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Health and Immune Function Benefits of Kiwifruit Derived Vitamin C by Dr Anitra Carr


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Dr Anitra Carr, Researcher at University of Otago, New Zealand, presentation at 1st International Symposium on Kiwifruit and Health:

Vitamin C is an essential micronutrient. Unlike most animals, we have lost the ability to synthesise our own vitamin C and must therefore obtain it from our diet. Fresh fruit and vegetables are the best source of vitamin C, and regular and adequate daily intake of vitamin C is required to prevent marginal vitamin C status (hypovitaminosis C) and the potentially fatal deficiency disease scurvy. Kiwifruit are an outstanding source of vitamin C with one kiwifruit providing twice the Recommended Dietary Intake (RDI) of vitamin C.

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Health and Immune Function Benefits of Kiwifruit Derived Vitamin C by Dr Anitra Carr

  1. 1. Health and Immune Function Benefits of Kiwifruit-Derived Vitamin C Dr Anitra C. Carr University of Otago, Christchurch
  2. 2. Presentation outline • Bioavailability studies • Functional studies Well-being Immune function • Recommended Dietary Intake
  3. 3. Vitamin C content of food
  4. 4. Vitamin C bioavailability studies • KiwiC pilot study Pilot study to determine dose of kiwifruit for optimal vitamin C uptake into circulation • Bioavailability study Uptake of kiwifruit-derived vitamin C into biological fluids, cells and tissues
  5. 5. Pilot bioavailability study
  6. 6. Urinary vitamin C excretion Carr et al. J Nutr Sci, 2012. 1 gold kiwifruit = 100 mg vitamin C Plasma vitamin C uptake Pilot bioavailability study
  7. 7. Main bioavailability study
  8. 8. Bioavailability Study Protocol Measurements: Dietary Intake Plasma Urine Semen Leukocytes Muscle tissue HPLC-ECD
  9. 9. Main Bioavailability Study Carr et al. Am J Clin Nutr, 2013. () 0.5 kiwifruit/d (50 mg/d vitamin C) (○) 2 kiwifruit/d (200 mg/d vitamin C) Saturating Adequate Marginal
  10. 10. Summary of bioavailability studies • Optimal intake of kiwifruit 0.5 kiwifruit/d (50 mg/d vitamin C) – adequate 2 kiwifruit/d (200 mg/d vitamin C) – saturating/optimal • Tissue and cell uptake Linear uptake of kiwifruit-derived vitamin C into skeletal muscle tissue and white blood cells
  11. 11. Functions of vitamin C Enzyme cofactor Protein 3◦ structure Hormone & neurotransmitter synthesis Mitochondrial energy production Metabolic regulation Epigenetic regulation
  12. 12. Vitamin C functional studies • Kiwifruit and well-being Effect of kiwifruit-derived vitamin C on measures of well-being e.g. vigour • Kiwifruit and immune function Effect of kiwifruit-derived vitamin C on measures of leukocyte function
  13. 13. Effect of kiwifruit on well-being The symptoms of depression, fatigue and irritability are known to precede the overt physical symptoms of the vitamin C deficiency disease scurvy.
  14. 14. P = 0.061 Effect of kiwifruit on well-being ± 2 kiwifruit/d (200 mg/d vitamin C) n=17 0.5 kiwifruit/d vs 2 kiwifruit/d POMS – Profile of Mood States Carr et al. J Nutr Sci, 2013. P = 0.029 High TMD sub-group (± 2 kiwifruit/d) n=8
  15. 15. Potential well-being mechanism Carnitine biosynthesis
  16. 16. Neurotransmitter synthesis Potential well-being mechanisms
  17. 17. Neutrophils and immune function
  18. 18. Neutrophil bacterial killing Neutrophil Extracellular Traps (NETs)
  19. 19. Neutrophil apoptosis and clearance
  20. 20. Kiwifruit and neutrophil function Measurements: Plasma vitamin C Neutrophil vitamin C Neutrophil chemotaxis Neutrophil oxidant production Neutrophil extracellular traps Neutrophil apoptosis
  21. 21. Kiwifruit and neutrophil function
  22. 22. Kiwifruit-derived micronutrients
  23. 23. Summary of functional studies • Kiwifruit enhances well-being 2 Kiwifruit/d enhances well-being by ↓ fatigue, ↑ vigour • Kiwifruit enhances neutrophil function 2 Kiwifruit/d enhances neutrophil vitamin C levels and functions e.g. ↑ chemotaxis and ↑ oxidant production
  24. 24. International RDIs for vitamin C UK 40 mg/d AUS/NZ 45 mg/d* USA/Canada 75-90 mg/d** Europe 95-110 mg/d*** * Based on an intake at which body content is halfway between tissue saturation and the point at which clinical signs of scurvy appear. ** Based on an amount that provides antioxidant protection and derived from near maximal neutrophil concentrations with minimal urinary loss. *** Based on the amount of vitamin C that compensates for metabolic losses and ensures a fasting ascorbate plasma level of 50 µmol/L.
  25. 25. NZ MOH Suggested Dietary Target for the reduction of chronic disease risk 200 mg/d Time for a new RDI for vitamin C? Adapted from Levine et al. PNAS, 1996. Saturating Adequate Marginal Deficient  Animals  New USA RDI  Old USA RDI  NZ/AUS RDI
  26. 26. Acknowledgements Vitamin C Team Prof Margreet Vissers Dr Stef Bozonet Dr Anitra Carr Dr Juliet Pullar Vitamin C Funding Zespri International Ltd Ministry of Business, Innovation & Employment