Health Benefits of Broccoli

Broccoli has an impressive Nutrivore Score of 2833, which makes it a super nutrient-dense food! Broccoli is particularly high in beneficial phytonutrients (especially glucosinolates and antioxidant polyphenols), biotin, vitamin C and vitamin K. So, it’s no surprise that eating broccoli can improve our health. Let’s dive into the many ways eating more broccoli is good for us!

Broccoli Is a Cruciferous Veggie

Cruciferous vegetables, also called Brassicas or the cabbage family, are members of the Brassicaceae family, many of which are actually cultivars of a single species (Brassica oleracea): cabbage, Savoy cabbage, cauliflower, broccoli, Brussels sprouts, collard greens, kohlrabi, gai lan, and kale! Additional crucifers include cultivars of Brassica rapa (turnips, napa cabbage, bok choy, and rapini), horseradish, watercress, garden cress, radish, daikon, collard greens, rutabaga, and mustard greens. The term “cruciferous” comes from the Latin cruciferae, which means “cross-bearing” and refers to the shape of these plants’ flowers.

All of these veggies are powerhouses of nutrition and linked to numerous health benefits, including lower risks of all-cause mortality (general measure of health and longevity), cardiovascular disease and cancer. Cruciferous vegetables are high in dietary fiber and rich in vitamins and minerals, but even more impressive is the array of beneficial phytonutrients that crucifers are famous for (especially sulfur-containing glucosinolates).

Let’s take a look at the health benefits associated with cruciferous vegetable consumption, in general!

Cruciferous Veggies Reduce Cardiovascular Disease Risk

A study found a 22% reduced risk for total mortality and 31% reduced risk for cardiovascular disease mortality among individuals with the highest intake of cruciferous vegetables.

A 2017 systematic review and meta-analysis, which included data from 95 studies that evaluated fruit and vegetable intake, showed eating 100 grams of cruciferous vegetables per day (about 1 serving), on average, led to an 18% decrease in ischemic stroke, a 17% decrease in hemorrhagic stroke, a 16% decrease in total cancer risk, and a 12% decrease in all-cause mortality and cardiovascular disease. Wow!

A 2011 analysis of the Shanghai Women’s Health Study and Shanghai Men’s Health Study (encompassing 134,796 adults) found a 31% reduced risk for cardiovascular disease mortality and a 22% reduced risk for total mortality among individuals who ate 1 or 2 servings of cruciferous vegetables daily (average of 166 grams per day for women and 208 grams per day for men) compared to those with the lowest cruciferous vegetable intake, only 1 or 2 servings of cruciferous vegetables per week (average 28 grams per day for women and 34 grams per day for men).

A 2019 meta-analysis showed that cruciferous vegetables were some of the most important fruits or vegetables to consume on a daily basis (root vegetables and green leafy vegetables were also important, as were mixing up eating raw versus cooked vegetables). For every 100 grams of cruciferous vegetables consumed daily, risk of cardiovascular disease decreased by 11% and risk of all-cause mortality decreased by 10%.

One 2014 human trial also found that eating a high-cruciferous-vegetable diet reduced some markers of inflammation associated with several disease states (particularly the inflammatory cytokine interleukin-6 [IL-6]), pointing to one mechanism through which cruciferous vegetables reduces cardiovascular disease risk.

Cruciferous Veggies Reduce Cancer Risk

Cruciferous vegetables are a unique source of a class of phytonutrients, called glucosinolates, which are particularly well-known for their cancer prevention benefits. Glucosinolates produce isothiocyanates when the vegetable is damaged (for example, sliced, crushed or chewed), and many of these are known to upregulate genes involved in protecting against DNA damage, inflammation, and oxidative stress, as well as increase the activity of phase II detoxification enzymes (such as quinone reductase and glutamate cysteine ligase) that help remove toxic substances and carcinogens from the body.

