Serum concentration of adypocytokines in prepubertal vegetarian and omnivorous children
Stężenie adipocytokin w surowicy krwi dzieci stosujących dietę wegetariańską i tradycyjną
Jadwiga Ambroszkiewicz1, Witold Klemarczyk2, Joanna Gajewska1, Magdalena Chełchowska 1, Grażyna Rawicka2, Mariusz Ołtarzewski1, Teresa Laskowska-Klita1
11Screening Test Department
Chief of Department: dr n. biol. M. Ołtarzewski
2Department of Nutrition
Chief of Department: dr hab. n. med. H. Weker
Institute of Mother and Child in Warsaw
Director: S. Janus
Abstract
The aim of our study was to investigate associations between serum adipocytokines status and
anthropometric parameters as well as total energy and macronutrient intake in vegetarian, normalweight
omnivorous and obese omnivorous children.
Material and methods: We examined 90 healthy prepubertal children aged 4-10 years who had been
referred to the Department of Nutrition at the Institute of Mother and Child in Warsaw for dietary
consultation. Patients with endocrine disorders or genetic syndromes, as well as those who were taking
medications that could affect growth, pubertal development or nutritional status were excluded. Children
were divided into groups: vegetarians (n=30), normal-weight omnivores (n=30) and obese omnivores
(n=30). Anthropometric measurement (weight, height) was performed in all children and body mass
index (BMI) was calculated. A whole body dual-energy X-ray absorptiometry (DXA) scan was performed
to determine fat mass, the percentage of body fat and lean body mass using a Lunar Prodigy (GE, USA).
Dietary constituents were assessed by questionnaire (nutrient intake from a 3-day period: 2 weekdays
and 1 weekend day) and calculated using the nutritional computer program Dietetyk2®. Serum total
cholesterol, high-density and low-density lipoproteins, and triglycerides concentrations were assessed
by standard enzymatic methods. Serum levels of leptin, soluble leptin receptor and adiponectin were
determined by immunoenzymatic assays.
Results: There were no significant differences in body weight, height, BMI and lean mass values
between vegetarians and normal-weight children on traditional mixed diet. Children on vegetarian
diet had lower fat mass (p<0.05) and fat mass/lean mass ratio (p<0.05) than normal-weight
omnivores. However, omnivorous children with simple obesity had significantly higher body weight,
height, BMI, fat and lean mass in comparison to vegetarian as well to normal-weight omnivorous
children. The fat mass/lean mass ratio in obese children was about 2.5-fold higher than in normalweight
subjects on traditional diet. Total energy and percentage of energy from macronutrients in
diets of all children were within the recommended daily intake. Children on vegetarian diet was
related with lower fat and higher carbohydrates intake in comparison to their omnivorous peers.
Vegetarian children had significantly lower mean total cholesterol (151.5±18.0 mg/dL), low-density
lipoprotein (81.0±13.6 mg/dL) and triglycerides (61.6±20.5 mg/dL) than omnivores, especially
the obese ones (165.0±22.3 mg/dL, 94.7±19.2 mg/dL, 82.4±32.3 mg/dL, respectively). These
differences were statistically significant (p<0.05). Serum concentration of leptin was significantly
lower in vegetarian children (3.0±2.1 ng/ml) compared with omnivores (6.8±3.4 ng/ml in normalweight
versus 37.8±12.7 ng/ml in obese) (p<0.0001). However, serum soluble leptin receptor as
well as adiponectin were at higher levels in vegetarians than in omnivores (p<0.001 and p<0.05,
respectively). We observed that serum leptin levels positively and soluble leptin receptor negatively correlated with body mass index and fat mass in prepubertal children. Moreover, leptin levels
negatively correlated with its soluble receptor and with adiponectin.
Conclusions: In children different kinds of diet might modify not only body mass and lipid pro le but
also serum concentration of adipocytokines. Determination of leptin and its soluble receptor, as well
as adiponectin levels may be clinically useful in the medical and nutritional care of obese as well as
vegetarian prepubertal children.
