AgroFood industry hi-tech - March/April 2009 - vol 20 n 2
confirms that Lactobacillus helveticus fermented milk containing IPP and VPP tripeptides reduces blood pressure in
hypertensive subjects. Functional foods containing bioactive milk peptides can be useful as part of dietary treatment and
prevention of hypertension.
Bioactive milk peptides and
TiinA JAuhiAinEn1,2*, RiiTTA KoRpElA1,2, hEiKKi vApAATAlo1,
Anu M. TuRpEinEn2, hAnnu KAuTiAinEn3
1. institute of Biomedicine, pharmacology, university of helsinki, p.o.Box 63 00014 helsinki, Finland
2. valio ltd, Research and development, p.o.Box 30 00039 helsinki, Finland
3. Medcare ltd, hämeentic 1, 44100 Äänekoski, Finland
ABSTRACT: We have shown in several clinical trials that the milk protein-derived bioactive peptides isoleucine-proline-proline
(IPP) and valine-proline-proline (VPP) lower blood pressure, but a critical meta-analysis had yet to be conducted based on
these studies. A total of five randomized controlled clinical trials with 295 voluntary subjects were included in the meta-
analysis. The overall effect in the meta-analysis was a -4.0 mmHg (95 percent Cl:-5.9 to -2.1, p<0.001) reduction in systolic
blood pressure and -2.1 mmHg (95 percent Cl:-3.4 to -0.8, p=0.002) reduction in diastolic blood pressure. The meta-analysis
Biologically active peptide fragments are formed during
degradation of the milk proteins whey and casein by
digestive enzymes in the gastrointestinal tract and by
lactobacilli during fermentation of milk. in these
processes, a variety of peptides containing 2-20 amino
acid residues are formed. Milk peptides have been
shown to possess multiple physiological properties,
including antimicrobial activity, opioid activity,
modulation of digestive enzymes, nutrient absorption
and immune responses (1). properties related to
cardiovascular health include blood pressure lowering,
a n t i t h r o m b o t i c , a n t i o x i d a t i v e
hypocholesterolemic effects. of the various peptides,
the casein-derived tripeptides isoleucine-proline-
proline (ipp) and valine-proline-proline (vpp) have
been studied most extensively. The majority of the
studies have focused on the blood-pressure lowering
effects of these peptides, showing a hypotensive
effect both in animals and in humans (for review, see
2). ipp and vpp have been shown to act as inhibitors of
angiotensin-converting enzyme (ACE), a key regulator
of blood pressure, but other mechanisms may also be
involved (for review, see 3).
We have conducted several clinical trials with milk
products containing ipp and vpp tripeptides, but a
comprehensive meta-analysis had not yet been
conducted. This analysis was performed to present an
overview of our clinical studies on milk products
containing ipp and vpp.
a n d
Lactobacillus helveticus fermented products
containing the bioactive tripeptides ipp and vpp
reduced blood pressure significantly. The meta-analysis
indicated an overall effect of -4.0 mmhg (95 percent
Cl:-5.9 to -2.1) reduction in systolic blood pressure and
-2.1 mmhg (95 percent Cl:-3.4 to -0.8) in diastolic blood
pressure (Figure 1).
The effects in systolic and diastolic blood pressure
compared to control were statistically significant, p<0.001
and p=0.002, respectively. There was no statistically
significant heterogeneity observed in this meta-analysis
(p=0.61 for systolic blood pressure and p=0.44 for diastolic
Additionally i2, which describes the percentage of the
variability in effect estimates that is due to heterogeneity,
was 0 percent.
KEYWORDS: meta-analysis, blood pressure, clinical trial,
milk derived peptides.
Figure 1. Meta-analysis on the effects of fermented milk products containing
1000-2000 mg calcium
Epidemiologically, a 2 mmhg
reduction in systolic blood
pressure reduces the overall
expected risk of stroke by 4
percent and risk of myocardial
infarction by 4 percent (8).
Respectively, the risk of stroke is reduced by 30-40 percent
with a 9-10 mmhg reduction in systolic blood pressure or a
5-6 mmhg reduction in diastolic blood pressure (9).
hypertension is a worldwide health problem, which has
serious complications and causes significant costs for the
society. The prevalence of hypertension varies with gender,
age and nationality. A large worldwide data analysis
estimated that 26.4 percent of the adult population had
hypertension in the year 2000 (10), and it has been
estimated that the figure will increase
to 29.2 percent by 2025. prevention
and early identification of hypertension
are the best ways to reduce the overall
risk of cardiovascular morbidity and
mortality (11). lifestyle modification is
the principal strategy to control mild
hypertension. Fermented milk products
containing bioactive peptides can be
easily added to a heart-healthy diet.
our results are well in line with another
recent meta-analysis including nine clinical studies on the
effects of ipp and vpp on blood pressure (12).
