Read on Twitter
Matthew claimed my answers to his question were false but didn't want to prove his claim. I've evidenced these all before in tweets. I'll now respond in detail under each heading. It will take a while because there is much evidence. At the end I'll say what's right with the GL. 1 https://twitter.com/mosca_matthew/status/1385893588089774082
"They are a collection of hypotheses that fail when tested together"
This is the hierarchy of evidence. Note that the GL are a series of recommendations put together by expert opinion (the lowest level of evidence). Each one is supposed to be a specific recommendation like ... 2
This is the hierarchy of evidence. Note that the GL are a series of recommendations put together by expert opinion (the lowest level of evidence). Each one is supposed to be a specific recommendation like ... 2
... "Do whole grains protect against type 2 diabetes?" then the whole evidence pyramid is used to see if this is a good recommendation. Let's use this as an example using the Australian 2013 GL (much the same evidence base as the US). Here is the actual evidence text. 3
Now you might think this is a solid recommendation as we are told whole ad-nauseum that whole grains work to prevent diabetes, but it's a weak grade C association so it's at hypothesis level. Much of guidelines is based on evidence like that. But that is half the problem. 4
We should put this together as an eating pattern & test it to see if the hypothesised benefits are delivered. This was basically never done & I would have said "never tested" in my headline. The Australian ones never have been but the US ones were recently tested. The USDA ... 5
... did this RCT. It didn't deliver any of the hypothesised benefits against an average US diet. We test the Mediterranean diet pattern, low carb diets, etc but the GL are a collection of hypotheses largely untested & the US GL failed when tested. QED 6 https://pubmed.ncbi.nlm.nih.gov/30101333/
"[They are] Built on weak & flawed science"
Let's start with Nutritional Epidemiology that form the bulk of the evidence that GL are built upon. NE rarely shows effect sizes large enough to indicate likely casuality. We should have RCTs to look at too but they are said to ... 7
Let's start with Nutritional Epidemiology that form the bulk of the evidence that GL are built upon. NE rarely shows effect sizes large enough to indicate likely casuality. We should have RCTs to look at too but they are said to ... 7
... be too difficult. Instead, the large number of cheaper observational studies with weak effects 'add to the weight of evidence', even to the point that contradictory RCTs become ignored. Ioannidis explains some of the major problems of NE here. 8 https://jamanetwork.com/journals/jama/article-abstract/2698337
Ioannidis further gave his estimated claim in this talk that [in his unproven estimation] 90% of nutritional science was biased. He names industry as being one corrupting influence in that bias. It's obvious that the GL would be a prime target. Is it? 9
Well here again from the [Australian] GL is a count of the cited papers showing 'whole grains are good'. The 10 non-industry papers don't support these propositions but add in the 59 industry papers & they all become recommendations. 59/69=86%, not far from Ioannidis' 90%. 10
![Well here again from the [Australian] GL is a count of the cited papers showing 'whole grains are good'. The 10 non-industry papers don't support these propositions but add in the 59 industry papers & they all become recommendations. 59/69=86%, not far from Ioannidis' 90%. 10](https://pbs.twimg.com/media/Ez57GSvVoAAYKWN.jpg "Well here again from the [Australian] GL is a count of the cited papers showing 'whole grains are good'. The 10 non-industry papers don't support these propositions but add in the 59 industry papers & they all become recommendations. 59/69=86%, not far from Ioannidis' 90%. 10")
Beyond Ioannidis, the National Academies of Science Engineering & Medicine was tasked by Congress to investigate the DGA process & issued the attached report. Sections 6 & 7 deal with the poor science used. Issues that I believe remain unaddressed. QED 11 https://www.ncbi.nlm.nih.gov/books/NBK469837/pdf/Bookshelf_NBK469837.pdf
"They don't work."
Obviously true or they would have prevented the obesity/ diabetes crisis.
Some say "It's because people don't follow them." which is a dodge. Why?
1. No one would buy an undrivable car (it doesn't work), no one will adopt hard to follow GL (they don't work) 12
Obviously true or they would have prevented the obesity/ diabetes crisis.
Some say "It's because people don't follow them." which is a dodge. Why?
1. No one would buy an undrivable car (it doesn't work), no one will adopt hard to follow GL (they don't work) 12
A nutritionist followed the US GL for 2 weeks as an experiment. She found it challenging. What chance does the average person have? 13 http://www.sheilakealey.com/2018/08/24/restrictive-diets-appeal/
2. People not following them doesn't prove they work
3. We also have an RCT of the DGA which says the average US diet is likely just as good
4. They are designed for healthy people when most of the US population has metabolic disease. QED 14
3. We also have an RCT of the DGA which says the average US diet is likely just as good
4. They are designed for healthy people when most of the US population has metabolic disease. QED 14
"[They are] born of a political process."
Obviously also true. For a start the USDA that oversees that organises this as an organisation that's primary role is agriculture production. Criticism of this conflict goes back (at least) to Luise Light: 15
http://www.whale.to/a/light.html
Obviously also true. For a start the USDA that oversees that organises this as an organisation that's primary role is agriculture production. Criticism of this conflict goes back (at least) to Luise Light: 15
http://www.whale.to/a/light.html
Next, anyone who has watched the public submissions of a procession of interest groups including vegans, industry, & others wouldn't describe it as anything but political. 16 https://nutritionfacts.org/video/highlights-from-the-2020-dietary-guidelines-hearing/
The scramble to choose committee members for influence is another political aspect that can't be denied. It's interesting to look at two of the last choices. 17 https://twitter.com/MacroFour/status/964869223678791680
Great if you have someone that is deciding on recommending what you eat, but then simply reduces those recommendations to calories which can be sugar from a processed cereal. 18 https://twitter.com/DietHeartNews/status/1375234270093049865
But that's conspiracy talk while the case for politics is more easily backed up by NASEM's reports again. This time I attach the first one which was focused to address bias in the committee selection. I understand these reports were unimplemented. QED 19 https://www.nap.edu/read/24637/chapter/1
I could add much more about what's wrong with GL. For one, they get used inappropriately to manage disease like T2 diabetes or condition like obesity, but that's more a problem of misuse by the dietetic profession than the GL themselves. So, what's right? 20
Being positive about them, if you are healthy, exercise vigorously, & don't eat too much of the foods they promote (with the exception of the processed grains & cereals) you would likely stay healthy. Unfortunately, that works for a minority of people. End
