Editor’s Note: Each month, HerbalEGram highlights a conventional food and briefly explores its history, traditional uses, nutritional profile, and modern medicinal research. We also feature a nutritious recipe for an easy-to-prepare dish with each article to encourage readers to experience the extensive benefits of these whole foods. With this series, we hope our readers will gain a new appreciation for the foods they see at the supermarket and frequently include in their diets.
The basic materials for this series were compiled by dietetic interns from Texas State University (TSU) in San Marcos and the University of Texas at Austin (UT) through the American Botanical Council’s (ABC’s) Dietetic Internship Program, led by ABC Education Coordinator Jenny Perez. We would like to acknowledge Jenny Perez, ABC Special Projects Director Gayle Engels, and ABC Chief Science Officer Stefan Gafner, PhD, for their contributions to this project.
By Hannah Baumana, Genesis Valdesb, and Candace Charlesb
a HerbalGram Assistant Editor b ABC Dietetics Intern (UT, 2015)
History and
Traditional Use
Range and Habitat
Tomato
(Solanum lycopersicum, Solanaceae) is,
botanically, a fruit. Nevertheless, in the 1893 Nix v. Hedden decision, the
United States Supreme Court classified tomatoes as a vegetable, which created
an economic advantage for US producers, because taxes were levied on vegetables,
but not fruits, imported into the US.1 The Supreme Court decided that “in the common
language of the people, whether sellers or consumers of provisions, all these
are vegetables … are usually served at dinner … and not, like fruits generally,
as dessert.”2 The tomato is a common ingredient in cuisines around
the world, and is cultivated as an annual food crop, although technically it is
classified as a short-lived perennial.3
A
member of the nightshade family, the tomato is related to the potato (Solanum tuberosum), eggplant (S. melongena), bell
pepper (Capsicum annuum), and chili pepper (C. frutescens). Tomatoes are colorful, with various
tomato cultivars producing fruit that is generally red, orange, and yellow in
different sizes and shapes. Tomato plants grow 3-10 feet in height and have a
sprawling growth habit, with hairy stems, bright green compound leaves, and
small yellow flowers.4,5 The tomato plant produces a fleshy fruit
with seeds embedded in a watery matrix that requires delicate care during
transport.6
Tomatoes
grew wild as a weed in South and Central America, and the size of the original
tomato was more comparable to the cherry tomato than the larger varieties.6,7
Aztecs and Incas were among the first to cultivate the tomato due to its
resemblance to the green tomatillo (Physalis philadelphica and P.
ixocarpa, Solanaceae),
one of their cuisine staples.4,6 After arriving in Mexico, Spanish
conquistadors were intrigued by the tomato and took seeds to Europe. The tomato
spread throughout Europe and made its way into Mediterranean cuisine during the
16th century. Today, the tomato and potato dominate the US vegetable market in
dietary intake and economic value.1
Phytochemicals and Constituents
Tomatoes
are a good source of vitamin C, vitamin A, folate, potassium, carotenoids, and
flavonoids.5 The tomato skin contains 98% of the tomato’s total
flavonol content, which includes quercetin and kaempferol. Studies have shown
that potassium and vitamin C in the diet lowers blood pressure, which is good
because high blood pressure is a risk factor for cardiovascular disease (CVD).8
Tomatoes also contain minerals including phosphorus, magnesium, molybdenum, and
calcium.5 Tomato-based products, including tomato paste, contain
these same nutrients in varying concentrations depending on how the tomatoes
were processed.9
The
fruit is dense in lycopene and several other carotenoids, including phytoene,
phytofluene, zeta-carotene, beta-carotene, gamma-carotene, and neurosporene.5
Carotenoids give tomatoes their varying colors.10 Tomatoes and tomato products are the richest sources
of lycopene in the American diet, representing more than 85% of all dietary
sources of lycopene.
Because
of its chemical structure, lycopene is one of the most potent antioxidants.11
Lycopene provides many health benefits, including reducing the risk of cellular
oxidative damage, inflammation, and modulation of cellular signaling pathways.
There is a strong correlation between lycopene/tomato product intake and the
reduction of CVD and cancer incidence.5,8 In vitro studies demonstrate
that lycopene reduces cellular proliferation induced by insulin-like growth
factors in various cancer cell lines, and protects important cellular
biomolecules, including lipids, proteins, and DNA.11 Additionally,
lycopene can suppress carcinogen-induced phosphorylation of regulatory proteins
and stop cell division in cancer cell lines, providing a mechanism to explain
putative cancer preventive effects.
