The study from the USDA’s Agricultural Research Service, published on Wednesday in the Journal of Agriculture and Food Chemistry, compared spinach leaves kept under continuous lighting against spinach kept in the dark, each for three to nine days.
It found the spinach kept under lighting had significantly higher levels of vitamins C, K and E and folate, and the carotenoids lutein and zeaxanthin, reported Reuters.
Comparatively, the spinach stored in the dark lost nutrients. The research should extend to other vegetables.
The idea for the study came to researcher Gene Lester while shopping, he said. Seeing spinach kept in supermarkets at 4°C under fluorescent lighting, he wondered if it was good or bad for the vegetables.
“It is about time we asked some of these questions and do some of the science,” he told Reuters, adding the findings should ultimately not be surprising.
“These vitamins are basically in the plant for photosynthesis and we humans, being the biggest predator of plants, have evolved over time to utilise them as opposed to we having to manufacture them,” he explained.
“As long as there is moisture in the leaves and as long as there is gas exchange and light, it is good to go whether they are picked or not.”