The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 11 No. 6 • October 2008


Oleic Acid Responsible for the Blood Pressure-Reducing Effect of Olive Oil

Although numerous studies have reported that high intake of olive oil reduces blood pressure, the mechanism has remained unclear, with some proposing that olive oil’s high oleic acid content is largely responsible while others believe that the polyphenols in olive oil may play a large role.

A new study1 now reports evidence that strongly supports the hypothesis that it is oleic acid, through its effects on membrane lipid content and certain aspects of cell signaling (G protein-mediated signaling), that causes the reduction in blood pressure from consuming a diet (such as the Mediterranean diet) enriched in olive oil.

The authors of the new paper cite earlier work of theirs in which they showed that oleic acid, but not its structural analogs elaidic and stearic acid, regulates the activity of the alpha2A/D adrenoceptor (one of the types of the receptor that responds to adrenaline and noradrenaline)/G protein/adenylyl cyclase-cAMP/pKA system by modulating the structure of plasma membrane lipids.1 The authors note that “altered levels and function of G proteins have been reported in both hypertensive humans and experimental models of hypertension. . . . Indeed, a rise in the expression of inhibitory G1 proteins in the aorta of hypertensive animals precedes the development of high BP, which is probably a major contributory factor in the pathogenesis of hypertension.”

Remarkably, the authors demonstrate that oleic acid could cause an acute and significant reduction of blood pressure in Sprague-Dawley rats after both acute (2 hours) and chronic yet short (2 weeks) administration. The rats received an oral dose of 1 g/kg one time for the acute determination and once each 12 hours for 14 days for the chronic determination. (This scales to a human dose—as a percentage of food—of about 5–10 g twice per day.) “Although the hypotensive effects of acute (single dose) olive oil were transient (with a peak at 2–4 hours after treatment), reductions in BP were not only marked but they were also stable after 3 or 4 days of high olive oil intake. This rather rapid effect after acute intake of free fatty acids and related lipids is most likely caused by their easy transfer from the small intestine to blood vessels, where they can regulate cell signaling in vascular cells.”

That the blood pressure-reducing effect was caused by oleic acid was supported by the finding that “. . . the correlation between the reduction of BP [blood pressure] and the dose of cis-MUFAs [oleic acid moieties] administered to animals was highly significant (r = 0.94; P < 0.001; n = 8).”1 Blood pressure was also reduced similarly by virgin olive oil and triolein (the major constituent of virgin olive oil, consisting of a triglyceride with three oleic acid moieties).

The authors conclude that the increased concentration of cis-MUFA (oleic acid, a monounsaturated fatty acid) in lipid membranes “regulates the localization, activity, and expression of important signaling molecules in the adrenergic receptor pathway, enhancing the production of vasodilatory stimuli (e.g., cAMP and PKA) and restricting vasoconstriction pathways (inositol-triphosphate, Ca2+, diacylglycerol, and Rho kinase).”

Another paper2 reports finding similar changes in G proteins as well as in PKCalpha activity in plasma membrane lipids from elderly persons with type 2 diabetes after consuming a diet rich in sunflower oil (not the high-oleic acid variety that we use) followed by a diet enriched in virgin olive oil for 4 weeks. The authors believe that these changes “probably account for the positive effects of VOO [virgin olive oil] on glycemic homeostasis.”

While olive oil contains an average of about 85% oleic acid,3 our high-oleic sunflower oil contains about 96% oleic acid. Hence, we would expect it to have similar (or perhaps greater) effects on blood pressure in comparison to olive oil. We prefer the high-oleic sunflower oil because it contains much less of the atherogenic palmitic acid,4 which comprises reportedly 10.9% of fatty acid content of virgin olive oil.2

References

  1. Teres et al. Oleic acid content is responsible for the reduction in blood pressure induced by olive oil. Proc Natl Acad Sci USA 105(37):13811-6 (2008).
  2. Perona et al. Consumption of virgin olive oil influences membrane lipid composition and regulates intracellular signaling in elderly adults with type 2 diabetes mellitus. J Gerontol A Biol Sci Med Sci 62A(3):256-63 (2007).
  3. Wahle et al. Olive oil and modulation of cell signaling in disease prevention. Lipids 39(12):1223-31 (2004).
  4. Olefsky. Fat talks, liver and muscle listen. Cell 134:914-6 (2008).

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