Importance of functional foods in the Mediterranean diet

Abstract

Analyse the importance of components of Mediterranean diet in functional feeding.
We have based the study in a bibliographic review.
Many of the characteristic components of the traditional Mediterranean diet (MD) are known to have positive effects on health, capacity and well-being, and can be used to design functional foods. Vegetables, fruits and nuts are all rich in phenols, flavonoids, isoflavonoids, phytosterols and phytic acid--essential bioactive compounds providing health benefits. The polyunsaturated fatty acids found in fish effectively regulate haemostatic factors, protect against cardiac arrhythmias, cancer and hypertension, and play a vital role in the maintenance of neural functions and the prevention of certain psychiatric disorders. Accumulating evidence suggests that olive oil, an integral component of the MD, may have health benefits, including the reduction of the risk of coronary heart disease, the prevention of several types of cancer and the modification of the immune and inflammatory responses. Olive oil is known for its high levels of monounsaturated fatty acids and is a good source of phytochemicals, such as polyphenolic compounds, squalene and alpha-tocopherol. In the context of the MD, the benefits associated with the consumption of several functional components may be intensified by certain forms of food preparation. In addition, the practice of more physical activity (once common among Mediterranean populations) and the following of other healthy lifestyle habits may have additive effects.
The identification of the active constituents of the MD is crucial in the formulation of appropriate dietary guidelines. Research into the pharmacological properties of the minor components of this diet (vitamins, sterols, polyphenols, etc.) is very active and could lead to the formulation of functional foods and nutraceuticals.

Full text

Importance of functional foods in the Mediterranean diet
RM Ortega*
Departamento de Nutricio
´
n, Facultad de Farmacia, Universidad Complutense, 28040-Madrid (Spain)
Submitted 18 April 2006: Accepted 26 November 2006
Abstract
Objective: Analyse the importance of components of Mediterranean diet in functional
feeding.
Design: We have based the study in a bibliographic review.
Results: Many of the characteristic components of the traditional Mediterranean diet
(MD) are known to have positive effects on health, capacity and well-being, and can be
used to design functional foods. Vegetables, fruits and nuts are all rich in phenols,
flavonoids, isoflavonoids, phytosterols and phytic acid—essential bioactive com-
pounds providing health benefits. The polyunsaturated fatty acids found in fish
effectively regulate haemostatic factors, protect against cardiac arrhythmias, cancer
and hypertension, and play a vital role in the maintenance of neural functions and the
prevention of certain psychiatric disorders. Accumulating evidence suggests that olive
oil, an integral component of the MD, may have health benefits, including the reduction
of the risk of coronary heart disease, the prevention of several types of cancer and the
modification of the immune and inflammatory responses. Olive oil is known for its high
levels of monounsaturated fatty acids and is a good source of phytochemicals, such as
polyphenolic compounds, squalene and a-tocopherol. In the context of the MD, the
benefits associated with the consumption of several functional components may be
intensified by certain forms of food preparation. In addition, the practice of more
physical activity (once common among Mediterranean populations) and the following
of other healthy lifestyle habits may have additive effects.
Conclusions: The identification of the active constituents of the MD is crucial in the
formulation of appropriate dietary guidelines. Research into the pharmacological
properties of the minor components of this diet (vitamins, sterols, polyphenols, etc.) is
very active and could lead to the formulation of functional foods and nutraceuticals.
Keywords
Functional foods
Mediterranean diet
Fruits
Vegetables
Cardiovascular disease
Cancer
Degenerative diseases
Antioxidant capacity
Introduction
The Mediterranean diet (MD), a dietary pattern detected in
the olive-growing areas of the Mediterranean (mainly
Greece, Spain, Italy and France) in the late 1950s and early
1960s, is a very healthy dietary model. Numerous
epidemiological studies have shown that the people of
Mediterranean countries have a longer life expectancy and
a lower risk of suffering certain chronic diseases
1–3
,
including cardiovascular disease, metabolic disorders and
certain types of cancer
4–8
. Many authors have underlined
the beneficial role of the MD on lipid metabolism, blood
pressure
6,9
, body mass index
6,7
, inflammation and
coagulation
8
.
Importance of functional components in the
Mediterranean diet
The traditional MD is characterised by an abundance of
vegetable foods, such as bread, pasta, vegetables,
legumes, fruits and nuts. Olive oil is the main source of
fat, and the intake of fish, poultry, dairy products and eggs
is moderate. In addition, variable amounts of wine are
usually consumed with meals
3
. Many of the characteristic
components of the MD are functional components with
positive effects on health, capacity and well-being; these
may be responsible for the advantages associated with this
diet
10 – 13
.
. Nuts in particular are rich in phenols, flavonoids,
isoflavonoids, phytosterols and phytic acid, and have
been linked to reductions in plasma lipids and
protection against cardiovascular disease
3
.
. Vegetables are the most important sources of phenolic
compounds in the MD. Flavonoids in particular are
thought to be essential bioactive compounds that
provide health benefits
14,15
.
. Several carefully studied Mediterranean and Asian
populations, whose traditional diets consist largely of
foods of vegetable origin, show low incidences of
certain chronic diseases and enjoy long life expec-
tancies
13
. Many case-control and prospective studies
have provided evidence that a high consumption of
plant foods confers numerous health benefits. There
*Corresponding author: Email rortega@farm.ucm.es q The Author 2006
Public Health Nutrition: 9(8A), 1136–1140
DOI: 10.1017/S1368980007668530

