The dietary guidelines were created to make sure consumers are kept in touch with the latest science and that taxpayer-funded programs like school lunches are properly feeding developing brains.
Though they are updated every five years, and claim to be based on the latest evidence, dietary guidelines really aren't. What did we learn about salt in five years that we did not learn about magnesium in 25? Nothing, neither has changed biologically or chemically, and yet magnesium and Vitamin C daily intake recommendations have not changed since the 1990s while salt consistently gets ratcheted down. Due to epidemiology suggestions it might be a risk factor for a risk factor for heart disease, not science.
Vitamin C is not alone in getting no attention in the latest version, almost none of the Dietary Reference Intakes, of which Recommended Dietary Allowance (RDA) is the most well-known, have been examined in the last 10 years. Even more oddly, RDA reference values themselves were created by the predecessor of the Food and Nutrition Board all the way back in World War II - and haven't been updated since 1968.
The Dietary Guidelines for Americans 9th Edition (2020-2025) claims to be cutting-edge science and is required by Congressional statute to be based on “the preponderance of current scientific and medical knowledge.”
Yet they aren't.
Lots of pictures like this, but what won't you find in the US dietary guidelines is anyone eating meat.
A Dietary Guidelines Advisory Committee does exist to keep the science current and they got a 'thank you' from the Secretaries the U.S. Department of Agriculture and U.S. Department of
Health and Human Services on page one of their most recent version but they were actually for the most part ignored. They had recommended numerous improvements, like new intake recommendations for everything, segmented by all age-sex groups and all life stages, but all we got was the usual guidelines scaled down to 0-23 months and not much new at all. Eat more veggies, eat less salt and "added" sugar. They could have been written in 1985, and parts perhaps were since they also continue to push fat-free milk and less "processed" meat, whatever that means.
The science is out there even if it isn't in the new document. Choline, for example, shows neuroprotective benefits for infants and it is clear that infancy is a crucial time in development yet we won't know that if we go by the latest Dietary Guidelines for Americans 9th Edition. Instead, they continue to push eating more vegetables for all ages instead of meat.
In the National Research Council's 1968 version of the "Recommended Daily dietary Allowances", they said men should get 65 grams of protein and women should get 55, now they say that is 56 and 46 - and has been since 1980. What changed about human evolution between 1968 and 1980? Not much, but if recommendations changed by nearly 15 percent in 12 years how did they not change at all in 40? The newest document is larger than ever yet seems to contain less new science.
It is especially clear that nutrients need a reexamination, because of modern supplement culture. We're no longer a world where people get nutrients primarily from food - and that has benefits for areas that cannot grow some foods, but it also carries risk. No one ever overdosed from vitamin A due to eating too much liver but if you buy vitamin A (Retinol) supplements it can be toxic, while carotenes found in carrots can't.
A science-based diet document would be less about steering us toward diet fads like vegetarianism for school kids and more about giving us concrete information. We get that they won't be hard rules, but why are they timid about endorsing meat when they create a cap on salt? Why not include information on benefits of low-carbohydrate foods if they are going to push vegetarian food? Harvard T.H. Chan School of Public Health demographers may cheer that USDA won't take a stand and be trusted guides but the rest of us worry that it's only going to get worse next time.
Instead, it can get better. By using a tiny part of their combined $1.6 trillion annual budgets to create a public document every five years that will be informative and educational instead of being what it is now - aspirational.
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