Cardio-metabolic and Immunological Impacts of Extra Virgin Olive Oil Consumption in Overweight and Obese Older Adults

A Randomized Controlled Trial

Mitra Rozati; Junaidah Barnett; Dayong Wu; Garry Handelman; Edward Saltzman; Thomas Wilson; Lijun Li; Junpeng Wang; Ascensión Marcos; José M. Ordovás; Yu-Chi Lee; Mohsen Meydani; Simin Nikbin Meydani

Disclosures

Nutr Metab. 2015;12(28) 

In This Article

Results

Assessment of Dietary and Macronutrients Intake

The average amount of study oil and spread consumption was similar in the CON and the OO group ( Table 2 ). We assessed compliance by conducting both dietary assessment ( Table 3 ) and plasma fatty acid analysis ( Table 4 ). No difference was found in macronutrient intake at baseline between groups. The OO group showed an increase of total monounsaturated fatty acids (MUFA) (P < 0.001) and oleic acid (P < 0.001) consumption compared to the CON group, and the CON group had increased polyunsaturated fatty acids (PUFA) intake (P < 0.05) compared to the OO group after 3 months. No difference in intake of other macronutrients including total fat, carbohydrates, protein, fiber, and energy was observed between the groups after 3 months.

Plasma fatty acid analysis ( Table 4 ) indicated that participants in the OO group had increased plasma oleic acid (P < 0.05), total MUFA (P < 0.05), and oleic acid/PUFA ratio (P < 0.05) compared to the CON group after 3 months. In addition, there was a reduction in total plasma PUFA in the OO group compared to the CON group after 3 months (P < 0.05).

Demographic, Anthropometrics, Blood Pressure, Blood Chemistry, and Lipid Profile

There was no significant difference in age, gender and race between the two groups at baseline ( Table 5 ). We observed a reduction in systolic blood pressure in the OO group compared to the CON group (P < 0.05) after 3 months ( Table 5 ). There was no difference in other anthropometric measures between the two groups at baseline or after 3 months of intervention. In addition, participants in the OO group showed a trend (P = 0.06) toward an increase in plasma HDL-C levels compared to the CON group after 3 months ( Table 5 ). No difference was found in other parameters of lipid profiles tested including total cholesterol, LDL-C, and triglycerides as well as in blood glucose concentration between the two groups at month 3.

Immunological Assessments

CBC-Differential and Lymphocyte Phenotypes. No difference was found in total number of white blood cells, percent or total number of lymphocytes, monocytes, neutrophils, eosinophils, and basophils at baseline or after 3 months of intervention between the two groups (data are not shown). There was no difference in the changes between the two groups in any of the blood lymphocyte phenotypes measured over 3 months ( Table 6 ).

Lymphocyte Proliferation. We found significant increase in T cell proliferation in response to anti-CD3/anti-CD28 (1 mg/L) after 3 months in the OO group compared to the CON group (P < 0.05). There was no difference in T cell proliferation in response to Con A between the two groups ( Table 7 ).

Cytokine Production. No difference was found in T cell cytokine and pro-inflammatory cytokine production between the two groups after 3 months of intervention ( Table 8 ). There was heterogeneity in the change of plasma oleic acid concentrations following intervention in both groups. For the CON group, the range of change in plasma oleic acid was between −5.14 and 3.15 %; in the OO group, the range of change was between −3.84 and 7.32 %. This may be partly due to inter-individual variability in endogenous oleic acid production and difference in compliance. As such, we ranked the change in blood oleic acid levels between baseline and month 3 in all participants in quintiles and evaluated the change in cytokine levels between baseline and month 3 in relation to the quintiles 1 and 5 of plasma oleic acid changes. We found that participants who had the highest quintile of oleic acid changes had a higher increase in IL-2 production compared to the participants in the lowest quintile (P < 0.01) (Fig. 2). No such association with other cytokines was noted.

Figure 2.

Association between changes in plasma oleic acid content (%) and IL-2 production (all participants). The percent changes in plasma oleic acid were ranked in 5 quintiles, Q1 (−5.14 to-2.68); Q2, (−2.69 to −0.35); Q3, (−0.18 to 0.5); Q4, (0.89 to 2.66), and Q5, (2.78 to 7.32); N = 8 participants in each quintile. The change in IL-2 production in response to anti-CD3/anti-CD28 after 3 months is shown in Q1 and Q5. * Significantly different from Q1 by ANCOVA adjusting for age, sex and the baseline values of oleic acid and IL-2 at P < 0.01

Delayed-Type Hypersensitivity Skin Test (DTH). Both the CON and OO groups showed an increase in the diameter of skin induration after 24 and 48-h of DTH implant at month 3 compared to baseline, but the increase was similar between the two groups ( Table 9 ).

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