Published in Applied Research
Peptides in fermented milk may reduce blood pressure
Functional dairy products that lower blood pressure and heart rate may offer consumers an effective alternative to antihypertensive drugs.  This effect has been attributed to bioactive peptides within dairy proteins which are released during fermentation.  An invited review published in the Journal of Dairy Science has reported on available information (in vitro and vivo studies) relating to the evaluation of fermented milk containing antihypertensive peptides so that the product can be introduced into the market. The authors note there are only a few commercially available fermented milks with antihypertensive effects and these are developed using Lactobacillus helveticus. 
Vellejo-Cordoba et al. report that milk bioactive peptides consisting of 2 to 20 amino acid residues that, besides being a good source of essential amino acids also have specific biological properties, including antioxidant and antihypertensive actions. The team notes the renin-angiotensin system is the metabolic pathway in humans responsible for controlling blood pressure and vascular tone.  Angiotensin-converting enzyme (ACE) plays a key role, and inhibiting ACE will lower blood pressure.  Several peptides found in fermented milk are reported as anti-inhibitory substances. 
The researchers reported that the most common strategy to select fermented milk with antihypertensive potential was to identify ACE inhibitory peptides in vitro.  The majority of studies, have started the process of developing an antihypertensive fermented milk by screening different lactic acid bacteria for their ability to exhibit high ACE inhibition.  Fermented milk with Lactobacillus strains were the most studied.  However, the team report that some strains inhibiting ACE in vitro did not reduce blood pressure in rats. 
The scientists report that in vivo studies have demonstrated the hypotensive effects of fermented milk, with rats being orally fed fermented milk.  The team evaluated 13 studies with spontaneously hypertensive rats and seven randomized controlled clinical trials in which an antihypertensive effect was demonstrated. Most were based on Lactobacillus helveticus. 
The investigators note that several fermented milk products already on the market attribute their antihypertensive effect to the bioactive peptides present in the fermented milk and note some of these commercial products possess intellectual property rights. However, the scientists report that these products may also contain minerals such as potassium and calcium, which may have a positive effect on blood pressure.
The team note that future research should include in vitro lactic acid bacteria screening for ACE-inhibitory effects, in vivo studies with spontaneously hypertensive rats, and clinical trials to test the efficacy of the fermented milk product.
A recent study presented at this year’s American Society of Hypertension has also found an ounce a day of Italian Grana Padano PDO consumed for 2 months to have an antihypertensive effect in 30 hypertensive adults.  The team from the Hypertension Unit of Guglielmo da Saliceto Hospital and Catholic University of Piacenza, Italy, report that after intervention the participants had between a 7-8 mmHg drop in systolic blood pressure and a 5-7 mmHg drop in diastolic blood pressure.  This finding was attributed to the peptide content within the cheese.

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