Researchers at the Roswell Park Cancer Institute (Buffalo, NY) showed that CLA, derived mainly from dairy products, reduced the incidence of breast cancer (Ip et al. 1999). Animal experiments showed that only 50% of rats feeding on CLA butter developed mammary tumors when exposed to high doses of known carcinogens, compared to 93% of the rats deprived CLA. This research demonstrated for the first time that CLA in foods is biologically active and that a food can offer significant protection against cancer (Cornell News 1999).
Anticancer Research published supporting data that CLA (in both test tube and animal models) demonstrates strong antitumor activity. Particularly gratifying effects were observed regarding inhibition of growth and metastatic spread of transplantable mammary tumors in severely immune deficient mice. The mice were fed CLA for 2 weeks prior to inoculation with human breast adenocarcinoma cells (107 MDA-MB468) and throughout the trial. CLA completely abolished the spread of breast cancer cells to the lungs, blood, and bone marrow. These results indicate that CLA blocks the local growth and spread of human breast cancer via mechanisms independent of the immune system (Visonneau et al. 1997; Banni et al. 1999; Ipet al. 1999).
The effects of CLA and beta-carotene were assessed on white blood cell (lymphocyte) and macrophage function. CLA alone increased lymphocyte numbers and their cell killing ability. Conversely, CLA inhibited interleukin-2 production (a desirable cytokine) and suppressed the ability of macrophages to destroy foreign material. When given together, CLA and beta-carotene interacted in an additive manner to increase lymphocyte production and their cytotoxicity. In addition, beta-carotene was able to overcome the inhibitory action of CLA on the phagocytic activity of macrophages (Chew et al. 1997).
Note: The Melanoma Center at the University of Pittsburgh Cancer Institute showed a potential role for histamine in cancer immunotherapy. A Phase II trial of IL-2 versus IL-2 and histamine in patients with metastatic melanoma demonstrated a trend toward a superior survival benefit from IL-2 and histamine for all patients enrolled and a statistically significant survival benefit for patients with hepatic metastasis (Agarwala et al. 2001).
The effect of three different diets on the local growth and metastatic potential of human prostatic carcinoma cells (DU-145) in severely immune-deficient mice was studied. Animals were fed either a standard diet or diets supplemented with 1% linoleic acid (LA) or 1% CLA for 2 weeks prior to inoculation with cancer cells and throughout the 14-week study. Mice receiving the LA-supplemented diet displayed significantly higher body weight, lower food intake, and increased local tumor load as compared to the other two groups of mice. Mice fed the CLA-supplemented diet exhibited not only smaller local tumors, but also a significant reduction in lung metastasis (Cesano et al. 1998). It was estimated that CLA inhibited the formation of premalignant lesions by approximately 50%, while increasing apoptosis in diseased cells (Ip et al. 2000).
CLA, in a dose-related fashion, has an ability to suppress arachidonic acid (AA). Since AA produces inflammatory mediators that can promote cancer at initiation and progression, CLA’s ability to stifle AA elevates its status as a chemopreventive (Miller et al. 2001; Urquhart et al. 2002).
In 1996, the Life Extension Foundation was in the forefront, recommendingCLA; after evaluating the results of numerous studies, the Foundation presented the promising anticarcinogenic nature of CLA to members. Relatively small doses (3-4 grams of CLA) are effective. For example, young female rats (still maturing) fed 0.8% of their diet from CLA achieved long-term protection against breast cancer. The dose of 0.8% correlates positively to the recommended daily dosage of 3-4 grams endorsed by the Foundation. A dose of six 1000-mg CLA capsules (76%) each day is suggested for cancer patients, pregnant and lactating women should avoid CLA.
