Over the past decade, interest has been rising in fermented dairy foods that promote health and could potentially prevent diseases such as hypertension (high blood pressure).
Functional dairy products that lower blood pressure and heart rate may offer consumers an effective alternative to anti-hypertensive drugs, if their effectiveness can be demonstrated, according to investigators that prepared a review article in the Journal of Dairy Science on the scientific basis of reported claims and identified opportunities for developing products based on new lactic acid bacteria.
Globally, hypertension affects more than 1 billion people, according to the World Health Organization. It is also an important risk factor for developing other cardiovascular diseases, stroke, renal failure, cerebrovascular accidents and many other medical complications. Although hypertension can be treated with drugs, these often involve significant side effects; therefore, scientists are seeking out food substances that can help reduce or prevent hypertension.
"Fermented milk has been promoted as a non-pharmacological treatment for hypertension, mainly because of the lack of undesirable side effects, but as yet, there is insufficient evidence to support this, according to the European Food Safety Authority," explained lead investigator Dr. Belinda Vallejo-Córdoba of the Center for Food Research & Development in Sonora, Mexico. "The most studied bioactive peptides derived from dairy proteins are anti-hypertensive peptides; however, existing studies need to be evaluated before a health claim may be associated with products. With this in mind, we have carefully reviewed in vitro, in vivo and clinical studies of fermented milk containing anti-hypertensive peptides."
The team of investigators established that the most common strategy to select fermented milks with anti-hypertensive potential was to identify angiotensin-converting-enzyme (ACE) inhibitory peptides by in vitro studies. However, they observed that some strains inhibiting ACE activity in vitro did not reduce blood pressure in rats. They evaluated 13 studies with spontaneously hypertensive rats and seven randomized controlled clinical trials in which an anti-hypertensive effect was demonstrated. Most were based on Lactobacillus helveticus.
Scientifically proven health claims and the acquisition of exclusivity rights for using novel food ingredients in functional food products have been observed as a critical factor in the ultimate success of these food products in the market. The investigators noted that several fermented milk products already on the market attribute their anti-hypertensive effect to the bioactive peptides present in the fermented milk and draw attention to the fact that some of these commercial products possess intellectual property rights. However, they pointed out that these products may also contain minerals such as potassium and calcium, which may have a positive effect on blood pressure.
"Although much research related to anti-hypertensive peptides has already been done, there is a great need for exploration of new lactic acid bacteria that possess the ability to generate this bioactivity as well as good technological properties for the production of fermented dairy products. As commercial fermented milks with anti-hypertensive effects are scarce and most of the current products are based on L. helveticus, there is a great opportunity here," Vallejo-Cordoba said.
The investigators recommended that future studies 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.
"It is also important to develop the regulatory legislation that allows the introduction of health claims for functional dairy foods, especially in countries where this subject is underdeveloped," Vallejo-Cordoba concluded.