Thought for Food Blog

Q. How to Take Nutrition Studies?                               A. With a Grain of Salt

Nutrition Studies | IFIS Publishing

If there’s one thing that is sure to confound the general public – and arguably many in the food industry too – it’s the often conflicting nutrition research news. The most recent example? Salt.

The American Journal of Hypertension recently published a study – Reduced Dietary Salt for the Prevention of Cardiovascular Disease: A Meta-Analysis of Randomized Controlled Trials (Cochrane Review) – that concluded, contrary to popular belief, dietary salt reduction has no positive impact on stroke or heart attack prevention. This led to numerous headlines along the lines of ‘Review raises questions over benefits of cutting salt’ and ‘Now salt is safe to eat – Health fascists proved wrong after lecturing us all for years’, etc…

However, commentary in The Lancet rebutted the conclusion of the Cochrane Review, asserting:

This study is disappointingly weak and contributes little to our understanding of salt and disease. It is likely to confuse public perceptions of the importance of salt as a risk factor for high blood pressure, heart disease and stroke. Questions of intervention and outcome, such as sodium intake and CVD events, cannot be answered by small observational studies. It is dangerous to jump to conclusions on the basis of single studies and ignore the totality of evidence.

In fact, a reevaluation of the Cochrane data found that reducing salt intake can in fact lead to ‘a significant reduction’ in cardiovascular events, just as was previously thought.

So, how should the food industry and food scientists respond? Arguably the most robust answer can be found in a recent article on the Harvard School of Public Health’s website, The Nutrition Source, Nutrition Research and Mass Media: An Introduction. While admittedly intended for consumers who want to try and make sense of the media’s version of research, it’s a straightforward discussion for those seeking to produce healthier foods and drinks:

The research process is like placing stones on an old-fashioned balance scale. When enough weight accumulates on one side, the scale tips in favor of a particular recommendation. And the more weight there is on one side, the stronger the recommendation is and the more evidence it would take to change it.

The article used the link between alcohol and heart disease as an example of an established relationship:

But not all topics are as clear-cut as this. Often, the weight of evidence is not as great. In some cases, only a handful of studies have addressed a particular question. In other cases, a large number of studies may support one side, but there may be some particularly significant studies supporting the other side as well—just enough to cast some doubt. In these instances, we’d say that there is a probable link between a behavior and a disease.

What, if any, conclusions can be drawn from such research and debate? Broadly, as well as taking the public’s pulse, we all – food scientists, food researchers, food producers and food manufacturers alike – need to do a more-judicious review of the studies that are fueling the public’s perception and, ultimately, follow the science.

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