Does the Timing of your Fruit and Veggie Consumption Matter?

Fresh apples, corn and Swiss chard from the Green City Market

Labor day is the unofficial start of fall and with it comes one of my favorite seasons for fruits and veggies. From apples to pumpkins to sweet corn, fall offers a bounty of delicious fruits and veggies ripe for the picking whether found at your local grocery store, farm stand or my favorite – the Green City Market here in Chicago.

Fruits and Veggies have an Internal Clock

As a dietitian, I’ve often been asked how to make sure you get the most from your produce. You may know that an orange loses it’s vitamin C content over time. What if you could boost the beneficial compounds in your fruits and veggies simply by simulating the light-dark cycle? Circadian rhythms, or our internal clock, are found not only in humans, but in fruits and vegetables as well. And a new study, published in Current Biology, found that there may be a way to boost some of the beneficial compounds in plants by simulating the light-dark cycle after crops are harvested.

As our veggies go from the field to the store or market and then ultimately to our homes, levels of some of the important compounds–like glucosinolates found in cruciferous vegetables (i.e., cabbage)–are lost. Researchers at Rice University studied the effect of the light-dark circle on fruits and vegetables, simulating conditions found in the field and post-harvest. They found that even after harvest, levels of beneficial compounds seemed to peak at certain points in the day.

In the field, plants use circadian rhythms to know when to release certain innate chemicals to fend off pests or to cope with environmental stress like heat or drought—often peaking in the afternoon. What’s significant is that these researchers actually found that levels of beneficial compounds continued to peak even after being picked.

Is it time for a Fruit and Veggie Happy Hour?

While more research is needed – this study suggests we may be able to maximize the nutritional profile of many of the fruits and vegetables we eat. How? You or your favorite produce vendor might consider storing your fruits and veggies under a light-dark cycle. Or you might time your produce consumption for the afternoon hours.

Enjoy the fruits (and veggies) of fall!


[This post has been adapted from a post I originally wrote for the Chicago Dietetic Association, found here:


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