Comparison of the Effects of Natural Polyphenols, Acarbose, and Placebo on the Post-Prandial Glucose Levels and Insulin Response

Sladkorna bolezen (SB) je ena najpogostejših endokrinih presnovnih bolezni. Sodi v skupino presnovnih bolezni, katerih skupna značilnost je hiperglikemija. SB nastane zaradi pomanjkljivega izločanja inzulina ali njegovega pomanjkljivega delovanja na ciljne celice in/ali obojega hkrati. Posledica je motena presnova ogljikovih hidratov, maščob in beljakovin. Povezana je s številnimi akutnimi in kroničnimi zapleti. V zdravljenju SB se poleg spremembe življenjskega sloga uporabljajo številne učinkovine, nobena od le-teh pa ni brez neželenih učinkov. Velik izziv pri iskanju tako imenovanega »idealnega zdravila« predstavlja težnja po doseganju optimalne učinkovitosti zdravila in zmanjšanju tveganja za pojav neželenih učinkov le-tega na najnižjo možno raven. Naraščajo potrebe po uporabi dopolnilnih zdravljenj, vključno s funkcionalno hrano in nutracevtiki. Potrjeno je, da imajo ugodne učinke pri zdravljenju SB mnoge rastline, pri katerih domnevajo, da so ključne aktivne učinkovine polifenoli. Izvlečki iz lesa bele jelke (lat. Abies alba) vsebujejo številne farmakološko aktivne polifenole. Hipoglikemični učinki prehranskih polifenolnih učinkovin so povezani z inhibicijo α-amilaze v slini in trebušni slinavki ter α-glukozidaze v resicah tankega črevesja, s čimer zmanjšajo absorpcijo ogljikovih hidratov iz črevesja. Namen raziskave je bil ugotoviti, ali izvleček iz lesa bele jelke po zaužitju standardiziranega obroka zniža koncentraciji glukoze in inzulina v plazmi venske krvi in primerjati njegove učinke z učinki akarboze, izvlečkom kostanja in placeba. 31 zdravih preiskovancev je zaužilo 100 g belega kruha štirikrat zaporedoma (z enotedenskim zaporednim premorom) skupaj s kapsulo z izvlečkom lesa bele jelke, s kapsulo z izvlečkom kostanjevih polifenolov, s placebom ali z akarbozo (aktivna kontrola). Površino pod krivuljo časovnega poteka koncentracije glukoze v krvi (AUC) smo izračunali za vsakega prostovoljca in za vsak obrok posebej, uporabili smo inkrementno metodo. Glikemični indeks (GI) smo izračunali kot razmerje med AUC ob zaužitju obroka skupaj s testno snovjo in AUC ob zaužitju obroka skupaj s placebom. Srednje vrednosti GI so bile izračunane kot harmonična sredina. Za testiranje hipotez o razlikah smo uporabili parni t-test. Za mejo statistične značilnosti smo uporabili vrednost p < 0,05. Rezultati klinične raziskave na 31 zdravih prostovoljcih so pokazali, da izvleček lesa bele jelke, zaužit skupaj s standardiziranim obrokom, v povprečju zniža GI obroka za 35 %. Za toliko se zniža tudi postprandialna koncentracija glukoze v plazmi venske krvi, kar pomeni zmanjšanje dejavnika tveganja za razvoj mnogih bolezni, vključno s SB, srčno-žilnimi obolenji in nekaterimi vrstami raka. Izvleček lesa bele jelke verjetno tudi preprečuje preobremenjenost trebušne slinavke, saj zmanjša izločanje inzulina po obroku.Diabetes mellitus (DM) is one of the most common endocrine metabolic disorders. It comprises a group of metabolic disorders characterized by hyperglycaemia. DM results from defects in insulin secretion and/or insulin activity in target cells. The consequences are abnormalities in metabolism of carbohydrates, lipids, and proteins. It is associated with several acute and long-term complications. In addition to lifestyle modifications, treatment of diabetes involves reduction in hyperglycaemia by various groups of synthetic medicines. Unfortunately, none of the conventional therapies for diabetes are without side effects. A huge challenge in finding a so-called "ideal medicine" represents the establishment of a balance between its optimal performance and the risk of adverse effects. There is an increased demand for use of supplementary treatments, including functional foods and nutraceuticals. Many plants are confirmed to have beneficial effects in the treatment of DM, in which the main active constituents are believed to be polyphenols. Extracts from the silver fir (lat. Abies alba) wood are known to contain polyphenols with various pharmacological activities. The hypoglycaemic effects of dietary polyphenolic compounds are related to inhibition of carbohydrate digestion by inhibiting salivary and pancreatic α-amylase and α-glucosidase in the small intestinal brush border. The aim of this study was to test if the extract from silver fir wood reduces the blood glucose and insulin concentrations after the consumption of a standard meal, and to compare its effects with the effects of acarbose, chestnut extract, and placebo. 31 healthy participants consumed 100 g of white bread 4-times (with 1 week consecutive washout period) concomitantly with capsule of silver fir wood, capsule of chestnut extract, placebo, and acarbose (active control). Glucose and insulin in the blood were measured before and after the meal. The area under the curve (AUC) was calculated for each person and each test, using the incremental AUC (iAUC) method. Glycaemic index (GI) was calculated for each subject as a ratio between AUC in test substance and AUC in placebo. The mean GI was calculated as harmonic mean (the reciprocal of the arithmetic mean of the reciprocals). We used paired t-test for testing hypotheses about the differences. An alpha level of p