Association between the metabolic syndrome and cancer risk : the potential role of fatty acids on body composition

Johnson, Olga (2016-12)

Thesis (MSc)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Background: Sub-Sahara Africa is experiencing an epidemiological transition with an increasing burden of non-communicable diseases (NCDs) including obesity, hypertension, insulin resistance (IR) and dyslipidaemia. These NCD are collectively labelled the metabolic syndrome (MetS). The MetS is characterised by dyslipidaemia, and in particular, distorted fatty acid (FA) metabolism. Additionally, the MetS and its components are also associated with different FA classes. Furthermore, several lifestyle-cancers have also been associated with the MetS and its components. Aim: To determine the association and interaction between the MetS and cancer risk and the likely influence of FAs on body composition in a female population residing in the Western Cape, South Africa. Methods: Female farm workers in the Cape Winelands region (n=80) aged 20-60 years were randomly selected and categorised as having the MetS (n=34 MetS and n=46 non-MetS) using the International Diabetes Federation (IDF) criteria. All participants were additionally classified according to their body mass index (BMI). Blood pressure was measured, followed by blood sampling to determine blood glucose and insulin levels, as well as a full lipid profile. Selected red blood cell (RBC) membrane FAs and FA ratios were analysed, and enzyme-linked immunosorbent assays (ELISAs) were used to quantify serum insulin-like growth factor-1 (IGF-1) and leptin concentrations. Anthropometric measurements and bioelectric impedance analyses (BIA) were also performed. Results: The prevalence of the MetS was 42.5 % with abdominal obesity (100.0 % for the MetS, and 39.1 % for the non-MetS), hypertension (82.4 % for the MetS, and 47.8 % for the non-MetS), and low high-density lipoprotein cholesterol (HDL-c) (76.5 % for the MetS, and 34.8 % for the non-MetS) being the most prevalent MetS risk factors. Several statistically significant differences were observed between the MetS and non-MetS groups for blood parameters, including insulin and HDL-c levels (p<0.001), and glucose, IGF-1, and leptin levels (p<0.05). The MetS group also presented with significantly higher anthropometric measurements, including BMI (p<0.05), waist circumference (WC), waist-to-hip ratio (W:H), and the sagittal abdominal diameter (SAD) (all p<0.001). Furthermore, BIA (including visceral adipose tissue (VAT) area, percentage VAT (VAT %) and -subcutaneous adipose tissue (SAT %), and VAT to SAT ratio (VAT:SAT) (p<0.001 for all) also differed between the MetS and non-MetS groups. No significant differences were noted for any of the individual FAs or FA ratios. Categorisation according to metabolic status and BMI was shown to influence several metabolic-associated blood parameters, anthropometric measurements, BIA. However, metabolic status and BMI did not influence individual FA levels or FA ratios. The obese MetS group presented with significantly higher IGF-1 levels compared to their normal weight non-MetS counterparts. Correlation analyses indicated several significant associations between anthropometric measurements, BIA, FAs and metabolic-associated blood parameters. Conclusion: The results from this study suggest that metabolic status alone, and the combined effect of metabolic status and BMI, may predict alterations in metabolic-associated blood parameters, anthropometric measurements, and BIA in women, possibly linking obesity and the MetS to an increased risk of developing lifestyle-associated cancer. Keywords Metabolic syndrome, fatty acid profile, body composition, leptin, cancer risk