is evidence to support links between increased
vegetable, fruit and fibre consumption and a lower
incidence of certain cancers, coronary heart disease,
neural tube defects and cataracts. Although the
mechanisms are not fully understood, carotenoids,
folic acid and fibre, all of which are abundant in the
MD, appear to play important roles in the prevention
of coronary artery disease
13
.
. Vegetables are also an important source of phytosterols,
the intake of which is associated with a reduction in
serum cholesterol levels and of cardiovascular risk. This
could be of great importance in developed societies in
which cardiovascular disease is the main cause of
death
16
.
. Fruits also provide fibre, as well as vitamins, minerals,
flavonoids and terpenes, many of which provide
protection against oxidative processes
3
. Due to the
phytoestrogenic substances they contain, an increased
consumption of fruits, vegetables, whole grains and
pulses (common in the MD) may offer an alternative to
hormone replacement therapy in menopausal women.
In the intestine, these compounds turn into oestrogen
and help counteract the hormonal deprivation suffered
at menopause. Several types of flavone and isoflavone
purified from habitually consumed Mediterranean
vegetables have been shown to possess this oestrogenic
activity
17
.
. The polyunsaturated fatty acids found in fish (eicosa-
pentaenoic and docosahexaenoic acids) effectively
regulate haemostatic factors, and provide protection
against cardiac arrhythmias, cancer and hypertension.
They also play a vital role in the maintenance of neural
functions and the prevention of certain psychiatric
disorders
3,18
.
. Accumulating evidence suggests that olive oil, an
integral component of the MD, may have health
benefits, including the reduction of coronary heart
disease risk, the prevention of several types of cancers
and the modification of the immune and inflammatory
responses
19
. It also appears to have a role in bone
mineralisation (thus reducing the risk of osteoporosis).
Olive oil is known for its high levels of monounsatu-
rated fatty acids and it is a good source of
phytochemicals, such as polyphenolic compounds,
squalene and a-tocopherol. This food therefore has
several components t hat contribute to its overall
protective effect
19
.
. Phenolic compounds have been shown to inhibit LDL
oxidation in vitro and ex vivo
20
. In a dietary intervention
involving volunteers, foods rich in phenolic compounds
affected LDL composition. No changes were observed
in the short term, but after 1 week of olive oil
consumption and following the MD, changes in the LDL
composition became apparent
20
.
. The dairy products characteristic of the MD, such as
cheese and yoghurt, are better tolerated by lactose-
intolerant individuals. In addition, lactic acid bacteria
confer probiotic benefits, including improvements in
gastrointestinal health and of the immune response
21
.
The consumption of yoghurt might induce favourable
changes in the faecal bacterial flora and have a positive
effect on colon cancer risk indices. It may also help
regulate mouth to caecum transit time
21,22
.
. Garlic, onions, herbs and spices are used as
condiments in the MD, and may increa se the
nutritional value of food. Some also contain large
quantities of flavonoids (fennel, chives, etc.) or allicin
(raw garlic and onion); the latter may have
cardiovascular benefits and help improve cognitive
function
3
. The caper, Capparis spinosa L., which is
found al l over the Me di terr ane a n basin and i s
consumed in salads or on pizzas, etc. has been used
in traditional medicine for its diuretic and anti-
hypertensive effects, and to treat certain conditions
related to uncontrolled lipid peroxidation
15
. Caper
extract contains flavonoids (kaempferol and quercetin
derivatives) and hydrocinnamic acids with known
anti-inflammatory and antioxidant effects. Panico
et al.
15
concluded capers to have a chondroprotective
effect; they might therefore be of use in the
management of cartilage damage during the inflam-
matory phase.
. Some of the beneficial effects of the MD with respect
to human disease have been attributed to the
polyphenols in red wine. The antioxidant activity of
these compounds may also be responsible for the
cytoprotective action of red wine reported in some
papers
23,24
. Wine exerts its protective effect via the
induction of changes in the lipoprotein profile,
coagulation and fibrinolytic cascades, platelet aggre-
gation, oxidative mechanisms and endothelial func-
tion. The endothelium regulates vascular tone by
delicately balancing vasorelaxation (nitric oxide, NO)
and vasoconstriction (endothelins) factors (produced
by the endothelium itself) in response to different
stimuli. Wine and other grape derivatives exert an
endothelium-dependent vasorelaxatory effect via the
NO-stimulating activity of their polyphenol com-
ponents. Under experimental conditions, reservatrol
(a stilbene polyphenol) was found to protect the heart
and the kidneys from ischaemia-reperfusion injury via
its antioxidant activity and the upregulation of NO
production. Red wine, dealcoholised wine extract and
even purple grape juice have all been reported to
have positive effects on endothelial function
24
.Itis
likely that regular and prolonged moderate wine
drinking positively affects endothelial function. The
beneficial effects of wine on cardiovascular health
would, of course, be greater if associated with a
healthy diet. The most recent nutritional and
epidemiological studies show that the ideal diet
closely resembles the MD
24
.
Functional foods in Mediterranean diet 1137

