Broccoli, cabbage, kale, cauliflower, Brussels sprouts and kohlrabi are all one species, Brassica oleracea. Farmers and breeders shaped a single wild plant into very different vegetables. Genetic work points to a wild relative from the Aegean, Brassica cretica, as the closest living cousin of the whole group.
Intact broccoli contains no sulforaphane, the compound behind most of the research. It holds a precursor, glucoraphanin, and sulforaphane forms from it when the enzyme myrosinase gets to work as the tissue is crushed or chewed. Heat destroys that enzyme, and in lab tests boiling stopped sulforaphane from forming. In a trial of 12 adults, 1 g of mustard powder, which brings its own enzyme, raised sulforaphane absorption from cooked broccoli more than fourfold.
Many of the sulforaphane studies below used concentrated broccoli sprout extracts, so they do not show what a plate of florets does. Your genes may also shape how bitter broccoli tastes. Variants of a taste receptor gene, TAS2R38, change how strongly people taste bitter plant compounds such as glucosinolates, though a study of 500 Danes found they did not predict how much of these vegetables people ate.
Health benefits of broccoli
The top findings from 30 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★★Slightly lower cholesterolPooled trials of Brassica vegetables like broccoli found a small drop in total cholesterol, but not in LDL. A special high-glucoraphanin broccoli, not ordinary store broccoli, lowered LDL by 5 to 7% in two trials.
- ★★May change how the body processes some drugsDiets rich in cruciferous vegetables such as broccoli raised activity of the drug-processing enzyme CYP1A2 by 20 to 40% across 23 trials. People on drugs cleared by this enzyme could see different drug levels, but the clinical importance is unclear.
- ★★Slightly eased autism symptoms in sulforaphane trialsAcross 6 randomized trials, total symptoms fell by a small amount (a standardized 0.27). These were supplements of sulforaphane, a compound from broccoli, not broccoli itself.
- ★★Higher urine markers of benzene clearanceIn people in China living with heavy air pollution, a broccoli sprout drink raised urine markers of benzene clearance by 61% in 12 weeks. A second trial found a 63% rise at the full dose only; both measured urine markers, not illness.
- ★More sulforaphane absorbed from raw broccoliMen absorbed about 37% of the sulforaphane from raw broccoli, against 3.4% from cooked. Adding 1 g of mustard powder to cooked broccoli raised sulforaphane absorption more than fourfold.
All 30 studies, strongest evidence first
Eating Brassica vegetables such as broccoli lowered total cholesterol in trials, but not LDL, triglycerides or blood sugar
Meta-analysis of 9 randomized trials (548 people) of Brassica vegetables, a group that includes broccoli, cabbage and cauliflower. Total cholesterol fell by a small amount (a standardized difference of 0.28), while LDL, HDL, triglycerides, fasting blood sugar and HbA1c did not change significantly. The authors call for more high-quality trials.
Eating 400 g a week of high-glucoraphanin broccoli for 12 weeks lowered LDL cholesterol by 5 to 7%
Two double-blind randomized trials (37 and 93 people) compared a high-glucoraphanin broccoli with standard broccoli. LDL fell 7.1% and 5.1% on the high-glucoraphanin broccoli, and 1.8% and 2.5% on standard broccoli, which was not a significant drop. This was a special variety, not ordinary store broccoli.
A daily broccoli sprout drink for 12 weeks raised urine markers of benzene detoxification by 61% in people living with heavy air pollution
Placebo-controlled trial in 291 people in rural Qidong, China, where airborne pollutants are high, using a drink with 600 µmol of glucoraphanin and 40 µmol of sulforaphane a day. Acrolein markers rose 23% and the effect held for all 12 weeks, but crotonaldehyde did not change. It measured urine markers, not illness.
A broccoli sprout drink for 10 days raised a urine marker of benzene detoxification by 63% at the full dose but not at lower doses
Placebo-controlled trial in 170 people in Qidong, China, who drank a placebo or one of three strengths of the drink. The half dose raised the benzene marker by 11.3% and the one-fifth dose lowered it by 6.4%, and neither differed from placebo. Like the study above, it measured a urine marker.
