All About Tomatoes (And Asking The Right Questions)
I generally do not read the food columns in the newspaper. Though a recipe may highlight a seasonal food, many of the other ingredients are not seasonal, fresh, local, or easily affordable. But last week my attention was grabbed by a column in a leading newspaper asking: How Healthy Are Tomatoes? Curious as how a short article basically introducing recipes would cover the enormous topic, I read on. But the article was typical of what I often see in terms of health information... generalizations, statements lacking data and incomplete information. As I looked into this further, I realized it was a good example (or perhaps more accurately a bad example) of a general problem. Everyone seems to have their own truth these days but for health and scientific information I want accuracy. I want the hard science. And so should you.
When I need to do some fact checking, I have two sources I go to before all others. I look for the most recent peer reviewed publications in PubMed from the NIH National Library of Medicine. And I check with Nature Publishing, which has multiple peer-reviewed international, interdisciplinary journals of high quality. There may be a pay wall, but abstracts are free and can give a good summary of the work. On a regular basis, I recommend subscribing (it's free) to Nature Briefing, which has a daily summary of the up-to-the-minute findings on the latest science news.
And now about those tomatoes...
In the article three reasons were given as to what makes a tomato healthy. 1. They're hydrating. 2. Their lycopene may help protect against cancer. 3. They are abundant in vitamins and minerals. This may be accurate. But how accurate and complete? And under what conditions? The answers are not so simple.
A fresh, right off the vine tomato is, in fact, one of the most hydrating fruits (and a tomato is, technically, a fruit). But it is not as hydrating as a glass of water, which is far more readily available to most people. Practically speaking, I need at least eight cups of water daily. I don't think I can eat the equivalent—ten tomatoes—each day. Then there is the matter of lycopene, a carotenoid, the pigment which gives red tomatoes their color. The amount of lycopene in a tomato is dependent on the genetics—some red varieties have more than others, and only the red varieties. After that the amount of lycopene, if there is any in the tomato, depends on how the tomato was grown, the amount of sunlight, how and when the fruit was harvested, how it was stored and shipped... and how it was prepared. Even the fluctuation of the surface temperature of the growing fruit is a factor; the biosynthesis of lycopene in tomatoes is sensitive to any change in temperature. (And, honestly, it is a lot more complicated than that.) And here is the tricky part... it turns out that lycopene may help only with certain cancers, particularly prostate and gastric cancers. I could not find a recent study. NIH says that there is simply not enough data. A current (2025) article in Frontiers in Nutrition said although there are several meta-analyses in this area, we found no meta-analysis that considered all the exposures (tomato intake, dietary and blood levels of lycopene) together and the risk of cancer incidence/mortality.
The issue of the amounts of vitamins and minerals in a tomato is the same as the presence and amount of lycopene; there are many factors which control the kind and amount of nutrition in a tomato. In fact, the answer as to whether a tomato is healthy is it depends... It depends on a complex interplay of genetics, farming practices, the weather, and the environmental conditions. These are what determine if the tomato is healthy. Here are some of the considerations: There is a nutritional difference between a just-picked mature tomato from the vine and one shipped from across the continent, picked while green and gassed to turn red. And mature or not, the health benefits depend on whether the tomato was greenhouse grown or field grown, whether it was grown in a healthy soil community with lots of organic matter, the distance and length of time in transport, whether it was stored in energy-intensive refrigeration units or left sitting outside for hours in the sun on a loading dock and whether it was sealed in plastic and then how long it sat on the grocer's shelf before being purchased. And then, the preparation is important; whether it was eaten raw or cooked—and with what. All those factors affect the health benefits. (As they do all our food.) And there are a slew of questions about commercial canned tomatoes and tomato sauce versus homemade and homegrown.
And then there are the environmental costs. For whom is the tomato a healthy choice? The consumer? The agricultural worker? The environment? Agriculture accounts for 25% to 30% of global anthropogenic emissions—and my guess is that is a low estimate. Tomatoes from anywhere but immediately local, tomatoes grown with commercial fertilizers, tomatoes in greenhouses—especially if those greenhouses are made of plastic—tomatoes packed in plastic film... are part of those emissions. And when we look at the environmental damage, even from most field-grown tomatoes one has to factor in deforestation, soil degradation, habitat loss, as well as forced labor (yes, in the U.S. and Europe) and illness to farm workers using pesticides.