Historical and Commercial Uses
The
tomato was not a popular food when introduced to Europe and was originally
grown as an ornamental plant. The Solanaceae family famously contains some plants
that are poisonous, such as deadly nightshade (Atropa belladonna) and black henbane (Hyoscyamus niger), which made many people suspicious of
the bright red fruit.4,6 Europeans overcame their fear of the tomato
by the late 18th century, but conflicting information persists in modern times
regarding tomato leaves.6,12 The leaves were believed to be as
poisonous as the fruit — once thought to be toxic as well — but scientific
literature remains undecided on the leaves’ actual toxicity to humans and
animals.12 Some chefs and home cooks have reported no adverse
effects while cooking with and consuming tomato leaves, but evidence remains
largely anecdotal on both sides.
Though
little research exists on tomato’s efficacy for skin conditions, such as acne
or sunburn, folk remedies recommend preparations of tomato mixed with other
ingredients, such as avocado (Persea
americana, Lauraceae), honey, yogurt, or lime (Citrus x latifolia, Rutaceae) juice, applied to the face or other
afflicted areas.13
As
tomato consumption spread throughout Europe, it gained more acceptance as a
versatile food, which inspired Italians to begin mass-producing and canning
tomatoes (known as pomodoro, or “golden
apple” in Italian) by the early 19th century. The US soon followed, and by the
1830s, ketchup (catsup) became the “national condiment.”4 Currently,
the tomato has a wide variety of uses and is one of the most popular vegetables
worldwide. In the US, the tomato is the most commonly consumed vegetable.1
The average American consumes nearly 18 pounds of fresh tomatoes and almost 69 pounds of processed
tomato products every year.10 The Economic Research Service of the
US Department of Agriculture estimates that of total raw tomato processing, 35%
is processed into sauces, 18% into tomato paste, 17% into canned tomatoes, 15%
into juices, and 15% into ketchup. The tomato was the first
genetically-engineered food, modified to maintain the firmness of the fruit for
longer periods of time during transport.7
Modern Research
The
tomato and tomato products have gained greater attention because of the
increasing research surrounding their antioxidant and anti-inflammatory
properties.9
Tomatoes
have a variety of nutrients and compounds that may contribute to the prevention
of CVD and certain cancers by decreasing inflammation. Recent studies have
identified lycopene as a beneficial compound that reduces inflammation and
oxidation. Oxidative stress at the cellular level leads to the damage of cell
membranes and eventually causes inflammation. The chemical transfer of
electrons of ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) prevents
damage to fat cells, therefore indirectly preventing inflammation.
Lycopene and Inflammation
Vitamin
C and vitamin E may work in combination with lycopene to increase beneficial
effects. Researchers observed a greater production of anti-inflammatory
cytokines with the combination of the three compounds (lycopene, ascorbic acid,
and alpha-tocopherol) compared to the individual compounds or a combination of
two.14 (Cytokines are chemical messengers produced by immune cells
to communicate with damaged cells and initiate immune response.) This indicates
that consuming tomato provides greater health benefits versus isolated single
compounds.
Tomato
products may also benefit overweight or obese individuals.15 After
20 days of consuming 330 mL of tomato juice daily while otherwise maintaining
their normal diet, overweight and obese women had a decrease in the
concentration of certain inflammatory factors compared to baseline and compared
to the control group, possibly decreasing the risk of inflammatory conditions
such as CVD, diabetes, and other chronic diseases.
Cancer
Chronic
inflammation is associated with an increased risk of degenerative diseases like
cancer. In healthy human subjects, dietary supplementation with lycopene for
just one week increased serum lycopene levels and reduced oxidation of lipids,
proteins, lipoproteins, and DNA, whereas subjects with diets free of lycopene supplementation
or tomato products showed low blood levels of lycopene and increased lipid
oxidation.11 Blood and tissue levels of lycopene were inversely
associated with risks of breast cancer and prostate cancer. Several
epidemiological studies have found that high intake of tomatoes/tomato products
was linked to lower incidences of gastrointestinal (GI) cancer and a 50%
reduction in cancer death rates in an elderly US population.16 In a
review of 72 epidemiological studies, 57 (79%) confirmed an inverse association
between tomato intake and risk of several different types of cancer, measured
by serum lycopene levels and predisposition to cancer.
