While a lot of us may feel like we have “no sense of time,” science has long decreed the opposite – each of us has an “internal clock".

1. Do Your Veggies Have An Internal Clock?
While a lot of us may feel like we have “no sense of time,” science
has long decreed the opposite – each of us has an “internal clock,”
known as circadian rhythms that regulate a number of bodily
functions including the sleep-wake cycle, the temperature of the
body, and the release of hormones. Although they are most often
associated with animals and humans, fruits and vegetables now
seem to also have internal clocks – clocks that dictate the
expression of genes and regulate a variety of plant processes. Interestingly, recent research has found
that regulating the internal clocks of fruits and vegetables could increase their nutrient profile and
strengthen their ability to operate as functional foods (foods that promote health and/or prevent
disease).
Scientists have long known that plants have internal clocks, but in 2012 researchers at Rice University
discovered that plants use those clocks to regulate the production of compounds that defend against
insects. They found that the internal clocks functioned intelligently, causing an increase in the
production of insect-fighting compounds a few hours before dawn, which is the very time that hungry
insects begin to feast on plants. This discovery prompted Rice University biologist, Janet Braam, to
investigate whether or not the internal clocks of fruits and vegetables also regulate compounds that are
beneficial to human health.
Braam’s team began the investigation by attempting to reset the internal clocks of post-harvest cabbage
by using controlled lighting in a sealed chamber. “Vegetables and fruits don’t die the moment they are
harvested…they respond to their environment for days…,” said Braam. Braam and her team discovered
that they could both reset the internal clocks of post-harvest cabbage and also use light to manipulate
the cabbage into making more antioxidants at certain times of day. More specifically, they were able to
increase the production of glucoraphanin, which is a powerful antioxidant that allows cruciferous
vegetables to operate as functional foods. Not only does glucoraphanin help to fight free radicals, it also
helps to fight against cancer, detoxify the body, and may help prevent ulcers, gastritis, and a variety of
degenerative disorders.
The researchers continued the investigation by testing out the effects of controlled lighting on other
fruits and vegetables including lettuce, carrots, spinach, zucchini, sweet potatoes and blueberries. “We
were able to entrain each of them, even the root vegetables,” said lead author, Danielle Goodspeed.
According to Braam and Goodspeed, these findings suggest that storing fruits and vegetables in dark
trucks, boxes and refrigerators post-harvest, may comprise their ability to keep daily rhythms, which
could ultimately reduce their shelf life and their health promoting properties. “We cannot yet say
whether all-dark or all-light conditions shorten the shelf life of fruits and vegetables,” Braam said. “What
we have shown is that keeping the internal clock ticking is advantageous with respect to insect
resistance and could also yield health benefits.”
Although we are not there yet, scientists may be able to use this discovery to amplify the functional food
properties of the fruits and vegetables that arrive on our plate. “It’s exciting to think that we may be

2. able to boost the health benefits of our produce simply by changing the way we store it,” Goodspeed
said. Simple strategies such as developing refrigerators that are programmed to sync with the hours of
the day may result in fruits and vegetables that both last longer and provide greater health benefits.
Until such technologies are developed, you can ensure you are receiving optimal nutrients from your
fruits and vegetables by buying fresh, organically grown produce at your local farmers market.