Some phytochemicals can help our bodies detoxify by making our livers more efficient. One of them, for example, is sulforaphane.
In 1992 researchers from John Hopkins University in Baltimore discovered that cruciferous vegetables and especially broccoli contained a substance referred to as glucoraphanin. It is a precursor to the natural antioxidant and cancer-inhibiting detoxifying isothiocyanate called sulforaphane.
It is a chemical that is present almost exclusively in cruciferous vegetables and with adequate levels only in fresh broccoli.
Broccoli sprouts are the richest origin of glucosinolates and isothiocyanates that boost antioxidant status, induce phase 2 detoxification enzymes in the liver, and protect animals against chemically induced cancer.
Phase 1 enzymes activate or deactivate carcinogens. Phase 2 enzymes detoxify.
For more than 20 years researchers had known that eating cruciferous vegetables induce enzyme detoxification in experimental studies. Isothiocyanate sulforaphane is identified as the principal phase 2 inducer in broccoli extracts. Sulforaphane is the most potent natural phase 2 enzyme-inducer know to science. It is also demonstrated that sulforaphane is a dose-related inhibitor of carcinogen-induced mammary tumorigenesis.
So eat broccoli, but there is a catch, it must be raw and well-chewed same as garlic. Also, broccoli sprouts contain 10–100 times the phase 2 inducer activity of mature broccoli plants. If we want to boost liver function adding raw broccoli sprouts to the salad is a good option. Supplement single-nutrient approaches to cancer prevention and detoxifying, and inflammation lowering have usually yielded worsening results. Isolated phytochemical approaches can be proven to be equally disappointing and are not recommended at least at the time being until supplemental sulforaphane is not thoroughly tested in double-blind studies on humans. So far broccoli extract which contains sulforaphane is tested with positive results. Alternatively, eat raw broccoli.
In micromoles per gram mature broccoli has 64 of sulforaphane, the number two kohlrabi 28 and cauliflower 11. Broccoli raab is just 0.13 not even worth mentioning. While broccoli, broccolini, and Chinese broccoli are closely related to cabbage, the closest kin to broccoli rabe is turnips. Also, there is no sulforaphane in frizzed broccoli in cooked broccoli in steamed broccoli, and actually, there is none in raw broccoli as well. It is only formed when something bites the broccoli flower as a defensive mechanism. Sulforaphane is a natural pesticide for insects.
The enzymes that create sulforaphane are heat sensitive but the sulforaphane itself is not. If we freeze or cook before we bite, there is nothing in it. The more we chew, the better and yes that is the taste that gives the broccoli bad raps. The same pesticide that forces the insects to spit the stuff out. Broccoli sprout taste is not that bad and can go nicely with little salad dressing or in a sandwich.
Our bodies have detoxifying enzymes not just in the liver but in the lungs and throat to help us deal with air pollutants directly before they enter the bloodstream. Some people are born with less active detox enzymes in the airways and have an allergic reaction to pollutants in the air like diesel exhaust and can have asthma attacks. These enzymes clean the pollutants from the air which enter our lungs and lowers the inflammation. The estimate was that 15-20 percent of the general population has some of the defective enzymatic functions in air pathways making them prone to allergic reactions and asthma. Short-term ingestion of broccoli sprout homogenates has been shown to reduce nasal inflammatory responses to oxidant pollutants (1). There are the same enzymes in our air pathways that exist in the liver. So the sulforaphane increases the effectiveness of our lungs too not just the liver. C reactive protein (inflammation marker) can be elevated 20 years after quitting but with feeding people raw broccoli (250 grams a day) like in the above study plasma CRP level decreased 48% after ten days.
In this study (2) they discovered that sulforaphane induces mucosal phase 2 enzyme expression in the upper airway of human subjects and confirms the effect of phase 2 enzyme initiation in the airway as a method to decrease the inflammatory impacts of oxidative stress. How much more? About 100 times more detox enzyme expression.
