The efficacy of conjugated linoleic acid in mammary cancer prevention is independent of the level or type of fat in the diet

Abstract

The objective of the present study was to investigate whether the anticarcinogenic activity of conjugated linoleic acid (CLA) is affected by the amount and composition of dietary fat consumed by the host. Because the anticancer agent of interest is a fatty acid, this approach may provide some insight into its mechanism of action, depending on the outcome of these fat feeding experiments. For the fat level experiment, a custom formulated fat blend was used that simulates the fatty acid composition of the US diet. This fat blend was present at 10, 13.3, 16.7 or 20% by weight in the diet. For the fat type experiment, a 20% (w/w) fat diet containing either corn oil (exclusively) or lard (predominantly) was used. Mammary cancer prevention by CLA was evaluated using the rat dimethylbenz[a]anthracene model. The results indicated that the magnitude of tumor inhibition by 1% CLA was not influenced by the level or type of fat in the diet. It should be noted that these fat diets varied markedly in their content of linoleate. Fatty acid analysis showed that CLA was incorporated predominantly in mammary tissue neutral lipids, while the increase in CLA in mammary tissue phospholipids was minimal. Furthermore, there was no evidence that CLA supplementation perturbed the distribution of linoleate or other fatty acids in the phospholipid fraction. Collectively these carcinogenesis and biochemical data suggest that the cancer preventive activity of CLA is unlikely to be mediated by interference with the metabolic cascade involved in converting linoleic acid to eicosanoids. The hypothesis that CLA might act as an antioxidant was also examined. Treatment with CLA resulted in lower levels of mammary tissue malondialdehyde (an end product of lipid peroxidation), but failed to change the levels of 8-hydroxydeoxyguanosine (a marker of oxidatively damaged DNA). Thus while CLA may have some antioxidant function in vivo in suppressing lipid peroxidation, its anticarcinogenic activity cannot be accounted for by protecting the target cell DNA against oxidative damage. The finding that the inhibitory effect of CLA maximized at 1% (regardless of the availability. of linoleate in the diet) could conceivably point to a limiting step in the capacity to metabolize CLA to some active product(s) which is essential for cancer prevention.

Incorporation of conjugated linoleic acid (CLA) and α-linolenic acid (LNA) in pacu fillets

“…Among the health benefits attributed to the CLA, anticarcinogenesis (Ha et al, 1987;Ip et al, 1996), reduction in the development of arteriosclerosis (Chouinard et al, 1999;Kritchevsky et al, 2004), immunomodulation (Cook & Pariza, 1998), and the capacity to change lipid metabolism in humans (Gaullier et al, 2004) stand out.…”

Nutritional Importance of Monounsaturated and Polyunsaturated Fatty acids of Perilla Oil

“…These two specific ω-3 fatty acids metabolites are inserted in cell membranes throughout the body, where cellular machinery converts them into substances which prevent abnormal clotting, and relax blood vessels and improved ventilatory parameters. The ω-3 rich fatty acids, which may lead to prevention of coronary heart disease and decrease blood clotting [21,22] . In platelets, the cell products in the blood which aid in clotting, ω-6 fatty acids are converted to thromboxane-A2 (TXA2).…”

“…LTB5 is antiinflammatory. Health demands normal functioning of both systems [20][21][22] . 2.1.2 Anti-inflammatory and rheumatoid arthritis benefits: Perilla oil is rich in the ω-3 fatty acids, on metabolism gives EPA and DHA, which can displace arachidonic acid (AA) from cell membranes.…”

“…Animal studies have indicated that LA reduces the incidence of tumors induced by carcinogens. The LA, appears to be unique among fatty acids because low levels in the diet produce significant cancer protection [20,22,25] .…”

Os efeitos do ácido linoléico conjugado no metabolismo animal: avanço das pesquisas e perspectivas para o futuro

“…Visando a investigar a influência da quantidade e da composição dos lípides dietéticos sobre o efeito protetor do CLA contra tumor mamário induzido por dimetilbenzo--antraceno, Ip et al 53 suplementaram ratos fêmeos com misturas de óleos vegetais, em diferentes concentrações, que variaram de 10% a 20%, acrescidas ou não de 1% de CLA. Segundo os autores, a ação anticarcinogênica do CLA é independente tanto da quantidade quanto da qualidade dos lípides dietéticos.…”