Benefits of Kiwifruit Versus Vitamin C Supplement on Vitality

by | Dec 7, 2020 | 2020, Fruits and Vegetables, Vitamin C, Vitamins

Written by Jessica Patella, ND. Both kiwifruit and vitamin C tablet interventions significantly increased plasma vitamin C levels in study participants; however, only kiwifruit significantly improved subjective vitality.

kiwiVitamin C is associated with improving health and consuming fruits and vegetables is associated with greater feelings of vitality.  However, these statements have rarely been studied in controlled, randomized trials.  Previous research by the authors has found that consuming vitamin C-rich kiwifruit increased vitality and decreased fatigue in young men with low vitamin C levels, but it was not clear if it was the fruit or the vitamin C in the fruit that resulted in the reaction.  Therefore, they conducted a randomized, placebo-controlled trial with kiwifruit, vitamin C and placebo 1.

Fruits and vegetables are the main source of vitamin C for humans, since it is an essential nutrient that cannot be made by the liver 1,2.  Vitamin C is found in different concentrations in the body, but is in highest concentrations in the brain and adrenal glands, due to the increased use of vitamin C by these organs 1,3.  Early signs of vitamin C deficiency include, fatigue, depression, mental weariness, and reduced motivation and arousal (hypovitaminosis C <23 micromol/L) 4. In severe cases, insufficient intake of vitamin C results in the disease scurvy, which results in bruising, bleeding gums and poor wound healing (<11 micromoL/L) 1,5.

The research included 167 young adults with plasma vitamin C <40 micromoL/L.  The participants were randomized into three interventions: kiwifruit (2 kiwifruit/day; n=57), vitamin C (250mg tablet/day; n=56), placebo (1 tablet/day; n=54).  The trial included a 2-week lead in period, 4 weeks of intervention with either kiwi, vitamin C or placebo and a 2-week washout period.  Plasma vitamin C and vitality questionnaires were measured every 2 weeks.  Self-reported sleep quality and physical activity were measured every other day through smartphone surveys.

The following results were observed:

  • Plasma vitamin C reached saturation levels within two weeks, for both the kiwifruit and vitamin C group
  • Participants in the kiwi group showed significant improvement in mood and well being
  • Decreased fatigue and increased well-being were observed in the vitamin C group, but only for participants with consistently low vitamin C levels during lead-in
  • Diet records showed participants consuming kiwifruit reduced their fat intake
  • No changes in vitamin C status or vitality were observed in the placebo group.

These results indicated that consuming kiwi fruit or a vitamin C supplement daily will improve plasma levels of vitamin C in the blood.  Both kiwi fruit and vitamin C showed improvements in vitality, but in different ways, indicating there maybe additional or different benefits from consuming the whole fruit of kiwi.  Research suggest it could be due to additional vitamins and nutrients found in kiwifruit 1.

In conclusion, consuming kiwifruit improved subjective vitality in adults with low vitamin C levels.  Similar, but not identical changes were observed in consuming a vitamin C tablet daily, suggesting additional properties of kiwifruit may contribute to improved vitality 1.

Source: Conner, Tamlin S., Benjamin D. Fletcher, Juliet M. Pullar, Emma Spencer, Louise A. Mainvil, and Margreet Vissers. “KiwiC for Vitality: Results of a Randomized Placebo-Controlled Trial Testing the Effects of Kiwifruit or Vitamin C Tablets on Vitality in Adults with Low Vitamin C Levels.” Nutrients 12, no. 9 (2020): 2898.

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution(CC BY) license (http://creativecommons.org/licenses/by/4.0/)

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Posted December 7, 2020.

Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.

References:

  1. Conner TS, Fletcher BD, Pullar JM, Spencer E, Mainvil LA, Vissers MCM. KiwiC for Vitality: Results of a Randomized Placebo-Controlled Trial Testing the Effects of Kiwifruit or Vitamin C Tablets on Vitality in Adults with Low Vitamin C Levels. Nutrients. 2020;12(9).
  2. Block G, Norkus E, Hudes M, Mandel S, Helzlsouer K. Which plasma antioxidants are most related to fruit and vegetable consumption? Am J Epidemiol. 2001;154(12):1113-1118.
  3. Hasselholt S, Tveden-Nyborg P, Lykkesfeldt J. Distribution of vitamin C is tissue specific with early saturation of the brain and adrenal glands following differential oral dose regimens in guinea pigs. Br J Nutr. 2015;113(10):1539-1549.
  4. Kinsman RA, Hood J. Some behavioral effects of ascorbic acid deficiency. Am J Clin Nutr. 1971;24(4):455-464.
  5. Granger M, Eck P. Dietary Vitamin C in Human Health. Advances in food and nutrition research. 2018;83:281-310.