Given these unique nutrients, it’s no surprise that a variety of prospective cohort and case-control studies have found that overall cruciferous vegetable consumption is associated with lower risk of:

• bladder cancer (up to a 20% lower risk),
• breast cancer (up to a 15% lower risk),
• colorectal cancer (up to an 18% lower risk),
• endometrial cancer (up to a 21% lower risk),
• gastric cancer (up to a 19% lower risk),
• liver cancer (up to a 27% lower risk),
• lung cancer (up to a 25% lower risk),
• ovarian cancer (up to an 11% lower risk),
• pancreatic cancer (up to a 21% lower risk), and
• prostate cancer (up to a 10% lower risk).

Yes, cruciferous vegetables are absolute rock stars when it comes to our health!

Now, let’s examine the health benefits of broccoli, specifically!

Broccoli Reduces Cardiovascular Disease Risk

Broccoli can lower LDL (the bad kind of ) cholesterol levels in people with mild or moderate cardiovascular disease risk. In two 2015 independent double-blind, randomly allocated parallel dietary intervention studies, 130 volunteers were assigned to consume either 400 grams standard broccoli or 400 grams high glucoraphanin broccoli per week for 12 weeks (broccoli was blanched and frozen). In the high glucoraphanin group, LDL cholesterol decreased by 7.1% (study 1) or 5.1% (study 2), while in the standard broccoli group LDL decreased slightly but was not significantly different from baseline. The results indicate that the reduction in LDL cholesterol is due to the activity of glucoraphanin and are of significance because at a population level, a 1% reduction in LDL cholesterol has been associated with a 1–2% reduction in risk of coronary artery disease!

In a 1986 prospective study of 34,492 postmenopausal women, the association of flavonoid intake with coronary heart disease and stroke mortality was examined. Women were followed annually for 10 years. When adjusted for age and energy intake, the results showed that broccoli very significantly reduced the risk of coronary heart disease and there was a trend towards decreased stroke mortality.

Studies on consumption of broccoli sprouts have also shown a reduced risk of developing cardiovascular problems in stroke-prone rats, while a 2004 clinical study on humans showed eating broccoli sprouts (100 grams per day) for a week reduced LDL and total cholesterol and increased HDL (the good kind of) cholesterol. Another 2017 study in humans showed daily intake of broccoli sprout extract for 12 weeks improved blood sugar regulation (reduced fasting blood levels of glucose and improved levels of glycated hemoglobin) in patients with poorly controlled type 2 diabetes and obesity (BMI > 30); the observed effects were on top of those of metformin. In another 2019 study in humans broccoli sprout ingestion (30 grams per day for 10 weeks) resulted in a reduction in the levels of inflammatory factors, IL-6 and C-reactive protein, corresponding to an increase in broccoli metabolites.

Broccoli Reduces Breast Cancer Risk

In a 2004 study looking at broccoli consumption specifically, eating more broccoli appears inversely associated with breast cancer risk in premenopausal women (based on ~10 servings broccoli consumed per month as self reported by participants).

Broccoli Improves Liver Health

In a 2016 study in mice, daily consumption of broccoli (10% by weight) showed benefit in protecting against non-alcoholic fatty liver disease and liver cancer growth. Broccoli in the diet resulted in a decrease in hepatic lipidosis (accumulation of fat in the liver) and suppression of the activation of hepatic macrophages, which promote fat build up in the liver and contribute to the progression of non-alcoholic fatty liver disease. For example, consumption of broccoli decreased hepatic CD36 expression by as much as 35%! This is important because CD36 is a major fatty acid transporter responsible for absorption of lipids into the liver. Furthermore, addition of broccoli to the diet was able to decrease liver damage and protect against both the initiation and progression of liver tumorigenesis (liver cancer). 

How Does Broccoli Mediate Health Benefits?

What is in this awesome green vegetable (or sometimes purple!) that accounts for these amazing health benefits?

