There are no clear health benefits of replacing saturated fats with starchy foods (reducing the total amount of fat we eat).Oh my.
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Mice with 8% linoleic acid diets (comparable to modern human diets) had elevated levels of linoleic acid and arachdonic acid in the cell membranes (not surprising) compared to the historic 1% mice (ahem, human) diets. Levels of the endocannabinoids were tripled in the 8% LA diets. Dietary LA increased body weight, food intake, and fat tissue in the mice.
Here's the key, however: Adding 1% EPA and DHA omega 3s to the mouse diets seemed to undo much of the problems caused by the gallons of omega 6. Omega 6 in the cell membranes dropped, as did the levels of endocannabinoids, as did the fatty tissue, weight, and overeating in the mice. These mice didn't look quite as nice metabolically or had as beautiful cell membranes as the 1% LA mice, but it was loads better than the 8% LA omega 3 deficient mice.
Dietary LA also increased leptin and decreased adiponectin.
In the human population, dietary consumption of soybean oil, poultry, shortening, and sugars (but not grains, beef, fish, eggs, dairy, or vegetables) were positively correlated with obesity in several epidemiology cohorts from 1909 to 1999.
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