2015 US Dietary Guidelines critique
The new USDA Nutrition Guidelines are about to be unleashed on the American people.
American dietary policy (aka “MyPlate,” formerly known as the “Food Pyramid”) is undergoing its regular five-year checkup. This past February, the US Dietary Guidelines Advisory Committee (DGAC), made up of 14 PhDs and MDs, reviewed the latest research and submitted its recommendations to the US Department of Agriculture (USDA) and the US Department of Health and Human Services. Their 571-page behemoth of a report is the bedrock upon which the 2015 U.S. Dietary Guidelines will sit, (mis)informing nutrition policy nationwide.
I realize that many of you already know better than to trust conventional nutritional advice, which has historically been unsupported, or even outright contradicted, by science, not to mention common sense. Conflicts of interest, personal beliefs, grandiosity, wishful thinking, and intellectual laziness reign supreme in the halls of public health policy-making institutions. Unless you do your own homework, you are at the mercy of nutritional epidemiologists, who will continue to destroy your good health with bad information.
That’s what happened to me. Like so many of you, I ate the way they told me to for most of my adult life—whole grains, salads and steamed vegetables, fat-free yogurt, egg whites, tofu, fish, and skinless chicken breast. Meanwhile, my appetite grew, my weight crept up, and my health circled the drain. It wasn’t until I dug into the science myself that I discovered the US Dietary Guidelines were all smoke and mirrors, full of sound and fury, signifying nothing.
En Guarde! Nina Teicholz throws down the gauntlet
Investigative journalist extraordinaire Nina Teicholz, author of The Big Fat Surprise, recently raked the DGAC’s report over the coals in a fresh and controversial editorial in the BMJ: The scientific report guiding the US dietary guidelines: is it scientific? In this excellent piece, she articulately questions the committee’s methods and motives, and makes it clear that the science upon which the report is based is the result of biased cherry-picking. She criticizes in particular the committee’s outdated position against saturated fat and its unwillingness to evaluate the latest evidence in support of the safety and efficacy of low-carbohydrate diets.
Inspired by her analysis, I held my nose and dove into the belly of the beast myself to see what all the fuss was about. What I discovered was an unnecessarily complicated and confusing document that led me along twisted paths of weak and contradictory arguments and yet somehow magically arrived at clear, confident one-size-fits-all dietary advice that is almost identical to the 2010 recommendations.
I’ll walk you through a glaring example of how shamefully unscientific the DGAC’s process is, but first . . . the big picture.
What does the DGAC think we should eat?
The DGAC emphasizes that its recommendations are not about the health risks and benefits of individual foods and food groups, but rather about the healthfulness of dietary patterns, and gives the following three patterns its seal of approval:
- “Healthy U.S.-style” pattern
- “Healthy Mediterranean-style” pattern
- “Healthy vegetarian” pattern
By “healthy” they mean that all of these diets are good for you, so long as they are each:
- whole grains
- low-fat/non-fat dairy products
- alcohol (for those who can safely drink)
- red/processed meat*
- added sugars (maximum 10% of daily calories)
- saturated fat (maximum 10% of daily calories)
- sodium (maximum 2,300 mg/day)
- refined grains (3 oz per day)
*In a footnote at the bottom of the page: “As lean meats were not consistently defined or handled similarly between studies, they were not identified as a common characteristic across the reviews. However, as demonstrated in the food pattern modeling of the Healthy U.S.-style and Healthy Mediterranean-style patterns, lean meats can be a part of a healthy dietary pattern.” [Part B, Chapter 2, Page 2]
What the committee gets right
Cholesterol is OK. (Hallelujah!):
“Previously, the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 mg/day. The 2015 DGAC will not bring forward this recommendation because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol. . . . Cholesterol is not a nutrient of concern for overconsumption.”[Part D, Chapter 1, Lines 642-646]
[To see how sugar, not cholesterol, causes high cholesterol, see my cholesterol page.]
Added sugars are BAD. (Can I get another Hallelujah?!)
