The story reports that a small study of overweight adults found that avocado consumption can lead to a decrease in LDL cholesterol levels. Thanks in part to extensive comments gleaned from one of the researchers in an interview (something lacking from some competing coverage that was based on a press release), the story does a good job of placing the findings in context and showing how LDL cholesterol is tied to human health. Notably, it was the only story we reviewed that explained what’s considered a healthy level of LDL cholesterol.
If we had to pick one way we’d like to see this story improved, it would be to explain how the changes observed in the study translate to overall cardiovascular risk. In other words, what does a 13-point drop in LDL mean for someone’s risk of a heart attack or stroke?
According to a 2011 report from the CDC, 71 million people in the United States have high cholesterol, which increases risk for heart disease and stroke (the first and fourth leading causes of death, respectively, in the U.S. as of 2010). LDL is the form of cholesterol that can build up in arteries, which is what causes that increased risk. Managing cholesterol is both a public health issue and an economic issue, given the enormous amounts of money spent in the U.S. on cholesterol management drugs, diets and other management techniques.
The story does not address costs. An avocado a day might add up to $30 or more per month, so that’s not irrelevant. Competing stories gave pricing information or at least noted that avocados can be expensive.
The story accurately compares the reduction of LDL cholesterol in study participants who ate avocado to reductions in LDL among study participants who did not — the avocado group’s LDL levels dropped by just over 13 milligrams per deciliter of blood (13.5 according to the news release), compared to reductions of 8.3 and 7.4 for two other groups. The story also provides readers with a frame of reference for those numbers, noting that overall LDL levels should be below 100 (which makes a difference of 5 or 6 mg/dl fairly significant). The story also explicitly makes the connection between LDL cholesterol and human health, noting that it is a significant risk factor for heart disease.
We wish the story had explained how the changes observed in the study would affect someone’s risk of a heart attack or stroke. In addition, there’s a reference to the “plaque-busting” properties of monounsaturated fatty acids that is a bit of unnecessary hype. There is no medication or nutrient that “busts” plaque, but rather a healthy lifestyle, diet, and medications for some will help prevent its accumulation. Given the other strengths discussed above, we don’t think these problems are sufficient enough to warrant an unsatisfactory rating.
The story explicitly states that “too much of a good thing can be harmful,” explaining that avocados are high in calories. The story quotes a researcher associated with the study as saying that people should not simply add avocados to their current diets, but find a way to incorporate the avocado into their diets without increasing overall calorie consumption. That’s the best discussion of this issue that we’ve seen in any of the four stories we reviewed on this topic.
This was a tough call. The story does explain that the study included only 45 participants, all of whom were obese or overweight. And the story also frames the findings in context, calling it “one more piece of evidence in favor of adding good fats to the diet,” and discussing related studies (with links). In short, for the most part the story doesn’t oversell the findings. We also appreciated this story’s clear explanation of the study design, and how we can be sure that it’s the avocados that are responsible for the drop in LDL cholesterol.
However, as we’ve noted in our reviews of the competing stories that covered this study, one of the crucial issues missing in this discussion is the fact that the primary outcome — LDL cholesterol — is an intermediate marker of heart disease risk and only one of many different factors that affects risk. Thus, the findings are not as strong as those of some other studies that the story linked to, which assessed the number of heart attacks and strokes that occurred after dietary changes. Our standard is for stories to mention such important limitations. We offer a primer on this general topic.
One of the researchers pointed to another key limitation in the news release that accompanied the study: “This was a controlled feeding study, but that is not the real world — so it is more of a proof-of-concept investigation.” The story could have earned a satisfactory by including some of that context.
The story didn’t engage in disease mongering.
The story does not quote any independent sources. But it somewhat makes up for this omission through an extensive interview with one of the study researchers, who provides excellent context. The story also clearly states that the study received funding from an avocado industry organization.
The story makes it clear that there are multiple ways that people can change their diet to improve cardiovascular health — avocados are not the only way to go. For example, the story points to studies which found that consuming other foods high in monounsaturated fatty acids (such as olive oil) were linked to reduced risk of heart disease and stroke. The story also notes that saturated fats increase heart disease risk. Ergo, another way to reduce risk is to lower consumption of meat and butter, rather than eating avocados. The story does not mention additional ways to lower LDL cholesterol, such as taking statin drugs, increasing exercise, quitting smoking, or limiting alcohol intake.
The story gives the impression (largely correct) that avocados are widely available. As with the competing stories, we would have liked to have seen some acknowledgment that there are areas where avocados may be more difficult to find.
While the story does place the work in context with other diet studies linked to cardiovascular health risk (which is great), it does not mention the multitude of other studies that have been done on avocados and cholesterol (many of which are — worth noting — not human diet studies). We wish the article had explained how the study fit into that larger body of literature on this specific subject, or why it was sufficiently novel that it falls outside of the previous work.
The story clearly went beyond the news release. It included an interview with the researcher and brought in a significant amount of additional context from other diet studies.