The meta-analysis included our five studies and four
Japanese studies. A significant effect for these tripeptides
on both systolic (-4.8 mmhg, 95 percent Ci -6.3 to -3.7)
and diastolic (-2.2 mmhg, 95 percent Ci -3.1 to -1.3)
This meta-analysis showed that
fermented milk containing ipp
and vpp reduces systolic blood
pressure on average 4 mmhg
and diastolic blood pressure on
average 2.1 mmhg in
moderately hypertensive subjects. The antihypertensive
effects of ipp and vpp are at least partly mediated via
inhibition of ACE. In vitro, ipp and vpp dose-dependently
inhibit ACE at micromolar concentrations. decreased ACE
activity has also been shown in animals even after a single
oral dose (4). however, it has been proposed that other
mechanisms may also be involved, e.g. inhibition of
chymase or arginase activity or inhibition of bradykinin
The reduction of 4 mmhg in systolic
blood pressure and 2 mmhg in
diastolic blood pressure can be
regarded as clinically relevant in the
dietary treatment of high-normal
blood pressure or stage 1 hypertension.
in combination with other dietary
changes, an even more pronounced
effect can be achieved. A reduction
of 2 g in salt intake decreases systolic
blood pressure by -5.2 mmhg and
diastolic blood pressure by -3.7 mmhg (5). Also, potassium
and calcium supplementations have beneficial effects on
blood pressure: a 3 g potassium supplementation reduces
blood pressure on average by -3.1/-2.0 mmhg (6) and a
reduction of -1.4 mmhg in systolic blood pressure and -0.8
mmhg in diastolic blood pressure can be achieved with a
Milk protein-derived tripeptides
isoleucine-proline-proline (iPP) and
valine-proline-proline (VPP) have
been shown to lower blood pressure
both in animals and humans
A meta-analysis containing
five clinical studies showed
a significant reduction both
in systolic (-4.0 mmHg) and
diastolic (-2.1 mmHg)
blood pressure in
AgroFood industry hi-tech - March/April 2009 - vol 20 n 2
dietary treatment and prevention of
hypertension. in combination with other
lifestyle changes, they can offer an
alternative to pharmacological treatment.
referenCes And notes
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b l o o d p r e s s u r e w a s s e e n i n
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hypertensive than pre-hypertensive
subjects and with increasing length of the
intervention. pripp (13) conducted a
meta-analysis on the effects of both
whey- and casein-derived peptides on
blood pressure. The result once again
confirmed the hypotensive effects of milk
peptides: systolic blood pressure decreased on average 5.1
mmhg and diastolic blood pressure 2.4 mmhg in subjects
with high-normal or stage 1 hypertension.
Generally, effects of the peptides on blood pressure are
seen within a few weeks. no adverse effects have been
reported even with high peptide intakes in animals or
humans (14, 15). As the side effects and high costs of
antihypertensive drugs are avoided, bioactive milk
peptides can be considered a safe and convenient way to
control blood pressure.
A total of five randomized controlled double-blind
intervention trials examined the blood pressure lowering
effects of Lactobacillus helveticus fermented milk products
containing casein-derived bioactive tripeptides and were
included in the meta-analytical approach (14, 16-19). The
total number of moderately hypertensive subjects was 295.
The intervention periods varied from 8 to 24 weeks.
Subjects consumed daily a fermented milk drink containing
5 mg/day (17-19) or 50 mg/day of ipp and vpp peptides or
an indentical fermented milk drink without peptides. Blood
pressure was measured using office measurement by a
physician or an experienced nurse (16, 18-19), by self
registration at home (17) or using a 24 hour registration (14).
All subjects reported in the articles were included in the
meta-analysis except in the Tuomilehto et al. (19) study,
where only the first part of the study was included
due to the carry-over effect.
We adopted a fixed effects model
(StataCorp, College Station TX, uSA) for the
meta-analysis of the difference in change
(weighted mean difference) in systolic
blood pressure and diastolic blood
pressure. We used χ2 to assess
heterogeneity and the higgins i2
statistic to determine the
percentage of total variation
in conclusion, the
h e l v e t i c u s
and vpp reduces
blood pressure in
h y p e r t e n s i v e
peptides are thus
useful as part of
milk peptides can be
useful as part of
dietary treatment and
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