Grocery Store Cabbage Is Alive And On A Circadian Rhythm
June 20, 2013

Grocery Store Cabbage Still Alive And On A Circadian Rhythm

Michael Harper for – Your Universe Online

A new study from Rice University and the University of California at Davis (UC Davis) could have vegetarians questioning their motivations for avoiding meat. According to these researchers, vegetables are still very much alive even after they've been harvested, and are even beholden to the circadian rhythms of dark and light schedules. What's more, these vegetables might even be healthier for us at certain times of the day, say the researchers. Rice biologist Janet Braam led the research which appears in this week's edition of the journal Current Biology and suggests perhaps we should begin to take a new look at how we store our vegetables.

"Vegetables and fruits, even after harvest, can respond to light signals and consequently change their biology in ways that may affect health value and insect resistance," said Braam in a press statement.

"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."

Braam and team found in their research that plants could change their physiology at different parts of the day. This change seems to be driven by circadian rhythms, or the shifts between light and dark periods in the day. Plants and vegetables are composed of many different parts, like modules and leaves. As these elements are able to live independently of each other, they are able to continue living even after the vegetable has been removed from the ground. The researchers discovered this by subjecting blueberries, cabbage, carrots and squash to simulated light and dark cycles in the lab. Even after the plants had been harvested, they continued to change their chemical makeup in accordance with the light cycles.

Braam worked with Rice graduate student Danielle Goodspeed to get the vegetables on a regular cycle between dark and light periods. After locking them in a lighted and sealed chamber, the researchers studied several different fruits and vegetables and measured their chemical levels at different points of the simulated day.

"We were able to entrain each of them, even the root vegetables," said Goodspeed in a statement.

Of course this study could mean storing fruits and veggies in dark refrigerators could hinder their ability to cycle through their chemical production.

These vegetables have a reason for staying alive after harvest. Braam believes (and has previously shown) vegetables like cabbage, spinach and others alter the levels of important chemicals in their leaves to keep insects and other herbivores at bay during the nighttime. When the test veggies were placed in simulated day and night conditions, they suffered less damage from hungry insects. This, says Braam could mean humans gain more cancer fighting phytochemicals when eaten at just the right moment.

"We cannot yet say whether all-dark or all-light conditions shorten the shelf life of fruits and vegetables," said Braam.

"What we have shown is that keeping the internal clock ticking is advantageous with respect to insect resistance and could also yield health benefits.

"It may be of interest to harvest crops and freeze or otherwise preserve them at specific times of day, when nutrients and valuable phytochemicals are at their peak."

Circadian rhythms are known to be important parts of all living things, especially the human body. Previous studies have found the regular cycle of the circadian rhythm is responsible for producing amino acids, carbohydrates and lipids in humans and that it can even influence the way we metabolize our food.