NHL in older women may be associated with a high fat, high protein diet, according to a recent study.

An increased risk for NHL was found in a study of more than 35,000 healthy Iowa women aged 55-69 years (JAMA, 1996; 275: 1315-21). The researchers found that the higher the intake of animal fat, saturated fat, monounsaturated fat (e.g. olive oil) and red meat (especially hamburger), the higher the risk of developing NHL.Unlike the results of other studies, no association was found between NHL and milk or other dairy products.

On the positive side, the study clearly showed that high consumption of cruciferous and carotene rich vegetables, and all types of fruits had a protective effect.

Brian Chiu and his co-authors speculated that excessive intake of fat and protein may induce chronic hyperstimulation of the immune system, making it unresponsive and possibly leading onto to the development of cancers like NHL.

More recently, as part of the ongoing Nurses' Health Study at Harvard, more than 88,000 women have been followed for 14 years. Researchers found that the greatest increase in risk nearly two and a half times was associated with trans unsaturated fat intake, not saturated fats.

High intake of beef, pork or lamb as a main dish (not as a mixed dish or in sandwiches) more than doubled the risk of developing NHL over in take of these meats less than once a week (J Natl Cancer Inst, 1999; 91: 1751-8).