Diets rich in cruciferous vegetables raised the activity of the drug-processing enzyme CYP1A2 by 20 to 40%
Review of 23 dietary trials with a meta-analysis, using vegetables such as broccoli, Brussels sprouts and cabbage. Activity of glutathione S-transferase alpha rose 15 to 35%. The authors say people on drugs cleared by these enzymes could see different drug levels if they eat large or very changeable amounts, and the clinical importance is still unclear.
Sulforaphane, a compound from broccoli, modestly eased autism symptoms across 6 randomized trials
Meta-analysis of 6 randomized trials of sulforaphane in autism spectrum disorder. Total symptoms fell by a standardized 0.27, a small effect, while irritability and anxiety did not change significantly and side effects were similar to placebo. These were supplements, not broccoli, and the authors urge caution because of the rating tools and treatment length.
About 300 g a day of cruciferous vegetables for 2 weeks lowered 24-hour systolic blood pressure by 2.5 mm Hg compared with root vegetables
Randomized crossover trial in 18 older Australian adults with mildly raised blood pressure, testing cruciferous vegetables as a group, not broccoli alone. Daytime pressure fell 3.6 mm Hg and triglycerides 0.2 mmol/L. It was small and each diet lasted only 2 weeks.
250 g of broccoli a day for 10 days cut blood CRP by 48% in young male smokers, but other inflammation markers did not change
Crossover study in young men who smoke. The CRP drop came from a post-hoc analysis, so it needs a trial built to test it. TNF-alpha, IL-6 and adiponectin did not change, while folate rose 17% and lutein 39%.
Eating 200 g of cooked broccoli a day for 18 days shifted gut bacteria toward more Bacteroidetes
Controlled-feeding crossover trial in 18 healthy adults, who also ate 20 g of raw daikon radish a day. Compared with the control diet, Bacteroidetes rose 10% and Firmicutes fell 9%, most clearly in people with a body mass index under 26. The study did not test health effects.
Men absorbed about 37% of the sulforaphane from raw broccoli, against 3.4% from cooked
Randomized open crossover trial in 8 men who ate 200 g of crushed broccoli, raw or cooked, with a warm meal. Sulforaphane also peaked sooner after raw broccoli (1.6 hours against 6 hours). Only eight men took part.
Soup made from fresh broccoli gave about ten times more sulforaphane than soup made from commercial frozen broccoli
Randomized crossover trial in 18 healthy volunteers who ate lightly cooked soups. The authors trace the gap to the short blanching step used before freezing, which destroys the enzyme myrosinase. Human gut bacteria can also make some sulforaphane from glucoraphanin.
Adding 1 g of mustard powder to cooked broccoli raised sulforaphane absorption more than fourfold
Randomized crossover trial in 12 healthy adults who ate 200 g of cooked broccoli with or without brown mustard powder. The urine marker rose from 9.8 to 44.7 µmol per gram of creatinine. Mustard brings its own myrosinase, the enzyme that cooking destroys in broccoli.
10 g a day of broccoli sprout powder for 4 weeks lowered triglycerides and the oxidized LDL ratio in people with type 2 diabetes
Randomized trial in 81 people taking 10 g, 5 g or placebo, of whom 72 finished. Only the 10 g dose showed these effects, and HDL cholesterol was also higher on it. The trial was small and short.
Broccoli sprout extract for 12 weeks lowered fasting glucose by only 0.2 mmol/L in prediabetes, short of the 0.3 mmol/L goal
Placebo-controlled trial in 74 adults with prediabetes (35 on the extract, 39 on placebo). One subgroup had a 0.4 mmol/L drop, but that finding came from an exploratory analysis and needs a new trial. A supplier gave the extract and co-funded the study, and some authors hold patents or shares in sulforaphane companies.
70 g a day of broccoli sprouts for 8 weeks lowered markers of H. pylori infection in infected patients, but they returned after stopping
Randomized trial in 48 infected patients that compared broccoli sprouts with the same weight of alfalfa sprouts. The urea breath test, stool antigen and pepsinogens fell, then went back to their starting levels 2 months after treatment ended. It lowered markers of infection and did not clear it.
Sulforaphane from broccoli sprout extract added to antibiotics did not raise H. pylori cure rates
Randomized trial in 183 patients who took standard triple therapy alone, with a probiotic or with sulforaphane (61 in each group). In the intention-to-treat analysis, cure rates were 85.2% with antibiotics alone and 81.6% with sulforaphane. Side effects did not differ.
