The bottom line is it depends on the nutrient solution the vegetables are grown in, but hydroponically grown vegetables can be just as nutritious as those grown in soil.
“Much as I think that soil is just great for growing plants, hydroponics has come a long way,” said Marion Nestle, a professor of nutrition, food studies and public health at New York University. “I’ve seen hydroponic producers who have tested their leafy greens for key nutrients, and the amounts fall well within normal limits for their crop and are sometimes even higher.”
Traditionally, plants obtain nutrients from soil. With hydroponics, the plants get nutrients from a solution instead. (Aeroponics, in which the plants’ roots are suspended in the air, is similar except fertilizer is misted onto the roots.) Usually inhabiting large warehouses or greenhouses, hydroponic plants are arranged indoors, often in tall shelves, and they rely on artificial light rather than sunlight.
Plants make their own vitamins, so vitamin levels tend to be similar whether a vegetable is grown hydroponically or in soil. It’s the mineral content that can vary in hydroponic crops, depending on the fertilizer used.
“You can enhance” a plant’s nutrient levels “simply by adding nutrients to the solution" they’re grown in, said Allen V. Barker, a professor at the Stockbridge School of Agriculture at the University of Massachusetts, Amherst. “You could add whatever you wanted: calcium or magnesium, or minor elements like zinc or iron.” The result is that vegetables grown hydroponically could even be “nutritionally superior” to traditionally grown ones, he said.
Keep in mind that nutrient content varies for produce in general, regardless of the growing method. The differences relate to the type of fruit or vegetable, the time of year it is harvested, how long after harvesting the crop gets eaten, and how it is handled and stored from farm to fork.
Remember, too, that these differences in nutrient levels are unlikely to have a significant impact on overall health. The key message from most nutrition experts is simply the more vegetables you eat, the better.
Sophie Egan is the author of "Devoured." Follow her on Twitter @SophieEganM