A study that followed in excess of 110,000 men and women for more than 30 years has suggested that eating two servings of avocado a week reduces the risk of developing cardiovascular disease (CVD).
Researchers also found that replacing half a serving of butter, cheese, bacon, or other animal product with an equivalent amount of avocado was associated with up to 22% lower risk for CVD events.
The findings add to the evidence base of other studies that have shown that avocados – which contain multiple nutrients, including fibre and unsaturated, healthy fats – have a positive impact on CVD risk factors, first author Lorena S. Pacheco, PhD, a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health, Boston, told Medscape Cardiology.
“This research complements and expands on the current literature that we have on unsaturated fats and reduced risk of cardiovascular disease, and also underscores how bad saturated fats, like butter, cheese, and processed meats, are for the heart. For the most part, we have known that avocados are healthy, but I think this study, because of its numbers and duration, adds a little more substance to that knowledge now,” Pacheco said.
The findings were published online in the Journal of the American Heart Association.
To see the effect avocados can have on cardiovascular health, Pacheco and her team turned to two large, long-running cohort studies: the American Nurses’ Health Study (ANHS), which began in the early 1970s with 68,786 women 30 to 55 years of age; and the Health Professionals Follow-up Study (HPFS), which ran from 1986 to 2016 and followed 41,701 men 40 to 75 years of age.
All were free of cancer, coronary heart disease, and stroke at study entry.
Participants completed a validated food frequency questionnaire at baseline and every four years thereafter. The questionnaire asked about the amount and frequency of avocado consumed. One serving equalled half an avocado, or half a cup.
In the early days of the ANHS, very few participants said they ate avocados, but that began to change over the years, as the popularity of avocados grew.
“The ANHS cohort was recruited back in the late ’70s and the health professionals cohort did not start until the mid-1980s, when avocado consumption was really low. What is beautiful about these cohorts is we are able to ask participants questions and then save the answers that they give us throughout the years to answer questions that might arise whenever the question is right. So, it just depends on when you accrue enough data to ask those questions about potential cardiovascular benefit with avocados,” Pacheco said.
There were 9,185 coronary heart disease events and 5,290 strokes documented over the 30 years of follow-up.
After adjustment for lifestyle and other dietary factors, those with a higher avocado intake – at least two servings per week – had a 16% lower risk for CVD (pooled hazard ratio [HR], 0.84; 95% CI, 0.75 – 0.95) and a 21% lower risk for coronary heart disease (pooled HR, 0.79; 95% CI, 0.68 – 0.91).
No significant associations were seen for stroke, but this is because the study did not have sufficient numbers, Pacheco explained.
A statistical model also determined that replacing half a serving daily of margarine, butter, egg, yogurt, cheese, or processed meats, such as bacon, with the same amount of avocado was associated with a 16% to 22% lower risk for CVD events.
“I want to emphasize that the study is an epidemiological observational study and cannot prove cause and effect. It’s not a clinical trial – it’s based on observational epidemiology – but we saw patterns in the model: avocado consumption and substituting avocado for other unhealthy fats reduced the risk of having a cardiovascular event or coronary heart disease,” Pacheco concluded.
Avocados are dense with nutrients and although they have a high fat content, these are monounsaturated and polyunsaturated fats which are viewed as good. A medium-sized (136 g) Haas avocado, which is the most commonly consumed avocado in the United States, contains roughly 13 g of oleic acid. Avocados also contain dietary fibre, potassium, magnesium, phytonutrients, and bioactive compounds.