Updated December 4, 2013
Your friends are reading today (February 26, 2013) The New England Journal of Medicine article about how adding olive oil and nuts to their usual diet will reduce their risk of heart attacks by 30 percent. This article has also told them that a low-fat diet fails to help (again). Stroke was the only problem where the tested Mediterranean diet made a real difference. The diet had no effect on heart attacks or death rates overall. The popularity of this message proves once again that “people love to hear good news about their bad habits.” They are reassured that simply by adding more olive oil and nuts you will improve your health…cutting out the brie and beef stroganoff are secondary thoughts.
The article begins by saying, “The traditional Mediterranean diet is characterized by a high intake of olive oil, fruit, nuts, vegetables, and cereals; a moderate intake of fish and poultry; a low intake of dairy products, red meat, processed meats, and sweets; and wine in moderation, consumed with meals.” Of course, this diet is an improvement over the usual fare consumed in the US and Europe, and that is why benefits were seen. The study lasted five years and involved about 7,447 people, ages 55 to 80, in Spain.
There was no reason to say the low-fat diet is a failure based on this research, because participants in the “low-fat” group made no real change in their diets. In the “low-fat” group, total fat consumption decreased insignificantly from 39 to 37 percent. Why was so little effort placed on teaching and then testing a really healthy low-fat diet like mine (the McDougall Diet is 7 percent fat), and then comparing it with the Mediterranean diet? There was no financial interest in pursuing this end. The vested interest was in selling olive oil and nuts. Two companies supplied the olive oil (Hojiblanca and Patrimonio Comunal Olivarero), and the nuts came from a nut producer in Spain (La Morella Nuts) and the California Walnut Commission. Plus many of the authors have extensive financial ties to food, wine, and other industry groups.
One major disadvantage of replacing saturated fats (meats and dairy) with olive oil and nuts is that there is no weight loss from exchanging one type of fat for another: “The fat you eat is the fat you wear.” When this same group of researchers published their earlier findings in 2006 they found that their “olive oil” group lost less weight than did the “low-fat” group (0.19 Kg) and the “nut” group lost about the same (0.26 Kg) as the “low-fat” group in 3 months.1 (Remember they were not really following a low fat diet.) With the McDougall diet we have found an average weight loss of five times as much, 1.6 Kg (3.5 pounds), in a week and participants are encouraged to eat as much as they want, buffet style.
The obesity-causing effects of all that olive oil are also seen in the countries in southern Europe. When 54 obese women in a Mediterranean country were studied, they were found to be following a diet low in carbohydrates (35% of the calories) and high in fats (43% of the calories)…and 55% of the total of these fats came from olive oil.2 Overweight and obesity lay the foundation for type-2 diabetes and degenerative arthritis of the lower extremities, as well as cancer, heart disease, and strokes.
Common knowledge is using olive oil (monounsaturated fat) and eating nuts (polyunsaturated fats) are protective against heart disease, but there is evidence that questions the real life benefits:* Serial angiograms of people’s heart arteries show that all three types of fat—saturated (animal) fat, monounsaturated (olive oil), and polyunsaturated (omega-3 and -6 oils)—were associated with significant increases in new atherosclerotic lesions over one year of study.3 Only by decreasing the entire fat intake, including poly- and monounsaturated-oils, did the lesions stop growing.* Dietary polyunsaturated oils, both the omega-3 and omega-6 types, are incorporated into human atherosclerotic plaques; thereby promoting damage to the arteries and the progression of atherosclerosis.4* A study in African green monkeys found when saturated fat was replaced with monounsaturated fat (olive oil), the olive oil provided no protection from atherosclerosis.5
* One of the most important clotting factors predicting the risk of a heart attack is an elevated factor VII. All five fats tested—rapeseed oil (canola), olive oil, sunflower oil, palm oil, and butter—showed similar increases in triglycerides and clotting factor VII.6
Most likely, the heart benefits of a Mediterranean diet are due to it being a nearly vegetarian diet. The Mediterranean diet is a good diet in spite of the olive oil and added nuts.7
I believe the reason this New England Journal of Medicine study shows benefits is because the people in the Mediterranean diet group reduced their intake of meat and dairy foods and increased their intake of starches (cereals and legumes), vegetables, and fruits. The inclusion of olive oil and nuts was not a “magic pill” that spared their ailing arteries from forkfuls of bacon and eggs. However, the reader should consider these findings of this study important because they do show that people can change their diets when instructed to do so and that removing animal foods from the diet is beneficial. But recommending more olive oil, nuts, seeds, and fish is not the message people deserve to hear. They need to know that a truly healthy diet provides the bulk of the calories from traditional starches, like rice, corn, and potatoes. Commercialism needs to be eliminated when life and death issues for you and your family are at stake.
1) Estruch R, Martinez-Gonzalez MA, Corella D, Salas-Salvado J, Ruiz-Gutierrez V, Covas MI, Fiol M, Gomez-Gracia E, Lopez-Sabater MC, Vinyoles E, Aros F, Conde M, Lahoz C, Lapetra J, Saez G, Ros E.Effects of a Mediterranean-Style Diet on Cardiovascular Risk Factors: A Randomized Trial. Ann Intern Med. 2006 Jul 4;145(1):1-11.
2) Calle-Pascual AL, Saavedra A, Benedi A, Martin-Alvarez PJ, Garcia-Honduvilla J, Calle JR, Marañes JP. Changes in nutritional pattern, insulin sensitivity and glucose tolerance during weight loss in obese patients from a Mediterranean area. Horm Metab Res. 1995 Nov;27(11):499-502.
3) Blankenhorn DH, Johnson RL, Mack WJ, el Zein HA, Vailas LI. The influence of diet on the appearance of new lesions in human coronary arteries. JAMA. 1990 Mar 23-30;263(12):1646-52.
4) Felton CV, Crook D, Davies MJ, Oliver MF. Dietary polyunsaturated fatty acids and composition of human aortic plaques. Lancet. 1994 Oct 29;344(8931):1195-6.
5) Rudel LL, Parks JS, Sawyer JK. Compared with dietary monounsaturated and saturated fat, polyunsaturated fat protects African green monkeys from coronary artery atherosclerosis. Arterioscler Thromb Vasc Biol. 1995 Dec;15(12):2101-10.
6) Larsen LF, Bladbjerg EM, Jespersen J, Marckmann P. Effects of dietary fat quality and quantity on postprandial activation of blood coagulation factor VII. Arterioscler Thromb Vasc Biol. 1997 Nov;17(11):2904-9.
7) Keys A. Mediterranean diet and public health: personal reflections. Am J Clin Nutr. 1995 Jun;61(6 Suppl):1321S-1323S.