Increased
lycopene intake from various tomato products has been shown to correlate with a
reduced risk of developing prostate cancer.11 Lycopene’s prostate
cancer-prevention benefits are thought to stem from mechanisms of inhibiting proliferation,
anti-androgen and antigrowth factor effects, and decreasing levels of oxidative
damage to DNA and T-cells.9 In fact, consumption of 10 or more
servings per week showed a 35% reduction in risk of even the most aggressive
types of prostate cancer. Epidemiological evidence confirms the relationship
between tomato/lycopene consumption and prostate cancer risks. A survey of 51,529
male health professionals between 40 and 75 years old found that consuming more
than two servings a week of tomato products resulted in a dose-dependent risk
reduction in incidence of prostate cancer. Greater risk reduction is associated
with tomato sauce consumption than with lycopene supplementation alone.9
Cardiovascular Health
More
than 70 million Americans have some form of CVD, which accounts for 38% of all
deaths in the US.9 Higher concentrations of lycopene in fat tissue
were noted to be protective against CVD. When
tomatoes/tomato products are removed from the diet, the antioxidant capacity of
plasma decreases, and then increases when they are added back. Consuming tomato
products daily for two-four weeks increases antioxidant enzyme defenses and has
been shown to reduce plasma lipid peroxides and the susceptibility of low-density
lipoprotein (LDL) to oxidation.17 In 2004, researchers reported an
inverse association for women consuming more than seven servings per week of
tomato-based products and CVD. This association was not observed with lycopene supplementation
alone.
Different
tomato products contain various concentrations of lycopene and other nutrients.
Tomato paste is one of the most lycopene-rich tomato products. A 2012 study
examined the effect of tomato paste in the endothelial function of 19 young,
healthy individuals.9 After consuming 70 g of tomato paste daily for
15 days, researchers reported that subjects experienced a significant increase
in flow-mediated dilation and a significant decrease in total oxidative stress
(TOS) compared to baseline. This may indicate that the decrease of TOS
increases endothelial function, therefore decreasing the risk of future CVD.
Bioavailability
The
bioavailability of a compound refers to the amount that is absorbed and used by
the body. Thus, increased bioavailability means increased activity and possible
benefits from that compound. Tomatoes are one of the few fruits or vegetables
whose nutrients are absorbed more readily when cooked. When tomatoes are processed,
lycopene becomes more bioavailable, especially when heat is used, which softens
cell walls in tomato tissues, and other dietary lipids are present during
processing.11,17
The
popular combination of tomatoes with olive oil may be as healthy as it is
delicious. Researchers observed subjects who consumed tomatoes in conjunction
with olive oil and those who consumed tomatoes alone.18 The results
found significantly increased plasma concentrations of lycopene in the olive
oil group. The dietary sources that deliver the most concentrated sources of
lycopene are processed tomato products including tomato juice, ketchup, paste,
sauce, and soup.19 Consuming lycopene from whole food products,
including tomatoes, instead of in supplement form, confers the benefits from
the interaction with and enhancement from different constituents.17
Nutrient Profile20
Macronutrient Profile: (Per 1 large tomato
[approx. 182 g])
33 calories 1.6 g
protein 7.08
g carbohydrate 0.36
g fat
Secondary Metabolites: (Per 1 large tomato
[approx. 182 g])
Excellent source of: Vitamin
C: 24.9 mg (41.5% DV) Vitamin
A: 1,516 IU (30.3% DV)
Very good source of: Vitamin
K: 14.4 mcg (18.0% DV) Potassium:
431 mg (12.3% DV) Molybdenum:
9 mcg (12.0% DV) Manganese:
0.21 mg (10.5% DV)
Good source of: Dietary
Fiber: 2.2 g (8.8% DV) Vitamin
B6: 0.15 mg (7.5% DV) Folate:
27 mcg (6.8% DV) Niacin:
1.08 mg (5.4% DV)
Also provides: Magnesium:
20 mg (5.0% DV) Vitamin
E: 0.98 mg (4.9% DV) Thiamin:
0.07 mg (4.7% DV) Phosphorus:
44 mg (4.4% DV) Iron:
0.5 mg (2.8% DV) Riboflavin:
0.04 mg (2.4% DV) Zinc:
0.31 mg (2.1% DV) Calcium:
18 mg (1.8% DV)
DV =
Daily Value as established by the US Food and Drug Administration, based on a
2,000-calorie diet.
Recipe: Gazpacho
Salad Adapted from The New Spanish
Table21
Ingredients:
- 2 1/2 cups day-old dense country bread diced into
1-inch cubes
- 2 garlic cloves, peeled and chopped
- 1/4 teaspoon kosher salt
- 1/4 teaspoon cumin seeds
- 3 tablespoons sherry vinegar or red wine vinegar
- 1/3 cup extra-virgin olive oil
- 1 2/3 pounds fresh tomatoes, cored and diced into
3/4-inch cubes
- 1/2 cup cucumber, seeded and diced
- 1/2 cup white onion, finely diced
- 1/2 cup seedless green grapes, cut in half
- 1/2 cup slivered fresh mint or basil (or
combination)
Directions:
- Heat
the oven to 350°F.
