Effect of Iron and Zinc Supplementation on B-carotene Bioavailability in Healthy Males

Study Overview
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Brief Summary
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In vitro studies found supplemental levels of iron and zinc to inhibit the micellization and cellular uptake of β-carotene. Here, we investigated this in vivo, in a double-blind 3-arm crossover human trial. Healthy males (n=6) ingested, with breakfast, a single dose of 15 mg β-carotene in combination with either a placebo, 25 mg iron or 30 mg zinc capsule. Blood samples were collected at baseline and hourly for 10 hours. The triacylglycerol-rich fraction (TRF) was analysed for concentrations of β-carotene and plasma for β-carotene, retinol, triacylglycerols, LDL- and HDL-cholesterol.

Detailed Description
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The study followed a double-blind crossover design with three study arms separated by one week washout periods. In short, the participants were asked to follow a diet low in carotenoids by avoiding all orange, yellow, red and green fruits and vegetables for four days. This was followed by three days of a strictly carotenoid-free diet, which only allowed foods from a specified list (Supplemental Table A2). On each study day, β-carotene was administered in the morning after a >10 hour overnight fast (Supplemental Figure A1). All participants orally ingested, in random order, a single dose of 15 mg β-carotene (BIOVEA) with either a placebo (empty capsule), 25 mg iron (FeSO4; Woerwag Pharma GmbH & Co. KG, Boeblingen, Germany) or 30 mg zinc (ZnSO4; Woerwag Pharma) capsule. A standardised dinner was provided on the evening before the trial and standardised meals were provided during the entire intervention day (Supplemental Table A3). On the first study day, the amount of food (weight or volume) consumed by each participant for each meal was recorded and the same amounts provided during the following two arms to ensure similar food consumption, especially of fat. Water was available unrestricted for consumption throughout the day. Blood samples were drawn from an indwelling venous cannula and collected at 0 hours directly before β-carotene supplementation and then every hour for 10 hours. For the determination of plasma concentrations of β-carotene, LDL- and HDL-cholesterol, and triacylglycerols (TAG), blood was collected in tubes containing EDTA (Sarstedt AG & Co, Nuebrecht, Germany) and immediately centrifuged (3000 × g, 10 min, 4 °C). From the obtained plasma samples, three aliquots were stored at -80 °C until further analysis and the rest ultracentrifuged to obtain the triacylglycerol-rich fraction (TRF). For the analyses of liver and kidney function markers, plasma and serum were obtained from blood sampled at the 0- and 4-hour time points. The TRF was prepared according to [10]. Briefly, plasma (3.5 mL) was transferred to an ultracentrifuge tube and carefully overlaid with 8 mL 1.3% sodium chloride and then ultracentrifuged (Beckman Coulter, OptimaTM L-80 XP Ultracentrifuge) using a swinging bucket rotor (SW41Ti) at 150 000 x g for 1 hour at 4 °C. Afterwards, the TRF was isolated by transferring the upper  6 mL, which was then overlaid with nitrogen gas to minimize oxidation and stored at -80 °C until extraction. The plasma samples were randomly extracted and analysed by HPLC according to [15]. Briefly, 40 µL plasma was extracted with an ethanol/n-butanol mixture (50:50) containing apo-80-carotenal-methyloxime (12µL/100 mL; Fluka Analytical (Merck Group KGaA), Darmstadt, Germany) as internal standard. After centrifugation, the clear supernatant was analysed by HPLC. The TRF was extracted and analysed by HPLC [15]. For the extraction, 100 µl apo-80-carotenal-methyloxime (12 µL/100 mL) and 2 mL ethanol (for deproteination) were added to 3 mL of the TRF and vortexed for 30 sec. The solution was extracted twice with 2 mL hexane. The hexane layers were removed, combined and evaporated in a centrifugal vacuum concentrator (Christ, RVC 2-25 CD plus) and the dried sample re-dissolved in 100 µL acetonitrile and immediately analysed by HPLC. Both the plasma and TRF samples were analysed using a Shimadzu HPLC (LC-10AD) equipped with a UV-Vis detector (SPD 20A, set at 450 nm). Carotenoids were separated using a ReproSil 80 ODS-2 column (3 µm, 250 x 4.6 mm; Dr. Maisch GmbH, Ammerbuch, Germany) and an eluent in recirculation mode (82% acetonitrile, 15% 1,4-dioxin, and 3% methanol (vol/vol) containing 100 mM ammonium acetate and 10 mM triethylamine) at a flow rate of 1.5 mL/min [15]. A β-carotene standard (≥97.0% purity, Sigma-Aldrich) was used to construct a standard curve. Plasma TAG, HDL- and LDL-cholesterol were analysed by a clinical laboratory (Laborärzte Sindelfingen, Sindelfingen, Germany).

Official Title
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Effect of Simultaneously Consuming Iron and Zinc Supplements With That of B-carotene, on the B-carotene Bioavailability in Healthy Males

Conditions
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Bioavailability

Intervention / Treatment
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* Dietary Supplement: Control beta-carotene supplement plus Placebo
* Dietary Supplement: Control beta-carotene supplement plus iron Supplement
* Dietary Supplement: Control beta-carotene supplement plus zinc Supplement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male aged 18 and 50 years Exclusion Criteria: overweight (BMI >25 kg/m2), metabolic and endocrine diseases, drug abuse, use of dietary supplements, us of any form of medication, smoking, frequent alcohol consumption (>20 g ethanol/day), adherence to a restrictive dietary regimen, physical activity of more than 5 h/wk, participation in a clinical trial within the past 3 months prior to recruitment, a known intolerance against β-carotene, iron and/or zinc supplements.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: double-blind crossover
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Control plus Placebo<br>B-carotene supplement (15 mg) consumed in the morning after a >10 hour overnight fast. | Dietary Supplement: Control beta-carotene supplement plus Placebo<br>* 15 mg beta-carotene supplement from BIOVEA consumed before breakfast together with an empty capsule.<br>|
| Experimental: Control plus iron Supplement<br>B-carotene supplement (15 mg) and iron sulphate supplement (25 mg) consumed in the morning after a >10 hour overnight fast. | Dietary Supplement: Control beta-carotene supplement plus iron Supplement<br>* 15 mg Beta-carotene supplement from BIOVEA consumed before breakfast together with 25 mg iron (FeSO4; Woerwag Pharma GmbH & Co. KG, Boeblingen, Germany)<br>|
| Experimental: Control plus zinc Supplement<br>B-carotene supplement (15 mg) and zinc sulphate supplement (30 mg) consumed in the morning after a >10 hour overnight fast. | Dietary Supplement: Control beta-carotene supplement plus zinc Supplement<br>* 15 mg Beta-carotene supplement from BIOVEA consumed before breakfast together with 30 mg zinc (ZnSO4; Woerwag Pharma GmbH & Co. KG, Boeblingen, Germany)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TRF B-carotene | B-carotene concentration in the triacylglycerol-rich fraction of the plasma | 10 hours | 
| Plasma B-carotene | B-carotene concentration int he plasma | 10 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma LDL-cholesterol | LDL-cholesterol concentration in Plasma | 10 hours | 
| Plasma HDL-cholesterol | HDL-cholesterol concentration in Plasma | 10 hours | 
| Plasma TAG | triacylglycerol concentration in Plasma | 10 hours | 
| liver function markers | γ-GT, AST, ALT, Alkaline phosphatase and Bilirubin measured | 4 hours | 
| Kidney funtion markers | Creatinine i.S. and Uric acid measured | 4 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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B-carotene, Iron, zinc, Supplements