Tripeptides in milk and blood pressure

Peptides are molecules made from the linking of amino acids. Most proteins have a minimum of hundreds of amino acids while peptides range from 2 to about 40 or 50 amino acids although some consider a peptide up to 100 amino acids. A peptide bond forms when the amino group of one amino acid bonds to the carboxyl group of another amino acid.

Peptides are categorized into three large classes. These include ribosomal peptides, nonribosomal peptides, and digested peptides.

1. Ribosomal peptides are usually found in higher organisms and funciton as hormones and signalling molecules.

2. Nonribosomal peptides are confined primarily to unicellular organisms, plants, and fungi.

3. Digested peptides are the result of digestion of proteins in the gastrointestinal system. When certain food proteins such as gluten, casein, and egg protein are broken down, opioid peptides are formed. These peptides are quite short and are given names such as casomorphine, gluten exorphine and dermorphine.

Tripeptides in fermented milk
A traditional Scandinavian beverage, fermented milk, can help reduce blood pressure in people with hypertension. The drink has long been popular in Scandinavian countries and made by adding Lactobacillus to milk, which breaks down the milk protein casein into two types of protein fragments called tripeptides. The tripeptides, isoleucine-proline-proline and valine-proline-proline, have been shown in animal studies to reduce blood pressure and also lower blood pressure in people with mild hypertension. They may work by blocking the blood-pressure-raising chemical angiotensin-converting enzyme (ACE), the same mechanism employed by ACE inhibitor drugs. American Journal of Hypertension, December 2005.
   Comments: Supplements are now available with tripeptides that claim to lower blood pressure. Until human trials are done with such supplements, it is premature to claim that taking a tripeptide supplement lowers blood pressure.

Tripeptides - Peptides made of three amino acids
The tripeptide GLF (glycyl-leucyl-phenylalanine) is isolated from human milk proteins. This peptide increases phagocytosis by human and murine macrophages and protected mice against Klebsiella pneumoniae infection. Specific binding sites on human polymorphonuclear leukocytes (PMNs) have been demonstrated.

Tripeptides Questions
Q. I would like to know about milk tripeptides. I have been informed that they are very beneficial to lower blood pressure. For example the Evolus milk by Valio. I would like to acquire that product and I know that you are a very respected doctor. I haven’t been able to find too much data on milk tripeptides.
   A. We have not studied milk tripeptides in much detail due to a shortage of human research.

Q. Please put something on your website about the active ingredient in Ameal BP which is being advertised on radio and TV as a way to reduce high blood pressure. It has casein derived tripeptides valyl-prolyl-proline and isoleucyl-prolyl-proline.
   A. A search on Medline in May 2008 did not reveal any studies with Ameal BP product.  It is unclear from their website what the exact ratios of these tripeptides are, and whether there are additional amino acids or peptides in their formula, and I have not seen independent studies on the accuracy of labeling or purity of the product. Therefore, I do not have much hard data with which to base a reliable opinion on the benefits or side effects of Ameal BP at this time.
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This tripeptide page was last updated in June 2008.