Key words: leptin, soluble leptin receptor, adiponectin, anthropometric parameters, vegetarian
diet, children
Streszczenie
Cel: Celem pracy była ocena zależności pomiędzy stężeniem adipocytokin a parametrami antropometrycznymi
oraz podażą energii i makroskładników w diecie wegetarian oraz dzieci żywionych tradycyjnie
(z prawidłową masą ciała, jak też otyłych).
Materiał i metody: Badaniami objęto 90 dzieci w wieku przedpokwitaniowym, pozostających pod
opieką Instytutu Matki i Dziecka w Warszawie. Z badań zostali wykluczeni pacjenci z zaburzeniami
hormonalnymi oraz chorobami genetycznymi mogącymi mieć wpływ na wzrost, rozwój i metabolizm
kostny. Dzieci podzielono na trzy grupy: dzieci na diecie wegetariańskiej (n=30), dzieci
z prawidłową masą ciała na diecie tradycyjnej (n=30) oraz dzieci otyłe na diecie tradycyjnej (n=30).
U wszystkich dzieci wykonano pomiary antropometryczne (masa i wysokość ciała) oraz obliczono
wskaźnik masy ciała (BMI). Badania densytometryczne całego ciała (DXA) z uwzględnieniem masy
tłuszczowej, procentu tkanki tłuszczowej oraz beztłuszczowej masy ciała przeprowadzono z zastosowaniem
aparatu Lunar Prodigy (GE, USA). Sposób żywienia oceniono na podstawie dzienniczka
żywieniowego (jadłospisy z 3 kolejnych dni, w tym 1 świątecznego) obliczając wartość odżywczą
średnich całodziennych racji pokarmowych z wykorzystaniem programu komputerowego Dietetyk2®. Dokonano pomiaru stężenia cholesterolu całkowitego oraz lipoprotein o niskiej i wysokiej
gęstości, a także triacylogliceroli w surowicy krwi przy użyciu standardowych metod enzymatycznych.
Stężenia leptyny, rozpuszczalnego receptora leptyny oraz adiponektyny oznaczono z użyciem
metod immunoenzymatycznych.
Wyniki: Nie zaobserwowano istotnych różnic dotyczących masy i wysokości ciała, BMI oraz beztłuszczowej
masy pomiędzy wegetarianami i dziećmi z prawidłową masą ciała na diecie tradycyjnej. Dzieci
na diecie wegetariańskiej miały istotnie niższą masę tłuszczową (p<0,05) oraz stosunek masy tłuszczowej
do beztłuszczowej (p<0,05) w porównaniu z dziećmi na diecie tradycyjnej z prawidłową masą
ciała. Natomiast dzieci z otyłością prostą miały istotnie wyższą masę i wysokość ciała, BMI, masę tłuszczową
oraz beztłuszczową w porównaniu do grupy wegetarian, jak też do dzieci z prawidłową masą
ciała żywionych tradycyjnie. Stosunek masy tłuszczowej do beztłuszczowej u dzieci otyłych był około
2,5-krotnie wyższy niż u rówieśników z prawidłową masą ciała. Podaż energii oraz procentowy udział
energii z makroskładników w dietach wszystkich dzieci był zgodny z zaleceniami. W dietach wegetarian
stwierdzono niższy udział energii pochodzącej z tłuszczów, a wyższy z węglowodanów w porównaniu
do rówieśników żywionych tradycyjnie. Dzieci na diecie wegetariańskiej miały niższe stężenia
cholesterolu całkowitego (151,5±18,0 mg/dL), lipoprotein o niskiej gęstości (81,0±13,6 mg/dL) oraz
triacylogliceroli (61,6±20,5 mg/dL) niż dzieci na diecie tradycyjnej, szczególnie w grupie otyłych (odpowiednio:
165.0±22,3 mg/dL, 94,7±19,2 mg/dL, 82,4±32,3 mg/dL). Były to różnice istotne statystycznie
p<0,05. Stężenie leptyny w surowicy krwi było istotnie niższe (p<0,0001) u dzieci na diecie wegetariańskiej
(3,0±2,1 ng/ml) w porównaniu do dzieci z prawidłową masą ciała żywionych tradycyjnie
(6,8±3,4 ng/ml) i otyłych (37,8±12,7 ng/ml). U dzieci na diecie wegetariańskiej stwierdzono istotnie
wyższe stężenie rozpuszczalnego receptora leptyny (p<0,001) i adiponektyny (p<0,05) niż u rówieśników
stosujących dietę tradycyjną. We wszystkich badanych grupach dzieci zaobserwowano pozytywną
korelację pomiędzy stężeniem leptyny i negatywną pomiędzy rozpuszczalnym receptorem leptyny
a indeksem masy ciała i masą tłuszczową. Ponadto, stężenie leptyny ujemnie korelowało ze stężeniem
jej receptora oraz z poziomem adiponektyny.
