Increased dietary levels of α-linoleic acid inhibit mammary tumor growth and metastasis

The aim of this study was to determine whether alpha-linolenic acid (ALA omega-3 fatty acid) enriched diet affects growth parameters when applied to a syngeneic model of mammary carcinoma. BALB/c mice were divided and fed with: 1) a chia oil diet, rich in ALA or 2) a corn oil diet, rich in linoleic acid (LA omega-6 fatty acid). Mice were subcutaneously inoculated with a tumor cell line LM3, derived from a murine mammary adenocarcinoma. After 35 days, tumor incidence, weight, volume and metastasis number were lower in the ALA-fed mice, while tumor latency time was higher, and the release of pro-tumor metabolites derived from omega-6 fatty acids decreased in the tumor. Compared to the control group, a lower number of mitosis, a higher number of apoptotic bodies and higher T-lymphocyte infiltration were consistently observed in the ALA group. An ALA-rich diet decreased the estrogen receptor (ER) alpha expression, a recognized breast cancer promotor while showing an opposite effect on ER beta in tumor lysates. These data support the anticancer effect of an ALA-enriched diet, which might be used as a dietary strategy in breast cancer prevention.