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 and Stephanie Darbyb
a HerbalGram Assistant Editor b ABC Dietetics Intern (TSU, 2015)
History and Traditional Use
Range and Habitat
Broccoli is a
cultivar of wild cabbage. Wild cabbage originated along the northern and
western coasts of the Mediterranean Sea, where it became a domesticated food
crop thousands of years ago. Over time, the wild cabbage was eventually bred by
growers into distinctly different varieties or cultivars of B. oleracea, including broccoli,
Brussels sprouts, cauliflower, collard greens, and kale.1 Because B. oleracea hybridizes so easily,
taxonomy for members of this species varies depending on the source. Other
scientific names for broccoli include B.
oleracea var. italica and B. oleracea, broccoli group.
Broccoli is a fast-growing annual food crop that grows two to three feet tall
and yields broccoli crowns, or florets, within 60-150 days (growing time
primarily depends on variety and climate conditions).1 The broccoli
vegetable is usually eaten at the crown stage, which is actually the immature
flower (inflorescence) stage. When the plants remain in the field past the
crown stage and allowed to flower, they produce broccoli seeds. Broccoli
sprouts are produced when broccoli seeds are grown with light and water for
approximately 3 or 4 days.
Broccoli is characterized by its thick stalk and a crown of densely-packed
flower heads arranged in a tree-like fashion, both of which are edible.1,2
The branching nature of this vegetable allows for numerous sprouts that form
the crown. Though green broccoli is the most common cultivar, purple broccoli
and Romanesco broccoli, which has greenish-yellow heads that grow in a conical
shape, also are available on the market. If allowed to flower, broccoli
produces small yellow or white blossoms.
Phytochemicals and Constituents
Broccoli is a very nutrient-dense, low-calorie vegetable. One cup of broccoli
florets contains the same amount of protein as one cup of rice, with one-third fewer
calories.3 Broccoli is also high in vitamins C, K, and A, folic acid,
and soluble fiber. As a therapeutic food, broccoli consumption is recommended
for treating xerophthalmia, or abnormal dryness and inflammation of the
conjunctiva and cornea of the eye due to vitamin A deficiency, infantile scurvy
resulting from vitamin C deficiency, and anemia resulting from folate
deficiency.4 In a clinical study of 14 volunteers who consumed 200 g
of broccoli once a day for seven days, blood tests showed an increase in serum
concentrations of the carotenoid lutein and vitamin E. Important secondary metabolites found in broccoli include selenocysteine,
glucosinolates, and phenolic compounds. Selenocysteine is a form of selenium,
which plays a role in anticancer function by increasing glucosinolate
production.5 Glucosinolates found in broccoli are sulfur-containing compounds,
most highly concentrated in the stalks, that greatly enhance detoxification
processes in the body. Glucosinolates in turn are converted into isothiocyanates,
which have antibacterial and antifungal properties.6 Phenolic
compounds, including phenolic acids and flavonoids, are also found in
significant quantities in broccoli, particularly in the seeds and sprouts,
providing protection against free radicals and oxidative stress, and reducing
inflammation.5
A specific type of glucosinolate called glucoraphanin can further be converted
into sulforaphane, its more bioactive isothiocyanate form. It is a chemopreventive
agent that activates antioxidant enzymes and decreases inflammation.7
One study determined that glucoraphanin content varied by as much as 10-fold
among different varieties of broccoli found in supermarkets and also that the
broccoli seeds and sprouts contained much higher concentrations of
glucoraphanin (as much as 50-fold greater.)8 Broccoli sprouts
contain the highest levels of glucoraphanin, which has the valuable ability to
aid the human body in metabolizing environmental pollutants and carcinogens,
eliminating them through the urine.9
Research conducted on glucoraphanin and sulforaphane shows promising results
for subjects living in regions with heavy air pollution, such as China.10
The ability to remove toxins from the body has also opened up research into the
possibility of using glucoraphanin as a treatment for the lung disorder chronic
