Health Benefits of Tomatoes


Tomatoes, which are members of a family of plants known as nightshades, were once rumoured to be poisonous, and the fact is that many fans of whole foods still regard them with some scepticism. It's true that the leaves and stems of the tomato plant actually are poisonous. Eating tomato “greens” will give you a nasty case of indigestion at the very least.

The fruit (botanically speaking, the berry) of the tomato, however, is non-toxic when eaten in moderate amounts. It is a wonderfully versatile food that comes in over 1000 different varieties, and in many different shapes, sizes, and colours. There are plate-sized Beefsteak tomatoes, and tiny red, yellow, orange or purple cherry tomatoes. Italian tomatoes look like small yellow pears, and green tomatoes are well known as tasty fried classic in American cuisine.

What Are the Key Nutritional Benefits of Tomatoes?

Tomatoes are one of the best sources of potassium. The body uses potassium to counterbalance the sodium in salt and processed foods. It is essential for “charging” cells so that they can receive oxygen, amino acids, and hormonal messengers from the bloodstream.

Tomatoes are also a good source of fructose. This sugar gets a bad rap because of the overuse of high-fructose corn syrup in soft drinks and pre-packaged foods, but small amounts of fructose, up to 25 grams (100 calories) per day can actually be beneficial. Just a little fructose, up to 10 grams (40 calories, equivalent of a large tomato) per meal helps the liver process the other important dietary sugar, glucose. Glucose prevents blood sugar levels from rising too rapidly when you eat. Tomato juice can also help athletes recover from workouts. It does this by providing fructose which is then taken up by the liver so the muscles can take up glucose to restore the glycogen, the substance that “pumps up” muscle.

The best known nutritional benefit of tomatoes, however, is being the most abundant source of the antioxidant lycopene. Unlike beta carotene, to which it is similar, lycopene does not get converted in the body to vitamin A. Lycopene can perform its unique functions longer than the other carotenoid compounds in colourful vegetables.

Tomatoes contain compounds in their peel that are beneficial to health. As soon as the fruit is formed, the tomato generates a cuticle that keeps moisture inside. This cuticle contains edible waxes called amyrins. These amyrins seem to raise the threshold of pain, help to lower anxiety levels, and reduce allergic responses. There are also amyrins that stop itching. These amyrins are not found in the waxes of other fruits or vegetables, but they are found in variable amounts in tomatoes, depending on how they were grown. A tomato that is raised under drought conditions produces more amyrins, or perhaps tomatoes from your own garden that you forgot to water on a roasting hot day.  Tomatoes that are deprived or water while they are growing produce more of these compounds compared to ones that are well watered. These amyrins stay in the peel, so you have to eat the tomato whole in order to get the benefits.

What Health Concerns Are Especially Responsive to Tomatoes?

There are well over 1000 studies on the antioxidant properties of tomatoes as recorded in scientific literature. Strong evidence supports the idea that eating tomatoes on a regular basis protects against several forms of cancer, especially prostate cancer in men.

The phytochemical alpha-tomatine, a tomato chemical that creates a slight foam in tomato juice, has been shown to prevent the changes in DNA that transform healthy prostate cells into prostate cancer cells. Alpha-tomatine also triggers a process called apoptosis, or programmed cell death, in those prostate cells that have already become cancerous, thus preventing them from multiplying and spreading further. Alpha-tomatine also interferes with the metabolism of the microorganism that causes a disease called leishimaniasis, a tropical parasitic infection that is often difficult to treat.

Another antioxidant in tomatoes, lycopene, is associated with prostate health in a different way. In addition to contributing towards the prevention of prostate cancer, it also improves “semen quality” in younger men, making sperm better swimmers, meaning they are more likely to fertilize an egg.

But tomatoes aren't just linked to prostate health. There is strong evidence that shows regular consumption of the tomato antioxidant lycopene is also linked to lower rates of breast cancer in women.  In a study of Louisiana oil field and dock yard workers – who had been exposed to asbestos – eating just one tomato per month reduced the risk of an especially aggressive form of lung cancer called mesothelioma. Other studies have found a preventive value in consuming a few servings of tomatoes every week, and that is the prevention of non-small cell lung cancer. Others studies have found that eating tomatoes reduces the risk of Hodgkin's disease.  Most studies carried out on the relationship between tomatoes and cancer, find that a single serving each day, or even less, is enough to make a positive difference.

Tomatoes have also been found useful in managing the following conditions:

HDL (Protective) Cholesterol: Mexican scientists conducted a clinical trial in which overweight women were asked to eat either two Roma tomatoes or 300 grams of raw cucumber every day for two weeks, while keeping other aspects of their diet the same. At the end of the trial, the women who ate the tomatoes had higher HDL cholesterol, 1-12 mg/dl, not a lot, but comparable to the changes after taking conventional medications.

Meat spoilage: Adding up to 10% tomato paste to meat, imparts a yellow rather than a red colour to the meat itself, and also reduces spoilage, especially in the fats of the meat. Meat dishes made with tomato paste are less likely to have a “warmed over” flavour when they are stored in the refrigerator for a few days and reheated.

