Dr Anitra Carr, Researcher at University of Otago, New Zealand, presentation at 1st International Symposium on Kiwifruit and Health: http://www.kiwifruitsymposium.org/presentations/health-and-immune-function-benefits-of-kiwifruit-derived-vitamin-c/ 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.

1. Health and Immune Function Benefits of
Kiwifruit-Derived Vitamin C
Dr Anitra C. Carr
University of Otago, Christchurch

2. Presentation outline
• Bioavailability studies
• Functional studies
Well-being
Immune function
• Recommended Dietary Intake

3. Vitamin C content of food

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. Pilot bioavailability study

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. Main bioavailability study

8. Bioavailability
Study Protocol
Measurements:
Dietary Intake
Plasma
Urine
Semen
Leukocytes
Muscle tissue
HPLC-ECD

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. 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. Functions of vitamin C
Enzyme cofactor
Protein 3◦
structure
Hormone &
neurotransmitter
synthesis
Mitochondrial
energy production
Metabolic
regulation
Epigenetic
regulation

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. 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. 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. Potential well-being mechanism
Carnitine biosynthesis

16. Neurotransmitter synthesis
Potential well-being mechanisms

17. Neutrophils and immune function
www.slideshare.net/kiweewab/lecture6-inflammationpptx

18. Neutrophil bacterial killing
Neutrophil Extracellular
Traps (NETs)
courses.washington.edu/conj/bloodcells/phagocytes.htm
www.nature.com/nm/journal/v16/n9/covers/index.htm

19. Neutrophil apoptosis and clearance
www.nature.com/nm/journal/v16/n9/covers/index.htm

20. Kiwifruit and neutrophil function
Measurements:
Plasma vitamin C
Neutrophil vitamin C
Neutrophil chemotaxis
Neutrophil oxidant production
Neutrophil extracellular traps
Neutrophil apoptosis

21. Kiwifruit and neutrophil function

22. Kiwifruit-derived micronutrients

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. 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. 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. 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