“Intake of added sugars from food and/or sugar-sweetened beverages are associated with excess body weight in children and adults . . . increases the risk of type 2 diabetes . . . is consistently associated with increased risk of hypertension, stroke, and CHD [coronary heart disease] . . . higher blood pressure and serum triglycerides . . . and the development of dental caries.” [Part D, Chapter 6, Lines 704-724]
[To learn how sugar—and excess carbohydrate in general—contributes to these and other health problems (including cancer, Alzheimer’s disease, and fatty liver), calculate your own risk, and learn what you can do about it, see my post "How to Diagnose, Prevent, and Treat Insulin Resistance."]
What the committee gets wrong
Almost everything else, as you’re about to see. Why are these guidelines untrustworthy? Too much of the research used to support these dietary patterns is epidemiological in nature, or uses wildly inaccurate methodologies such as the infamous “Food Frequency Questionnaires” to understand what people are eating. How many epidemiological studies should public health officials rely on to make nutrition recommendations to our people? ZERO.
Epidemiological studies are not experiments, so they are impotent when it comes to the ability to show cause and effect. The best they can do is generate educated guesses about how food affects our health—hypotheses that then must be tested in clinical studies to see whether they are true or not. This is the heart of the scientific method. If scientists in most other fields relied on epidemiological findings they would be laughed out of their professions.
By basing so much of its recommendations on epidemiological studies, what the DGAC is doing (once again) is asking us to conduct a nationwide experiment—to test out its pet diets on ourselves and our loved ones to see what happens to our health. We essentially become laboratory rats. We’ve all seen what has happened to the health of our country—our friends and family members—over the past 35 years during which these guideline-generating groups have been experimenting on us.
The DGAC explains that it recommends the three “healthy” patterns listed above because those diets are rich in the nutrients Americans don’t eat enough of:
- Vitamins A, C, D and E
- Folate, calcium, magnesium, potassium
The problem with this approach is that they look at micronutrients as individual entities instead of as integral components of whole foods—they don’t take digestion, absorption, or bioavailability into consideration. Just because a food contains a particular nutrient doesn’t mean your body can absorb it or use it.
Let’s take a closer look at how the DGAC thinks about food. Below are some excerpts from the report for us to ponder.
“Half of all grain intake should come from whole grains. . . . Refined grains, such as white flour and products made with white flour, white rice, and de-germed cornmeal, are part of the intake recommendation because they are commonly enriched with iron and several B vitamins, including thiamin, niacin, and riboflavin. . . . Since 1998, enriched grains also have been fortified with folic acid and are thus an important source of folic acid for women of childbearing potential. . . . The 2015 DGAC concluded that consumption of only whole grains with no replacement or substitution would result in nutrient shortfalls.” [Part D, chapter 1, lines 1088-1156]
Notice the committee finds itself in the strange position of recommending that half of all the grains we eat be refined, despite massive evidence that refined carbohydrates endanger our health. Why does the committee emphasize the importance of eating fortified grain products? Because these foods in their unprocessed state don’t naturally contain what we need.
The truth is that whole grains are not only poor sources of essential nutrients, but that they actually contain anti-nutrients such as phytic acid, a natural compound which interferes with our ability to absorb key minerals like calcium and iron. [For more information please see my grains page]. Interestingly, red meat contains plenty of B vitamins and iron, without need for fortification or consumption of risky refined carbohydrates. For that matter, animal foods in general are better sources of most essential nutrients than plant foods are:
“The most important and well-recognized role for fiber is in colonic health and maintenance of proper laxation, but a growing body of evidence also suggests that fiber may play a role in preventing coronary heart disease, colorectal and other cancers, type 2 diabetes, and obesity.” (Part D, Chapter 1, Lines 585-595)
The DGAC apparently wasn’t aware that the FDA published a report announcing:
“Evidence is strong that there is not a relationship between dietary fiber and colorectal cancer.”
You can’t blame the DGAC for not having seen this report yet; after all it was only issued FIFTEEN YEARS AGO.