100 g a day of broccoli sprouts for 3 days did not reduce airway inflammation in adults with asthma
Placebo-controlled trial in 40 adults who ate broccoli or alfalfa sprouts. Blood sulforaphane rose markedly, but exhaled nitric oxide, lung function, inflammation markers and symptoms did not improve. Three days is a very short test.
A sulforaphane-rich broccoli sprout drink for 12 weeks did not change thyroid hormone levels in women
Safety check from a randomized trial of 45 women. Thyroid-stimulating hormone, free thyroxine, thyroglobulin and thyroid autoimmunity were all unaffected after 84 days. Broccoli sprout products had long been suspected of affecting the thyroid, which is why the authors checked.
Adults who ate broccoli 1 to 2 times a week had a 32 to 43% lower risk of dying than those who never ate it
US survey data (NHANES 2003 to 2006) on 12,486 adults followed for deaths. More frequent broccoli also went with lower cardiovascular and cancer mortality. Food questionnaires are imperfect, and people who eat broccoli may differ in other habits.
In an umbrella review of cruciferous vegetables, only gastric, lung and endometrial cancer and all-cause mortality had suggestive links to lower risk
Review of 41 meta-analyses covering 303 observational studies and about 13.4 million people. Sixteen more links were supported by weak evidence, and the authors say substantial uncertainty remains. It covers cruciferous vegetables as a group.
People who ate the most cruciferous vegetables had an 18% lower risk of colorectal cancer
Meta-analysis of 24 case-control and 11 prospective studies. Cabbage and broccoli analyzed on their own gave similar results. In the prospective studies alone the link was borderline, and case-control studies depend on people recalling past diet.
Chinese adults who ate the most cruciferous vegetables had a 22% lower risk of dying than those who ate the least
Two Shanghai cohorts with 134,796 adults, including 3,442 deaths among women and 1,951 among men. The link was mainly with cardiovascular deaths, not cancer deaths. It covers cruciferous vegetables as a group, from food questionnaires.
Japanese adults in the top fifth of cruciferous vegetable intake had an 11 to 14% lower risk of dying over about 17 years
Cohort of 88,184 people aged 45 to 74, with 15,349 deaths over a median 16.9 years. Lower cancer deaths showed only in men, and lower heart disease and stroke deaths only in women. It covers cruciferous vegetables as a group.
In Singapore, cruciferous vegetable intake was not linked to the risk of type 2 diabetes
Cohort of 45,411 adults with 5,207 cases. The top fifth against the bottom had a hazard ratio of 0.97 (range 0.88 to 1.06). A meta-analysis of 11 studies found a borderline link (0.87, range 0.76 to 1.00), which the authors call not convincing.
US adults who ate the most cruciferous vegetables had a 16% higher risk of type 2 diabetes
Three US cohorts with 200,907 people and 16,567 cases. Those in the top fifth for glucosinolates, the compounds sulforaphane comes from, had a 19% higher risk. The authors ask for repeat and biomarker studies, and a link is not proof of cause.
Higher intake of glucosinolates from cruciferous vegetables was linked to a 9% higher risk of coronary heart disease
The same three US cohorts, with 210,574 people and 8,010 cases. Eating Brussels sprouts once a week or more went with a 16% higher risk, and cabbage with 9%; the abstract does not single out broccoli. The authors call the link weak.
Steaming broccoli for 1 to 3 minutes increased sulforaphane yield while boiling and microwaving lost it after about a minute
Lab test on four broccoli varieties that were microwaved, boiled or steamed for different times. A heat-sensitive helper protein steers the reaction toward an inactive compound, and gentle heat removes it before it destroys the enzyme; the steaming window worked in three of the four varieties. This is lab chemistry, not a study in people.
Boiling broccoli prevented sulforaphane from forming but powdered mustard seed brought it back
Lab study of heat-processed broccoli. Boiling in water inactivated myrosinase, while sous vide cooking at 100°C for 8 and 12 minutes broke down under 12% of the glucoraphanin. Adding powdered mustard seed, which holds a more heat-resilient form of the enzyme, increased sulforaphane formation.
