Nutrients and non-essential metals in darkibor kale grown at urban and rural farms: A pilot study

Urban Farm DB summary

A pilot study (2024, PLoS ONE) planted Darkibor kale seedlings at three urban and four rural farms in and around Baltimore City, Maryland, had farmers grow them using their usual practices, and analyzed harvested kale for carotenoids, vitamins C and K1, ten nutritional elements, and eight non-essential metals. Sample sizes were in some cases too small to yield statistical significance, but the study identified potentially meaningful differences between urban and rural kale: mean carotenoid and vitamin concentrations were 22-38% higher in rural samples, while mean concentrations of eight nutritional elements were higher in urban samples, by as much as 413% for iron. Most of nine non-essential metals were higher on average in urban samples, though lead and cadmium concentrations across all samples stayed below public health guidelines; for six elements, variance within urban or within rural farms exceeded variance between the two groups, suggesting urbanicity may not be the primary driver of some differences, and some urban-rural gaps were more pronounced than in prior research.