Since diabetes has multiple etiologies and oxidative stress one of the proposed mechanisms, the objective is to determine the effect of supplementation with β-carotene to type 2 diabetics and healthy individuals, on iron metabolism, oxidative balance, and antioxidant plasma capacity, using doses similar to the daily nutritional requirement.
Type 2 diabetes is a chronic, multifactorial disease, and oxidative stress one of the pathophysiological mechanisms associated with its appearance and development. The objective was to determine the effect of supplementation with β-carotene to type 2 diabetics and healthy individuals, on iron metabolism, oxidative balance, and antioxidant plasma capacity, using doses similar to the daily nutritional requirement. A total of 117 volunteers participated in the study. Type 2 diabetics (34) and healthy individuals (24), received 6 mg β-carotene for 45 d, and were compared to similar non-supplemented diabetic (33) and control (26) groups. Blood samples were taken at the beginning, end and 30 days after finishing supplementation, to determine hemoglobin, hematocrit unsaturated iron binding capacity, total iron binding capacity, transferrin saturation, ferritin, glycemia, glycosylated hemoglobin, cholesterol, triglycerides, HDL, LDL, oxidized LDL, copper, zinc, TBARS, FRAP, nitrites, GPx, SOD, folates, retinol and β-carotene.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
117
6 mg betacarotene in caplets for 45 days (daily)and reevaluate parameters 30 days after finishing supplementation
Evaluate at time 0, 45 days and 75 days, but without receiving betacarotene supplements
Hospital Baudilio Lara
Barquisimeto, Lara, Venezuela
Changes in oxidative status
Time frame: Time 0, 45 days and 75 days after supplementation
Hemoglobin and hematocrit
Time frame: Time 0, 45 days and 75 days after supplementation
Ferritin
Enzyme linked immunosorbent assay (ELISA) with monoclonal antibodies
Time frame: Time 0, 45 days and 75 days after supplementation
Iron metabolism markers
Serum iron, total iron binding capacity (TIBC) and unsaturated iron binding capacity (UIBC) were determined by the methods proposed by the International Committee of Standardization of Hematology.
Time frame: Time 0, 45 days and 75 days after supplementation
Blood Chemistry
Glycemia, triglycerides, total cholesterol, LDL, and HDL were determined automatically in a Ciba Corning 550 Express autoanalizer, using classic enzymatic methods for the determination of these variables.
Time frame: Time 0, 45 days and 75 days after supplementation
Glycosylated Hemoglobin
It was determined using a commercial kit (Bioscience, Caracas, Venezuela),
Time frame: Time 0, 45 days and 75 days after supplementation
Oxidized LDL
Analyzed by a solid phase two-site enzyme immunoassay from Mercodia (Sweden), which contains 2 monoclonal antibodies directed against separated antigenic determinants on the oxidized apolipoprotein B molecule.
Time frame: Time 0, 45 days and 75 days after supplementation
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Thiobarbituric Acid Reactive substances (TBARS)
Were detected by the quantification of malondialdehyde present in the sample, by reacting 2 molecules of thiobarbituric acid with 1 molecule of malondialdehyde, which produces an abduct that is detected at 535 mn.
Time frame: Time 0, 45 days and 75 days after supplementation
Ferric Reducing ability of Plasma (FRAP).
Measured after 4 and 10 min incubation, was used to determine the ability of plasma to reduce iron from ferric to ferrous state, based on the formation of a triazine-Fe+3 complex, that when reduced to Fe+2, generate a change in color that is measured at 593 nm.
Time frame: Time 0, 45 days and 75 days after supplementation
Activities of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx).
Determined by commercial kits (Cayman Chemicals, Pittsburg) following the recommended protocols
Time frame: Time 0, 45 days and 75 days after supplementation
Serum zinc and copper.
By flame atomic absorption spectrophotometry
Time frame: Time 0, 45 days and 75 days after supplementation
β-carotene.
It was determined by HPLC, with a reverse fase C18 column.
Time frame: Time 0, 45 days and 75 days after supplementation
Serum retinol
It was determined by HPLC, with a reverse fase C18 column, as an indirect measure of betacarotene metabolism.
Time frame: Time 0, 45 days and 75 days after supplementation
Serum nitrites
Were determined as an indirect measure of the concentration of nitric oxide, since nitrites are the stable end products of its degradation. Nitrates were reduced to nitrites by activated cadmium. Then sulfanilamide and nitrites generate a chromophore that reacts with naftilethylenediamine, to generate a product visible at 540 nm.
Time frame: Time 0, 45 days and 75 days after supplementation
Serum and erythrocyte folates.
The method is based in the folate-dependent controlled growth of a Lactobacillus strain that is measured spectrophotometrically and quantified against a standard curve.
Time frame: Time 0, 45 days and 75 days after supplementation