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Young broccoli sprouts may offer myriad health benefits, as they have a higher concentration of polysulfides than mature broccoli. Dougal Waters/Getty Images
  • The age-old advice to “eat your greens” because they’re good for you is backed by growing scientific evidence that green vegetables can benefit your health.
  • Greens are high in fiber, which protects digestive health, and contain various antioxidants — chemicals that help prevent cell damage.
  • These antioxidants include polysulfides, compounds that have anticancer and heart-protective effects.
  • A new study found that young broccoli sprouts may offer myriad health benefits, as they have a significantly higher concentration of polysulfides than mature broccoli.

Broccoli, kale, collards, cabbage, Brussels sprouts, and mustard greens are cruciferous vegetables or brassicas we’re told are good for us.

Scientific evidence supporting the age-old advice to eat your greens is growing, with studies showing that brassicas may help:

Moreover, new evidence suggests those health benefits may be even greater if brassicas, particularly broccoli, are eaten as young sprouts soon after germinating.

A study from Osaka University, published in Redox Biology, found that broccoli sprouts have a significantly higher concentration of polysulfides than mature broccoli five days after germination.

The health effects of brassicas are generally attributed to their organosulfur compounds, which give them their strong smell and flavor. These include glucosinolates, isothiocyanates, and polysulfides.

In this study, researchers investigated the concentration of polysulfides in broccoli sprouts during germination and growth. The study built on their previous work on polysulfide concentrations in 22 vegetables, including onions, garlic, and broccoli.

They germinated and grew the seeds in ultrapure water — water purified to ensure it contained only water molecules — at around 25 degrees Celsius. They harvested some every 24 hours, then powdered them in liquid nitrogen and stored this powder at -80 degrees Celsius.

They then used chemical analysis to determine the concentration of polysulfides at each stage of germination and growth.

During the five days of growth, although the total sulfur content of the plants was unchanged, the proportion of polysulfide increased dramatically. From less than 1% polysulfide in the seed, by day 5, the shoots had 15.5% polysulfide, an approximately 20-fold increase.

Kelsey Costa, registered dietitian and nutrition consultant for the National Coalition on Healthcare, not involved in the study, told Medical News Today:

“The research suggests that the health benefits of broccoli sprouts can be attributed, in part, to the plentiful polysulfides present in them. Sprouts are the miniature, concentrated versions of the plants they will develop into. They offer a nutrient-dense, cost-effective, quick-growing option for anyone wanting to grow their own food in a small space.”

Costa said she was not surprised by the findings, but noted, “Further research is needed to fully understand the mechanics of polysulfide production and its role in seed germination and sprout growth.”

When asked why broccoli sprouts contain more polysulfides, Dr. Lauren Blekkenhorst, postdoctoral research fellow with the Nutrition and Health Innovation Research Institute at Edith Cowan University, Australia, explained:

“Broccoli sprouts are young in their growth phase and hence more vulnerable to environmental stressors. As a result, broccoli sprouts likely have higher concentration of polysulfide compounds to protect the plant from damage.”

“As the broccoli plant matures and becomes less vulnerable to environmental stressors, the levels of these compounds decrease but are still present as the plant still needs to be protected from environmental stressors but to a lesser degree,” she added.

As well as identifying the greatly increased concentration of known polysulfides, the researchers found several unknown ones.

The authors suggest that these compounds, for which the molecular structures have yet to be determined, could lead to more developments in studying how plant nutrients may benefit human health.

Free radicals are unstable atoms that cause oxidative stress, and antioxidants are substances that break them down or prevent them from forming in the first place.

Oxidative stress causes cell damage, leading to aging and, sometimes, illness, so increasing your intake of antioxidants can help reduce this damage.

Polysulfides are just one of many plant antioxidants found in broccoli and other brassicas, as well as in garlic, which is known to have many health benefits.

Other plant antioxidants include:

“Polysulfides have gained recent attention due to their potential health benefits serving as precursors for hydrogen sulfide (H2S), an important cell regulatory molecule,” Dr. Blekkenhorst told MNT.

“While scientists still have more research to do, H2S appears to have vasodilatory, anti-inflammatory, antioxidant, and anti-thrombotic effects, protecting our cardiovascular system. […] However, understanding polysulfides and their interactions with H2S have only just begun and their mechanistic pathways are expected to be discovered in coming years,” she added.

Costa explained that broccoli sprouts’ anticancer and antioxidant activities have been extensively researched and that in vitro carcinogenesis models have demonstrated that they may help prevent cancer.

She went on to outline why they have these benefits:

“The potential therapeutic properties of polysulfides can be attributed to their ability to stimulate the production of antioxidant enzymes in the body, reduce oxidative stress, and modulate inflammatory pathways. They also have shown potential for inhibiting cancer cell growth and promoting apoptosis (cell death) in various types of cancer.”

A wide-ranging study that analyzed over 3,000 foods and supplements found that plant-based foods were the best source of antioxidants, with spices and herbs containing the most. High-antioxidant foods include:

“Broccoli sprouts seem to have the highest amounts of polysulfides but other cruciferous vegetables such as broccoli and cabbage, and allium vegetables like garlic and onion are also rich sources of polysulfides.”

— Dr. Blekkenhorst, National Health and Medical Research Council of Australia Emerging Leadership Fellow

One study, which analyzed the polysulfide content of 22 different vegetables, found that onions contained the greatest concentration, with almost 800μg of polysulfide per gram of onion. Broccoli came second, closely followed by Chinese chives and garlic.

And the good news is that cooking can increase the concentration of polysulfides in your garlic.

Since young broccoli sprouts can be eaten raw or cooked, Costa advises that it is easy to incorporate them into a balanced, healthful diet.

More evidence is that greens are good for us and should be enjoyed as part of a healthy diet.