- Arrange
the bread cubes in a single layer on a large rimmed baking sheet and bake until
they are lightly browned, 8 to 10 minutes, stirring once. Let the bread cubes
cool to room temperature.
- Using
a mortar and pestle, mash the garlic, salt, and cumin seeds into a paste. Add vinegar
and olive oil and whisk to combine.
- Add toasted
bread, tomatoes, cucumber, onion, grapes, and herbs in a large bowl and toss to
combine. Add the dressing and toss to coat. Let the salad stand for 5 to 10
minutes before serving to allow the bread to soak up the dressing and vegetable
juices.
References
- Food Consumption
and Demand: Tomatoes. USDA Economic Research Service website. February 3, 2016.
Available at: www.ers.usda.gov/topics/crops/vegetables-pulses/tomatoes.aspx.
Accessed June 23, 2016.
- Nix v. Hedden. No. 137 (United States Supreme Court
1893).
- Van
Wyk B-E. Food Plants of the World. Portland, OR: Timber Press; 2006.
- The National Geographic Society. Edible: An Illustrated Guide to the World’s Food Plants. Lane Cove,
Australia: Global Book Publishing; 2008.
- Perveen R, Suleria
HA, Anjum FM, Butt MS, Pasha I, Ahmad S. Tomato (Solanum lycopersicum) carotenoids and lycopenes chemistry; metabolism,
absorption, nutrition, and allied health claims: A comprehensive review. Crit
Rev Food Sci Nutr. 2015;55(7):919-929.
- Murray M, Pizzorno J, Pizzorno L. The Encyclopedia of
Healing Foods. New York, NY: Atria Books; 2005.
- Green A. Field Guide to
Produce. Philadelphia, PA: Quirk Books; 2004.
- Willcox JK,
Catignani GL, Sheryl. L. Tomatoes and cardiovascular health. Crit Rev Food
Sci Nutr. 2010;1(43):1-18.
- Xaplanteris P,
Vlachopoulos C, Pietri P, et al. Tomato paste supplementation improves
endothelial dynamics and reduces plasma total oxidative status in healthy
subjects. Nutr Res. 2012;32(5):390-394.
- Canene-Adams K,
Campbell JK, Zaripheh S, Jeffery EH, Erdman JW. The tomato as a functional food.
J Nutr. 2005;135(5):1226-1230.
- Agarwal S, Rao AV.
Tomato lycopene and its role in human health and chronic diseases. CMAJ. 2000;163(6):739-744.
- McGee
H. Accused, Yes, but Probably Not a Killer. The
New York Times. July 28, 2009. Available at: www.nytimes.com/2009/07/29/dining/29curi.html?_r=2&ref=dining.
Accessed June 20, 2016.
- Khan
B. Tomato for Clear Skin. The Times of
India. April 21, 2013. Available at: http://timesofindia.indiatimes.com/life-style/beauty/Tomato-for-clear-skin/articleshow/7686230.cms.
Accessed June 20, 2016.
- Hazewindus M, Haenen
GR, Weseler A, Aalt. B. The anti-inflammatory effect of lycopene complements
the antioxidant action of ascorbic acid and a-tocopherol. Food Chem. 2012;132(2):954-958.
- Ghavipour M,
Saedisomeolia A, Djalali M, et al. Tomato juice consumption reduces systemic
inflammation in overweight and obese females. Br J Nutr. 2013;109(11):2031-2035.
- Giovannucci
E. Tomatoes, tomato-based products, lycopene, and cancer: review of the
epidemiologic literature. J Natl Cancer
Inst. 1999;91:317-31.
- Burton-Freeman
B, Reimers K. Tomato consumption and health: emerging benefits. Am J
Lifestyle Med. 2010;5(2):182-191.
- Fielding JM, Rowley
KG, Cooper P, O'Dea K. Increases in plasma lycopene concentration after
consumption of tomatoes cooked with olive oil. Asia Pac J Clin Nutr. 2005;14(2):131-136.
- Burton-Freeman B,
Sesso HD. Whole food versus supplement: comparing the clinical evidence of
tomato intake and lycopene supplementation on cardiovascular risk factors. Adv
Nutr. 2014;5(5):457-485.
- Basic
Report: 11529, Tomatoes, red, ripe, raw, year round average. USDA Agricultural
Research Service website. Available at: https://ndb.nal.usda.gov/ndb/foods/show/3223?manu=&fgcd.
Accessed June 22, 2016.
- Von Bremzen A. The New Spanish Table. New York, NY:
Workman Publishing Company; 2005.
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