Broccoli is a powerhouse of nutrition with a Nutrivore Score of 2833. A one-cup serving of raw broccoli, which is just over half a cup once cooked, is an excellent source of vitamin B7 (biotin), vitamin C, vitamin K, and phytonutrients (especially polyphenols, which are great antioxidants, and glucosinolates, which have cancer prevention properties). In fact, just one serving of broccoli (1 cup raw broccoli florets) provides 90% of the daily value of vitamin C, about three quarters of your vitamin K and 20% of your biotin. Plus, broccoli is a good source of dietary fiber, vitamin B5 (pantothenic acid) and vitamin B9 (folate)! And, eating broccoli delivers these high levels of essential nutrients for only 31 calories!

Broccoli also contains notable amounts per calorie of many other important nutrients, too, including: calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, zinc, vitamin A, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine), vitamin E, choline, and carotenoids, including beta-carotene, lutein and zeaxanthin. Yes, this dark green veggie really is a superstar!

But, the really special thing in broccoli is a class of phytonutrients called glucosinolates, which are well known for their antioxidant effects (meaning they combat free radicals) and cancer prevention benefits. Broccoli specifically contains a glucosinolate called glucoraphanin which gets converted an extra awesome phytonutrient called sulforaphane!

Broccoli Sulforaphane Reduces Cancer, Cardiovascular Disease, Diabetes, and More!

Broccoli is particularly high in the glucosinolate glucoraphanin, which gets converted to sulforaphane—a powerful antioxidant—during digestion. Sulforaphane is a health superstar!

In vitro and in vivo studies have shown that sulforaphane affects different steps of cancer development (impacts initiation of cancer, able to stop the growth of cancer cells and kills cancer cells). It reduces the effects of carcinogens through inhibition of phase I detoxification enzymes while upregulating a number of phase II detoxification enzymes (protect cells by converting carcinogens into inactive metabolites easily excreted by the body). Induction of phase II detoxification enzymes raises levels of glutathione (a powerful antioxidant) which is why broccoli helps combat diseases related to oxidative damage.

As well, sulforaphanes exhibit powerful anti-inflammatory abilities, delay progression of osteoarthritis, and exhibit cardioprotective effects.

Sulforaphanes have been shown to improve glycemic control (blood sugar regulation) in patients with obesity and poorly controlled type 2 diabetes as well as reduce hepatic gluconeogenesis. In mice and rats fed a high-fat or high-fructose diet to induce glucose tolerance, sulforaphane was able to suppress hepatic glucose production and improve glucose tolerance by a similar magnitude as metformin (first line therapy), as well as reverse the disease signature in the livers of these diabetic animals. 

Sulforaphanes have shown efficacy (in vitro and in vivo) for neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and multiple sclerosis, by activating genes and molecules with antioxidant, anti-inflammatory, and anti-apoptotic properties. They have therapeutic potential in kidney disease by stimulating the NRF2 pathway (important in protecting cells from oxidative injury). In addition, they exhibit antimicrobial activity (inhibit growth of both Gram-positive and Gram-negative bacteria) and antibacterial effects (in vitro against a range of food-borne pathogens and enteropathogenic microbes). In fact, sulforaphanes have been shown to prevent the growth of and were able to eliminate H. pylori from a human epithelial cell line (Hep-2). This is important because H. pylori is associated with gastric ulcers and enhanced risk of gastric cancer. Is there anything sulforaphanes can’t do?

Broccoli 3,3′-Diindolylmethane (DIM) Improves Estrogen

3,3′-Diindolylmethane (DIM), a metabolite of indole-3-carbinol, has been shown to have anticancer and anti-inflammatory properties as well as multiple immune stimulating and estrogen metabolism modulating effects. DIM also effects bone metabolism.