obstructive pulmonary disease (COPD), which can be caused by smoking or other
environmental factors.11 Sulforaphane also has an antibiotic effect on
microbes, notably Helicobacter pylori,
which causes stomach ulcers, gastritis, and can lead to gastric cancers.9
Preparation methods affect the quantity and quality of glucosinolates,
sulforaphane, polyphenols, and antioxidant activity in the broccoli plant.12
In general, boiling broccoli resulted in the largest losses of glucosinolates,
as these compounds are water-soluble. Broccoli boiled for 10 minutes lost 40%
of its glucosinolate content when compared to fresh broccoli.13 Microwaving,
steaming, or blanching for 2-5 minutes at temperatures lower than 100° C allows
for the greatest retention of glucosinolates, as well as the enzyme needed for
hydrolysis of glucoraphanin to its most active form, sulforaphane. Cutting or
chopping prior to cooking also maximized this effect.5 In some
studies, steam-processed broccoli demonstrated a higher antioxidant capacity
due to the increased bioavailability of phenols and flavonoids.5,12
Storage also plays a role: the processing necessary to produce commercial
frozen broccoli may degrade the bioavailability of sulforaphane when compared
to fresh broccoli.14
Proper selection and storage of broccoli is the key to maximizing nutrient
value. Crowns should be dark green or purple depending on the variety, and
stalks and stems should be firm to the touch. Broccoli sprouts should have
green tops and white stalks. Any yellowing or wilting indicates the loss of
nutrients.3 The crowns should be washed prior to use. Sprouts should
be washed immediately prior to use and be consumed within a few days of
purchase.
Historical and Commercial Uses
Broccoli was first cultivated in Italy and introduced to Britain, other
European countries, and North America in the 18th century.3,15 The
flower crown was traditionally used in its sprouted form, and was described as
“Italian asparagus” when it was first introduced to the American colonies.
Broccoli hybrids, such as broccolini and broccoflower, are becoming more common
in supermarkets. These hybrids fall within the same species and varietal as
broccoli, and with similar nutrient compositions of other plants in the genus Brassica.3
Broccoli has a history of medicinal use in its native Mediterranean area,
predominantly in Greece. Ancient literature provides examples of broccoli-based
treatments for gynecological disorders.16 Later, it became a panacea
for many different conditions, including gastric upset, tetanus, skin
infections, and, possibly, dropsy. (Now medically known as edema, dropsy is an
abnormal accumulation of fluid, usually in the lower extremities, caused by
cardiac insufficiency.)
In modern times, broccoli is available year-round at most supermarkets. While
it is most common to consume broccoli in its whole form, health companies and
agricultural producers are exploring the possibility of broccoli in other
forms. In an effort to reduce waste, by-products of broccoli cultivation (e.g.,
stalks and leaves) are being studied for their nutritive value and content of
bioactive compounds. Through extraction, these nutrients and bioactives add
value to otherwise wasted products, and could be used in supplements or as food
additives.17 Broccoli sprouts and broccoli seed extract are also
popular additives to nutritional beverages due to their high glucoraphanin concentrations.18
Modern Research
Broccoli sprouts are high in bioactive compounds that have been shown to
benefit patients with type 2 diabetes, various types of cancer, and
cardiovascular diseases.
In patients with type 2 diabetes, a diet that contained high levels of broccoli
sprouts could lower serum insulin levels and diminish insulin resistance.19
The high levels of sulforaphane were also shown to significantly decrease
oxidative stress, presumably through the compound’s known ability to prevent
the generation of oxidative radicals and by activating antioxidant enzymes. In
a clinical study of 81 diabetic patients, consumption of fresh broccoli sprouts
(10 g/day) for four weeks was associated with a significant reduction in serum
insulin concentrations.20 However, further studies need to be done
to determine the most effective dosage and duration of treatment.