In this study in China (3) which has the highest level of air pollution in the world broccoli extract increased the levels of excretion of benzene by 61%, and acrolein by 23% (irritant for the skin, eyes, and nasal passages). There was concern that this level of lowering inflammation response might be dangerous because it might end up lowering our inflammation response to influenza viruses too. The studies that looked into this, showed no immune suppressive effect but completely the opposite, increasing the immune effect besides lowering the inflammation. The best of both worlds.
The bottom line is to eat raw broccoli. Also, chew it well. If you want to you can add it in a green smoothie or blend it and let it sit there for some time and then use it for something maybe soup. There was one study (4) that found the addition of raw powdered mustard seeds to the heat-processed broccoli significantly increased the formation of sulforaphane. Both mustard and broccoli are from the same family of plants and have these enzymes. The researchers found out that adding a minor quantity of ground raw mustard seeds to the heat-processed broccoli significantly increased the formation of sulforaphane. The amount of sulforaphane that is formed in this way is almost identical to the amount that is formed when eating raw broccoli so if you do not dislike muster taste you can go for it. The myrosinase enzyme is found in mustard seeds in horseradish, wasabi powder, or daikon radish.
Broccoli consumption is one of those food items that offer unique benefits. There is nothing besides these detoxifying enzymes that we would not be able to find in some other food items. There are foods that are much richer in terms of antioxidant content. There are foods that are much richer in terms of micronutrient content. There are foods that are much more palatable. The only reason why you would want to incorporate broccoli into your diet is because of its unique detoxicating properties. Especially if you have asthma or allergies or you are a smoker or have some other respiratory issues. There are one more unique properties of cruciferous vegetables in general and that is that they have very strong cancer prevention abilities. They are nutritionally dense, especially kale, have lots of vitamins, minerals, antioxidants, fiber, and on top of all of that, that we can find in other food items, they have these two unique characteristics.
Glucosinolate Content of Selected Cruciferous Vegetables
| Food (raw) | Serving | Total Glucosinolates (mg) |
| Brussels sprouts | ½ cup (44 g) | 104 |
| Garden cress | ½ cup (25 g) | 98 |
| Mustard greens | ½ cup, chopped (28 g) | 79 |
| Kale | 1 cup, chopped (67 g) | 67 |
| Turnip | ½ cup, cubes (65 g) | 60 |
| Cabbage, savoy | ½ cup, chopped (45 g) | 35 |
| Watercress | 1 cup, chopped (34 g) | 32 |
| Kohlrabi | ½ cup, chopped (67 g) | 31 |
| Cabbage, red | ½ cup, chopped (45 g) | 29 |
| Broccoli | ½ cup, chopped (44 g) | 27 |
| Horseradish | 1 tablespoon (15 g) | 24 |
| Cauliflower | ½ cup, chopped (50 g) | 22 |
| Bok choi (pak choi) | ½ cup, chopped (35 g) | 19 |
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Sources:
Passages selected from a book: “Go Vegan? Review of Science: Part 1” [Milos Pokimica]
- Effect of 10-day broccoli consumption on inflammatory status of young healthy smokers. Int J Food Sci Nutr. 2014 Feb;65(1):106-11
- Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway. doi: 10.1016/j.clim.2008.10.007
- Rapid and sustainable detoxification of airborne pollutants by broccoli sprout beverage: results of a randomized clinical trial in China. Cancer Prev Res (Phila). 2014 Aug;7(8):813-823
- The potential to intensify sulforaphane formation in cooked broccoli (Brassica oleracea var. italica) using mustard seeds (Sinapis alba) https://doi.org/10.1016/j.foodchem.2012.10.119
- Current potential health benefits of sulforaphane doi: 10.17179/excli2016-485
- Prevention of Carcinogen-Induced Oral Cancer by Sulforaphane doi: 10.1158/1940-6207.CAPR-15-0290
- Sulforaphane suppresses EMT and metastasis in human lung cancer through miR-616-5p-mediated GSK3β/β-catenin signaling pathways doi: 10.1038/aps.2016.122
- Sulforaphane improves the bronchoprotective response in asthmatics through Nrf2-mediated gene pathways doi: 10.1186/s12931-015-0253-z
