Consume The 4 Glucosinolate Rich Foods To Produce The 4 Isothiocyanates In Order To Reduce the Risk Of Cancer

image_pdfimage_print

Glucosinolates are natural components of many pungent plants that occur as secondary metabolites of most of the Brassicales family, or the cruciferous vegetables.   When these vegetables are chewed, a pungent taste arises due to the breakdown products of glucosinolates.

Scientist have surmised that the pungent taste of these vegetables is a plant defense system against pests and diseases.

There are a number of vegetables, sprouts and seeds that contain glucosinolates.  Table I below is a comprehensive list:

Table 1:  Vegetables, sprouts and seeds containing Glucosinolates

White cabbage

Wasabi

Garden cress

Chinese cabbage

Broccoli

Watercress

Capers

Radishes

Horseradish

Brussel sprouts

Broccoli sprouts

Collards

Arugula

Bok choy

Cauliflower

Daikon radish

Kale

Kohlrabi

Maca root

Mustard greens

Papaya seeds

Turnip

Mustard seeds

Broccoli raab

Each vegetable, sprout and seed usually contains more than one glucosinolate.  However, certain vegetables, sprouts and seeds may contain a predominant amount of one glucosinolate.  An example is the following:

  • Broccoli and broccoli sprouts contain large amounts of glucoraphanin
  • Mustard seeds and Brussel sprouts contain a large amount of Sinigrin
  • Garden cress and cabbage contain a large amount of glucotropaeolin
  • Watercress contains a large amount of gluconasturtiin

The total number of documented glucosinolates from nature can be estimated to around 132, as of 2011.  1  For purposes of this article, we will focus on the 4 most important glucosinolates and the ones that have been the subject of the majority of medical research.  These 4 glucosinolates include:

  • Gluconasturtiin
  • Glucoraphanin
  • Glucotropaeolin
  • Sinigrin

Gluconasturtiin, also known as phenethylglucosinolate, is a widely distributed glucosinolate in cruciferous vegetables.  The name is derived from it occurrence in watercress which has the botanical name Nasturtium officinale

Glucoraphanin is a glucosinolate distributed in broccoli, Brussel sprouts, cabbage and cauliflower.  It is also found in large amounts in young sprouts of cruciferous vegetables, like broccoli sprouts.

Glucotropaeolin is a phytochemical from Tropaeolum majus, which is commonly known as garden nasturtium, Indian cress or monks cress.  It is also found in cabbage.

Sinigrin is widely distributed in the plants of the Brassicaceae such as Brussel sprouts, broccoli, horseradish and black mustard seeds.

Each of the vegetables, sprouts and seeds contain the enzyme myrosinase, which is activated when the vegetable, sprout or seeds is damaged (chopped or chewed) in the presence of water.  The glucosinolate converts to an isothiocyanate (or thiocyanate) through the enzymatic activity of myrosinase.  These isothiocyanates are the defensive substances of the plant.

Thus glucosinolates are the precursors to isothiocyanates through the breakdown of the enzyme myrosinase.  Myrosinase activity on the glucosinolate also continues in the gastrointestinal tract through intestinal bacteria which allows for some further formation and absorption of isothiocyanates.  2

Following is the list of glucosinolate precursors to isothiocyanates:

Glucosinolate precursor

Isothiocyanate

Vegetable, Sprout and Seed Source

Gluconasturtiin

Phenethyl-Isothiocyanate (PEITC)

Watercress, horseradish, cabbage, mustard

Glucoraphanin

Sulforaphane (SFN)

Brussels sprouts, cabbage, cauliflower, bok choy, kale, collards, Chinese broccoli, broccoli raab, broccoli sprouts, kohlrabi, mustard, turnip, radish, arugula, and watercress

Glucotropaeolin

Benzyl Isothiocyanate (BITC)

Cabbage, garden cress, Indian cress, papaya seeds, mustard greens, mustard seeds

Sinigrin

Allyl Isothiocyanate (AITC)

Broccoli, Brussels sprouts, cabbage, horseradish, wasabi, mustard, radish, black mustard seeds (Brassica nigra) or brown Indian mustard seeds (Brassica juncea).

Isothiocyanates and their glucosinolate precursors have been found to inhibit the development of various cancers, such as:  3  4

  • breast cancer
  • colon cancer
  • esophagus cancer
  • liver cancer
  • lung cancer
  • small intestine cancer
  • stomach cancer

There is also some evidence that higher consumption of the food sources listed in Table 1 are associated with a decreased risk of cancer.  5 

A number of prospective cohort studies have been published indicating that consumption of cruciferous vegetables on a weekly basis has been associated with a significant reduction in cancer risk.  A prospective cohort study takes a group of people who are interviewed or tested for risk factors like nutrient intake and then followed up at subsequent times to determine their status with respect to a disease or health outcome.  Three prospective studies have assessed the reduced risk of cancer and cruciferous vegetable consumption:

Feskanich D, Ziegler RG, Michaud DS, et al. Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women. J Natl Cancer Inst. 2000;92(22):1812-1823. 

Giovannucci E, Rimm EB, Liu Y, Stampfer MJ, Willett WC. A prospective study of cruciferous vegetables and prostate cancer. Cancer Epidemiol Biomarkers Prev. 2003;12(12):1403-1409.

Michaud DS, Spiegelman D, Clinton SK, Rimm EB, Willett WC, Giovannucci EL. Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort. J Natl Cancer Inst. 1999;91(7):605-613.

These prospective studies emphasize the importance of consuming as many of the foods listed in Table 1 on a weekly basis to insure the reduction of risk of various cancers.

Table 2 below lists the various foods and the corresponding glucosinolate content. 

Table 2. 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
Turnip ½ cup, cubes (65 g)
60
Cabbage, savoy ½ cup, chopped (45 g)
35
Kale 1 cup, chopped (67 g)
67
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 choy (pak choi) ½ cup, chopped (35 g)
19

Source:  Linus Pauling Institute Micronutrient Information Center –  Isothiocyanates

 


    Print This Post Print This Post