Marcus Nilsson

Local Tomatoes Really Are Healthier. Here's Why

To-may-toh, to-mah-to. No matter how you say it, all produce isn’t created equal. That shipped-from-afar fruit isn't just lacking flavor—it also falls short on nutrition compared to a freshly picked, local one. Turns out that with produce, time is the enemy.
June 14, 2018

I had to take the farmer’s word that the field of spinach that spread out before us was truly organic. I was visiting California’s Salinas Valley, which is in the central coastal part of the state and has earned itself the nickname “America’s Salad Bowl.” Earlier that same day, the farmer and I had driven past dozens of conventional, industrial-scale spinach fields where machines cut the leaves and funneled them into tractor trailers for the journey to a packing plant. The plantings were as flat (and weedless) as billiard tables, extending for miles east toward the Santa Lucia Mountains. Now, the organic field before us appeared identical to all the others. But when I later encountered the organic grower’s spinach beside conventionally grown spinach in a New England supermarket, I noticed quite a difference: The organic greens cost 20% more.

That got me wondering. Was the price difference worth it? Are there really flavor and nutritional advantages to buying organic produce versus fruits and vegetables grown conventionally? And what about locally grown produce versus that which is shipped from afar?

My quest to answer those questions began in the produce section of my favorite grocery store, City Market, in the small city of Burlington, Vermont, where I met Jason Pappas, the produce manager. “I’m a total produce nerd. Don’t get me started,” he warned, by way of introduction. “I won’t shut up.”

I knew immediately he was the perfect guy to answer my questions. “Most conventional produce is grown to look good and travel long distances,” he said, leading me to a display of salad greens. “A shipment from California is a week to 10 days old when it gets here. Our local greens have been picked the day before or earlier the same day.” He reached for a bag of California-grown salad mix. “Feel the leaves. They’re tough. They have to be. You can see brown on the ends where they were clipped.” Plucking a bag of similar greens grown locally, he said: “No brown ends. Feel how tender they are.”

Time Is the Enemy

Credit: Marcus Nilsson

Research shows that the difference between the contents of those bags goes beyond appearance and texture. The amount of time that elapses between when a vegetable is harvested and when a shopper serves it is a big enemy of nutritional content, whether the crops are conventional or organic. 

A study in 2007 led by Joy C. Rickman of the University of California, Davis showed that loss of nutrients in fresh produce during storage was far higher than had previously been believed. Levels of vitamin C in refrigerated green peas fell by half during the first 48 hours after picking. After seven days, carrots lost 10% of their vitamin C, spinach lost 75%, and green beans lost 77%. Seven days is less time than it would take a produce-laden semitruck to get across the country. (Interestingly, freezing had a vastly different outcome—these vegetables lost only a small percentage of their vitamin C after a yearlong freeze.) 

Breaks in what the industry calls the “cold chain,” or the temperature-controlled supply chain, occur when produce is allowed to get warm during the packing and transporting steps, and that can make the passage of time even more devastating. Rickman found that spinach left at room temperature for a week lost all of its vitamin C. “For produce that needs to be kept cold, every hour at room temperature is equal to a day in the refrigerator,” says Steve Savage, a California-based food and agricultural consultant.

Nutrition in general took a hit when plant breeders began selecting varieties with an emphasis on ever-increasing yields. In 2009, Donald R. Davis, who has since retired from the University of Texas, published the results of a study that showed a correlation between the rising yields of commercial produce varieties and the decline in the levels of nutrients, such as calcium, iron, vitamin A, and the B vitamin thiamine. He called it “the dilution effect.” Davis found that since the 1940s, minerals, vitamins, and protein had seen a median decline between 5% and 40%, especially in vegetables. Since the 1960s, levels of vitamin C and thiamine in tomatoes alone have dropped by nearly half, according to the United States Department of Agriculture. Put simply, the produce of our parents’ generation was more nutritious than most of what we’re purchasing at the grocery store today.

All of this argues in favor of filling your shopping basket with produce grown by nearby farmers who have no need to grow crops able to withstand a week or more in the back of a refrigerated transport truck.

The Cooking Light Lab Test

Credit: Marcus Nilsson

We put tomatoes to the test in our own informal experiment: Five farms sent local organic and nonorganic tomatoes directly to a lab to have their content of vitamin C and carotene (a group of antioxidants) measured against nonlocal, nonorganic tomatoes from a large-scale grocer in Pennsylvania.

The results? Organic, local varieties had more vitamin C and more of most carotenes than both conventional, local produce and conventional fruits imported from Mexico. In fact, the nonorganic, imported tomatoes offered the least amount of every nutrient tested. So although our “study” wasn’t all that rigorous, for the most part it aligns with the latest published science: When it comes to fruit and vegetable nutrition, time is detrimental, so choose produce grown closer to home whenever you can. And sometimes farming practices impact nutrition, so don’t dismiss organic.

