Interesting research in animals has found that the amount of unsaturation in the cell membranes of animals determines their longevity [1]. Low levels of polyunsaturation are linked with increased longevity. Certain animals (and even animals within the same species) with greater longevity show that they have less polyunsaturated-fats incorporated in their cell membranes than other animals.
Bumble-bees are an interesting example. Worker-bees have a much reduced lifespan compared to the queen-bee. The reason scientists believe this to be true is due to the different diets of the bee’s and the different fatty-acid composition of the bee’s cells… with worker-bee’s containing more polyunsaturated-fats than the queen-bee’s which are much more monounsaturated.
Worker-bee’s eat pollen which contains a generous amount of polyunsaturated-fat, while the queen-bee is fed royal-jelly, which contains very little polyunsaturates. The queen-bee is then able to synthesize saturated-fat from the royal-jelly and from the saturated-fats synthesize monounsaturated-fats.
The scientists believe that more polyunsaturation leads to accelerated oxidation and free-radical production, inflammation and apoptosis.
Now what implications does this have for humans? Since humans cannot make polyunsaturated-fats, the amount we consume directly affects the composition of our cells. The American-diet has become more and more polyunsaturated since the early 1900’s [2] (mainly due to a huge increase in use of vegetables-oils and the use of corn and soybeans in animal-feedlots). Along with this novel dietary-change came the rampant increase of cancer and metabolic-syndrome. Since polyunsaturated-fats are unable to be synthesized by the human body… the total amount of polyunsaturation of our cell membranes depends entirely on the amount we consume.
Monounsaturated-fats (omega-9) seem to be the healthiest fat for the composition of the cells and supporting proper membrane fluidity. Saturated-fats are too stiff and tend to make the cell-membrane hard and inflexible; this impairs the flow of hormones (like insulin) into and out of the cells, while polyunsaturated-fats are too soft and pliable and tend to make the cell-membrane prone to oxidation.
Monounsaturated-fats are the perfect balance between the two extremes. Monounsaturated-fats are soft enough to allow insulin to enter the cell but hard enough to resist oxidation. This is why substituting monounsaturated-fats for saturated-fats improves insulin-sensitivity [3].
So how do we decrease the polyunsaturation of our cells and increase the amount of omega-9 concentration? The first step comes from removing overt sources of polyunsaturated-fats from the diet (like oils, nuts and animal-fats). This will decrease the overall polyunsaturation of our cell-membranes, leading to less lipid peroxidation within our body.
The next step is to synthesize more omega-9 fatty acids. Normally the body converts saturated-fats (which are harmful because an excessive accumulation of saturated-fatty acids leads to lipotoxicity and insulin-resistance) into the beneficial monounsaturated-fats thru an enzyme called delta-9-desaturase.
Delta-9-desaturase is activated by the hormone insulin [4]. So by eating insulinogenic-foods, you will accelerate the conversion of saturated-fats into monounsaturated-fats (which are beneficial). However delta-9-desaturase is deactivated in insulin-deficient or insulin-resistant states like diabetes [5].
[1] Age (Dordr). 2008 Sep;30(2-3):89-97. Explaining longevity of different animals: is membrane fatty acid composition the missing link? Hulbert AJ.
[2] Am J Clin Nutr. 1990 Sep;52(3):457-69. Trends in individual consumption of dietary fat in the United States, 1920-1984. Stephen AM, Wald NJ.
[3] Diabetologia. 2001 Mar;44(3):312-9. Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: The KANWU Study. Vessby B, Uusitupa M, Hermansen K.
[4] Scand J Clin Lab Invest. 2011 Jul;71(4):330-9. Insulin induces fatty acid desaturase expression in human monocytes. Arbo I, Halle C, Malik D.
[5] Diabetes. 1979 May;28(5):479-85. Fatty acid desaturation in experimental diabetes mellitus. Eck MG, Wynn JO, Carter WJ.
Edited by misterE, 02 December 2013 - 01:32 AM.