Thursday, March 26, 2009

Nuts, Olive Oil, and Fish Oil

Nuts, when consumed with a meal, will significantly reduce the post-prandial glucose excursion by slowing digestion. Recent studies show that almonds, pistachios, or peanuts, when eaten along with high glycemic index carbohydrates such as white bread or mashed potatoes, will reduce the post-prandial glucose area under the curve by approximately 30% to 50%. Importantly, nuts also decrease meal-induced oxidative protein damage because they lower post-prandial oxidative stress and additionally provide antioxidants.
A recent trial randomized 772 subjects at high risk for CAD to a low-fat diet or a Mediterranean-style diet supplemented with either walnuts (30 g/day) or virgin olive oil (1 l/week). This trial found that after 3 months the Mediterranean diets supplemented with either nuts or olive oil produced clinically significant reductions in systolic blood pressure, fasting glucose, and inflammatory biomarkers compared with the low-fat diet.

Epidemiologic studies consistently indicate that consumption of nuts at least 5 times per week will reduce CAD and diabetes risks by 20% to 50%. Tree nuts are comprised predominantly of monounsaturated fats and are a rich source of antioxidants, fiber, phytosterols, magnesium, and folic acid, which might beneficially influence CV risk. Replacing refined carbohydrates with monounsaturated fats (using nuts and/or olive oil) will reduce post-prandial hyperglycemia and hypertriglyceridemia, increase high-density lipoprotein, and decrease oxidative stress . One practical way to accomplish this is to substitute nuts (all of which have very low glycemic indexes) for the sugary and starchy snack foods that are staples in the American diet.

Fish oil (omega-3 fatty acids) lowers post-prandial triglyceride levels by 16% to 40% in a dose-dependent fashion, in part by upregulating lipoprotein lipase activity and accelerating the clearance of chylomicrons. Thus, some of the documented anti-inflammatory and cardioprotective activities of omega-3 fatty acids may be conferred in part by significant improvements in post-meal lipid levels

Source: James H. O’Keefe, MD*, Neil M. Gheewala, MS and Joan O. O’Keefe, RD Dietary Strategies for Improving Post-Prandial Glucose, Lipids, Inflammation, and Cardiovascular Health. J Am Coll Cardiol, 2008; 51:249-255, doi:10.1016/j.jacc.2007.10.016

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