DIM contributes to a shift in estrogen metabolism. The endogenous estrogen 17β-estradiol can be converted to either 16α-hydroxyestrone (16αOHE1) or 2-hydroxyestrone (2OHE1). These are sometimes viewed as ‘bad’ and ‘good’ estrogen metabolites since 16αOHE1 acts as a breast tumour promoter while 2OHE1 does not and further inhibits angiogenesis and suppresses tumor growth. Higher urinary values for the 2:16 ratio suggest protection from breast cancer risk. In one four week study on 34 healthy postmenopausal women it was shown that for each 10 gram per day increase in Brassica consumption, there was an increase in the 2:16 ratio of 0.08 (suggests that the population would need to increase Brassica consumption by 12.5 to 75 grams per day to move 2:16 ratios to a favorable level). Furthermore, independently DIM has been shown to shift the metabolism of 17β-estradiol toward 2OHE1 and away from 16αOHE1. One 2004 study showed that supplementation with 108 mg/day of DIM increased urinary 2OHE1 levels in postmenopausal women. The overall shift in estrogen metabolism could decrease the risk of estrogen-sensitive cancers such as breast cancer but further study is required.

In one 2015 study in mice the effect of DIM on bone mass under physiological and pathological conditions was determined. Female mice received injections of 0.1 milligrams per gram DIM, twice a week for four weeks. DIM treatment significantly increased bone mass by reducing bone resorption (removal of old or damaged bone) but not by increasing bone formation. The results were consistent under both physiological and pathological (estrogen-deficient mouse model) conditions. Bone resorption may be substantially increased as a result of various diseases and in postmenopausal osteoporosis bone loss is due to diminished estrogen. As such, DIM shows potential value as a treatment for postmenopausal osteoporosis.

Other Superstar Broccoli Phytonutrients

In addition to the sulforaphane and DIM, broccoli contains many other beneficial phytonutrients. Of particular note are:

• Glucobrassicin produces indole-3-carbinol, which, when broken down, has been shown to cause cancer cell death and cell cycle arrest, along with altering estrogen metabolism.
• Gluconasturtiin, which produces phenethyl ITC when broken down, has shown a chemo-protective effect for human prostate cancer.
• Sinigrin produces allyl isothiocyanate, which has been shown as a factor that may reduce the risk of atherosclerosis and exhibits anticancer, anti-inflammatory, antibacterial, antifungal, antioxidant and wound healing effects.
• S-methyl cysteine sulphoxide (SMCSO), in addition to its metabolites, has been shown to exhibit protective effects against cancer, diabetes, and cardiovascular disease.
• Beta-carotene is know for its provitamin A activity (meaning it can be converted into vitamin A by your body), but it also is a strong immune system enhancer that neutralizes free radicals and reduces the risk of some cancers and cardiovascular disease.
• Lutein and zeaxanthin play a major role in maintaining eye health, protecting critical parts of the eye from light-induced oxidative damage. As a result, they’ve been implicated in prevention and treatment of age-related macular degeneration, protecting against cataracts and reducing the risk of retinitis pigmentosa.

Benefits of Broccoli Vitamin C

A 1-cup serving of raw, fresh broccoli delivers 90% of the daily value of vitamin C, so it’s worth discussing how this dose of vitamin C can benefit our health!

Vitamin C is an absolute rock star when it comes to our health! Vitamin C is a water-soluble vitamin with potent antioxidant activity: it’s vital for the protection of many molecules in the body (including proteins, lipids, carbohydrates, and the nucleic acids RNA and DNA) against oxidative stress, i.e., damage generated by free radicals and reactive oxygen species. Vitamin C is also involved in recycling other antioxidants, such as vitamin E (which vitamin C helps regenerate from its oxidized form), making it supportive of antioxidant status even beyond its own direct activity.

Vitamin C is also an essential cofactor for a number of enzymes — particularly those involved in collagen biosynthesis (which is essential for the health of our bones, joints, teeth, blood vessels, skin and eyes), carnitine biosynthesis, neuropeptide production, tyrosine metabolism, histone demethylation, and DNA demethylation. So, vitamin C is essential for the biological functions that rely on these enzymes, including wound healing, energy production (particularly, the transport of long-chain fatty acids into mitochondria, which carnitine plays a critical role in), the formation of neurotransmitters (including dopamine and serotonin), and the formation of catecholamines (including cortisol, epinephrine [adrenaline] and norepinephrine [noradrenaline], which is how vitamin C regulates the stress response).

