Comparison of purple carrot juice and b-carotene in a high-carbohydrate, high-fat diet-fed rat model of the metabolic syndrome
Hemant Poudyal1, Sunil Panchal1,2 and Lindsay Brown1,2*
School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, AustraliaDepartment of Biological and Physical Sciences, University of Southern Queensland, Toowoomba, QLD 4350, Australia
(Received 7 January 2010 – Revised 5 May 2010 – Accepted 10 May 2010 – First published online 12 July 2010)
British Journal of Nutrition
Anthocyanins, phenolic acids and carotenoids are the predominant phytochemicals present in purple carrots. These phytochemicals could be useful intreatment of the metabolic syndrome since anthocyanins improve dyslipidaemia, glucose tolerance, hypertension and insulin resistance; the phenolic acids may also protect against CVD and b-carotene may protect against oxidative processes. In the present study, we have compared the ability of purple carrot juice and b-carotene to reverse the structural and functional changes in rats fed ahigh-carbohydrate, high-fat diet as a model of the metabolic syndrome induced by diet. Cardiac structure and function were deﬁned by histology, echocardiography and in isolated hearts and blood vessels; liver structure and function, oxidative stress and inﬂammation were deﬁned by histology and plasma markers. High-carbohydrate, high-fat diet-fed rats developed hypertension, cardiac ﬁbrosis, increased cardiacstiffness, endothelial dysfunction, impaired glucose tolerance, increased abdominal fat deposition, altered plasma lipid proﬁle, liver ﬁbrosis and increased plasma liver enzymes together with increased plasma markers of oxidative stress and inﬂammation as well as increased inﬂammatory cell inﬁltration. Purple carrot juice attenuated or reversed all changes while b-carotene did not reduce oxidativestress, cardiac stiffness or hepatic fat deposition. As the juice itself contained low concentrations of carotenoids, it is likely that the anthocyanins are responsible for the antioxidant and anti-inﬂammatory properties of purple carrot juice to improve glucose tolerance as well as cardiovascular and hepatic structure and function. Purple carrots: Anthocyanins: b-Carotene: Metabolic syndrome:High-carbohydrate, high-fat diet-fed rats
Diet plays an important role in the aetiology and prevention of the risk factors of the metabolic syndrome(1). Many epidemiological studies have shown a strong inverse association between an increased consumption of fruits and vegetables and a decreased incidence of CVD(2 – 5), especially stroke(3), IHD(2,3), CHD(4) and blood pressure(5). Although therisk of type 2 diabetes is not related to the consumption of fruit or vegetables, the intake of antioxidant phytochemicals has been associated with reduction in the risk of type 2 diabetes(6,7). Close relationships between obesity, the metabolic syndrome and the development of non-alcoholic fatty liver disease (NAFLD) have been described, with most NAFLD patients displaying multiple components of themetabolic syndrome(8). However, the effects of increased intakes of fruit and vegetables on NAFLD patients have not been studied. Glucosinolates, ﬂavonoids, tannins, carotenoids, phytates and phyto-oestrogens represent the major classes of phytochemicals present in fruits and vegetables(9). These nutrients may improve health through many mechanisms, such as reducing oxidative stress andinﬂammation, improving lipid proﬁles, lowering blood pressure and enhancing glucose metabolism(9). Anthocyanins, a subclass of ﬂavonoids, are
pigments of red fruits such as cherries, plums, strawberries, raspberries, blackberries, grapes, red and black currants and, together with the phenolic acids, are the major phytochemicals in the human diet(10). Although research on the therapeutic uses of the...