Wnioski: Rodzaj stosowanej diety może wpływać nie tylko na masę ciała i profil lipidowy, ale również na
stężenie adipocytokin w surowicy krwi dzieci w wieku przedpokwitaniowym. Oznaczanie leptyny, rozpuszczalnego
receptora leptyny oraz adiponektyny może być użyteczne w postępowaniu medyczno-żywieniowym
u dzieci z otyłością prostą, jak też u dzieci na diecie wegetariańskiej.
Słowa kluczowe: leptyna, rozpuszczalny receptor leptyny, adiponektyna, parametry
antropometryczne, dieta wegetariańska, dzieci
INTRODUCTION
In recent years, adipose tissue has been recognized as an
endocrine organ which produces many biologically active
substances. The secretory products of mature adipocytes,
proteins called adipocytokines, play a significant role in
the regulation of important systemic processes (endocrine
function) as well as local metabolic functions (autocrine
and paracrine). Leptin and adiponectin are essential for
the regulation of body weight by inhibiting food intake
and stimulating energy expenditure (1, 2, 3).
Leptin, a product of the ob gene, is localized in humans
on chromosome 7q31. This protein consisting of 167 amino
acids is formed by four α-helices
and two short β-strands
that contain an intrachain
disulfide bond responsible for
its biological activity. Leptin is largely synthesized in white
adipose tissue, however, its small amounts are also secreted
from secondary sources (muscle, blood, bone, placenta and
pancreatic beta cells). Leptin interacts directly with the
leptin receptor (OBR),
which belongs to the large cytokine
receptor family. In humans there are four known isoforms
of leptin receptor with different Cterminal
cytoplasmatic
domains. All these forms have identical extracellular ligand
binding domains but differ in the intracellular carboxy
terminal region. The OBR
isoforms were divided into three
classes: long (OBRb),
short (OBRa),
and soluble (sOBR).
Soluble leptin receptor represents the main leptinbinding
activity in human blood. sOBR
modulates leptin levels
by binding free leptin in the circulation, and preventing
hormone degradation and clearance (1, 2, 4, 5).
Adiponectin is a biologically active 244-amino
acids protein of a molecular weight 28kDa, coded by
ACDC gene. It is expressed by mature adipocytes, with
increasing secretion during the process of adipocyte
differentiation. Higher adiponectin expression was
observed in subcutaneous than in visceral fat. Structurally,
adiponectin belongs to the collagen superfamily. Its
monomeric subunits (3 kDa), built of a Cterminal
globular
domain oligomerize to trimers that further associate
through disulphide bonds with the collagenous domain to
form polymeric complexes of higher structure, including
hexameres (approximately 180 kDa). These higher order
complexes are the predominant forms in human serum
and being biologically active play multivalent functions
including regulation of insulin resistance, glucose, and
lipid homeostasis (6, 7, 8).
In healthy humans serum adipocytokines change
markedly during growth. Generally, there are no gender
differences in leptin in prepubertal children, but during
puberty girls have higher serum leptin levels than boys.