Vitamin C is also involved in immunity through several avenues. In vitro, vitamin C has been shown to stimulate the production and function of white blood cells such as lymphocytes, phagocytes, and neutrophils; these cells also accumulate high levels of vitamin C as protection against oxidative damage, which is particularly important for phagocytes, since one of their roles is to release reactive oxygen species to kill pathogens (and therefore they need vitamin C to protect against self-inflicted damage!). Additionally, vitamin C stimulates cellular motility, phagocytosis (the cellular ingestion of bacteria and other particles), and chemotaxis (the chemically-stimulated movement of cells towards more beneficial environments). And, vitamin C can enhance the capacity of neutrophils to kill microbes while also stimulating the proliferation and differentiation of T- and B-lymphocytes.

Higher intakes of vitamin C are linked to lower risk of heart disease, some forms of cancer, type 2 diabetes, cataracts, age-related macular degeneration, and gout. Vitamin C can also help regulate the stress response, thereby reducing risk for depression and anxiety; and, there’s preliminary evidence that it may also help prevent Alzheimer’s disease.

Learn more about vitamin C here.

Other Great Sources of Vitamin C

Benefits of Broccoli Vitamin K

One cup of broccoli (raw) delivers 77% of the daily value of vitamin K, so it’s worth discussing how this dose of vitamin K can improve our health!

Vitamin K is actually a group of fat-soluble vitamins with a similar structure, existing in the forms K1 (phylloquinone), multiple isoforms of K2 (menaquinones), and the synthetic form K3 (menadione). It is critical for making important proteins in the body that are involved in blood clotting and metabolism, and are also central to maintaining bone and cardiovascular health. In fact, there is an inverse relationship between vitamin K intake and all-cause mortality—that means getting enough vitamin K just might mean living a longer life.

Vitamin K is most famous for its role as an essential cofactor for vitamin K-dependent proteins needed for blood coagulation, including proteins which act as pro-coagulants that prevent or stop bleeding but also counterbalancing proteins that act as anti-coagulants that inhibit blood clotting, thus safeguarding against uncontrolled clotting (which can be just as dangerous as uncontrolled bleeding!). This means vitamin K is absolutely essential for healthy blood clotting. And, although low vitamin K can increase the risk of excessive bleeding, the opposite isn’t true: even very high vitamin K intake isn’t known to cause abnormal clotting, or even possess any toxicity. Note that if you’re taking anticoagulant medications (like warfarin [Coumadin] or heparin), vitamin K can cancel out the effects of these drugs, so it’s best to seek medical advice from your doctor before increasing their habitual vitamin K intake!

Vitamin K is particularly critical for calcium metabolism, which is why it is central in maintaining bone health and protecting against bone fracture and osteoporosis—vitamin K maintains skeletal health and bone mineral density. Several bone-related proteins require vitamin K in order to carry out their functions. For example, osteocalcin (a protein secreted by bone-forming cells called osteoblasts) relies on vitamin K-dependent carboxylation in order to effectively bind calcium.

Vitamin K can also prevent cardiovascular disease, especially the formation of atherosclerotic plaque in arterial walls. One way that vitamin K improves vascular health is via a protein called matrix gamma-carboxylated glutamate protein (MGP; which is synthesized and secreted by vascular smooth muscle cells). MGP requires vitamin K to prevent calcification in soft tissue like cartilage, skin elastic fibers, and blood vessel walls — atherosclerotic plaques are deposits of calcium and fatty material in arteries and can lead to heart attack and stroke.

Vitamin K is important in regulating the Gas6 gene, which is involved in diverse cellular functions and regulates aging.  Gas6 is found throughout the body; the nervous system is its main cellular home, but it is also in the heart, lungs, stomach, kidneys, and cartilage! Defects or improper functioning of Gas6 has been linked to some serious health issues and chronic diseases, including clot formation, atherosclerosis, chronic inflammation, and cancer growth.