The committee also doesn’t mention the excellent studies conducted in recent years demonstrating that fiber is not helpful for digestive problems, and can even worsen digestive problems. A 2007 review of fiber and overall digestive health concluded:
“A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has fiber been found to be useful in chronic constipation and irritable bowel syndrome. It is also not useful in the treatment of perianal conditions. The fiber deficit-diverticulosis theory should also be challenged.”
A clinical study conducted in 2012 found:
“Idiopathic constipation and its associated symptoms can be effectively reduced by stopping or even lowering the intake of dietary fiber."
A 2013 review stated:
“Even when used judiciously, fiber can exacerbate abdominal distension, flatulence, constipation, and diarrhea.”
[To see how foods can cause digestive problems, please see my post "Common Constipation Culprits." For more information about how fiber affects your digestive tract and why it is not even a necessary nutrient, please see my fiber page.]
“Dairy foods are excellent sources of nutrients of public health concern, including vitamin D, calcium, and potassium. Consumption of dairy foods provides numerous health benefits including lower risk of diabetes, metabolic syndrome, cardiovascular disease and obesity.” (Part D, chapter 1, Lines 1158-1219)
Yes, we need vitamin D, but milk contains zero units of vitamin D unless it’s fortified. Potassium is easy to obtain from a wide variety of plant and animal foods. The argument that milk is the best source of dietary calcium and that we must consume it because we require calcium to grow and maintain strong bones flies in the face of logic. How is it that other mammals all seem to have bones, including obligate carnivores such as cats, despite not drinking milk after weaning? Where do they get their calcium? Are they hiding behind trees, secretly downing TUMS?
The belief that milk consumption reduces risk for metabolic syndrome and related conditions comes from epidemiological studies. The CLINICAL studies, however, are all over the map. A 2015 review of ten intervention studies concluded:
“In adults, four of the dairy interventions showed a positive effect on insulin sensitivity…one was negative and five had no effect.”
Interestingly, the authors of that same review recently published a clinical study finding that replacing dairy products with red meat improved insulin sensitivity:
“In contrast to some epidemiologic findings, these results suggest that high consumption of dairy reduces insulin sensitivity compared with a diet high in lean red meat in overweight and obese subjects, some of whom had glucose intolerance.”
That study was released after the DGAC’s review had been completed, so it couldn’t have been included in the report; I mention it here to make the point that eating dairy products may not be good for people with insulin resistance. It makes sense that dairy foods could increase risk for metabolic syndrome due to its natural ability to raise insulin levels. For more information, please see my dairy page.
I refer you to Nina Teicholz’s analysis for excellent coverage of this complicated topic.
“Overall, it appears that only limited evidence is available to address the relationship between low-carbohydrate diets and health, particularly evidence derived from U.S.-based populations.” (Part D, chapter 2, lines 224-253)
The committee concludes there’s not enough evidence to say that low-carbohydrate diets are better for weight loss than any other type of diet and that all diets that restrict calories work equally well.
It’s absolutely true that calorie restriction can lead to weight loss regardless of what kind of diet you eat. But it is very difficult for most people, especially those of us with insulin resistance, to stay on a low-calorie, high-carb diet for very long, because in a cruel double-play, carbs and insulin not only make us hungry (see this excellent Gary Taubes piece in the New York Times), but they also turn off our ability to burn fat.
DGAC members chose not to include the latest research about low-carbohydrate diets, and instead decided to rely on the old 2010 guidelines, which state that diets containing less than 45% carbohydrate “may be less safe”, without explaining how or why. On what planet is a 45% carbohydrate diet a low-carb diet? Most low-carbohydrate diet experts recommend that carbohydrate be restricted to less than 15% of calories. [As a person with insulin resistance, if my diet consisted of 45% carbohydrate, I would be a tub.] Strange also that the committee implies that evidence from non-US-based populations would be less relevant, given that numerous studies on other topics included in the report were conducted outside of the United States.