Is Organic More Nutritious?

Early studies suggested that organic produce was not more nutritious than conventional. In 2009, Alan D. Dangour and a team at The London School of Hygiene and Tropical Medicine published a survey that compared the results of 55 individual studies conducted between 1958 and 2008. Dangour’s conclusion: “There is no evidence of a difference in nutrient quality between organically and conventionally produced foodstuffs.” Three years later, a Stanford University group came to a similar conclusion.

Recent broader studies, however, contradict the work of both the London and the Stanford researchers. A paper published in the British Journal of Nutrition in 2014 examining 343 scientific articles published between 1992 and 2011 concluded that organic crops had higher levels of antioxidants than conventional. Since the original reviews came out, more research has been published, and some say the newer studies are designed better than earlier ones.

John Reganold, a professor of soil science and agroecology at Washington State University, authored a rigorous study published in 2010 involving organic and conventional strawberries grown by the same groups of farmers in adjacent fields. The research found that organic berries had longer shelf lives (which Reganold speculates is because organic berries develop tougher skins) and higher levels of antioxidants, vitamin C, and phenolic compounds, which may play a role in cancer prevention. Going one step further, Reganold ran a blind taste test of one variety: Panelists judged the organic berries to be sweeter and more flavorful than their conventional counterparts. 

Reganold feels that the weight of the evidence has shifted in favor of organic being more nutritious. “There have been 17 large scientific reviews of studies looking at the difference in nutrient levels between organic and conventional foods,” Reganold says. “Fourteen out of the 17 say that organic usually contains more antioxidants and vitamin C.”

It is true, though, that you are likely to pay more for organic—most of the time. In a 2010 sampling taken by the USDA, organic produce costs between 7% and 60% more than conventional. But Pappas says shoppers should not assume that all organic produce is more expensive. To prove his point, he led me to a table heaped with 5-pound bags of red potatoes. Organic spuds grown in a town a few miles up the road cost $3.49; conventional ones trucked in from hundreds of miles away were $4.69, a 34% difference. And the future looks promising for organic produce shoppers. “We’re starting to see price competition between local and organic growers,” says Pappas. “Not so a few years ago.”

Tastier Is a Sign of Healthier

Credit: Marcus Nilsson

Marion Nestle, the Paulette Goddard professor of nutrition, food studies, and public health, emerita at New York University and author of the book Food Politics, feels that the debate over nutrient levels in organic versus conventional produce misses the bigger point: We should all eat more produce. The USDA says adults should eat between 2 and 3 cups of vegetables each day; it makes no distinction between organic and conventional vegetables. “They say ‘eat your veggies,’” Nestle says. “That’s the most important thing. Venturing into the debate about nutrition and organics is a complicated argument. Nutrition is not what organics is all about. It’s about the earth and the environment—erosion, depletion of topsoil, biodiversity loss, greenhouse gas emissions. You should buy organic because it is kinder to the planet. But taste—that reflects what’s going on in the plant.”

Toward the end of my visit to City Market, Pappas and I stood before a veritable cornucopia of organic and conventional tomatoes from Mexico, the United States, and Canada: lumpy heirlooms in reds, yellows, purples, and even green-and-white stripes; picture-perfect, perfectly round hybrid slicers; salad tomatoes; grape tomatoes; plum tomatoes; and cherry tomatoes. Off to one side, I saw a lonely stack of clear plastic clamshell containers filled with a colorful medley of cherry-size tomatoes labeled “Little Guys” that were grown and shipped in-state. I bought a box of Little Guys and went out to my car to retrace the journey my tomatoes had taken. 

About two hours later, I found myself inside one of the two large greenhouses that Dave Chapman operates at Long Wind Farm in East Thetford, Vermont, near the New Hampshire border. Each of the structures could shelter a soccer field. This one was filled floor to ceiling with lush, green tomato vines laden with fruit, not only the colorful Little Guys I’d encountered in City Market but also several rows of larger slicing tomatoes.

Chapman has been farming organically for nearly four decades, supplying Wegmans, Whole Foods Market, and other grocers in the northeast. His own trucks deliver directly to stores, assuring that his produce arrives within two days. “The varieties I grow don’t produce high yields,” he says. “But they taste good. Consumers should trust their taste buds.”

I decided to do just that. On the way home, I stopped at a chain supermarket and picked up a package of tomatoes that looked similar to Chapman’s Little Guys, except they had been imported from Mexico. The foreign tomatoes cost $5.99 per container, exactly one dollar less than Chapman’s. Back in my kitchen, I assembled an unscientific tasting panel consisting of my wife and stepdaughter. They both frowned at the utterly flavorless conventional tomatoes. But after tasting the Little Guys, they nodded: “That tastes like a tomato.” 

Given the sad gustatory state of today’s supermarket tomato, I interpreted this as high praise. And well worth the extra buck.