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Know Your Nutrients: Sulforaphane

Sulforaphane belongs to
the isothiocyanate class of phytochemicals. Phytochemicals

are compounds found in plant foods that exhibit potentially therapeutic properties through anticarcinogenic, anti-inflammatory, and antioxidant actions.1 Sulforaphane is metabolized in the body from a compound called glucoraphanin, found in cruciferous vegetables such as broccoli, cabbage, cauliflower, and kale.2 Sulforaphane is a well-studied phytochemical, and the scientific literature on the compound has investigated and described its antioxidant, antimicrobial, anticancer, anti-inflammatory, anti-aging, neuroprotective, and antidiabetic capabilities.2

Antioxidant activity.

Sulforaphane has been shown to increase cellular levels of an antioxidant called glutathione, as well as certain enzymes that protect cells against oxidative stress.3

Antimicrobial activity.

Sulforaphane has demonstrated the ability to inhibit the growth of Heliobacter pylori, a common strain of bacteria, usually found in the stomach, that can lead to gastritis. Additional research has demonstrated the antimicrobial ability of sulforaphane against other gastrointestinal pathogens, including Escherichia coli, Salmonella, and Shigella, along with organisms that cause skin infections, including Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, and Cryptococcus neoformans.4

Anticancer properties.

Human studies on the effects of sulforaphane on cancer have found it to be a safe and relatively nontoxic compound for the prevention of cancer in humans.5 Many human and animal studies point to a diet abundant in cruciferous vegetables containing sulforaphane as a way to possibly prevent many cancers, including colorectal, gastric, lung, breast, prostate, bladder, and endometrial cancers.6,7 In addition, sulforaphane has been cited as a potential adjunctive to standard cancer treatments based on its ability to inhibit tumor growth and increase the sensitivity of cancer cells to chemotherapeutic agents.7

Diabetes.

In a study by Axelsson et al8 that investigated the potentially therapeutic effects of sulforaphane for people with Type 2 diabetes, researchers examined the effects of broccoli sprout extract on hepatic glucogenesis, or the generation of glucose from the liver to provide the body with energy. The liver plays an important role in maintaining glucose homeostasis, as it is the main organ for glucose storage and endogenous production.10 Abnormal increases in glucose production from the liver significantly impairs glucose homeostasis and is described in the literature as a central disease mechanism in people with Type 2 diabetes.9 Axelsson et al first treated hepatic cells from rats with sulforaphane and found that glucose production was decreased by 41 percent in the treated cells. Next, the team tested the compound in mice and rats with glucose intolerance induced by a high-fat or high-sugar diet and found that sulforaphane suppressed glucose production in the liver to a similar degree as metformin, a prescription drug that is widely used for blood sugar control. The research team then moved on to a human study, in which they administered broccoli seed extract or a placebo to 97 patients with Type 2 diabetes, 37 of which were classified as having poorly controlled diabetes. After 12 weeks, the team observed reduced fasting blood glucose levels and hemoglobin A1c in the portion of the patients with poorly controlled disease. With further research, investigators are optimistic that sulforaphane can become a formidable treatment tool for patients with Type 2 diabetes.10

Cardiovascular benefits.

A study by Shehatou and Suddek11 conducted on rabbits found that sulforaphane was effective in halting the progression of atherosclerotic lesions (i.e., buildup in the arteries) induced by a high- cholesterol diet; the authors of this study and others similar to it attribute these cardiovascular benefits to sulforaphane’s antioxidative and anti- inflammatory actions.12

Should I supplement?

The benefits of sulforaphane have not gone unnoticed by supplement companies. Unsurprisingly, a search for the compound on Google returns a long list of sulforaphane supplement options that range in price from $4
to $60. However, as always, we here at NHR suggest prioritizing food over supplements in order to get your fill of healthy compounds and micronutrients, and sulforaphane is abundantly available in cruciferous vegetables, such as broccoli, cabbage, cauliflower, and kale.

Increasing absorption.

