Glucosinolates are naturally occurring chemicals found in cruciferous vegetables (cabbage, sprouts kale and mustard seeds).  

The term glucosinolates refer to a library of more than one hundred sulfur-containing compounds (glycosides).  

Upon hydrolysis, (addition of water) these glycosides yield isothiocyanates, thiocyanates, and indoles.

Thiocyanates and isothiocyanates block tumor production and inhibit tumor growth in a variety of body sites.

Presumably, this occurs due to plant compound's inhibition of the binding of carcinogen (active agent) to the DNA.

Several of the plants that make this library of glucosinolates are vegetables including the hundreds of varieties of cabbage, broccoli and Brussels sprouts. These are members of the genus Brassica and are considered cancer-preventive foods.

Cauliflower, kale and turnips also contain high concentrations of isothiocyanates.

Cabbage was originally used as a medicinal herb when it was first cultivated in Western Europe 3000 years ago and was a staple for the workers building the Great Wall in China.

Allyl compounds, found in plants of the genus Allium, are believed to prevent disease and increase longevity.

Foods in this group include garlic, onions, leeks and chives. Foods that have been known over the centuries to ward off insects and bacteria. This in addition to the flavor and aroma they add to meals.

These foods are effective in warding off disease and stimulates appetite due to the phytonutrients they contain.