Boiling, microwaving and stir-frying broccoli caused significant vitamin C losses, but steaming did not
Lab comparison of five household cooking methods. Steaming kept the most glucosinolates, and stir-frying, with or without boiling, lost the most. These are measurements of the cooked vegetable, not a study in people.
Mice fed a diet with 10% broccoli had less fatty liver, but the same rate of liver cancer
Study in mice, not people. Mice given a liver-cancer-causing chemical ate a Western-style diet with or without 10% broccoli from 4 weeks to 7 months of age. Broccoli lowered liver fat, liver damage and TNF by month 5 without changing body weight, but all of the mice developed cancer.
Who should be careful with broccoli
Most people can eat broccoli freely. Take a little care if one of these applies:
- Warfarin. Broccoli contains vitamin K, which can change how this blood thinner works. You do not need to avoid it; keep the amount steady from week to week and check with your clinic before big changes.
- Irritable bowel syndrome or a gassy gut. Monash University found broccoli heads low in FODMAPs in moderate servings, while the stalks were higher in excess fructose. Heads are the safer part.
- Broccoli sprouts. The CDC advises children, older adults, pregnant women and people with weakened immune systems to avoid raw or lightly cooked sprouts of any kind. Cook them thoroughly.
How to choose, store and eat broccoli
- Raw: chewing starts the sulforaphane reaction, and 8 men absorbed about 37% of it from raw broccoli against 3.4% from cooked.
- Steamed: lab tests found steaming for 1 to 3 minutes raised sulforaphane yield and kept vitamin C. It is the gentlest method.
- Boiled or frozen: boiling loses vitamin C and stops sulforaphane forming, and soup from commercial frozen broccoli gave about a tenth of the sulforaphane of fresh. Mustard powder on cooked broccoli raised absorption more than fourfold.
Pick firm heads with tight, dark green florets and no yellowing, and keep them unwashed in a bag in the fridge for up to five days. Residues are no reason to skip broccoli: in USDA tests of 708 samples in 2021, only one had a residue above the legal limit.
Sources
- Dietary advice for patients taking warfarin. Cambridge University Hospitals NHS Foundation Trust.
- Anticoagulant medicines: considerations. NHS.
- FODMAP content of broccoli and broccolini. Monash FODMAP blog. 2017.
- Salmonella Montevideo infections linked to raw sprouts: advice to consumers, restaurants and retailers. CDC. 2018.
- Vermeulen M, Klöpping-Ketelaars IW, van den Berg R, Vaes WH. Bioavailability and kinetics of sulforaphane in humans after consumption of cooked versus raw broccoli. J Agric Food Chem. 2008.
- Wang GC, Farnham M, Jeffery EH. Impact of thermal processing on sulforaphane yield from broccoli. J Agric Food Chem. 2012.
- Yuan GF, Sun B, Yuan J, Wang QM. Effects of different cooking methods on health-promoting compounds of broccoli. J Zhejiang Univ Sci B. 2009.
- 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.
- Okunade O, Niranjan K, Ghawi SK, Kuhnle G. Supplementation of the diet by exogenous myrosinase via mustard seeds to increase the bioavailability of sulforaphane in healthy human subjects after the consumption of cooked broccoli. Mol Nutr Food Res. 2018.
- Broccoli. University of Nebraska–Lincoln Extension.
- Pesticide Data Program annual summary, calendar year 2021. USDA Agricultural Marketing Service.
History of broccoli
Broccoli took shape in Italy. Its origins lie in early cultivated forms grown in the Roman Empire more than 2,000 years ago. Plant scientists think the crop was improved in the central Mediterranean, probably in southern Italy and Sicily, and heading types of broccoli and cauliflower were recorded in 15th-century southern Italy and Sicily.
The name comes from the Italian plural of broccolo, the flowering crest of a cabbage. English speakers began using the word in the 17th century. Southern Italian types reached Britain in the 18th century, and immigrants from southern Italy later brought a type called calabrese to the United States.
In California, Sicilian brothers built a broccoli business. Andrea and Stefano D’Arrigo came from Messina and formed a produce company in 1923. Stefano noticed Italian growers near San Jose, California, growing broccoli, and planted 24 acres with seed sent by his father in Italy. According to the company, the first ice-packed broccoli went east by rail to Andrea in Boston in 1924, full rail cars followed in 1925, and in 1926 the brothers began branding it with a photo of Stefano’s small son Andy.
