Americans need to adopt a more plant-based diet, rich in fruits and vegetables, according to a recent report that proposed updates to federal dietary guidelines. And for good reason: Plants offer a host of health benefits. Aside from their fiber, vitamins, and minerals, evidence suggests that fruits and veggies contain compounds that play a role in preventing certain cancers as well as heart disease and stroke, for which supplements are no substitute, says dietitian Elizabeth Pivonka, president of the nonprofit Produce for Better Health Foundation.
Beta carotene found in carrots and sweet potatoes, for example, has been shown to help protect against lung cancer, but may be harmful when taken in pill form. And the latest research suggests that calcium supplements may raise the risk of heart attacks in adults while doing little to benefit bone health. (That's why some researchers are now encouraging folks to get the nutrient in their diet instead. Spinach and broccoli are good sources.)
Getting more isn't always easy. Supermarket produce can be expensive, making packaged snacks—already sweeter or saltier and higher in calories than fruits and vegetables—all the more tempting. A cheaper alternative: Grow your own. Home-grown produce has other advantages beyond its low cost. It's often tastier and arguably a bit more nutritious. Here's why:
Those bright red bell peppers or crisp green beans at the supermarket are likely to have traveled many miles over several days before landing in your cart. Although both the vegetables are a good source of vitamin C—known for bolstering the immune system—a long journey from farm to table gives the nutrient ample opportunity to degrade, especially if exposed to heat. In fact, temperature is the most important factor in keeping harvested fruits and vegetables in good shape, says Diane Barrett, a food biochemist from the University of California, Davis, who helps teach best practices to locals who grow, ship, and distribute fresh produce. One would expect then that temperature is tightly controlled in transit, but in realty she says that does not always happen.
Complicating matters is that the optimal temperature differs from plant to plant, she says. Tomatoes, for example, should not be refrigerated and are generally best if stored between 50 and 55 degrees Fahrenheit. (During the cooking phase, however, heat can unlock one of their beneficial ingredients, a chemical called lycopene, which like beta carotene has antioxidant properties in humans.) Despite the different needs of certain fruits and vegetables, they may be shipped together.
In terms of taste, fresh is best. Supermarket tomatoes are frequently picked green before they have the chance to fully develop flavor, a technique that helps them withstand transport, says Raoul Adamchak, coordinator of the Market Garden at the UC Davis Student Farm. (Later, they are artificially ripened with ethylene, a gas that plants produce naturally.) Moreover, growers who ship their produce cross-country may favor certain varieties over others not for their taste, but because they travel well. Heirloom tomatoes, for example, are too delicate to be shipped and are often absent from store shelves.
For your own garden, relish the freedom to pick among the most flavorful varieties (more than 400 types of tomatoes exist). And don't neglect color: Compounds called phytochemicals provide protection for plants and may give humans some padding against aging. Lycopene and beta carotene are phytochemicals; anthocyanins are another kind. Found in blueberries and cranberries, anthocyanins have been shown to aid memory. Eating an array of colors, says Pivonka, will ensure you get an assortment of nutrients and protective phytochemicals.
Still, home-grown produce may have only a slight nutritional advantage over the store-bought kind. What really matters, says Pivonka, is that you eat more. Half your plate should contain fruits or vegetables at every meal, she says.