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Questions about fats, cholesterol, oxidation, and heart disease

  1. Just have a few questions about the cause of heart disease and oxidation of fats. I am looking for some studies that relate to the questions if possible.

    1. Does saturated fat cause atherosclerosis or is it the oxidized cholesterol that usually accompanies it (as in most cooked animal products), or a combination? I'm assuming 'oxidized' saturated fats are less problematic due to their resilience to oxidation, but this is dependent on the following question:
    2. What temperatures are needed to cause oxidation of cholesterol and saturated fat at a non-negligable rate in various foods?
    3. Are other oxidized fats such as monounsaturated fatty acids and polyunsaturated fatty acids as bad or worse than saturated fats or oxidized cholesterol?

    What I am getting at with the first two questions is whether foods high in saturated fat are always bad, or if it is just when they are cooked at high temperatures as they usually are nowdays, which usually causes cholesterol and possibly satfat oxidation?
     
  2. jcsd
  3. What cooking does is change unsaturated trans fatty acids (TFAs) to partially saturated (hydrogenated) TFAs. These have been associated with heart disease in many studies which can be found online. Unsaturated TFAs in cooking oils will degrade to partially saturated TFAs at the smoke point. Saturated fats are generally resistant to oxidation and hydrogenation at high cooking temperatures since they are already fully hydrogenated.

    Recent studies have shown an association between circulating oxidized phospholipids in LDL cholesterol (oxLDL)and heart disease. The relationship of these to diet remains unknown, As a general rule, saturated fats and polyunsaturated fats should be reduced in the diet in favor of monounsaturated fats.

    http://www.exrx.net/Nutrition/Fat.html

    http://whatscookingamerica.net/Information/CookingOilTypes.htm

    http://www.nutrinfo.com/pagina/info/grasas_trans_uauy_tavella_nutrition.pdf

    There's a vast literature on the net on diet and heart disease for both the layman and professional. Some of it is conflicting and confusing. For example, some studies have shown an increase in circulating oxLDL with low fat diets. However, this might be due to decreased uptake of oxLDL by atheromatous lesions in the vascular wall. Despite the state of uncertainty in the knowledge of the pathology, population based studies have consistently shown a decrease in coronary heart disease with diets such as the Mediterranean, which is high in monounsaturated fats.

    http://www.mayoclinic.com/health/mediterranean-diet/CL00011
     
    Last edited: Jul 27, 2010
  4. Thanks, I'll have a look at the links you posted
     
  5. You're welcome. I didn't link to articles re oxLDL because there doesn't seem to be any known connection between oxLDL and oxidation of foods. The latter results in the formation of free radicals which pose cancer risks such as with the excessive consumption of charred meats.

    Your question was in relation to CHD, so at this point there doesn't seem to be a relation between highly oxidized (rancid at room temerature or charred) foods and CHD. Also, I didn't say much about polyunsaturated fats (PUFAs) because this is a diverse group. Omega-3 FAs are good but high omega-6/omega-3 ratios are bad. Most sources say replacing saturated fats with PUFAs is good but it depends on which PUFAs. Food labels (at least in the US) do not specify specific PUFAs. The following article discusses PUFAs, but there are different opinions.

    http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000252
     
    Last edited: Jul 31, 2010
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