Adult females have a significantly higher serum leptin
concentration and lower levels of soluble leptin receptor
compared to males. Adiponectin levels correlate negatively to
age, being higher in children than in adults. Its concentrations
decrease most substantially during puberty and are lower
in male adults compared to females (4, 9, 10).
Clinical studies have shown that leptin levels are
increased in obese subjects and markedly lowered by
fasting or dieting, however, they are rapidly recovered
during refeeding (11, 12, 13, 14). On the other hand,
concentrations of soluble leptin receptor and adiponectin
increase in lean subjects or with weight reduction. Their
lower expressions were observed in obese subjects (5, 13).
The identification of body composition and dietary factors
that could be associated with circulating adipocytokines
could be of clinical importance. It is known that leptin
correlates positively and adiponectin negatively to the
amount of fat mass and percentage of body fat (14).
The literature data regarding adipocytokines are mostly
related to adults and apply to diabetic, anorexic or obese
patients. However, studies binding relations between
diet and body composition parameters and levels of
adipocytokines with the kind of diet in childhood are still
scarce. To our knowledge, there are no reports concerning
serum leptin, its soluble receptor and adiponectin levels
in subjects consuming vegetarian diets.
Recently, vegetarian diets are seen as an alternative
to the traditional model of nutrition and are growing in
popularity in developed countries, including Poland. The
official position of the American Dietetic Association
points out that wellplanned
vegetarian diets are healthy,
nutritionally adequate and appropriate for individuals at all
stages of life, including infants, children, adolescents, adults
and elderly (15). Researchers suggest that vegetarianism
can be a healthy dietary option which offers a number of
nutritional benefits and is associated with reduced risk of
certain chronic diseases, including diabetes, coronary heart
disease, and some cancers (16, 17, 18, 19, 20). Moreover,
vegetarians consume a diet high in fruit and vegetables
and low in energy density, which put them at decreased
risk for obesity. On the other hand, individuals choosing to
follow vegetarian restrictive diets might experience mineral
and vitamins deficiencies and notice that using fortified
foods or supplements can be helpful in meeting dietary
recommendations (21, 22). This is especially important in
childhood and adolescence, when growth and development
are most intensive (23, 24).
The aim
of our study was to investigate associations
between serum adipocytokines status and anthropometric
parameters as well as total energy and macronutrient
intake in vegetarian, normalweight
omnivorous and
obese omnivorous children.
MATERIAL AND METHODS
We examined 90 healthy prepubertal children aged
410
years who had been referred to the Department of
Nutrition at the Institute of Mother and Child (Warsaw)
for dietary consultation. Patients with endocrine disorders
or genetic syndromes, as well as those who were taking
medications that could affect growth, pubertal development or nutritional status were excluded. The whole group of
investigated children was ethnically homogeneous and
in good general health. Among them 30 children (18
girls, 12 boys, median age 7 years) were vegetarians. They
came from vegetarian families and were on this kind of
diet from birth. In our group there were 15 lacto-ovovegetarians
(did not consume meat, poultry, fish, but ate
eggs and dairy products), 2 lacto-vegetarians (excluded
eggs, but ate milk products), 9 ovo-vegetarians (excluded
milk products, but ate eggs) and 4 vegans (excluded all
foods of animal origin).
The group consisting of 60 children (31 girls, 29
boys, median age 8 years) were omnivores. This group
was further divided in two subgroups: normal-weight
children (n=30, 15 girls, 15 boys, median age 8 years)
and obese children (n=30, 18 girls, 12 boys, median age
8 years). Children were considered as normal-weight
(z-score BMI <-1+1>) and as obese (z-score BMI >2).
In the over-weight group, only children with simple
obesity without endocrine disorders or genetic obesity
syndrome were included.
Anthropometric measurements (weight, height)
were performed on all children and body mass index
(BMI) was calculated. A whole body dual-energy X-ray
absorptiometry (DXA) scan was performed to determine
fat mass (FM), the percentage of body fat and lean body
mass (LM) using a Lunar Prodigy densitometer (GE,
USA). Dietary constituents were assessed by questionnaire
(nutrient intake from a 3-day period: 2 weekdays and
1 weekend day) and calculated using the nutritional
computer programme Dietetyk2®.
