Garlic And Onions Better Than Leeks In Blocking Carcinogens

July 01, 1997

University, Pa. --- In laboratory tests, garlic and onions block the formation of a potent carcinogen better than their milder cousin, the leek, a Penn State study has found.

Dr. John Milner, professor and head of the Department of Nutrition in Penn State's College of Health and Human Development, is leader of the study. He says the results are consistent with epidemiological evidence from China which shows that those who have a higher consumption of vegetables from the onion family have a reduced cancer risk.

The Penn State results are reported in the current issue (Vol. 28, No. 1) of the journal, Nutrition and Cancer, in a paper titled, "S-Allyl Cysteine Inhibits Nitrosomorpholine Formation and Bioactivation."

There is a growing body of evidence that plants from the garlic or Allium family, which includes onions, leeks and chives, are effective cancer fighters, says Milner. The Penn State study, however, is the first to show that not all Allium foods are equal in their ability to retard the formation of cancer causing compounds.

The researchers found that water extracts of garlic, deodorized garlic powder and onions each blocked the ability of two chemicals, nitrite and morpholine, to link to form N-nitrosomorpholine, a known liver carcinogen. The leeks' blocking ability, on the other hand, was minimal.

Milner says, "Since deodorized garlic powder and garlic produced comparable results, the benefits cannot relate to odor causing constituents."

N-nitrosomorpholine is a member of the nitrosamine family of chemicals, many of which are potent carcinogens. Most nitrosamines are produced naturally in the body from nitrates and nitrites in water and foods.

"Since garlic and onions can block the formation of N-nitrosomorpholine, it is likely it will reduce the formation of other nitrosamines, " Milner says.

The Penn State researchers also found that a water soluble, sulfur-containing compound found in processed garlic, called S-allyl cysteine, also depressed the formation of the carcinogen. In addition, the sulfur compound reduced N-nitrosomorpholine's ability to alter DNA, the genetic material present in cells.

Milner says, "The benefits of eating garlic and onions is more than a blocking of nitrosamine formation but is also due to blocking their subsequent metabolism."

"Well over 90 percent of nitrosamines are considered carcinogens," Milner noted, "anything you can do to counteract their effect should be important in reducing cancer risk." The study was supported, in part, with grants from the American Institute of Cancer Research and Wakunaga of America Co., Ltd.

Milner's co-authors are Mark E. Dion, who earned his master's degree at Penn State, and Melanie Agler, a Penn State undergraduate.


EDITORS: Dr. Milner can be contacted at (814) 865-0108 or on the Internet.
For other Penn State news, please visit our Home Page on the Web at:
Also browse this release at EurekAlert!, a comprehensive news server for up-to-date research in science, medicine,and engineering at

Penn State

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to