Title Utjecaj prehrane na razinu hormona štitne žlijezde u plazmi i njihova uloga u pregradnji kostiju Title (english) The influence of nutrition on plasma levels of thyroid hormones and their role in bone remodeling Author Dubravka Brdar Mentor Tatijana Zemunik (mentor)Committee member Tina Tičinović Kurir (predsjednik povjerenstva)Committee member Ivan Mihaljević (član povjerenstva)Committee member Joško Božić (član povjerenstva)Granter University of Split Defense date and country 2022-12-20, Croatia Scientific / art field, BIOMEDICINE AND HEALTHCARE Universal decimal classificationUDC ) 616 - Pathology. Clinical medicine Abstract Prva studija:
Cilj ovog istraživanja bio je analizirati povezanost prehrambenih skupina (faktora) s
razinom hormona štitnjače u eutiroidnih ispitanika. U ovu presječnu studiju uključeno je
4585 eutiroidnih ispitanika s područja Dalmacije u južnoj Hrvatskoj s mjerenjem razine
slobodnog trijodtironina (fT3), slobodnog tiroksina (fT4) i tireotropnog hormona (TSH).
Unos pojedinih namirnica procijenjen je prema podacima ispunjenog upitnika koji je
sadržavao pitanja o unosu 58 namirnica. Faktorska analiza provedena je kako bi se
konzumirane namirnice grupirale u prehrambene skupine, nakon čega je uslijedila linearna
regresijska analiza, kako bi se ispitala povezanost između prehrambenih skupina i razina
fT3, fT4 i TSH. Među 4585 eutiroidnih ispitanika, primijetili smo niže razine fT3 i fT4 u
plazmi i više razine TSH u žena nego u muškaraca. Utvrđeno je da pušači imaju znatno
niže razine TSH od nepušača i bivših pušača, a ispitanici s višim razinama glukoze natašte
imali su više razine fT4. Različite prehrambene skupine (faktori) pokazale su povezanost s
razinama fT3, fT4 i TSH. Uočeno je da prehrambene skupine (s čestom konzumacijom
voćnih sokova, Cedevita vitaminskog napitka i bezalkoholnih pića) koje su negativno
utjecale na razinu TSH, istovremeno imaju pozitivan učinak na fT4, što je zadovoljavalo
očekivani obrazac djelovanja. Zaključno, u našem istraživanju česta konzumacija hrane s
visokim glikemijskim indeksom pokazala je pozitivnu povezanost s razinama fT3 i fT4 i
negativnu povezanost s razinama TSH, dok je hrana bogata zasićenim masnim kiselinama i
s visokom koncentracijom proteina pokazala negativnu povezanost s razinama fT3 i fT4.
Druga studija:
Hormoni štitnjače (TH) imaju nezamjenjivu ulogu u razvoju skeleta i pregradnji kostiju.
Neke studije su izvijestile o povezanosti TH s razinama osteokalcina u serumu (OC), ali
rezultati su prilično nedosljedni, a molekularni mehanizam njihove istovremene ili
međusobno zavisne aktivnosti u kostima gotovo je nepoznat. Stoga je cilj ovog istraživanja
bio utvrditi moguće povezanosti razina TH s razinama OC u plazmi i njihov mogući
posrednički učinak na mineralnu gustoću kostiju (BMD) putem OC. U tu svrhu odabrali
smo zdrave, eutireoidne ispitanike (N = 330) s kontroliranim svim dostupnim zbunjujućim
čimbenicima koji mogu utjecati na funkciju štitne žlijezde i metabolizam kostiju.
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Osteokalcin je pokazao negativnu korelaciju s BMD, koja se izgubila nakon korekcije za
dob i spol, dok je TSH pokazao pozitivnu korelaciju s vrijednostima osteokalcina.
Utvrđeno je da TSH ima negativan učinak na BMD, koji se umanjuje kada se pridoda
utjecaj osteokalcina, čime je pokazan suzbijajući učinak osteoklacina na povezanost TSH i
BMD. Također je utvrđeno da fT3 ima negativan učinak na BMD koji se povećava kada se
pridoda utjecaj osteokalcina, što ukazuje na medijacijski učinak osteokalcina na
povezanost fT3 i BMD. Dob i spol mogu se smatrati prediktivnim varijablama za razinu
osteokalcina. Prema našem mišljenju, na zabilježene razlike u rezultatima među do sada
publiciranim studijama mogu utjecati nedosljedan odabir ispitanika i utjecaj zbunjujućih
čimbenika
Abstract (english) First study:
The aim of the study was to analyze the association of dietary groups (groups of food
items) with thyroid hormone levels in healthy individuals. This cross-sectional study
enrolled 4585 healthy individuals from the Dalmatian region of south Croatia with
measurements of plasma free triiodothyronine (fT3), free thyroxine (fT4), and thyroidstimulating hormone (TSH) levels. Dietary intake was assessed according to data of the
completed food frequency questionnaire, containing 58 food items. Principal component
analysis was performed to reduce food items into dietary groups, followed by linear
regression analyses to test the association between dietary groups and fT3, fT4, and TSH
levels. Among the 4585 healthy individuals, we observed lower plasma fT3 and fT4 levels
and higher TSH levels in women than in men. Smokers were found to have significantly
lower TSH levels than non-smokers and ex-smokers, and participants with higher fasting
glucose levels had higher fT4 levels. Different dietary groups (factors) showed association
with fT3, fT4, and TSH levels. It was observed that dietary factors (with frequent
consumption of fruit juices, Cedevita vitamin drink, and non-alcoholic drinks) that
negatively affected TSH levels simultaneously had a positive effect on fT4, satisfying the
expected pattern of effects. In conclusion, frequent consumption of foods with a high
glycemic index showed a positive association with fT3 and fT4 levels and a negative
association with TSH levels, whereas foods rich in saturated fatty acids and with a high
protein concentration showed a negative association with fT3 and fT4 levels.
Second study:
Thyroid hormones (THs) play an indispensable role in skeletal development and bone
remodelling. Some studies have reported associations of THs with serum osteocalcin (OC)
levels, but the results are quite inconsistent and the molecular mechanism of their
simultaneous or interdependent activity on bone is almost unknown. Therefore, the aim of
this study was to determine the possible associations of plasma THs with plasma OC levels
and their possible mediating effect on bone mineral density (BMD) via OC. For this
purpose, we selected healthy euthyroid participants (N = 330) controlled for all available
confounding factors that can affect thyroid function and bone metabolism. TSH was found
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to have a negative effect on BMD that decreases when the effect of osteocalcin is added
thus demonstrating the suppressive effect of osteocalcin on the association of TSH and
BMD. It was also found that fT3 has a negative effect on BMD, which increases when the
effect of osteocalcin is added, indicating a mediating effect of osteocalcin on the
association of fT3 and BMD. Age and gender can be considered predictive variables for
osteocalcin levels. In our opinion, the observed differences in results among the studies
published so far may be influenced by inconsistent selection of participants and the
influence of confusing factors.
Keywords
hormoni štitnjače
pregradnja kostiju
prehrana
Keywords (english)
Thyroid hormones
bone remodeling
nutrition
Language croatian URN:NBN urn:nbn:hr:171:639609 Promotion 2023 Study programme Title: Evidence-Based Clinical Medicine Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2023-01-26 07:45:54