Sunburn pain: When thin slices of raw tomato are placed directly over sunburnt skin it helps to relieve the pain. It's important not to peel the tomato first, since it's the peel which contains the chemicals that alleviate the hurt.

Some people are allergic to tomatoes, and, ironically, these tend to be the same people who grow and eat tomatoes fresh from their garden, which they consume several times a day. So, if you grow your own tomatoes and find yourself with a post-nasal drip, you might just have a persistent allergy to your tomatoes. Try going a few days without them to see if they are the problem.

The total antioxidant content of tomatoes isn't especially high. Pomegranates, for example, pack 30 times as much antioxidant power, and walnuts contain 60 times more antioxidants than is found in tomatoes. If you have to give up tomatoes for some reason, your general health won't necessarily suffer, although you may need to look at other ways of supporting recovery from specific conditions.

Where Do Tomatoes Fit in the Families of Fruit/Vegetables?

Tomatoes are members of the Nightshade Family (Solanaceae), which also includes potatoes (but not sweet potatoes), eggplants, peppers (but not black pepper), tomatillos, pimentos, cayenne (but not Szechuan pepper), and paprika. All of the nightshades contain small amounts of neuroactive chemicals called alkaloids; some of the nightshades that are never eaten as food actually contain sufficiently high concentrations of alkaloids which could result in serious illness or even death.

The Problem with Canned (“Tinned”) Tomatoes

Many tasty tomato products come in cans, but because tomatoes are highly acidic, cans for tomatoes have to be treated with a plasticizer chemical called BPA. This chemical is implicated in many of the hormonal disruptions plaguing the world today, including obesity, diabetes, and excessive oestrogen not just in women but also in men. Home-canned tomatoes are put up in containers that don't contain BPA, as are two excellent brands you can find commercially: Pomi Chopped Tomatoes, packaged in Italy (the word is they know a few things about tasty tomatoes!), and Bionaturae, strained tomatoes and tomato paste.

What Are the Best Ways to Eat Tomatoes Raw?

In the United States, probably the most popular way to eat tomatoes raw is as pico de gallo, literally “rooster's beak,” which is a combination of chopped raw tomatoes, chopped raw onions, and chopped hot peppers. Pureed tomatoes are made with cucumbers, bell peppers, and scallions, mixed together in a food processor with ice and served as gazpacho, a soothing summer soup. Tomatoes and spring greens, especially dandelion greens, make a detoxifying salad.

Raw tomatoes are naturally accompanied by extra virgin olive oil. The olive oil helps the tomato taste stay on the tongue long enough for grassy and leafy notes to be registered.

The best tomatoes for eating raw are those that have the most vibrant colours, namely the deepest reds, the darkest blacks and purples, the brightest oranges, and vibrant yellows. Tomatoes should be firm to the touch, and show no cracks or discoloration. Obviously you can eat tomatoes with minor imperfections, since a little cutting, coring, and trimming, may make the fruit aesthetically and nutritionally acceptable, but why not buy the best tomatoes you can find?

Tomatoes stop ripening when they are refrigerated. If you buy a tomato that is not fully ripe, you need to leave it on the counter, but out of direct sunlight, and at room temperature until it is ripe enough to eat. Once a tomato is fully ripened, then it is OK to place it in refrigeration. The juices of the tomato will retreat into the pulp when it is cooled, so it is best to allow the tomato to come back to room temperature before serving it. If you want a tomato to ripen faster, place it in a brown paper bag with a banana or apple. The other fruit will give off ethylene gas which accelerates the ripening process.

Most of the aroma of a tomato derives from aromatic compounds in its peel. If you eat tomatoes raw, be sure to wash but not peel them, and then serve at room temperature if at all possible. The taste compounds in the tomato are actually sensed in your nose, not on your tongue.

Sun-dried tomatoes are technically raw tomatoes, but they concentrate all the phytonutrients of the fruit. Sun-dried tomatoes contain 2 1/2 times as much lycopene as ketchup, five times as much lycopene as tomato juice, 15 times as much lycopene as canned tomatoes, and 22 times as much lycopene as fresh tomatoes. You can store sun-dried tomatoes in a cool place for up to three years. Note that they do not have to be packed in olive oil.

What Are the Best Ways to Eat Tomatoes in Salads?

Enthusiasts of paleo and primal diets, often combine tomatoes with boiled eggs, bacon, mayonnaise, anchovies, and olive oil. The tartness and sweetness of tomatoes complements oils and other pungent flavours such as dill, fennel, garlic, ginger, hot peppers, sweet peppers, lemon zest, mint, basil, perilla, and cheese.

What Are the Best Ways to Cook Tomatoes?

Tomatoes can react with metal cookware. Most whole foods enthusiasts avoid cooking tomatoes in aluminium pots and pans.

Tomato paste is used to impart an intense tomato flavour to casseroles and stews. Heating tomato paste in oil for one or two minutes before adding it to another dishes, caramelizes sugars and brings out flavour notes that cannot be tasted in the raw paste.