Venous blood samples were taken in the morning from
fasting patients. Serum was prepared by centrifugation
(1000 g for 15 min at 4°C) and concentrations of total cholesterol (TC), HDL-cholesterol (HDL-C), LDLcholesterol
(LDL-C) and triglycerides (TG) were measured by standard enzymatic methods using commercially
available kits from Roche (Switzerland). The remaining
serum samples were frozen and collected for the analysis
of leptin and its receptor and adiponectin, which were
measured immunoenzymatically using ELISA kits
(DRG Instruments, GmbH, Germany). Concentration
of leptin was determined by Leptin (Sandwich) ELISA
assay, the sensitivity of this method was 1 ng/ml; intraassay
coefficient of variation (CV) were 5.95% at 3.15
ng/ml and 6.91% at 24.62 ng/ml and inter-assay CVs
were 11.55% at 2.71 ng/ml and 8.66% at 26.15 ng/ml.
Soluble leptin receptor was measured by Leptin Receptor
(human) ELISA assay with detection limit 0.04 ng/ml;
the intra-assay precision was 7.23% at 17.35 ng/ml and
7.10% at 30.82 ng/ml; inter-assays CVs are 9.81% at 12.24
and 6.21% at 30.92 ng/ml. The level of adiponectin was
evaluated by Adiponectin (human) ELISA assay, the
sensitivity of which was 0.78 ng/ml; intra-assay CVs were
below 7.4% and inter-assay CVs were between 6.2-8.4%.
The protocol study was carried out in accordance with the
Helsinki Convention and was approved by the Ethics Committee
of the Institute of Mother and Child. Informed consent was
obtained from the parents of all the examined children.
The Statistica (version 8.0) computer software was used
for statistical analysis. Differences between vegetarian
and omnivores in their anthropometric parameters,
nutrient intake and biochemical measurements were
determined using the Student`s t-test. Correlation
analysis was performed using Pearson`s correlation
coefficients. Values presented in the text are means
± SD. The differences were regarded as statistically
significant at p<0.05.
RESULTS
Anthropometry and body composition
The results of anthropometric measurements of the
studied children are presented in table I. There were no
significant differences in body weight, height, BMI and lean mass values between vegetarians and normal-weight
children on traditional mixed diet. Children on vegetarian
diet had lower fat mass (p<0.05) and FM/LM ratio (p<0.05)
than normal-weight omnivores. However, omnivorous
children with simple obesity had significantly higher body
weight, height, BMI, fat and lean mass in comparison to
vegetarian as well to normal-weight omnivorous children.
The FM/LM ratio in obese children was about 2.5-fold
higher than in normal-weight subjects on traditional diet
and above 3-fold higher than in vegetarians.
Dietary intake
Nutrient intake from the 3-day dietary record kept by
the parents of the children was calculated and is described
in table II. Generally, all individuals had total energy and
macronutrient intakes within the recommended daily intake
for children (25). There were no significant differences
in dietary energy, carbohydrates and fat intake between
vegetarians and normal-weight omnivorous children.
Omnivorous obese children had significantly higher protein
(p<0.05) and dietary cholesterol (p<0.0001) intakes in
their diets than vegetarians. However, vegetarian diet was
characterized with a lower intake of fat (p<0.05) and higher
carbohydrates (p<0.05) in comparison to omnivorous
diet, especially to the group of obese children.
Biochemical measurements
Mean values of lipid parameters in all groups of children
were within the reference range. However, vegetarian
children had significantly lower mean total cholesterol,
LDL-cholesterol and triglycerides than omnivores, especially
obese children (tab. III). As for HDL-cholesterol level no
difference was reported between the studied groups of
children, but HDL-C/TC ratio was significantly higher in
vegetarians than in omnivorous obese subjects (p<0.01).
Figure 1 presents serum levels of leptin and its receptor
as well as adiponectin in the studied prepubertal children.