The above examples give you a taste of why MyPlate looks the way it does. Lots of plant foods, no mention of meat or fat. The report repeatedly sounds the monotonous recurring theme that diets higher in plant foods and lower in red meat and saturated fat are best for our health. So how exactly did the committee arrive at these recommendations? [Warning: the following content may cause intellectual vertigo and/or spontaneous combustion.]
Clear evidence of anti-meat bias
Allow me first to confess my food biases (something each member of the DGAC should also be required to do). I used to eat a low-fat, high-plant diet until I discovered that eating a high-fat, mostly-meat diet just so happened to be the key to restoring my health. I therefore believe, based on my personal experience and years of reading and writing about nutrition research, that meat is good for people. I have never found any scientific proof that red meat causes any human health problem, nor have I ever come across any plausible physiological mechanism to explain how red meat could cause a human health problem. [For more information, please see my meats page.]
Red meat and depression
Being a psychiatrist, I decided to focus on the portion of the report pertaining to depression risk [Part D, Chapter 2, Lines 1410-1439], and look specifically at the connection between depression and red meat. The DGAC based its recommendations about meat and depression on a total of 19 studies—17 epidemiological studies and 2 randomized controlled trials.
I read each and every one of those 19 studies to see what they showed about red meat and depression risk. I set aside the fact that epidemiological studies can only generate hypotheses that then need to be tested in randomized controlled trials (RCT’s). I also set aside the fact that it was easy to find high quality journal articles on the topic of dietary patterns and depression that were, for whatever reason, not included in the committee’s review. For the sake of this exercise, I simply took the evidence the DGAC presented at face value.
Briefly, here is what I discovered about these studies [DGAC study reference numbers are noted in parentheses]:
- 3 studies did not evaluate meat (175,182,197).
- 7 epidemiological studies tied red meat to increased depression risk.(189,194,196,200,201 203,205). However, all of them except for one (205) lumped meat in with dietary patterns that include junk foods high in refined carbohydrate.
- 7 epidemiological studies (190,191,192,193, 195,198,199), and 1 RCT (202), found no association between meat and depression risk. 2 of these studies (193, 198) lumped meat in with junk foods high in refined carbohydrates and still found no increase in depression risk.
- 1 RCT (204) concluded that increased red meat consumption REDUCED risk for depression.
[For more details about these studies, including citations, please see my Summary of DGAC Depression and Diet Studies]
Graphic by Suzi Smith
You do the math
For those of you keeping score at home, 16 studies looked at meat. One of them suggests meat increases risk for depression. Six of them suggest that meat lumped in with junk foods increases risk for depression. Nine studies specifically exonerate meat, including both of the RCTs, and one of these RCTs found that eating more red meat was actually protective against depression.
What would YOU conclude, gentle reader, about meat and depression risk from these findings?
Now, what do you think the committee concluded?
“Patterns emphasizing red and processed meats and refined sugar were generally associated with increased risk of depression.”
Hmmm. How could the committee so confidently conclude that meat consumption increases depression risk, when more than half of the studies exonerate meat, including both of the clinical trials? If this isn’t clear evidence of bias, intentional or not, then I don’t know what is. If a detailed examination of this small portion of the report is any indication of how the rest of the report was generated, then the DGAC has a lot of explaining to do. Why didn’t the report conclude that studies about meat and depression do not support the DGAC’s favorite dietary patterns, or at the very least admit that there is not enough evidence to come to a conclusion? These recommendations are clearly not grounded in science—not even in the science the committee hand-picked to support its favorite diets.
How did they decide which studies to include? Your guess is as good as mine:
“Searching, screening, and selecting scientific literature was an iterative process that sought to identify the most complete and relevant body of evidence to answer a SR (systematic review) question. This process was guided by inclusion and exclusion criteria determined a priori by the DGAC.” [Part C, Lines 258-260]
Why lie about meat?
Why did the DGAC lie (to themselves and/or to us) about studies demonstrating the health benefits of red meat? Why do they bury positive information about red meat in tiny footnotes? Do they think red meat is bad for us and that we shouldn’t eat it? Well, actually, no . . . strangely enough . . .