I think the question which needs asking is what makes for a healthy tomato? A little research found that a comparison of vine-ripened field tomatoes (and I would especially highlight the tomatoes of the small farmer working without machines, the allotment and backyard gardener, the community garden, the local CSA) with gassed tomatoes shipped as unripe fruit... showed significant differences in the metabolic profiles of fruits ripened on-and off-the-vine. The contents of metabolites involved in primary metabolism, and conferring the palatable properties of fruits, are altered when fruits are ripened off-the-vine. The consequence of this is the inferior quality of tomato fruits ripened off-the-vine due in part to the lower levels of fructose and glucose sucrose, which are involved in conferring the sweet taste to fruit, together with aspartate and glutamate, both implicated in UMAMI taste, and other compounds present at low concentrations. When tomatoes have been picked green and gassed with ethylene to make them red, they are simply not as delicious nor nutritious.
There is not enough information yet on the degradation and microplastics from the infinite variety of plastics used in greenhouse and polytunnel coverings, in containers, and food wrapping. They all breakdown. Very few are responsibly recycled. And as they are byproducts of petroleum their extraction and creation involve not just greenhouse gas emissions and ecosystem destruction, but intensive energy for refining. Preliminary research speculates that microplastics have the potential to be absorbed by plants, enter the human body through the food chain and pose a threat to human health. In addition, the large specific surface area of microplastics enabled them to become carriers of other pollutants (e.g. heavy metals, pesticides and antibiotics), causing combined pollution to the soil ecological environment. And right now, any high-tech greenhouse-grown food and any plastic-covered structure for growing plants has a large environmental impact. While these systems have clear productivity advantages, there are outstanding questions around their overall sustainability that merit evaluation. Compared to open-field production, high-tech greenhouses resulted in 6.4 times yield per unit area with 231 times energy, 18 times greenhouse gas, and 0.74 times water footprints (per unit of fresh tomato mass).
This is about informed decisions every one of us can make and taking responsibility for our actions. This is about choice. We are not powerless. Every time we make a purchase, especially with our food, there are consequences to our health and the health of our environment. This is becoming an increasingly important issue now that so much of our food arrives at the store embalmed in plastic. We can vote with our wallets. Our votes count. It is essential that we be informed. And really, this is not about tomatoes. Regardless of who might think they are in control of the government, we can take control of our health, of the health of our neighborhood, of the health of our farmland and forest. If the supermarket does not offer healthy choices, we can volunteer at a food bank, at a food coop, at a community garden. (Bring the kids along, what a great opportunity for them.) We can choose what we buy and what we won't buy based on a small amount of research. We all have a well-informed personal shopper in our hand. We can inform ourselves.
Of course, my bias, my suggestion is always the same; that we unplug from buying and we all borrow, rent, or buy a small piece of land to protect and grow our own food. But almost all of us could grow tomatoes in a sunny window, on a balcony, on the roof of our building, in a community garden, in a friend's backyard. (Even in winter. They are perennial plants in their country of birth.) I have grown many varieties since I lived on the 19th floor of a New York City apartment with a south facing window. To be clear, there is some irony in my realization that my favorite tomato is the Black from Tula variety which happily tolerates and ripens in our current 95 degree heat. Because they are grown in our compost, never sprayed, and eaten the day they are picked, they are high in vitamin C, potassium, vitamin K, and folate, low in carbs and high in fiber. I eat them drenched in olive oil. Exquisite! But there is little to no lycopene happening in these tomatoes, whether or not it may be helpful for my prostate gland :-). I will get the lycopene from our watermelons, another of numerous foods rich in the carotenoid. It may have almost as much lycopene as a tomato.
But don't take my word for it. Look it up in a science journal.
Perhaps https://www.webmd.com/diet/health-benefits-lycopene or https://pmc.ncbi.nlm.nih.gov/articles/PMC8626194/
© www.thesubversivefarmer.net Sept. 1 2025
In a previous lifetime, Zia Gallina worked as a botanist for the National Parks Service, on the C&O Canal outside of Washington D.C. (lecturing on wild indigenous and naturalized medicinal and culinary plants). She was also an adjunct professor teaching biology and environmental science at American University, Washington D.C. But she has always been a champion of small-scale biointensive farming, tagging behind Mother Nature, trying to stay as close as she can get.