Health benefits of Mediterranean diet
Greater adherence to the MD has been associated with a
lower incidence of degenerative disease, in particular
cardiovascular disease and cancer
11,25,26
. Pitsavos et al.
11
studied the effect of the MD on total antioxidant capacity
(TAC) in 3042 subjects who had no clinical evidence of
cardiovascular disease. Adherence to the MD was found to
be positively correlated with TAC. The subjects in the
highest dietary score tertile had, on average, 11% higher
TAC levels than those in the lowest tertile, even after
adjustment for confounding factors. Additional analysis
showed that TAC was positively correlated with the
consumption of olive oil, and of fruit and vegetables, and
inversely associated with the consumption of red meat
11
.
In another study, a nutritional intervention programme
promoting the MD food pattern was effective in modifying
the food habits of healthy women, and after 6 weeks
resulted in small but significant benefits with respect to
certain cardiovascular risks (lower total cholesterol and
apolipoprotein B levels, and lower body mass index)
2
.
Several unmodified MD foods with functional proper-
ties may protect against type 2 diabetes, includ ing
polyunsaturated fat products, vegetables, fruit, whole-
grain foods and low glycaemic index starchy foods
12
.
Obesity and excess body weight are frequ ently
addressed with diets that reduce calorie intake but which
are unbalanced. Usually, these diets involve increasing the
consumption of fats and proteins and reducing the intake
of carbohydrates
27
. Approximating the diet to the MD
profile could, however, help in weight control as well as
provide nutritional and health improvements
28,29
.
Recurrent myocardial infarction, total cardiovascular
events, and cardiac and overall death are significantly
reduced in patients recovering from myocardial infarction,
who habitually follow the MD. It is also known that fruits
and legumes (which have a pivotal role in the MD), reduce
serum homocysteine concentrations (tHcy) in men
26
, and
consequently the risk of coronary events, especially in
high-risk individuals. Dedoussis et al.
1
report, however,
that the effect of the methylenetetrahydrofolate reductase
gene–MD interaction on tHcy concentrations is indepen-
dent of fruit and vegetable consumption. This implies that
other foods in the MD may play a role in tHcy reduction.
Adherence to the MD is inversely associated with both
systolic and diastolic blood pressure. Vegetables, fruit and
olive oil (which induce a high ratio of monounsaturated to
saturated lipids) appear to be chiefly responsible for the
apparent protection offered by the MD against hyperten-
sion. Plant foods have high potassium, magnesium and
calcium contents which tend to reduce arterial blood
pressure. The high antioxidant content of plant foods and
olive oil may also contribute to the health of the vascular
system. In addition, the relatively high intake of fish and
seafood in the MD is associated with reduced systolic
blood pressure
18
.
Some components of the MD diet may also help
improve cognitive function and mood. In particular, some
flavonoids (which are frequently found in vegetables and
fruits) have anti-depressant activity
30
.
The effect of preparation methods
