12/13/2014 12:10 EST | Updated 02/12/2015 05:59 EST

Do Peanuts Spread Cancer?

The first study to examine the effects of certain compounds in peanuts on the spread of cancer is about to be published -- and the results show serious consequences for most people with metastatic cancer.

Certain proteins in peanuts, called peanut agglutinin (PNA), can fuel the spread of tumors, says a research team from the University of Liverpool. PNA is a type of lectin, proteins that stick to different molecules of carbohydrates, and the molecules that PNA targets are present in most human cancer cells.

"Previous studies have shown that PNA is highly resistant to cooking and digestion and rapidly enters the human blood circulation after peanut ingestion," say the authors. There it binds to cancer cells that have spread to the blood, helping them to form clusters and to stick to the lining of blood vessels, explained Dr. Lugang Yu, one of the study's authors. Most cancers spread -- or metastasize -- to distant organs by travelling through the bloodstream.

"As metastasis accounts for the majority of cancer-associated fatality, regular consumption of peanuts by cancer patients would therefore be expected to have an adverse effect on cancer survival," the authors conclude.

The journal Carcinogenesis has just published the abstract and will soon be publishing the full study. The work was done in cell cultures and animal models and focused on cancer cells that originate in the epithelial tissues that cover organs and line body cavities. Epithelial cancers account for 85-90 per cent of human cancers. CITE

"More studies will be needed to test if peanut agglutinin will affect metastasis in cancer that is not of epithelial origin," Yu said.

But what about lectins in other foods?

Lectins are common in many foods and concentrate in seeds -- including legumes, nuts and grains. Often, they're destroyed by methods of food preparation--soaking beans for several hours, for example, and/or cooking them with wet heat at high temperatures. (Don't cook beans in a crockpot or slow cooker. The low heat won't destroy lectins.)

While the research is limited, very few other foods have lectins like the one in peanuts, Yu said. Two other foods have similar lectins, but they don't necessarily behave like those in peanuts:

-- jackfruit, a popular food in Africa and Asia, and

-- Agaricus bisporus mushrooms -- the common white and brown buttons, including criminis, and their mature counterparts, portobellos.

The lectin in those buttons, however, "does not tolerate cooking and digestion," Yu said.

(Button mushrooms do have some good qualities. They contain a fatty acid that inhibits production of aromatase, an enzyme that fuels estrogen production, for example. And for many years, health guru Dr. Andrew Weil has been advising consumers to cook button mushrooms for several minutes, remove any gills and wipe off caps in order to inactivate other harmful compounds.)

"More work needs to be done," Yu said, to find out if lectins from other foods can a/ get into the bloodstream intact and then b/ bind to the types of carbohydrates that are common in cancer cells, like peanut lectins.

Stealth bombers or studying lectins? If you had your pick, how would you spend your money?

Kudos to the American Institute of Cancer Research for funding this groundbreaking work.

Contact your government representatives and tell them to stick their peanuts back in the ground and get to work on some serious humanitarian business -- funding scientists to figure out how common foods affect cancer.


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