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The health benefits of soil management techniques to improve flavor and phytochemical content of carrot: Linking healthy soil, healthy plants & healthy people

Activity summary

This activity explores the effects of agronomic practice on both the flavour and health-promoting properties of crops from a biochemical perspective, a necessarily broad-based investigation combining soil, plant and animal sciences.

There have been many studies comparing the nutritional value of organic vs. conventional food, with mixed results. In many cases, studies use commercially available produce without information on cultivar or production history, or they have collected produce from a number of local farms with widely variable soil conditions and production techniques. Studies that do control production usually examine differences in essential nutrient composition resulting from different production systems. These studies have uncovered some consistent differences (nitrate, minerals and ascorbic acid levels, water volume), however these differences are often no more significant than are year-to-year variations.

The health benefits of organic food, and of diets high in fruits and vegetables, may result from increased concentrations of non-essential bioactive phytochemicals. We will attempt to specifically target conditions supporting biosynthesis and bioaccumulation of secondary metabolites by growing carrots in a low input environment with increasing levels of soil organic matter amendments (compost), trace minerals, or both. We will examine the effects of these amendments on various soil parameters, including the activity of nutrient cycling soil enzymes, cation exchange capacity (CEC), base saturation of CEC, and trace mineral content of soil.

We will evaluate the changes in secondary metabolite accumulation in carrot, specifically total soluble solids, flavour compounds (evaluated with a trained tasting panel), carotenoids and the bioactive phytochemical falcarinol. The harvest from selected carrot treatments (low vs. high falcarinol) will be used in feeding trials to evaluate the health effects of agronomic practices. Rather than evaluating only nutritional content, this project focuses on the health protective effects of phytochemicals by taking gene-nutrient interaction and immunological approaches. We will use acute and chronic inflammation mouse models to evaluate the protective effect of falcarinol and whole carrot on liver, spleen and intestinal inflammation.

This project aims to offer a more complete understanding of parameters that influence phytochemical bioaccumulation that in the future can be combined and balanced with techniques that maximize harvest biomass, giving producers tools to create a higher value product and produce a crop that serves the needs of both consumer and producer. The ability to demonstrate that enhanced health effects are imparted by organic produce would help to justify the price premium for organic food. This project will support the organic industry by contributing to the body of knowledge that demonstrates the health benefits of plant-derived bioactive compounds.  A greater public understanding of the health-protective benefits of high quality produce should increase demand for high quality produce in general, and high quality organic produce in particular.

Materials and Results to Date

• Nutrients (2014) 6: 3777-3801

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