The thought of writing a paper has always intimidated me. Perhaps I’m just not thinking about it the right way, since I’ve typed e-mails that resemble editorials many times. This is a slightly post-edited e-mail to a friend whose cardiologist advised limiting saturated fats, while admitting that a high-carb diet may have lead to angina.
Why natural (minimally processed) fats are not likely to be a problem (when carbs are restricted, which by themselves can cause plenty of problems).
- The fat in arterial plaque depends on what one eats, especially if one eats seed oils, so-called vegetable oils, which are high in omega-6 fatty acids. Here’s a quote from analysis of fat tissue and plaque fatty acid composition: “[strong correlation] between adipose tissue and plaque omega-6 polyunsaturated fatty acids (r = 0.89)” and no association between stored saturated fat and saturated fat in plaques. “These findings imply a direct influence of dietary polyunsaturated fatty acids on aortic plaque formation and suggest that current trends favouring increased intake of polyunsaturated fatty acids should be reconsidered.” (1)
Take-away message: might be best to minimize corn/soy/canola oils.
- Basic biochemistry of fat metabolism (simplified): when insulin and blood sugar levels are low, fat is burned for energy. Both dietary fat, or fat released from fat cells gets converted to acetyl-COA in liver and other cells. Mitochondria then convert that acetyl-COA to energy, releasing water and CO2. When a lot of fat is liberated, there becomes a surplus of acetyl-COA in the liver. This surplus of acetyl-COA drives the production of ketone molecules, particularly beta-hydroxybutyrate. Ketones can cross the blood-brain barrier, providing an additional source of energy for the brain. This fills in gaps in glucose supply, suppressing hunger for long stretches between meals. Suppressing hunger is the often overlooked factor in weight maintenance.
- Low levels of omega-3 (EPA and DHA) are associated with the formation of arterial plaques.
“Patients with acute coronary syndrome had significantly lower levels of ω3 PUFAs (especially of EPA and DPA) than those without it.” (2)
- Felton CV, Crook D, Davies MJ, Oliver MF. Dietary polyunsaturated fatty acids and composition of human aortic plaques. Lancet. 1994 Oct. http://www.ncbi.nlm.nih.gov/pubmed/7934543
- Amano T, Matsubara T, Uetani T, Kato M, Kato B, Yoshida T, Harada K, Kumagai S, Kunimura A, Shinbo Y, Kitagawa K, Ishii H, Murohara T. Impact of omega-3 polyunsaturated fatty acids on coronary plaque instability: an integrated backscatter intravascular ultrasound study. Atherosclerosis. 2011 Sep. http://www.ncbi.nlm.nih.gov/pubmed/21684546