Dried tomatoes add an intense red colour to broths that are used to make soups, stews, and bean dishes. Just add chopped dried tomatoes at the beginning of cooking. If you don't chop them, they may swell to sizes that cannot be eaten easily.

And if you are still looking for great ways to use up your tomatoes, you might want to try the following:

  • Making a frittata of eggs, cheese, tomatoes, mushrooms, and basil.
  • Poaching fish in tomato broth. Salmon works especially well in this preparation.
  • Using tomatoes to flavour lima beans. Puree the beans to make an interesting starter soup.
  • Serving broiled tomatoes the way you might serve raw tomato slices, with Mozzarella or ricotta, and black pepper, salt, and basil.

We mentioned the problem with canned tomatoes earlier, but you don't have this problem if you ‘can' your own. Tomatoes are easy to “put up” because they do not have to be processed in a pressure cooker to stay sterile on the shelf. Simply place chunks of blanched tomato into clean Mason jars, seal with lids and rings, and then immerse the jars in a boiling water bath (completely covering the jar) for 10 minutes or until you hear a pop as the lid stretches all the way over the rim of the jar, whichever comes first. The acidity of the tomatoes will stop the growth of bacteria, and you will have your own safely canned tomatoes for up to three years when stored in a cool, dark place.

What Are Some Ways to Make Tomato Juice More Interesting?

Many adults find Bloody Marys a great way to make tomato juice more interesting. If you don't drink alcohol, use celery and Worcestershire sauce to complement the flavour of the juice.

There's nothing especially wrong with occasionally having a V-8, which is mostly tomato and carrot juice. However, if you make your own tomato and carrot juice, you can avoid all the salt that is required in making the canned juice beverage.

And don't underestimate the health benefits of ketchup. Dean of American storytellers and host of National Public Radio’s Prairie Home Companion, Garrison Keillor, frequently refers to an imaginary sponsor of his radio program, The Ketchup Advisory Board.

Every story line for The Ketchup Advisory Board features a dialogue between husband and wife Jim and Barb, in which they discuss the emptiness of their successful lives. In every vignette the key to spiritual satisfaction is found in ketchup, as in the following:

Jim: All you really need is ketchup. Ketchup fills that emptiness between the burger of our heart and the spiritual bun. It has natural mellowing agents that make you realize that, for people in our situation, we’re doing pretty well. This is as good as it gets.

Barb: Oh, Jim!

Singer offstage: These are the good years so let us all give thanks.

We have a roof above our head, even though it is the bank’s!

Life is flowing like ketchup on your franks.

Announcer: Ketchup. For the good times.

Singer: Ketchup! Ketchup!

Does ketchup really contain the “natural mellowing agents” as Keillor’s comedy troupe alludes on their show? Yes, actually, it does. In 2001, scientists at the Institut für Pharmazie und Lebensmittelchemie in Würzburg, Germany published a report on “carbohydrate-derived beta-carbolines in food.” Beta-carbolines increase the flow of tryptophan into the brain. The brain uses tryptophan to make serotonin, a mood chemical that relieves depression, thus energizing the brain to enable sensible decision making in life. Beta-carbolines do not, however, cause the brain to make so much serotonin that results in mania. The German scientists, perhaps following the lead of Garrison Keillor, found that highest concentrations of beta-carbolines are provided by ketchup, soy sauce, and fermented fish.

How Do I Get Kids to Like Tomatoes?

Kids, in general, are not overly fond of tomatoes. However, if they refuse to eat them in any form, then perhaps they have an allergy or sensitivity to them. If you see any signs that could relate to an allergy, be sure to keep their diet tomato-free for a week to see if behaviour and symptoms change.

How Long Do Tomatoes Keep?

Ideally, tomatoes are picked ripe off the vine and consumed within minutes. Before they ripen, they should be kept at room temperature. After they ripen, store them in the warmest part of the refrigerator, preferably at about 10 degrees Celsius/52 degrees Fahrenheit. If you can't eat tomatoes within one or two days of refrigeration, you can always freeze them. To freeze, blanch whole tomatoes in hot water, allow to cool down, and then slice so that they fit tightly in a freezer bag without air pockets. Once in the freezer, tomatoes will remain in good quality for two or three months, and are usually acceptable/edible even after a year.

Tips for Frugal Use of Tomatoes

If you can't consume all the tomatoes you buy, put some in the freezer (following instructions above) for later use, but make a point of always buying the best that you can find.

 

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Zareba P, Colaci DS, Afeiche M, Gaskins AJ, Jørgensen N, Mendiola J, Swan SH, Chavarro JE. Semen quality in relation to antioxidant intake in a healthy male population. Fertil Steril. 2013 Oct 1. pii: S0015-0282(13)02998-1. doi: 10.1016/j.fertnstert.2013.08.032. [Epub ahead of print].

 

 


About Andy Williams

Andy Williams has a Ph.D. in biology and a strong interest in health and nutrition. The Paleo Gut web site was created to explore the health benefits of the Paleo diet and see how it is changing lives. Also, get our free daily Paleo Gut newspaper delivered to your inbox. Please feel free to contact me and let me know about your Paleo experiences or favorite recipes.

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