This release summarizes observations drawn from a review of dozens of previous studies concerning the consumption of tree nuts and its impact on cardiovascular risk factors among healthy adults. While an impressive number (61) of studies were examined, just 21 dealt specifically with walnuts as opposed to the wider family of tree nuts. The study concerns eight types of tree nuts and does not single out walnuts as being superior over the others. The release contains a lot of good information that suggests tree nuts can help reduce the risk of cardiovascular disease, while it steers the reader toward choosing walnuts. But in the end, and as the published report suggests, any tree nut might do the same job.
Many people in the U.S. and other Western countries, particularly, are interested in reducing their risk for cardiovascular disease — and rightly so. People consuming Western diets face a higher proportion of cardiovascular conditions such as heart attack, stroke, heart valve issues, arrhythmia, many of which stem from atherosclerosis or plaque build up in the arterial walls. If consuming tree nuts can help reduce the risk of heart disease it is good to present new evidence supporting that idea.
It is important for the public to understand the dietary patterns that may help prevent cardiovascular disease. It is also important for them to understand that no one item “added on” to a poor diet is going to result in improved health or clinical outcomes. News releases such as this perpetuate the “add on” idea that adding a supplement rather than adopting a healthy dietary pattern will improve one’s health.
We won’t ding the story for not mentioning costs, although walnuts certainly are expensive. Each one of us passes by bags of walnuts every time we go to the grocery store and probably have at least a vague idea of what they cost.
While in most cases the release carefully states that the study analysis included “tree nuts, such as walnuts” without claiming the focus of the research was walnuts alone, in one paragraph the release says that decades of research have shown that walnuts can help reduce cardiovascular disease risk by decreasing LDL (bad) cholesterol by 9 to 16% and diastolic blood pressure by 2 to 3 mmHg.
But according to the study:
“Conclusions: Tree nut intake lowers total cholesterol, LDL cholesterol, ApoB, and triglycerides. The major determinant of cholesterol lowering appears to be nut dose rather than nut type. Our findings also highlight the need for investigation of possible stronger effects at high nut doses and among diabetic populations.”
The release could have done a better job giving and explaining absolute risk reduction for the cholesterol findings. From the study: Of 2,582 volunteers involved in one of 61 studies, lowered total cholesterol was −4.7 mg/dL; 95% CI: −5.3, −4.0 mg/dL.
A brief mention of nut allergies and high caloric content of nuts might be appropriate here since walnuts are being recommended as a daily health supplement for people with Type 2 diabetes. Diabetics and cardiovascular disease are often comorbidities of being overweight.
The release doesn’t clue readers in to important limitations in the data. Although the study was an expert, professional analysis, it still relied heavily on computer modeling and extrapolation to come up with data. For example, in the dozens of studies, volunteers consumed nine different types of tree nuts and they had “doses” ranging from 28 grams to 100 grams a day. The trials ranged from 3 weeks to 26 weeks in duration. In addition, the outcomes assessed were all surrogate or intermediate outcomes like cholesterol levels. The study didn’t look at the outcomes that truly matter to people such as heart attacks and strokes. The release should been more clear about this.
The release clearly states that the study is sponsored and funded by the California Walnut Commission with additional funding from the International Tree Nut Council Nutrition Research and Education Foundation.
No alternatives are mentioned such as exercise, medications, lifestyle changes and so on. In fact, other research points to olive oil, for example, as being helpful in modifying cholesterol and risk for cardiovascular disease. A brief mention of this would have been appropriate.
Walnuts are widely available so we won’t ding the story for not saying so.
It’s not really clear from the release what’s new about this study, beyond the fact that the meta-analysis conducted involved more studies than previous research. The study itself includes an extensive discussion of what’s new here, including the fact that previous studies looked only at specific types of nuts and not all tree nuts.
The release uses a measured, professional tone and no unjustifiable language.
Systematic, Criteria-Driven
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