What a study is asking
Some papers examine levels across a population, while others compare a defined intake over a set period. Their conclusions have different scopes: an observational study can describe a pattern across thousands of people without proving that one factor caused another, while a controlled trial can test a narrower question under closer supervision, often with a smaller and less varied group of participants. Reading the method section, not only the summary, is usually the fastest way to understand what a paper can and cannot tell a reader.
Dietary reference values published by bodies such as the European Food Safety Authority and UK nutrition advisory committees are set for population groups and reviewed periodically as new evidence appears. They are not designed to answer an individual's question about their own routine, which is one reason editorial writing on this subject should point back toward a GP rather than toward a fixed number presented as a target.
“A study result belongs to the people who were studied, under the conditions that were tested. Extending it further is where careful writing has to stop and honest uncertainty has to begin.”
That caution applies as much to headlines that sound encouraging as to ones that sound alarming. Both can flatten a nuanced finding into something simpler than the original researchers intended, and readers are usually better served by a slower, more qualified account of what was actually measured.