February 4, 2016
Guidelines Are Influencing Science
Bad guidelines don't just give bad advice but they also harm science and impede research. The new U.S. Dietary Guidelines are a perfect example of why we need to have fewer, shorter, and better guidelines. Guidelines should be used only when there is overwhelming evidence and near universal consensus.
Many readers are probably already aware of the most obvious kind of harm inflicted by bad guidelines. Bad advice leads to bad actions. The best example of this is that the earlier guidelines demonizing fat and dietary cholesterol. This has played a significant contributing role to the obesity and diabetes epidemic.
But, there is another sort of unintended consequence that is less obvious and rarely discussed, though it may well be equally harmful. By their very nature, the dietary guidelines present the illusion of successful science, the appearance that clarity and understanding has been achieved by the experts. When this happens, science is the victim.
One of the dangers of the dietary guidelines is that they are viewed as a victory by those that put them together. Then with the HHS and USDA putting an official sign of approval on them, all incentives to perform new research is put aside. For many people, looking at the hundreds of footnotes in a guideline, they would be hard pressed to expend more resources on a topic already supposedly well understood and proven.
A key to making progress is acknowledging how much we don't know and not trumpeting false knowledge. It is important that health organizations need to publicize how much is still unknown. This would instantly give them more genuine credibility, and would also serve to educate the general public about how science works and open the door to the need for more research.
In the end there are only a few public health policies on diet and lifestyle that we can recommend as a society in order to have credibility and so we have to choose them very carefully and focus on the ones for which we have the best evidence and those, which are most feasible. It is important that when new evidence emerges, guidelines should be re-evaluated objectively "rather than people or organizations digging in, and refusing to consider new evidence even when it may challenge one's own thinking. Policy must be based on reliable evidence and not on personal positions.
But another way that guidelines are bad for science is the forced, oversimplification of complex data into simple, often binary treatment recommendations. It is understandable from a practice standpoint to desire simple rules, but scientifically one loses much information by using binary cut points and oftentimes, journal and grant reviewers not only believe that an issue is 'settled' when it is not, but that the thresholds used in guidelines represent a biologically meaningful cut points, when they may have been used for expediency only.