Overall, research shows that getting enough vitamin K helps protect cardiovascular health, including reducing vascular calcification, reducing aortal stiffness, and lowering the overall risk of developing heart disease. Higher vitamin K intake is also associated with higher bone mineral density and a reduced risk of fractures; here, it has a highly synergistic relationship with vitamin D for maintaining calcium homeostasis and bone health. And, there’s interesting but much more limited evidence that vitamin K could exhibit some anti-cancer properties, reduce inflammation, support endocrine health, and support brain function—but more research is needed in all of these areas.

Learn more about vitamin K here.

You can increase the absorption of vitamin K from broccoli by consuming it at the same time as some healthy fat. So, go ahead and roast or stir-fry your broccoli in some olive oil! As another bonus, this will help increase absorption of broccoli carotenoids like beta-carotene, lutein and zeaxanthin, as well!

Benefits of Broccoli Selenium

The health benefits of broccoli can also be attributed to the vitamins and minerals it contains at lower levels. For example, selenium found in high-selenium broccoli is unique and superior to other forms of selenium for protection against several different cancers. In a 2000 study rats fed high-selenium broccoli diets for 2 weeks showed improved protection from precancerous lesions in the colon (indicative of colon cancer). The same effects were not observed with ingestion of broccoli or selenium alone (at equivalent levels).

With all of these health benefits, broccoli can truly be considered a superfood!

Broccoli is GREAT for Gut Health!

Broccoli is extremely beneficial for gut health as are all members of the cruciferous vegetable family. But, it’s also a two-way street. Our gut bacteria help us maximize the benefits from eating broccoli!

Some of the anti-cancer properties attributed to all cruciferous vegetables, including broccoli, are mediated by the microbiota. For example, crucifers contain sulfur-containing compounds called glucosinolates that can be hydrolyzed into isothiocyanates, which have powerful anticarcinogenic effects. The cells of cruciferous veggies contain the enzyme myrosinase, which catalyzes the hydrolysis of glucosinolates to isothiocyanates. However, certain members of the human gut microbiota also have myrosinase-like activity and can metabolize glucosinolates into isothiocyanates (which is a huge boon for us, because plant-derived myrosinases can be deactivated by cooking so we can’t always rely on the veggies themselves to facilitate this conversion!). As a result, our microbiota help us obtain the benefits of cooked crucifers in particular! In fact, studies have shown that urinary excretion of isothiocyanates decreases significantly when participants are first given antibiotics and bowel cleansing, supporting the idea that our microbiota are hard at work degrading glucosinolates into their active hydrolysis products. Several Lactobacillus species, several Enterococcus species, multiple Escherichia coli strains, Bacillus cereus, Bacteroides thetaiotaonicron, Bacillus subtilis, Staphylococcus aureus, and multiple Salmonella strains have all been shown to degrade glucosinolates into isothiocyanates.

Consumption of broccoli resulted in a decrease in the abundance of Desulfovibrionaceae, which has been associated with ulcerative colitis, obesity and irritable bowel syndrome.

A number of studies looking at the effects of broccoli on the gut microbiota have been conducted. In one 2018 controlled, randomized, crossover feeding study, healthy adults spent two 18-day treatment periods eating 200 grams of cooked broccoli per day versus a control diet. Broccoli consumption significantly increased the abundance of Bacteroidetes by 10%, decreased the abundance of Firmicutes by 9%, and increased the abundance of Bacteroides by 8% relative to the control (a microbiome composition associated with healthy weight loss). Intriguingly, the changes were the most dramatic among participants with BMIs greater than 26, and this group also demonstrated associations between relative bacterial abundance and glucosinolate metabolites. Further analysis showed that broccoli consumption increased the pathways involved in endocrine system function, transport and catabolism, and energy metabolism.

In a 2017 study in rats, consumption of both raw and cooked broccoli for at least four days resulted in greater production of isothiocyanates and alterations in the cecal microflora composition. A 2020 study in rats showed some bacteria from the phyla Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria changed significantly over 14 days of broccoli feeding. A correlation between the abundance of certain gut bacteria and levels of circulating plasma metabolites relating to pathways that impact liver health was shown. Overall, the broccoli diets caused plasma metabolite changes that correlated with diversity and abundance of gut microbiota, as well as improved glutathione status. This is great news since glutathione is a powerful antioxidant which helps in protection from oxidative stress.

