Lactotripeptides are two naturally occurring milk
peptides
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
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:
Isoleucine
Isoleucine (symbol Ile or I) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the depr ...
-
Proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the p ...
-Proline (IPP) and
Valine
Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotona ...
-Proline-Proline (VPP). These lactotripeptides are derived from
casein
Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins ( αS1, aS2, β, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of the proteins in hum ...
, which is a
milk protein also found in dairy products. Although most normal dairy products contain lactotripeptides, they are inactive within the original milk proteins. Dairy peptides can be effectively released through enzymatic predigestion – a process by which milk protein is enzymatically broken down into smaller pieces. Some clinical studies have suggested that these lactotripeptides help promote healthy blood pressure levels as part of a healthy diet and lifestyle.
However, other clinical trials have seen no effects from these compounds.
Proposed mechanism
Dairy peptides are proposed to inhibit the activity of the
angiotensin
Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adren ...
-converting
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
(
ACE). ACE is part of the
renin–angiotensin system
The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance.
When renal blood flow is reduced, ...
– a natural mechanism that helps regulate blood pressure in the body. In certain individuals, the renin–angiotensin system can become overactive, often due to stress, an unhealthy diet, and/or unhealthy lifestyle. Under such conditions, ACE becomes overactive and converts more angiotensin I into angiotensin II. Angiotensin II causes blood vessels to constrict, and so increases blood pressure, which has potential to lead to hypertension. But, when ACE activity is inhibited, the formation of angiotensin II is reduced. This then helps the blood vessels to relax and expand back to a normal healthy state, so blood pressure is lowered.
Clinical trials
Several human trials aimed to evaluate the effect of lactotripeptides on blood pressure. Some trials show a blood pressure-lowering effect of lactotripeptides in people with mild to moderate hypertension,
References
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Tripeptides
Antihypertensive agents