A Randomized Steady-State Bioavailability Study of Synthetic versus Natural (Kiwifruit-Derived) Vitamin C

Carr, Anitra C.; Bozonet, Stephanie M.; Pullar, Juliet M.; Simcock, Jeremy; Vissers, Margreet C.M.

doi:10.3390/nu5093684

Cited by 39 publications

(51 citation statements)

References 40 publications

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“…Our participants were supplemented with DL-α-tocopherol acetate, the synthetic form of vitamin E. The bioavailability and biological action of natural D-α-tocopherol/RRR-α-tocopherol may differ (Traber et al 1994;Burton et al 1998). Thus, we must be careful when comparing our results with those of studies that have administered the natural form of vitamin E. Concerning vitamin C, there seem to be no differences in blood and tissue bioavailability of synthetic and natural or flavonoid-rich vitamin C (Carr et al 2013).…”

Section: Supplement Considerationsmentioning

confidence: 83%

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Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double‐blind, randomised, controlled trial

Paulsen

Cumming

Holden

et al. 2014

The Journal of Physiology

259

239

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Key pointsr Recent studies have indicated that antioxidant supplementation may blunt adaptations to exercise, such as mitochondrial biogenesis induced by endurance training. However, studies in humans are sparse and results are conflicting.r Isolated vitamin C and E supplements are widely used, and unravelling the interference of these vitamins in cellular and physiological adaptations to exercise is of interest to those who exercise for health purposes and to athletes.r Our results show that vitamin C and E supplements blunted the endurance training-induced increase of mitochondrial proteins (COX4), which is important for improving muscular endurance.r Training-induced increases inV O 2 max and running performance were not detectably affected by the supplementation.r The present study contributes to understanding of how antioxidants may interfere with adaptations to exercise in humans, and the results indicate that high dosages of vitamins C and E should be used with caution.Abstract In this double-blind, randomised, controlled trial, we investigated the effects of vitamin C and E supplementation on endurance training adaptations in humans. Fifty-four young men and women were randomly allocated to receive either 1000 mg of vitamin C and 235 mg of vitamin E or a placebo daily for 11 weeks. During supplementation, the participants completed an endurance training programme consisting of three to four sessions per week (primarily of running), divided into high-intensity interval sessions [4-6 × 4-6 min; >90% of maximal heart rate (HR max )] and steady state continuous sessions (30-60 min; 70-90% of HR max ). Maximal oxygen uptake (V O 2 max ), submaximal running and a 20 m shuttle run test were assessed and blood samples and muscle biopsies were collected, before and after the intervention. Participants in the vitamin C and E group increased theirV O 2 max (mean ± S.D.: 8 ± 5%) and performance in the 20 m shuttle test (10 ± 11%) to the same degree as those in the placebo group (mean ± S.D.: 8 ± 5% and 14 ± 17%, respectively). However, the mitochondrial marker cytochrome c oxidase subunit IV (COX4) and cytosolic peroxisome proliferator-activated receptor-γ coactivator 1 α (PGC-1α) increased in the m. vastus lateralis in the placebo group by 59 ± 97% and 19 ± 51%, respectively, but not in the vitamin C and E group (COX4: −13 ± 54%; PGC-1α: −13 ± 29%; P ࣘ 0.03, between groups). Furthermore, mRNA levels of CDC42 and mitogen-activated protein kinase 1 (MAPK1) in the trained muscle were lower in the vitamin C and E group than in the placebo group (P ࣘ 0.05). Daily vitamin C and E supplementation attenuated increases in markers of mitochondrial biogenesis following endurance training. However, no clear interactions were detected for improvements inV O 2 max and running performance. Consequently, vitamin C and E supplementation hampered cellular adaptations in the exercised muscles, and although this did not translate to the performance tests applied in this study, we advocate caution when considering antioxidant supplemen...

