You would never know it from reading this story, but this was actually a negative study. Here is what the authors reported in the body of their paper under “Results”: “Overall, there was no significant difference in treatments for any parameter except day time pulse pressure (difference between systolic and diastolic pressures) of 1 mmHg higher on the placebo treatment. There were no statistically significant differences between the juices in average day time or night time blood pressures or heart rate.”
The statistically significant reductions in blood pressure reported by the story were found only in men (a subgroup representing only half the participants whose results should be interpreted very cautiously), at a specific timepoint (6 hours after ingestion), and only after the authors adjusted their analysis for baseline differences between the beet juice and placebo groups. Experts differ about the appropriateness of such statistical tinkering in a randomized trial, another reason why this result should be viewed very carefully.
So the overall conclusion should have been that beet juice did not lower blood pressure (at least not a statistically significant degree), and that there were some interesting trends suggesting a possible benefit that needs confirmation in stronger studies.
The paper, as published, addressed some of these issues about subgroup analyses of men only at 6 hours after consumption in the Conclusion section (a result of poor editing on the part of the journal, which arguably should not have allowed it). You need to read the whole paper to get the whole story.
If the blood pressure-lowering benefits of fruits and vegetables are primarily due to the nitrates found in those foods–a reasonable scientific hypothesis–perhaps beet juice (a very rich source of nitrate) would be a convenient way for people to tap into those benefits. But it’s wrong to tout those benefits when the supporting evidence isn’t there yet.
The story did not discuss the cost of beetroot juice. We saw some products advertised on Amazon for $8-10 for a 32 oz jar (about 2 days’ worth of juice at the dosage studied). Cheaper versions are probably available, or you could juice your own, but the story could have addressed this either way.
In keeping with the spirit of this criterion, ALL health care interventions cost something. Only about 30% of the stories we review ever adequately address this issue. Americans spend a greater percentage of their GDP on healthcare than any other country. Costs matter.
The story selectively reported the outcomes for a subgroup of men, and did not report that there was no significant effect in the study as a whole.
In addition, it’s important to note that these results are based on findings for one day after a single dose of beet juice. One of the study authors speculates that the effect “might be even greater over the long term if they are drinking it day upon day,” but it’s perhaps just as likely that the effect will dissipate over time. It’s also possible that the “benefits” are due to chance, a poorly conducted study, or data mining. The truth is we don’t know, but this story reported only on the optimistic interpretations of this research.
The story didn’t discuss potential harms. We’re not aware of any harms associated with drinking beet root juice, but there are concerns that getting too much nitrate could have have toxic effects, such as increasing the risk for cancer. (That’s why nutritionists often advise against eating meats cured with nitrates such as hot dogs.) The story could also have warned of possible adverse effects from supplements that contain nitrate or nitrite salts, which can be highly toxic. There is no information on Medlineplus.gov about beetroot. Medication interactions are also possible. Harm is always possible, even with nutritional supplements. We stand by our same hard line as with the “costs” criterion above. All interventions have potential harms; some discussion is warranted.
As stated above, the findings reported on were a subgroup of the main study (which was itself very small), and statistical tinkering was required to achieve statistical significance. The story did not give readers any sense of the true (very limited) strength of these findings. You can get some idea of the study’s limitations from reading this reviewer’s report about the manuscript.
The story quotes an expert not affiliated with the study, but this researcher is a well known advocate for increased nitrate consumption from foods. (See this article he wrote on the topic.) We suggest that if only one source was going to be quoted, there were probably better choices for a truly objective comment about the results.
That issue aside, we must flag the story for not mentioning that the research was commercially funded by the Sunraysia Natural Beverage Company, which sells beetroot juice.
The story mentions the “DASH (Dietary Approaches to Stop Hypertension)” diet, which has been proven to lower blood pressure. It could also have mentioned that there are effective blood pressure medications available.
The availability of beet juice is not in question.
The story notes that previous research has shown a blood pressure-lowering effect for beet juice in a laboratory setting.
We could not find a press release associated with this study. The story appears to meet our minimum criteria for original reporting.
Systematic, Criteria-Driven
The tale of two “negative” studies. Or, how spin is applied to make research findings look more impressive. A must read. https://johnmandrola.substack.com/p/the-tale-of-two-negative-studies
The @nytimes chose to interview one of the editors of the @AnnalsofIM (publisher of this paper) who "gushed with extraordinary glee: It’s huge! There are very few things that reduce your mortality by 30%."
Turns out coffee is not one of those few things despite all that glee. https://twitter.com/garyschwitzer/status/1533202075928215558
Comments (2)
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Gary Schwitzer
December 18, 2012 at 8:48 amPlease note: One of the authors of the research paper that was the subject of this story is on the editorial board of Clinical Nutrition Insight, a newsletter edited by Kevin Lomangino, one of our two reviewers of this story. That author was not quoted in the story. It was only in doing our own homework on the paper that we discovered that this person was a study co-author. It should be clear to anyone who reads our review of this story – and the comments on the limitations of the research – that neither of our two reviewers of this story pulled any punches. Nonetheless, in the interests of transparency, I wanted to disclose this fact.
Gary Schwitzer
Publisher, HealthNewsReview.org
Jack Valerio
April 6, 2015 at 11:27 pmI am soooooooooooooo pleased with your analyses for one extraordinarily important reason. I am generally very cautious about believig what I read and I often endeavor to check it out. This is especially true when it comes to informatin about nutirition, where I find more made up facts than in any other area. Having found the positive information I noted in WebMD, I was beginning to believe what I had read. Although, as a person who takes medication for several ailments, I wasn’t going to try beet juice since I am always concerned about drug interactions. Nonetheless, the points you made are quite valid and are a serious reminder that checking original sources is imperatve before making decisions upon which one’s health is dependent.
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