Non-Hodgkin lymphoma: Another cancer may be linked to diet

Non-Hodgkin lymphoma, a cancer of the lymph nodes, might be associated with a high-fat, high-protein diet in older women. An increased risk for this cancer was found in a new study of 35,156 healthy Iowa women, aged 55 to 69 years (JAMA, 1 May 1996). The women filled out questionnaires in 1986 and were followed for seven years. By the end of the study, 104 developed non-Hodgkin lymphoma.

Brian Chiu, M.S., University of Iowa, and colleagues, found that the higher the intakes of animal fat, saturated fat, monounsaturated fat (e.g., olive oil), and red meat (especially hamburger), the higher the risk of developing non-Hodgkin lymphoma. The researchers say that their results cannot be considered conclusive as one earlier study found a similar link and another one did not. Furthermore, future studies should evaluate cooking methods and how thoroughly the meat is cooked.

Non-Hodgkin lymphoma, the cancer that caused the death of Jacqueline Kennedy Onassis last year, has increased 73% in the last 20 years. It remains, however, an uncommon cancer, accounting for only 3% of all cancer diagnosed in the U.S. The term non-Hodgkin lymphoma covers several different cancers that develop from the lymphoid system, which is a complex network of cells and channels that runs throughout the body as a crucial foundation for the immune system.

There is a higher incidence in people with compromised immune systems for example, due to AIDS or organ transplant. Yet, despite studies linking non-Hodgkin lymphoma to hair dyes, occupational exposure to pesticides, blood transfusions,smoking, and drinking, there is no adequate explanation for the large increase in this form of cancer.

To explain the mechanism for their new findings, Dr. Chiu and colleagues speculate that excessive intake of fat and protein may induce chronic hyperstimulation of the immune system, and the result may be a "state of immune tolerance."

Contrary to earlier studies, Dr. Chiu and colleagues found no association between non-Hodgkin lymphoma and milk or other dairy products. The researchers believe their study suggests that a higher consumption of fruits protects against non-Hodgkin lymphoma. They. cited previous research suggesting that frequent consumption of citrus fruits, carrots, vitamin C, and dark green vegetables is associated with a decreased risk of this cancer for men but not for women.

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