Higher olive oil consumption associated with lower CV and CHD risk in U.S. adults

Introduction and methods

Consumption of olive oil has been associated with lower CV risk, as shown in ecological studies on a country-level [1], in clinical trials [2, 6] and in observational studies [3-5]. In addition, the findings from a recent meta-analysis suggested that olive oil consumption was protective of stroke, although there were inconsistencies between the studies which assessed CHD as endpoint [7]. However, all of these studies were limited to populations in Mediterranean countries.

The present study aimed to investigate, in the U.S. population, associations between CV risk and olive oil consumption, and estimate risk of CVD when consumption of margarine, butter, mayonnaise, dairy fat and plant oils were replaced by olive oil. In addition, the association between olive oil intake categories and blood lipid levels was analyzed. Two large U.S. prospective cohorts were used with a 24 years follow-up period, including the Nurse’s Health Study (NHS) (n=61181 female registered nurses ) and the Health Professional’s Follow-up Study (HPFS) (n=31797 male health professionals). Olive oil consumption was measured every 4 years with a food frequency questionnaire (FFQ), asking participants how often, on average, they had consumed specific foods, as well as types of fats, oils, and brand or type of oils used for cooking and added at the table in the preceding year. Olive oil intake was categorized into four categories: (1) never or less than once per month (NHS: n=32673, HPFS: n=16073), (2) >0 to ≤1 teaspoon (>0 to ≤4.5 g/d) (NHS: n=22918, HPFS: n=12853), (3) >1 teaspoon to ≤1/2 tablespoon (>4.5-≤7 g/d) (NHS: n=2412, HPFS: n=1246), and (4) >1/2 tablespoon (>7 g/d) (NHS: n=3178, HPFS: n=1625). Primary outcome measure was major CVD defined as a combined endpoint of nonfatal myocardial infarction, non-fatal stroke, or fatal CVD (fatal stroke, fatal myocardial infarction, and other CV death).

Main results

• After adjusting for demographic and lifestyle factors, compared with those who consumed olive oil less than once per month, those who consumed >0.5 tablespoon/day (or >7 g/day) had a 14% lower risk of total CVD (pooled HR: 0.86, 95% CI: 0.79-0.94, P-trend <0.001) and a 18% lower risk of CHD (pooled HR: 0.82, 95% CI: 0.73-0.91, P-trend=0.001). No significant associations were observed for total or ischemic stroke.
• In the pooled fully adjusted analysis, each 5 g/d increase in olive oil consumption was associated with a 19% lower risk of fatal CVD (95% CI: 0.71-0.93, P-trend=0.01) and a 9% lower risk of non-fatal CVD (95% CI: 0.82-1.01, P-trend=0.02).
• Replacing 5 g/d of margarine with 5 g/d of olive oil was estimated to be associated with 6% lower risk of CVD (95% CI: 0.91-0.97, P <0.001). The respective estimate for butter was 5% (95% CI: 0.91-1.00, P=0.06), for mayonnaise 7% (95% CI: 0.89-0.98, P <0.001), and for dairy fat 5% (95% CI: 0.92-0.98, P<0.001). Substituting olive oil for other plant oils was not significantly associated with CVD. Similar results were observed for CHD and no significant associations were observed for stroke.
• In secondary analyses in a subpopulation of the NHS, and HPFS cohorts with available biomarker data, higher olive oil intake (from never or <1/month until >7 g/day) was associated with lower levels of several inflammatory biomarkers, including interleukin-6 (P-trend=0.006; n=13797), soluble intercellular adhesion molecule-1 (sICAM-1) (P-trend=0.05; n=10296), and tumor necrosis factor-α receptor 2 (TNFα-R2) (P-trend=0.007; n=14310). For blood lipids, higher olive oil intake was associated with higher levels of HDL-c (P-trend=0.004; n=8733). No significant associations were observed for LDL-c or triglycerides.

Conclusion

References

Find this article online at J Am Coll Cardiol.