How the components of the MD diet are prepared may be
important from a health and functional point of view. For
example, the addition of olive oil to tomatoes during
cooking greatly increases the absorption of lycopene (a
carotenoid that reduces the risk of certain cancers and
heart disease)
31
.
The results highlight the importance of cuisine (i.e. how
a food is prepared and consumed) in determining the
bioavailability of dietary carotenoids, such as lycopene
31
.
Ninfali et al. investigated the antioxidant capacity of
different salads, and salads to which aromatic herbs had
been added. Lemon balm and marjoram at a concentration
of 1.5% (w/w) increased the antioxidant capacity of salad
portions by 150 and 200%, respectively. Olive oils and
wine or apple vinegars were the salad dressings that
afforded the greatest increase in antioxidant capacity
14
.
Importance of monitoring the whole diet
Recently, Martı
´
nez-Gonza
´
lez and Estruch
32
underlined the
need for randomised trials that investigate the whole diet
rather than its components or supplements when
evaluating the role of the diet in human health. In a
recent review, Martı
´
nez-Gonza
´
lez and Sanchez-Villegas
5
indicated that not all components of the MD are protective,
or at least may not provide equal levels of protection.
Thus, since food items and nutrients could have a
synergistic and antagonistic effect on health outcomes, the
study of overall dietary patter ns rather than single
nutrients would appear appropriate. In a recent editorial,
Trichopoulos and Lagiou
4
suggested that the evaluation of
whole-diet patterns and the use of dietary scores would
capture the extremes of dietary habits, pre-empt
nutritional confounding, and avoid bias. Many of the
health benefits associated with the intake of several MD
functional foods are greater if these components are part
of a healthy diet
24
.
Importance of physical exercise
Finally, the original description of the MD involved the
idea of extensive physical activity (mainly related to work
and outdoor leisure activities)—something quite common
among Mediterranean populations until the 1960s.
Recovering a higher level of physical activity may provide
benefits in addition to those associated with the regular
consumption of functional ingredients
33
.
RM Ortega1138

Conclusion
In conclusion, adherence to a Mediterranean-style diet
affords protection from degenerative diseases such as
cardiovascular disorders and cancer. The identification of
the active constituents of the MD is crucial to the
formulation of appropriate dietary guidelines. Research
into the pharmacological properties of the minor
components of this diet (vitamins, sterols, polyphenols,
etc.) is very active and might lead to the formulation of
functional foods and nutraceuticals
34
. To achieve nutri-
tional and health improvements in a population, it would
seem a priority to improve the global diet, approximating
it to the theoretical ideal of the MD. This should be
coupled with an increase in physical activity. The foods
showing the biggest gaps in terms of habitual and
recommended intake (e.g. the intake of vegetables and
whole-grain foods) deserve special correctional attention.
Acknowledgement
The author had no conflicts of interest to report.
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