Linoleic acid (LA) is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2(n-6). Linoleic acid is a polyunsaturated fatty acid used in the biosynthesis of arachidonic acid (AA) and thus some prostaglandins. It is found in the lipids of cell membranes. Thus, a lack of linoleic acid and other n-6 fatty acids in the diet causes dry hair, hair loss, and poor wound healing. However, linoleic acid is abundant in many foods, especially plant oils, thus, a deficiency in linoleic acid is almost impossible. [Wikipedia, 2011]
Epidemiological studies show that Omega-6 polyunsaturated fatty acids (n-6 PUFA) dietary intake significantly lowers blood LDL-cholesterol levels. In addition, n-6 PUFA intake lower several cardiovascular risk factors such as blood pressure, inflammatory markers, haemostatic parameters and obesity. [2] However, a study of 2069 men and women, linoleic acid intake was inversely associated with total cholesterol and HDL-cholesterol in women but not in men. Linoleic acid intake was not associated with the ratio of total to HDL-cholesterol. No association was observed between linoleic acid intake and CHD incidence. [1]
An international cross-sectional epidemiological study of 4680 men and women ages 40 to 59 suggests associations of linoleic acid intake of individuals with their blood pressure. Dietary linoleic acid intake may contribute to prevention and control of adverse blood pressure levels in general populations. [3]
Linoleic acid (LA) is know to induce proliferation and invasion in breast cancer cells. [4] Linoleic acid stimulated growth of the MDA-MB-231 and MCF-7 human breast cancer cell lines in culture. [5]Human MCF-7 breast cancer cells were incubated for 12 d in culture medium supplemented with various concentrations (1.78-7.14 x 10(-5) M) of linoleic acid (LA) or CLA. Linoleic acid initially stimulated MCF-7 cell growth with an optimal effect at concentrations of 3.57-7.14 x 10(-5) M, but was inhibitory at similar concentrations after 8 and 12 d of incubation. [6] Thus, at certain concentrations, linoleic acid is a cancer-enhancer while at certain concentrations, it is an anti-cancer agent.
REFERENCE
[1] de Goede J, et al,Linoleic acid intake, plasma cholesterol and 10-year incidence of CHD in 20 000 middle-aged men and women in the Netherlands. Br J Nutr. 2011 Aug 5:1-7.
[2] Czernichow S, N-6 fatty acids and cardiovascular health: dietary intake recommendations Med Sci (Paris). 2011 Jun-Jul;27(6-7):614-8.
[3] Miura K, et al, Relationship of dietary linoleic acid to blood pressure. The International Study of Macro-Micronutrients and Blood Pressure Study [corrected]. Hypertension. 2008 Aug;52(2):408-14.
[4] Espinosa-Neira R et al, Linoleic acid induces an EMT-like process in mammary epithelial cells MCF10A. Int J Biochem Cell Biol. 2011 Sep 16.
[5] Rose DP, Connolly JM. Stimulation of growth of human breast cancer cell lines in culture by linoleic acid. Biochem Biophys Res Commun. 1989 Oct 16;164(1):277-83.
[6] Shultz TD, Chew BP, Seaman WR., Differential stimulatory and inhibitory responses of human MCF-7 breast cancer cells to linoleic acid and conjugated linoleic acid in culture. Anticancer Res. 1992 Nov-Dec;12(6B):2143-5