Seasonal variability of the vitamin C content of fresh fruits and vegetables in a local retail market.

Seasonal variation of vitamin C in fresh fruits and vegetables is not reflected in food composition database average values, yet many factors influence content and retention.; Results: Fresh fruits and vegetables were sampled on three occasions in each season, from the same local retail outlets, for 1 or 2 years. Vitamin C was significantly higher in winter-sampled spinach (436 mg kg-1 ) compared with spring (298 mg kg-1 ) and summer/fall (180 mg kg-1 ); in potatoes in summer/fall (156 mg kg-1 ) versus winter/spring (106 mg kg-1 ); and in oranges in winter (616 mg kg-1 ), spring (592 mg kg-1 ), and summer (506 mg kg-1 ). Ranges were dramatic among sampling occasions for broccoli, oranges, potatoes, and spinach (700-1210 mg kg-1 , 420-780 mg kg-1 , 70-280 mg kg-1 , and 90-660 mg kg-1 respectively). Mean values for apples, bananas, tomatoes, and potatoes differed from the USDA National Nutrient Database for Standard Reference (SR) average by ≥10% of the daily recommended intake (90 mg). For broccoli, oranges, and spinach, vitamin C was substantially above or below the SR range in 50-100% of the samples. For spinach, the average content did not differ from SR, but vitamin C in winter was 55% higher than SR.; Conclusion: Database average values for vitamin C in fresh produce can significantly over- or underestimate the content in a specific food supply. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.