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Meta-analysis supports milk proteins for blood pressure improvements

By Stephen Daniells , 08-Sep-2008
Last updated on 08-Sep-2008 at 16:10 GMT

Peptides from milk may help to reduce blood pressure and ultimately the risk of cardiovascular disease, according to a new meta-analysis from China.

Researchers from Soochow and Peking Universities focused on the efficacy of milk-derived isoleucine-proline-proline (IPP) and valine-proline-proline (VPP) ingredients to impact blood pressure in pre-hypertensive and hypertensive subjects.

Reporting their findings in the journal Nutrition, the researchers stated the pooled data from the trials showed that the milk tripeptides were associated with a 4.8 mmHg reduction in systolic blood pressure and a 2.2 mmHg reduction in diastolic blood pressure.

“Our analysis provided evidence that milk-derived IPP and VPP have a hypotensive effect in pre-hypertensive and hypertensive subjects,” wrote lead author Jia-Ying Xu.

“Because milk protein produces many peptides, further RCTs should be done in different countries to test the hypotensive effect of these milk peptides.”

The meta-analysis appears to support the efficacy of the small number of milk-derived ingredients on the market positioned to improve cardiovascular health. DSM, for example, launched an IPP ingredient called TensGuard earlier this year.

On a similar but different point, Puleva Biotech is also looking at the potential of hydrolyzed caseins from goat's milk to prevent the development of high blood pressure, and have backed up their efficacy in animal and human studies.

With some one billion people worldwide suffering from high blood pressure - likely to more than double by 2025 - products aimed at cutting this will prove popular.

High blood pressure (hypertension),defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg, is a major risk factor for cardiovascular disease (CVD) - a disease that causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.

Analysis details

Xu and co-workers scanned the Medline, PubMed, Embase, Science Citation Index, and Cochrane Controlled Trials Register databases and identified 12 trials that matched their inclusion criteria. The trials included 623 participants with pre-hypertension and hypertension.

The pooled data showed significant decreases of 4.8 and 2.2 mmHg in systolic and diastolic blood pressure.

Furthermore, when the researchers analysed the results according to the blood pressure status of the participants, a greater effect for the IPP and VPP ingredients was observed in people with hypertension.

Additionally, the longer the intervention period, the “more obvious” the blood pressure-lowering effects, said the researchers.

“Our analysis and the RCTs [used in the analysis] have great implications for public health because prehypertension and hypertension are very frequent in developed and developing countries and even a small decrease in blood pressure is beneficial for CVD risk,” stated the researchers.

“Increasing the consumption of dairy products containing hypotensive components also avoids undesirable side effects from antihypertensive drugs and saves on the cost of drug therapy,” they added.

Mechanism

The researchers note that the mechanism has been studied mostly in relation to the angiotensin converting enzyme (ACE)-inhibitory activity of milk peptides. ACE inhibitors work by inhibiting the conversion of angiotensin I to the potent vasoconstrictor, angiotensin II, thereby improving blood flow and blood pressure.

Limitations

The researchers noted limitations with their analysis, including the inclusion of only a small number of trials. While the focus on IPP and VPP interventions restricted the number of studies eligible for the meta-analysis, this did enhance the homogeneity of the studies, said the researchers.

Another limitation was that the trials used in the meta-analysis were all conducted in either Japan or Finland.

“The narrow geographic region may have helped with the homogeneity in the present analysis,” stated Xu and co-workers.

“However, subjects from Japan and Finland represent only a fraction of the global population, which may result in an incomplete understanding of the effect of milk tripeptides on blood pressure.”

Independent comment

Commenting independently on the results, Cathy Ross, cardiac nurse at the British Heart Foundation (BHF) told NutraIngredients.com that the analysis does suggest there is evidence to support the claim that milk tripeptides help to reduce blood pressure.

“Tripeptides are found in some yoghurt and cheese products but the cheeses in particular may also be high in saturated fat and salt,” she said. “Being physically active, maintaining a healthy weight and stopping smoking are all things that we can do to keep our blood pressure within the recommended limit.”

Source: Nutrition (Elsevier)
Volume 24, Pages 933–940
“Effect of milk tripeptides on blood pressure: A meta-analysis of randomized controlled trials”
Authors: J.-Y. Xu, L.-Q. Qin, P.-Y. Wang, W. Li, C. Chang

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