AFRIKAANS OPSOMMING: Agtergrond: Tans ondervind Sub-Sahara Afrika ‘n epidemiologiese oorgang met toenemende las van nie-oordraagbare siektes (NOS’s) insluitend vetsug, hipertensie, insulienweerstandigheid (IW) en dislipidemie. Hierdie NOS word gesamelik na die metaboliese sindroom (MetS) verwys. Die MetS word gekenmerk deur dislipidemie, en veral ‘n verwronge vetsuur (VS)-metabolisme. Addisioneel word die MetS en komponente daarvan ook met die verskillende VS klasse geassosieer. Verskeie leefstylkankers word voorts ook met die MetS sy en komponente geassosieer. Doel: Om die verband en interaksie tussen die MetS en risiko vir kankerontwikkeling te bepaal, en die moontlike invloed van VSe op liggaamsamestelling in ‘n vroulike populasie wat woonagtig is in die Wes-Kaap, Suid-Afrika. Metodes: Vroulike plaaswerkers van die Kaapwynland distrik (n=80) tussen die ouderdomme 20-60 jaar, is ewekansig gekies en geklassifiseer met die MetS (n=34 MetS, en n=46 non-MetS) deur van die Internasionale Diabetes Federasie (IDF) kriteria gebruik te maak. Alle deelnemers is addisioneel volgens hulle liggaamsmassa indeks (LMI) geklassifiseer. Bloeddruk is bepaal, gevolg deur ‘n bloedmonster om bloedglukose, insulienkonsentrasie, en ‘n volledige lipiedprofiel te bepaal. Geselekteerde rooibloedselmembraan VSe en VS verhoudings is bepaal, terwyl daar van ‘n ensiemgekoppelde immunosorberende toets (ELISA) gebruik gemaak is om serum insulienagtige groeifaktor-1 (IGF-1) en leptienkonsentrasies te bepaal. Antropometriese metings en bio-elektrieses impedansie analises (BEI) is ook uitgevoer. Resultate: Die voorkoms van die MetS was 42.5 %, waarvan abdominale vetsug (100.0 % vir die MetS, en 39.1 % vir die nie-MetS), hipertensie (82.4 % vir die MetS, en 47.8 % vir die nie-MetS), en lae hoë-digtheidlipoproteïencholesterol (HDL-c) (76.5 % vir die MetS, en 34.8 % vir die nie-MetS) die mees algemene MetS risikofaktore was. Verskeie statistiesbetekenisvolle verskille is tussen die MetS en die nie-MetS groepe vir bloedparameters, insluitend insulien en HDL-c vlakke (p<0.001), glukose, IGF-1, en leptien vlakke (p<0.05) waargeneem. Die MetS groep het ook betekensivolle hoër antropometriese metings opgelewer, insluitend LMI (p<0.05), middelomtrek (MO), middel-heup verhouding (M:H) en sagitale abdominale deursnit (SAD) (almal p<0.001). Verder is betekenisvolle verskille in BEI (insluitend viserale vetweefsel (VVW) area, persentasie VVW (VVW %), subkutane vetweefsel (SVW %), en VVW:SVW verhouding (p<0.001 vir almal) tussen die MetS en nie-MetS groepe waargeneem. Geen betekensvolle verskil vir die individuele VSe of VS verhoudings is gevind nie. Klassifisering volgens die metaboliese status en LMI, het verskeie metabolies-geassosieerde parameters, antropometriese metings, en BEI voorspel. Die metaboliese status en LMI het nie die individuele VSe of VS verhoudings beïnvloed nie. Die vetsugtige MetS groep het verhoogde IGF-1 vlakke teenoor normale gewig, nie-MetS individue gelewer. Verskeie antropometriese metings, BEI, VSe en metabolies-gessosiëerde bloedmetings het korrelasies getoon. Gevolgtrekking: Die resultate van hierdie studie stel voor dat die metaboliese status, en die gekombineerde effek van die metaboliese status en die LMI verandering in die metabolies-geassosieerde bloedparameters, antropometriese metings en BEI, in vroue kan voorspel. Dit kan moontlik verdere vetsugtigheid in die MetS met ‘n verhoogde risiko vir die ontwikkeling van lewenstyl-geassosieerde kanker verbind. Sleutelwoorde: Metaboliese sindroom, vetsuurprofiel, liggaamsamestelling, leptien, kankerrisiko

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