Your plants are alive. And the way you store them once you bring them home from the grocery store could determine how many nutrients you're getting from them, a new study found.
A study published in Current Biology showed that even after a plant has been harvested, its cells are still active, and it's still sensitive to light. In an earlier study, the same group discovered that plants use this ability to sense light to prepare themselves for daytime insect attacks, judged using their circadian clocks. They pump themselves full of hormones, which causes an accumulation of chemical compounds called glucosinolates that repels the insects.
The glucosinolates, when eaten by humans, may have anti-cancer effects. The Canadian Cancer Society says studies show they may be associated with a lower risk of prostate cancer, specifically. They're found predominantly in cruciferous vegetables which includes broccoli, cabbage, Brussels sprouts and cauliflower.
For the study, the researchers used cabbages purchased from the grocery store, and kept them in a room with controlled lights that were on for 12 hours and then off for 12 hours. Researchers found that the presence of glucosinolates increased two-fold when there was light, and insects did less damage to the plants during that time.
What this means is that the way we store vegetables – in a crisper, for instance – might mean we're not getting these added health benefits.
"Perhaps we should be storing our vegetables and fruits under light/dark cycles and timing when to cook and eat them to enhance their health value," Dr. Janet Braam, professor of cell biology at Rice University in Houston, Tex., and leader of the study, said.
The other option, Braam said, would be to freeze or somehow preserve plants at specific times of the day when they're full of phytochemicals that would be beneficial to humans.
By storing our produce in dark places, we lose out on the phytochemicals the plants produce during a regular dark/light cycle.
Braam said there are more variables that need to be done to complete the study.
"We were working with one combination of one insect and one plant and, in this case, it worked out that the plant was using its clock to gain advantage over the insect," she said.
"But there are insects that are nocturnal feeders and so, in that case, the plants may not be resistant against them if they are acting to defend themselves only against daytime feeding insects."
Braam said she was excited about the study, because it draws attention to the great qualities plants possess.
"The message I hope people get from this is that plants are much more complicated and active and alive than people generally are aware of," she said.
"Even the trees outside: they don't move around but they are actively perceiving their environment and they do amazing physiology and developmental changes to adapt to their environment."