Studies have shown that the detoxifying qualities of broccoli can reduce excess
estrogen buildup that can lead to breast cancer, fibroids, and endometriosis.21
There is also a significant correlation between consuming Brassica vegetables and reduction in the incidence of bladder
cancer.22 Studies have also shown that high levels of sulforaphane
can block cancer initiation and slow progression by modifying tumor suppressor genes.23
Lastly, indole-3-carbinol, the breakdown product of another glucosinolate in
broccoli, glucobrassicin, has been shown to reduce the growth rate of cancer
cells, increase the ability of the liver to detoxify toxic compounds, and
decrease growth of the human papillomavirus (HPV), which is linked to the
development of cervical cancer.3
Broccoli constituents exhibit significant potential for protection against the
harmful effects of environmental toxins and carcinogens, including airborne
pollutants. Studies in China have shown that glucoraphanin- and sulforaphane-rich
broccoli sprout extracts can increase detoxification of benzene and acrolein
metabolites, which resulted from human exposure to airborne pollutants.24
In vitro studies have shown that isothiocyanate compounds, particularly sulforaphane,
both inhibit Phase I enzymes and induce Phase II detoxification systems, increasing
the body’s defense mechanisms against cancer-causing compounds.25,26
Other mechanisms by which broccoli constituents exert their anti-cancer effects
include: (a) inhibiting the proliferation of cancer cells by inducing cell
cycle arrest; (b) inducing apoptosis (programmed cell death); and (c) reducing
inflammation and angiogenesis (the formation of new blood vessels, which can
feed tumor growth).
Broccoli’s cardioprotective benefits can be obtained by consuming the sprouts,
as well as the mature florets. In one clinical study, 63 patients with type 2
diabetes consumed either dried broccoli sprout powder (5 or 10 g/day) or
placebo for four weeks. Compared to placebo, broccoli sprout powder significantly
reduced LDL cholesterol levels and increased total antioxidant capacity.27
In another study in hamsters, fresh broccoli sprouts had significant effects on
cholesterol homeostasis.28
Health Considerations
There are a few considerations for consumers regarding broccoli consumption.
Since broccoli contains high amounts of vitamin K, which aids in blood clot
formation, patients taking blood-thinning agents, such as warfarin (known by
the brand name Coumadin, among others), should check with their doctor to
discuss the appropriate dosage based on their current vitamin K consumption.
This goes for other vegetables in the genus Brassica
that are also high in vitamin K.29 Broccoli can also cause bloating
and gas as a result of its sulfur-containing compounds.
Another potential adverse effect linked to the consumption of broccoli is the
risk of hypothyroidism. Broccoli contains goitrogenic compounds, or compounds
with the ability to enlarge the thyroid gland and interfere with thyroid
function.3 However, studies confirm that cooking inactivates and
diminishes the effects of these goitrogens. In addition, due to their stage in
the plant lifecycle, broccoli sprouts contain virtually no goitrogenic
compounds, so those who are taking thyroid medications can still enjoy the long
list of benefits from this whole food.30
Nutrient Profile31
Macronutrient Profile: (Per 1 cup raw broccoli, chopped)
31 calories
2.57 g protein
6 g carbohydrate
0.34 g fat
Secondary Metabolites: (Per 1 cup raw broccoli, chopped)
Excellent source of: Vitamin C: 81.2 mg (135.3%
DV) Vitamin K: 92.5 mcg (115.6%
DV)
Very good source of: Folate: 57 mcg (14.3% DV) Vitamin A: 567 IU
(11.34% DV)
Good source of: Dietary Fiber: 2.4 g
(9.6% DV) Manganese: 0.18 mg (9%
DV) Potassium: 288 mg
(8.2% DV) Vitamin B6: 0.16 mg
(8% DV) Riboflavin: 0.11 mg
(6.5% DV) Phosphorus: 60 mg (6%
DV)
Also provides: Magnesium: 19 mg (4.8%
DV) Thiamin: 0.07 mg
(4.7% DV) Calcium: 43 mg (4.3%
DV) Iron: 0.66 mg (3.7% DV) Vitamin E: 0.71 mg (3.5% DV) Niacin: 0.58 mg (2.9%
DV)
DV = Daily Value as
established by the US Food and Drug Administration, based on a 2,000 calorie
diet.