Serum concentration of leptin was significantly lower
in vegetarian children (3.0±2.1 ng/ml) compared with
omnivores (6.8±3.4 ng/ml in normal-weight versus
37.8±12.7 ng/ml in obese) (p<0.0001). Mean leptin level
in children on vegetarian diet was about 2-fold lower than
in normal-weight and above 10-fold lower than in obese
children on omnivorous diet. Adequately serum soluble
leptin receptor (p<0.001) as well as adiponectin (p<0.05)
were at higher levels in vegetarians than in omnivores.
The leptin/sOB-R ratio was significantly lower (0.08) in
vegetarians than in normal-weight omnivores (0.21) and
in obese omnivores (1.98) (p<0.0001).
In examining, the association of adipokines and
anthropometric parameters, serum leptin levels positively
and soluble leptin receptor negatively correlated with BMI
and fat mass in the studied group of children (tab. IV).
We also found negative correlation between sOB-R and
lean mass and between adiponectin and BMI in vegetarian
and obese children. No statistically significant correlations
between serum adiponectin concentrations and fat mass as
well as lean body mass were observed. Apart from that, we
found that leptin levels negatively correlated with soluble
leptin receptor and with adiponectin.
DISCUSSION
Our studied group of children on vegetarian diet was
in good health with no noticeable problems and was
under regular medical and nutritional care. Generally,
children grew normally, all individuals had total energy
and macronutrient intakes within the recommended daily
intake for children (25, 26). There were no significant
differences in body weight, height, BMI and lean mass
values between vegetarians and their normal-weight
counterparts on traditional mixed diet. Several studies
showed that vegetarian diets contribute to a better lipid
profile and bring benefits in atherosclerosis protection
(27, 28, 29). These studies have been carried out mainly
on adults, few of them included children. Our results
point towards the association between vegetarian diet
(with lower fat and cholesterol intakes) and lower
serum total cholesterol, low-density lipoprotein and
triglycerides levels in prepubertal children. Moreover,
as for HDL-C level there were no differences between
the two groups of children, but HDL-C/TC ratio was
significantly higher in vegetarians versus omnivores,
especially in the obese subjects.
Our previous studies showed that vegetarian children
had lower serum leptin concentration than their
omnivorous peers (29, 30). To our knowledge there are
no data regarding soluble leptin receptor and adiponectin
levels in subjects on vegetarian diets. In our present
study mean serum leptin concentration in prepubertal
children on vegetarian diet was about 2-fold lower than
in normal-weight and above 10-fold lower than in obese
children on omnivorous diet. However, serum soluble
leptin receptor was at a higher level in vegetarians than
in omnivores. Its mean value in vegetarian children was
higher by 75% than in normal-weight and above 2-fold
higher than in obese omnivorous children. Moreover, the
leptin/sOB-R ratio was significantly lower in vegetarians
than in normal-weight as well as in obese omnivores
(0.08; 0.21; 1.98, respectively). Additionally, we showed
that serum leptin levels positively and soluble leptin
receptor negatively correlated with body mass index
and with fat mass in all the studied groups of children.
Similarly, Ogawa et al. (9) observed that serum sOB-R
level was negatively correlated with leptin and with serum
triglycerides levels and positively correlated with HDLcholesterol
and serum adiponectin levels in healthy
adult subjects. According to the authors these relations
were independent of age, sex, and BMI. Moreover, they
showed that the leptin/sOB-R ratio correlated positively
with BMI, the percentage of body fat and negatively
with HDL, adiponectin and sOB-R levels. In the group
of obese children, positive correlation between leptin
and the percentage of fat mass and negative with the
concentration of soluble leptin receptor were found.
