3 ms·

Scientific Report of the 2015 Dietary Guidelines Advisory Committee

20 points by mazsa 12y ago

jimrandomh 12y ago
I spot-checked a few sections of this document to see how accurately they matched my own conceptions of the state of the evidence. Specifically, I went to areas where I knew there was active controversy, to see which side they took, but more importantly whether they had acknowledged the presence of a controversy at all. Keep in mind that I specifically went to spots where I expected to find trouble; I did not look at all the parts I expected to be fine, and given the length (571 pages), that's most of it. So please don't take this as reflecting too negatively on the paper or its authors; these issues can almost certainly be addressed in a revision. So, with that out of the way... Part D, section 6 concerns sodium intake and its relationship to blood pressure and cardiovascular disease. This is an area of controversy; see for example Scientific American's "It's Time to End the War on Salt" (http://www.scientificamerican.com/article/its-time-to-end-the-war-on-salt/ http://www.scientificamerican.com/article/its-time-to-end-th...). This report could reasonably take either role, but it would be worrying if it did not acknowledge the existence of a controversy at all. Scientific American cites a number of negative results on reduced sodium intake. I didn't have time to track down all of the, but I did track down a few, including a Cochrane review "Reduced Dietary Salt for the Prevention of Cardiovascular Disease: A Meta-Analysis of Randomized Controlled Trials" (null result, http://ajh.oxfordjournals.org/content/24/8/843.short); http://ajh.oxfordjournals.org/content/24/8/843.short); "Fatal and Nonfatal Outcomes, Incidence of Hypertension, and Blood Pressure Changes in Relation to Urinary Sodium Excretion" (opposite result, more sodium increases survival; http://jama.jamanetwork.com/article.aspx?articleid=899663 http://jama.jamanetwork.com/article.aspx?articleid=899663). It mentions the INTERSALT study, which, apparently, has a different result depending on who's interpreting the data. This report doesn't cite any of those. It makes no mention of there being a controversy or mixed results regarding sodium intake. It says they conducted "a focused review of dietary sodium and its relationship with blood pressure as well as its relationship with CVD", but I don't think they did. I didn't have time for as thorough an inspection as with salt, but a cursory look suggests to me that there are also problems with its presentation of omega-6 fatty acid, which some believe to be very very bad but which is barely mentioned. I don't think this document is ready to be presented to policymakers in its present state. Presenting the appearance of consensus when there is none, is how nutrition got into this mess in the first place.

20 points by mazsa 12y ago

I spot-checked a few sections of this document to see how accurately they matched my own conceptions of the state of the evidence. Specifically, I went to areas where I knew there was active controversy, to see which side they took, but more importantly whether they had acknowledged the presence of a controversy at all. Keep in mind that I specifically went to spots where I expected to find trouble; I did not look at all the parts I expected to be fine, and given the length (571 pages), that's most of it. So please don't take this as reflecting too negatively on the paper or its authors; these issues can almost certainly be addressed in a revision. So, with that out of the way... Part D, section 6 concerns sodium intake and its relationship to blood pressure and cardiovascular disease. This is an area of controversy; see for example Scientific American's "It's Time to End the War on Salt" (http://www.scientificamerican.com/article/its-time-to-end-the-war-on-salt/ http://www.scientificamerican.com/article/its-time-to-end-th...). This report could reasonably take either role, but it would be worrying if it did not acknowledge the existence of a controversy at all. Scientific American cites a number of negative results on reduced sodium intake. I didn't have time to track down all of the, but I did track down a few, including a Cochrane review "Reduced Dietary Salt for the Prevention of Cardiovascular Disease: A Meta-Analysis of Randomized Controlled Trials" (null result, http://ajh.oxfordjournals.org/content/24/8/843.short); http://ajh.oxfordjournals.org/content/24/8/843.short); "Fatal and Nonfatal Outcomes, Incidence of Hypertension, and Blood Pressure Changes in Relation to Urinary Sodium Excretion" (opposite result, more sodium increases survival; http://jama.jamanetwork.com/article.aspx?articleid=899663 http://jama.jamanetwork.com/article.aspx?articleid=899663). It mentions the INTERSALT study, which, apparently, has a different result depending on who's interpreting the data. This report doesn't cite any of those. It makes no mention of there being a controversy or mixed results regarding sodium intake. It says they conducted "a focused review of dietary sodium and its relationship with blood pressure as well as its relationship with CVD", but I don't think they did. I didn't have time for as thorough an inspection as with salt, but a cursory look suggests to me that there are also problems with its presentation of omega-6 fatty acid, which some believe to be very very bad but which is barely mentioned. I don't think this document is ready to be presented to policymakers in its present state. Presenting the appearance of consensus when there is none, is how nutrition got into this mess in the first place.