Recipe: Sesame-Ginger Steamed
Broccoli
Ingredients:
- 1 lb. broccoli, cut into florets
- 2 tablespoons mirin or sake
- 1 tablespoon tamari or soy sauce
- 1 tablespoon fresh ginger, minced
- 1 teaspoon toasted sesame oil
- Salt, to taste
- 1 teaspoon sesame seeds
Directions:
- Place broccoli, mirin or sake,
tamari or soy sauce, ginger, oil, and 1/4 cup water in a large (2- to 3-quart) sauté
pan.
- Cover and bring to a simmer over
medium heat.
- Steam 4 minutes, or until broccoli
is bright green and crisp-tender. Drain off steaming liquid, then sprinkle
broccoli with salt and sesame seeds before serving.
References
- Broccoli. New World Encyclopedia website. October 7, 2008. Available here.
Accessed February 15,
2016.
- Van Wyk B. Food Plants of the World: An Illustrated
Guide. Portland, OR: Timber Press; 2015.
- Murray M, Pizzorno J, Pizzorno L. The
Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.
- Owis AI. Broccoli;
the green beauty: a review. J Pharm Sci
& Res. 2015;7(9):696-703.
- Mahn A, Reyes A. An overview of health promoting compounds of broccoli (Brassica oleracea var. italica) and the effect of processing. Food Science and Technology
International. 2012;18(6):503-514.
- Vale AP, Santos J, Melia N, et al. Phytochemical
composition and antimicrobial properties of four varieties of Brassica oleracea sprouts. Food Control. 2015;55:248-256.
- Jang HW, Moon JK, Takayuki S. Analysis and antioxidant activity of
extracts from broccoli (Brassica oleracea
L.) sprouts. J Agric Food Chem.
2015;63:1169-1174.
- Fahey JW, Zhang Y,
Talalay P. Broccoli sprouts: An exceptionally rich source of inducers of
enzymes that protect against chemical carcinogens. Proc Natl Acad Sci USA. 1997;94:10367–10372.
- Fahey, JW. Role of Glucoraphanin:
Role of glucoraphanin/sulfurophane from broccoli and broccoli sprouts in
protection against cancer and other oxidative and degenerative diseases. Talk
presented at: IFT Annual Meeting; July 15-20, 2005; New Orleans, LA. Available here. Accessed
February 12, 2016.
- Kensler TW, Ng D,
Carmella SG, et al. Modulation of the metabolism of airborne pollutants by
glucoraphanin-rich and sulforaphane-rich broccoli sprout beverages in Qidong,
China. Carcinogenesis.
2012;33(1):101–107.
- Experimental treatment
for COPD in development [press release]. Baltimore, MD: Johns Hopkins Bloomberg
School of Public Health; April 13, 2011. Available here.
Accessed February 11, 2016.
- Choudhury SP, Khaled
KL. Estimation of antioxidant and antinutritional factors of green broccoli florets
and their effects on boiling. American
International Journal of Research in Formal, Applied & Natural Sciences.
2014;8:41-43.
- Jones RB, Frisina
CL, Winkler S, Imsic M, Tomkins RB. Cooking method significantly effects
glucosinolate content and sulforaphane production in broccoli florets. Food Chemistry. 2010;123:237-242.
- Saha S, Hollands W,
Teucher B, et al. Isothiocyanate concentrations and interconversion of
sulforaphane to erucin in human subjects after consumption of commercial frozen
broccoli compared to fresh broccoli. Mol
Nutr Food Res. 2012;56(12):1906-16.