In order to increase the bioavailability of sulforaphane in broccoli and other cruciferous vegetables, research suggests cooking your vegetables versus eating them raw, as sulforaphane has actually been shown to become more bioavailable in broccoli after being lightly cooked for two minutes in a microwave. However, the same research found that bioavailability drops after being microwaved for five minutes.13,14

Interestingly, adding mustard or mustard powder to your broccoli has been shown to be an incredibly effective method for increasing sulforaphane’s bioavailability even further. As mentioned previously, sulforaphane is metabolized from a compound called glucoraphanin found in cruciferous vegetables. In addition, a compound called myrosinase must be present for this process to occur. Myrosinase is found in broccoli, but is reduced during cooking. Mustard seed is a rich source of myrosinase, and adding mustard or mustard seed to broccoli after cooking has been shown to increase the bioavailability of sulforaphane by four times.15

While sulforaphane shows great promise as a therapeutic and preventative agent against serious conditions, such as cancer, infections, and diabetes, supplementation with sulforaphane or an increased consumption of foods containing the compound is not a substitute for professional medical attention. If you suspect you are dealing with any of these conditions, be sure to talk to your doctor.

REFERENCES

  1. Grumezescu, AM. Nutraceuticals: Nanotechnology in the Agri-Food Industry. Volume 4. Elsevier; 2016.
  2. Kim JK, Park SU. Current potential health benefits of sulforaphane. EXCLI journal. 2016 Oct 13;15: 571–577.
  3. Fahey JW, Talalay P. Antioxidant functions of sulforaphane: a potent inducer of Phase II detoxication enzymes. Food Chem Toxicol. 1999;37(9-10):973–979.

Johansson NL, Pavia CS, Chiao JW. Growth inhibition of a spectrum of bacterial and fungal pathogens by sulforaphane, an isothiocyanate product found in broccoli and other cruciferous vegetables. Planta medica. 2008 Jun;74(07):747–750.

5. Jiang X, Liu Y, Ma L, et al. Chemopreventive activity of sulforaphane. Drug Des Devel Ther. 2018;12:2905.

6. Marmot M; World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer:
a global perspective. https://www.wcrf.org/ dietandcancer. Accessed Dec 10, 2019.

7. Lozanovski VJ, Houben P, Hinz U, et al. Pilot study evaluating broccoli sprouts in advanced pancreatic cancer (POUDER trial)-study protocol for a randomized controlled trial. Trials. 2014 Dec;15(1):204.

8. Axelsson AS, Tubbs E, Mecham B, et al. Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes. Sci Transl Med. 2017 Jun 14;9(394):eaah4477.

9. Sharabi K, Tavares CD, Rines AK, Puigserver P. Molecular pathophysiology of hepatic glucose production. Mol Aspects Med. 2015 Dec 1;46:21–33.

10. Holmes D. Diabetes: Could broccoli have a role in combating type 2 diabetes mellitus?. Nature Reviews Endocrinology. 2017 Jun 30;13(8):437.

11. Shehatou GS, Suddek GM. Sulforaphane attenuates the development of atherosclerosis and improves endothelial dysfunction in hypercholesterolemic rabbits. Bull Exp Biol Med. 2016 Feb;241(4): 426–436.

12. Babu P.V.A., Petersen C., Jia Z. (2017) Sulforaphane and Atherosclerosis. In: Mérillon JM., Ramawat
K. (eds) Glucosinolates. Reference Series in Phytochemistry. Springer.

13. Rungapamestry V, Duncan AJ, Fuller Z, Ratcliffe B. Effect of meal composition and cooking duration on the fate of sulforaphane following consumption of broccoli by healthy human subjects. Br J Nutr. 2007 Apr;97(4):644–652.

14. Wieczorek MN, Jeleń HH. Volatile Compounds of selected raw and cooked brassica vegetables. Molecules. 2019 Jan;24(3):391.

15. Okunade O, Niranjan K, Ghawi SK, et al. 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 Sep;62(18):1700980. NHR

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