The committee repeatedly sounds the drumbeat of “a healthy dietary pattern is higher in vegetables, fruits, whole grains, low- or non-fat dairy, seafood, legumes, and nuts; moderate in alcohol (among adults); lower in red and processed meat; and low in sugar-sweetened foods and drinks and refined grains”, despite the fact that one of the dietary patterns it recommends is actually higher in red meat than seafood, poultry, eggs, nuts, seeds, or soy. That’s right–surprisingly, buried in a single table [Table D1.10.] within the 571-page report, is the recommendation that non-vegetarians should eat 12-1/2 oz of meat, 10-1/2 oz of poultry, and 8 oz of seafood per week! [The Mediterranean-style pattern recommended includes twice the amount of seafood but the same amounts of red meat and poultry.] Why not tout throughout the report that red meat can be the main source of protein in a healthy diet?
I’m a psychiatrist. Thinking about people’s motivations and unconscious desires is an occupational hazard. When people behave irrationally, there’s usually an emotion at work. Like it or not, we humans make our most important decisions based on feelings, not on logic. I have many theories about why their report is so full of contradictions, omissions, and misrepresentations. But as I have never met any of the DGAC members, I can only speculate:
Theory #1: They believe that eating red meat is bad for the environment.
If you read the sustainability section of the report (which has since been deemed irrelevant by Congress) it is clear that they have come to this conclusion. A legitimate concern, at least when it comes to industrially-raised, grain-fed animals.
Theory #2: They believe that eating red meat is cruel to animals
Perhaps they can’t bear the thought of our fellow mammals being used for food. A legitimate concern, but we have no way of knowing whether any of them feel this way.
Theory #3: They value epidemiological findings over clinical trial outcomes.
The vast majority of studies claiming to conclude that meat is bad for human health are epidemiological studies, which cannot prove a cause and effect relationship. Of the 14 committee members, 9 are professional nutritional epidemiologists. Therefore, the majority of them, by virtue of their chosen professions, believe in the (nonexistent) power of epidemiology.
Theory #4: They have a vested professional interest in plant and/or fish-based diets which are low in saturated fat.
Of the 14 DGAC members, 9 have conducted studies focusing on the health benefits of plant ingredients and/or plant-based diets. Two have written books promoting plant-based diets. Therefore, most of these researchers have staked their careers at least in part on the theory that plant foods are superior to animal foods.
It’s a human thing. I don’t begrudge DGAC members their beliefs. But their report is supposed to be based on science, not on ideology. So here’s an idea. If you’re going to spend all kinds of time and money trying to legislate what people eat, at least lay everyone’s biases out on the table, and then choose a committee that includes people from many different points of view—pro-vegan, pro-Paleo, pro-Mediterranean, pro-vegetarian . . . you get the idea. And why not include some scientists from outside the politically-charged world of nutrition who might be capable of more objectivity? Maybe toss in a veterinarian, a physicist, a microbiologist . . . scientists who don’t have a stake in being right or wrong about their favorite diets.
And for Pete’s sake, leave the epidemiologists out of it. Epidemiological methods are incapable of concluding anything meaningful about food and health.
Where's the beef?
And so, dear DGAC, I’ll thank you to please keep your beliefs off of my table. See that plate full of anti-nutritious, poorly digestible grains and beans, metabolism-destroying refined carbohydrates, hormone-destabilizing dairy products, and refined seed oils loaded with pro-inflammatory omega-6 fatty acids? That is not My Plate. That’s YOUR plate. Now please pass the meat.
I’ve also posted a detailed critique of the World Health Organization’s October 2015 report claiming that red and processed meats cause cancer: "WHO Says Meat Causes Cancer?"
UPDATE: In March 2018 the USDA accepted public comments concerning the current dietary guidelines. You can read the comment I submitted in my Psychology Today post "Changes to Dietary Guidelines Needed to Preserve Our Sanity" where I specifically address how well the USDA food pattern variations meet nutrient recommendations for children and adults.