- National Geographic Society. Edible:
An Illustrated Guide to the World’s Food Plants. Lane Cove, NSW, Australia:
Global Book Publishing; 2008.
- Broccoli and other
wonder drugs of antiquity. New Scientist.
February 15, 2012. Available here.
Accessed February 11, 2016.
- Domínguez-Perles R,
Martínez-Ballesta MC, Carvajal M, García-Viguera C, Moreno DA. Broccoli-derived
by-products--a promising source of bioactive ingredients. J Food Sci. 2010;75(4):C383-92.
- Daniells S.
Glucorphanin from broccoli is similar to DHA: we’re educating the market that
not all broccoli extracts are equal, says BPP. NutraIngredients-USA website.
July 30, 2013. Available here.
Accessed February 12, 2016.
- Bahadoran Z, Mirmiran P, Azizi F. Potential
efficacy of broccoli sprouts as a unique supplement for management of type 2 diabetes and its
complications. J Med Food. 2013;16(5):375-382.
- Bahadoran Z, Mirmiran P, Hosseinpanah F,
Rajab A, Asghari G, Azizi F. Broccoli sprouts powder could improve serum
triglyceride and oxidized LDL/LDL-cholesterol ratio in type 2 diabetic
patients: A randomized double-blind placebo-controlled clinical trial. Diabetes Research and Clinical Practice.
2012;96:348-354.
- Evans JM. An integrative approach to fibroids,
endometriosis, and breast cancer prevention. Integrative Med. 2008;7(5):28-31.
- Hashem FA, Motawea H, El-Shabrawy AE,
Shaker K, El-Sherbini S. Myrosinase hydrolysates of Brassica oleracea L. var. italica
reduce the risk of colon cancer. Phytotherapy
Research. 2012;26(5):743-747.
- Wang Z, Fan J, Liu M, et al. Nutraceuticals
for prostate cancer chemoprevention: from molecular mechanisms to clinical
application. Expert Opin Investig Drugs. 2013;22(12):1613-1626.
- Egner PA, Chen JG, Zarth AT, et al. Rapid
and sustainable detoxication [sic] of airborne pollutants by broccoli sprout
beverage: results of a randomized clinical trial in China. Cancer Prev Res (Phila). 2014;7(8):813-823.
- Munday R, Munday CM. Induction of phase II
detoxification enzymes in rats by plant-derived isothiocyanates: Comparison of
allyl isothiocyanate with sulforaphane and related compounds. Journal of Agricultural and Food Chemistry.
2004;52:1867-1871.
- Talalay P, Fahey JW, Holtzclaw WD, Prestera
T, Zhang Y. Chemoprotection against cancer by phase II enzyme induction. Toxicology Letters. 1995;82:173-179.
- Bahadoran Z, Mirmiran P, Hosseinpanah F,
Hedayati M, Hosseinpour-Niazi S, Azizi F. Broccoli sprouts
reduce oxidative stress in type 2 diabetes: a randomized double-blind clinical
trial. Eur J Clin Nutr. 2011;65(8):972-977.
- Rodriguez-Cantu LN, Gutierrez-Uribe JA,
Arriola-Vucovich J, Diaz-De La Garza R, Fahey JW, Serna-Saldivar SO. Broccoli
(Brassica oleracea var. italica) sprouts and extracts rich in glucosinolates
and isothiocyanates affect cholesterol metabolism and genes involved in lipid homeostasis
in hamsters. Journal of Agricultural and
Food Chemistry. 2011;59:1095-1103.
- Bushra R, Alsam N, Yar Khan A. Food
Drug Interactions. Oman Medical Journal.
2011;26:77-83.
- Weil, AT. Is Broccoli
Bad for the Thyroid? June 21, 2005. Dr. Weil website. Available here. Accessed February 15,
2016.
- Basic Report: 11090,
Broccoli, raw. Agriculture Research Service, United States Department of
Agriculture website. Available here. Accessed February
12, 2016.
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