It is widely acknowledged that leptin is highly correlated
with the amount of adipose tissue and that is why obese
individuals have higher serum leptin levels and reduced
concentrations of soluble leptin receptor. It concerns
adults as well as children (11, 14, 31, 32). Soluble leptin
receptor represents the main leptin-binding compound
in plasma resulting in a fraction of bound and a fraction
of free leptin in plasma. In obesity, due to the abundant
food intake, high leptin levels are probably caused by high
leptin release by adipocytes. However, concentrations of
sOB-R are decreased compared to normal-weight subjects,
resulting in an increased fraction of free leptin. Reduction
of body weight through diet significantly decreases the
concentration of circulating leptin and increases the
level of soluble leptin receptor. This is connected with
an increase in the fraction of bound leptin (13). These
mechanisms are not clear, but studies on mice suggest
that leptin suppresses the expression of its own receptor
(4, 12). Thus, sOB-R might act as a modulating factor of
leptin action and play an important role in leptin resistance.
Although leptin is responsible for signaling satiety to the
hypothalamus, its concentration is paradoxically raised
in obesity. Therefore, hyperleptinemia was interpreted
as leptin resistance. In children, leptin resistance may
be a more salient indicator of risk for greater adipose
growth than in adults.
As far as our results are concerned, adiponectin was at
higher levels in vegetarians than in omnivores. Moreover,
the leptin/adiponectin ratio was significantly lower (0.22)
in vegetarians than in normal-weight omnivores (0.59) and
in obese omnivores (3.43). Adiponectin is an adipocytokine
which is down-regulated in obesity. The mechanism of
this negative regulation remains unclear. Probably, the
increasing mass of white adipose tissue in obesity reduces
adiponectin protein synthesis by feedback inhibition.
Furthermore, adiponectin secretion in vitro is lower in
visceral than in subcutaneous adipocytes in children,
indicating the influence of body fat distribution (7, 8).
Additionaly, leptin and adiponectin are adipocytokines
which increase tissue sensitivity to insulin. Both stimulate
the oxidation of fatty acids thus decreasing the amount
of accumulated triglycerides. Both acting at the level
of the central nervous system decrease food intake and
increase energy expenditure. Moreover, these hormones
regulate long term energy homeostasis (33).
It is interesting whether dietary patterns alter serum
adipocytokines concentrations independently of energy
intake. Limited studies in this field have revealed conflicting
results (34, 35, 36). Some authors found no association
between dietary intake of macronutrients and leptin
levels and hypothesized that fat mass rather than the
dietary origin of the energy is a critical determinant of
serum leptin concentration. Other researchers suggest
that different dietary and lifestyle interventions may
modify the predictive value of serum leptin. Larson
et al. (37) reported that higher carbohydrate dietary
intake and a high glycemic index diet caused decrease
in leptin concentrations. According to Yannakoulia et al. (38) energy provided by carbohydrates was positively
related to sOB-R, and negatively to leptin levels and to
the leptin/sOB-R ratio. The authors obtained opposite
results for the percentage of energy intake derived from
dietary fat, where an increase in dietary fat corresponds
to a decrease in sOB-R concentration and to an increase
in the ratio leptin/sOB-R).
These studies were carried out in adults, but there
were no data related to children. We presented for the
first time the concentrations of adipocytokines, including
adiponectin, in prepubertal children on vegetarian diet. In
our present study vegetarian children had higher dietary
intake of carbohydrates and lower dietary fat intakes than
omnivores. They had low serum leptin but high soluble
leptin receptor as well as adiponectin levels. However,
obese children with higher concentration of leptin and
lower levels of leptin soluble receptor and adiponectin,
consumed more fat and fewer carbohydrates.
CONCLUSIONS
1. Different kinds of diet can modify not only the body
mass and lipid profile but also the serum concentration
of adipocytokines.
2. Determination of leptin and its receptor, as well as
adiponectin may be clinically useful in the medical
and nutritional care of obese as well as vegetarian
prepubertal children.
3. Further studies are needed to assess the potential
long-term effects of the diet pattern on serum
adipocytokines levels.
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Adres do korespondencji / Address for correspondence:
Jadwiga Ambroszkiewicz
Screening Department
Institute of Mother and Child
ul. Kasprzaka 17a, 01-211 Warsaw
tel. (48 22) 32-77-260
bioklin.imid@imid.med.pl