Broccoli did not become popular in the US until after World War II. The open-pollinated variety Waltham 29 came out in 1950, and hybrids such as Premium Crop (1975), Packman (1983) and Marathon (1985) followed. Production moved to cooler valleys on the western coast for year-round supply.
Not everyone cheered. On March 22, 1990, President George H. W. Bush said he did not like broccoli and was not going to eat any more of it. California growers answered by sending trucks of broccoli to Washington, and it was given to a food bank.
Sources
- Mabry ME, Turner-Hissong SD, Gallagher EY, et al. The evolutionary history of wild, domesticated, and feral Brassica oleracea (Brassicaceae). Mol Biol Evol. 2021.
- Stansell Z, Björkman T. From landrace to modern hybrid broccoli: the genomic and morphological domestication syndrome within a diverse B. oleracea collection. Hortic Res. 2020.
- Broccoli. Wikipedia.
- Brassica oleracea. Wikipedia.
- The Original Andy Boy. D’Arrigo Bros. Co. of California, company history.
- George H. W. Bush broccoli comments. Wikipedia.
- Lipchock SV, Mennella JA, Spielman AI, Reed DR. Human bitter perception correlates with bitter receptor messenger RNA expression in taste cells. Am J Clin Nutr. 2013.
- Gorovic N, Afzal S, Tjønneland A, et al. Genetic variation in the hTAS2R38 taste receptor and brassica vegetable intake. Scand J Clin Lab Invest. 2011.
Frequently asked questions about broccoli
Is broccoli good for you?
For most people, yes. Raw broccoli has about 91 mg of vitamin C and 2.4 g of fiber per 100 g. Adults who ate it 1 to 2 times a week had a 32 to 43% lower risk of dying in a US survey, and a high-glucoraphanin broccoli lowered LDL cholesterol by 5 to 7% in two trials. The first is a link, not proof, and no broccoli finding here reaches strong evidence.
Is raw or cooked broccoli healthier?
Neither is simply better. Men absorbed about 37% of the sulforaphane from raw broccoli against 3.4% from cooked, but lab tests found steaming for 1 to 3 minutes raised sulforaphane yield and kept vitamin C. Boiling and stir-frying lose vitamin C. If you cook it, 1 g of mustard powder on cooked broccoli raised sulforaphane absorption more than fourfold in 12 adults.
How much broccoli should you eat a day?
No study here sets an ideal amount. Trials used 200 g of cooked broccoli a day for 18 days, 250 g a day for 10 days, and 400 g a week of a high-glucoraphanin variety for 12 weeks. In the US survey, 1 to 2 times a week went with the lowest risk for men and 3 or more times for women. If you take warfarin, keep the amount steady and ask your clinic.
Does broccoli cause gas?
It can in some people, and no trial here measured gas directly. Monash University found the heads low in FODMAPs in moderate servings and the stalks higher in excess fructose. If broccoli bothers you, try smaller servings of the heads without the stalks.
Are broccoli sprouts better than broccoli?
They are different foods, and no trial here compares them head to head. The sprout studies here used sprouts, powders, drinks or extracts, and the results were mixed: a sprout drink raised air-pollutant breakdown markers by up to 63%, but 100 g a day for 3 days did not reduce airway inflammation in asthma. Raw sprouts also carry a food-safety warning for children, older adults, pregnant women and people with weakened immune systems.
Is broccoli high in protein?
Not high, but it has some. Raw broccoli has about 2.6 g of protein per 100 g, or about 2 g in a cup (76 g). Protein supplies roughly a third of its calories, so it adds to a meal without being the main source.
Is broccoli good for weight loss?
No study here tested weight loss. Raw broccoli has 31 calories and 2.4 g of fiber per 100 g, so it fills a plate cheaply. That is a swap effect for higher-calorie foods, not a proven effect of broccoli itself.
Is broccoli good for people with diabetes?
It can fit, but the evidence is mixed. In an 81-person trial in type 2 diabetes, 10 g a day of sprout powder for 4 weeks lowered triglycerides. In prediabetes, sprout extract lowered fasting glucose by only 0.2 mmol/L, short of its goal. Large cohorts disagree too: no link in Singapore, but a 16% higher diabetes risk in the US. Check portions and choices with your care team.