In a 2019 study looking at mice, feeding them diets of raw or hydrolyzed broccoli resulted in increases of myrosinase-like activity in the colon contents of the broccoli-fed groups with profound changes in composition of gut microbiota after only 4 days! Consumption of broccoli resulted in a decrease in the abundance of Desulfovibrionaceae, which has been associated with ulcerative colitis, obesity and irritable bowel syndrome. The study also showed that consuming broccoli increased NQO1 activity in the caecum and colon of mice. NQO1 is an enzyme which provides protection against oxidative stress so increased activity provides health benefits! Interestingly, when the mice were fed a control diet including a type of glucosinolate, singrin, independent of the whole vegetable no increase on myrosinase activity was observed, indicating that broccoli components, other than glucosinolate, such as fiber are required to increase myrosinase-like activities. In other words, maximum health benefits are achieved when eating whole vegetables – no surprise there!

Another 2020 study looked at the effects of broccoli leachate (concentrated powdered broccoli) on the composition and function of human fecal microbiomes of five different participants under in vitro conditions. Microbial communities cultured in vitro in the broccoli leachate (BL) media were observed to have large increases in the proportion of Lactobacillus (lactic acid bacteria) as compared to the control. The average proportion of Lactobacillus present in the initial fecal samples was 0.5% (SD ± 0.7%), while the average proportion of the 5 donors increased to 42.0% (SD ± 31.4%) after 4 cycles in broccoli media. This change corresponded with an increase in the levels of lactate and short-chain fatty acids. Members of Escherichia isolated from these fecal communities were found to bioconvert glucosinolates and S-methylcysteine sulphoxide (SMCSO) to their bioactive breakdown products, which are responsible for a host of health benefits! Research into SMCSO and its metabolic products have shown that it may exhibit protective effects against cancer, diabetes and cardiovascular disease and we’ve already talked about the plethora of health benefits associated with glucosinolates and isothiocyanates. Overall this study showed that the composition of bacterial communities and the profile of their metabolites can be directly and beneficially affected by the addition of broccoli to the diet.

Broccoli is also high in cellulose, an important type of dietary fiber. Though cellulose isn’t readily fermented, it is beneficial to the gut microbiota. When combined with resistant starch it is able to shift resistant starch fermentation throughout a greater portion of the gut, significantly increasing the concentration of butyrate (the most important and biologically beneficial short chain fatty acid) in the distal colon. The major benefit of this is increased delivery of butyrate to regions of the colon where tumors commonly occur. Cellulose also appears to decrease colon transit time and increase the relative abundance of Bacteroidaceae.

In addition, broccoli is a rich source of flavonols, including kaempferol, myricetin, and quercetin. Clostridium and Eubacterium are the main bacterial genera that metabolize flavonols. Quercetin is metabolized by our gut bacteria, forming a variety of organic acids including: phenylacetic acid, hydroxyphenyl-acetic acid, and protocatechuic acid. Thanks to our gut bacteria, a single antioxidant polyphenol can be converted into a collection of beneficial polyphenols! Quercetin has been the subject of much research and has been shown to protect animals from high-fat-diet induced metabolic and fatty liver disease by restoring a healthy balance of microbiota and reducing inflammation, as well as modulating the gut microbiota in ways that exert anti-arthritis activity. 

A Healthy Gut Maximizes Broccoli Benefits!

It is important to note that the composition of the gut also influences how much benefit we derive from eating broccoli. If the gut is lacking glucosinolate-degrading bacteria, our ability to derive isothiocyanates (and the anti-cancer effects they bring!) from cooked crucifers will diminish considerably. Likewise, harboring an abundance of fiber- and lignan-degrading bacteria allows for greater fermentation of these substrates into important metabolites like SCFAs and enterolignans. The good news is that consuming cruciferous vegetables appears to increase the abundance of bacteria that can fulfill these functions in the gut, so start eating!