a1 Aging Regulation, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan
a2 Research and Development Department, Calbee, Incorporation, 23-6 Kiyohara Kougyoudanchi, Utsunomiya, Tochigi 321-3231, Japan
Potato (Solanum tuberosum) tubers contain vitamin C (VC) and commercial potato chips have more VC content per wet weight by dehydration during frying. However, intestinal absorption of VC from orally ingested potatoes and its transfer to the blood remains questionable. The present study was designed to determine whether the dietary consumption of potatoes affects VC concentration in plasma and urinary excretion of VC in human subjects. After overnight fasting, five healthy Japanese men between 22 and 27 years of age consumed 87 g mashed potatoes and 282 g potato chips. Each portion contained 50 mg of VC, 50 mg VC in mineral water and mineral water. Before and after a single episode of ingestion, blood and urine samples were collected every 30 min or 1 h for 8 h. When measured by subtraction of the initial baseline value before administration of potatoes from the values measured throughout the 8 h test period, plasma VC concentrations increased almost linearly up to 3 h. Subsequently, the values of potato-fed subjects were higher than those of water, but did not differ significantly from those of VC in water (P = 0·14 and P = 0·5). Less VC tended to be excreted in urine during the 8 h test than VC in water alone (17·0 (sem 7·5) and 25·9 (sem 8·8) v. 47·9 (sem 17·9) μmol/mmol creatinine). Upon human consumption, mashed potatoes and potato chips provide VC content that is effectively absorbed in the intestine and transferred to the blood. Clearly, potatoes are a readily available source of dietary VC.
(Received March 08 2011)
(Revised May 26 2011)
(Accepted June 05 2011)
(Online publication September 15 2011)
Abbreviations: AUC, area under the curve; ECD, electrochemical detector; MPA, metaphosphoric acid; VC, vitamin C