent ACE inhibitory activity. These amino acids are positioned into the hydrophobic pocket of the ACE active site and interact with its residues. CoMFA results for the dipeptides, on the other hand, identified favorable steric reactions at the C-terminus, which concurs with experimental data. They also noted that the milk dipeptides also exhibited favorable electronegativity at the C-terminus, which is important for their inhibiting activity.
"[Milk-derived di- and tripeptides] have significant antihypertensive activity and provide information for screening and design of novel ACE inhibitors that could be used as supplements in human nutrition," the researchers wrote in their report. "[These could be recommended] for application as functional food supplements and natural alternatives to ACE-inhibitory drugs."
Not all kinds of milk are created equal
Indeed, milk does contain health benefits – if you know which one to get. Unfortunately, the milk that's available in most supermarkets isn't the one you want.
Pasteurized milk, where milk is heated to kill pathogens, is linked to health problems, such as constipation in children. An Australian study found an association between cow's milk consumption and constipation in children and that withholding it can resolve the problem.
It's also produced in some of the dirtiest factories available. In his article, Mike Adams, the Health Ranger, wrote how pasteurization isn't about making milk safe, but ensuring that the dairy industry gets away with its unsanitary operations.
"Thanks to pasteurization, conventional (non-organic, non-raw) dairy operators have no need to thoroughly wash their milking machines, no need to sterilize any milk containers, no need to wash their hands, and no need to maintain a clean milking environment whatsoever," he added.
A safer alternative to conventional milk? Raw milk. Unlike the pasteurized variety, raw milk is full of probiotics which relieve constipation and are known to provide the body with multiple health benefits. It's also easier to digest. Fermented raw milk is even better. As Adams writes, fermented raw milk is "so packed with life it's actually fizzy (carbonated due to the off-gassing of bacteria) when you make it yourself at home."
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