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. 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 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 Project Number: IP-2019-04-2593 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
