Two stories we reviewed on this study about salt intake showed how two well meaning journalists could come to very different conclusions about how to present this information. The New York Times story took the most cautious approach, weighing the preponderance of evidence linking salt to heart disease against this single study with several limitations and giving more weight to the preponderance of evidence. The USA Today story decided to give both the critics of the study and the study itself equal weight and took the odd step of bringing in the salt industry. This is not “fair and balanced” journalism. This is he said/she said that lacks critical analysis and leaves readers frustrated and confused.
For years, high salt intake has been suggested as a cause of heart disease and early death. Researching the impact of salt, or any dietary factor, on health can be tricky, as both of these stories explain, and this study attempted to provide a deeper look at the connection between salt and health. But, as the authors themselves acknowledge in the paper, there are significant limitations to this study that should have given reporters more pause when reporting the findings. The biggest one was acknowledged by the New York Times in saying, “was observational, considered at best suggestive and not conclusive.” USA Today missed this point.
The focus of this story was avoiding harm by eating too much (or too little) salt. “The investigators found that the less salt people ate, the more likely they were to die of heart disease — 50 people in the lowest third of salt consumption (2.5 grams of sodium per day) died during the study as compared with 24 in the medium group (3.9 grams of sodium per day) and 10 in the highest salt consumption group (6.0 grams of sodium per day). And while those eating the most salt had, on average, a slight increase in systolic blood pressure — a 1.71-millimeter increase in pressure for each 2.5-gram increase in sodium per day — they were no more likely to develop hypertension.” It does a great job presenting the numbers in absolute terms.
This story did readers a great service by showing in the lead that this study had problems. It said at the top, “A new study found that low-salt diets increase the risk of death from heart attacks and strokes and do not prevent high blood pressure, but the research’s limitations mean the debate over the effects of salt in the diet is far from over. In fact, officials at the Centers for Disease Control and Prevention felt so strongly that the study was flawed that they criticized it in an interview, something they normally do not do.” The story then went on to discuss many of the study’s positives and negatives. The study, for example, only tested people’s sodium intake twice, over a period as long as 7.9 years. As the story says, “The researchers assessed the participants’ sodium consumption at the study’s start and at its conclusion by measuring the amount of sodium excreted in urine over a 24-hour period.” The conclusions drawn by the study are fairly significant given that they are based on only two tests taken over nearly 8 years in a total of 74 people who died over the course of the study. The USA Today story, by contrast, presented the evidence as worthy of equal consideration with the much larger body of evidence showing that salt does have harmful health effects in high quantities.
The story did a better job than USA Today finding experts who could give readers a broad context for the findings. We also appreciated how it noted that one of the experts had worked for the Salt Institute, which is the leading advocacy organization for more salt consumption.
[Addendum on May 6: It’s very difficult to find an “independent” expert to comment on the evidence base on salt. Dr. Alderman, who is quoted in the Times story and frequently weighs in on this controversy, has an asterisk next to his name (appropriately so) because of his previous ties to the salt industry. But it’s worth noting that the independent experts in this field, such as Dr. Appel and Dr. Sacks (who are also quoted in the Times story), are closely affiliated with NHLBI which funds much of the research on sodium. And as Gary Taubes posited many years ago in Science magazine, the NHLBI may not be a dispassionate arbiter of the evidence. (The full text of his story can be accessed at the National Association of Science Writers website: http://www.nasw.org/1999-science-society-awards.) ]
This criterion does not apply with this story.