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Section: Supplement Considerationsmentioning

confidence: 83%

“…Thus, we must be careful when comparing our results with those of studies that have administered the natural form of vitamin E. Concerning vitamin C, there seem to be no differences in blood and tissue bioavailability of synthetic and natural or flavonoid‐rich vitamin C (Carr et al . ).…”

Section: Discussionmentioning

confidence: 97%

Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double‐blind, randomised, controlled trial

Paulsen

Cumming

Holden

et al. 2014

The Journal of Physiology

259

239

View full text Add to dashboard Cite

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“…Seminal fluid vitamin C levels are also significantly higher than plasma levels and are well conserved, indicating a necessary (but unknown) function (Carr et al, 2013). As a known antioxidant, vitamin C could potentially offset oxidative injury to spermatozoa.…”

Section: Discussionmentioning

confidence: 99%

Elevated seminal plasma myeloperoxidase is associated with a decreased sperm concentration in young men

et al. 2017

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Myeloperoxidase is a major neutrophil protein which generates oxidants that are highly reactive, and if present in seminal fluid, could be potentially damaging to spermatozoa. We recruited young males aged 18-35 years, unscreened for fertility status, for a pilot study measuring seminal plasma myeloperoxidase. On three occasions, over a 3-month period, we measured parameters of semen quality and correlated these with seminal myeloperoxidase protein and activity. After baseline measurement, participants were supplemented daily with 250 mg of vitamin C, a potent scavenger of reactive oxygen species with antiinflammatory activities. Seminal plasma from eight of the 12 participants had measurable concentrations of myeloperoxidase protein, across a broad range (15-250 ng/mL). Median myeloperoxidase protein concentrations were ~45-fold higher in semen samples with low vs. high sperm concentrations. Seminal plasma myeloperoxidase protein concentration was inversely correlated with the percentage of rapidly motile spermatozoa assessed by computer-assisted sperm analysis, and the total number of spermatozoa per ejaculate, but positively correlated with sperm maturity, measured by DNA staining ability. We measured an inverse correlation between semen vitamin C concentration and seminal plasma myeloperoxidase protein concentration, although vitamin C supplementation had no effect on semen quality. Our pilot data suggest that high concentrations of myeloperoxidase were present in the seminal plasma of many of our young participants, and that this may be associated with decreases in semen quality. A larger study is required to confirm these findings.

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“…, >50 μmol/L) baseline levels of plasma vitamin C [89]. The participants received either a chewable tablet (200 mg vitamin C) or the equivalent dose from gold kiwifruit.…”

Section: Pharmacokinetic Bioavailability Studies In Humansmentioning

confidence: 99%

Synthetic or Food-Derived Vitamin C—Are They Equally Bioavailable?

Carr

Vissers

2013

Nutrients

Self Cite

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Vitamin C (ascorbate) is an essential water-soluble micronutrient in humans and is obtained through the diet, primarily from fruits and vegetables. In vivo, vitamin C acts as a cofactor for numerous biosynthetic enzymes required for the synthesis of amino acid-derived macromolecules, neurotransmitters, and neuropeptide hormones, and is also a cofactor for various hydroxylases involved in the regulation of gene transcription and epigenetics. Vitamin C was first chemically synthesized in the early 1930s and since then researchers have been investigating the comparative bioavailability of synthetic versus natural, food-derived vitamin C. Although synthetic and food-derived vitamin C is chemically identical, fruit and vegetables are rich in numerous nutrients and phytochemicals which may influence its bioavailability. The physiological interactions of vitamin C with various bioflavonoids have been the most intensively studied to date. Here, we review animal and human studies, comprising both pharmacokinetic and steady-state designs, which have been carried out to investigate the comparative bioavailability of synthetic and food-derived vitamin C, or vitamin C in the presence of isolated bioflavonoids. Overall, a majority of animal studies have shown differences in the comparative bioavailability of synthetic versus natural vitamin C, although the results varied depending on the animal model, study design and body compartments measured. In contrast, all steady state comparative bioavailability studies in humans have shown no differences between synthetic and natural vitamin C, regardless of the subject population, study design or intervention used. Some pharmacokinetic studies in humans have shown transient and small comparative differences between synthetic and natural vitamin C, although these differences are likely to have minimal physiological impact. Study design issues and future research directions are discussed.

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A Randomized Steady-State Bioavailability Study of Synthetic versus Natural (Kiwifruit-Derived) Vitamin C

Cited by 39 publications

References 40 publications

Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double‐blind, randomised, controlled trial

Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double‐blind, randomised, controlled trial

Elevated seminal plasma myeloperoxidase is associated with a decreased sperm concentration in young men

Synthetic or Food-Derived Vitamin C—Are They Equally Bioavailable?

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