Changes to Dietary Guidelines Needed to Preserve Our Sanity
How to improve and restore faith in U.S. nutrition policy—a psychiatrist's view.
Posted Mar 31, 2018
Since the most recent incarnation of the Dietary Guidelines for Americans was released by the USDA in December 2015, a debate has raged about the scientific process (or lack thereof) used to generate the nutrition policies that dictate how schools, hospitals, and other institutions feed people, and how people across the country think about food. In response to widespread criticism, the USDA sought public comment about the recommendations this month, and received thousands of submissions.
I have studied the guidelines in some depth and discovered countless inconsistencies, omissions, biases and errors within this 144-page document that cause me great concern--both as an American citizen and as a psychiatrist specializing in nutrition. [For my tragicomic critique of the 2015 Dietary Guidelines Advisory Committee report, upon which the guidelines are based, please see: US Dietary Guidelines Hazardous to Health?]
I am convinced that our national nutrition recommendations pose significant risks to brain health that our society cannot emotionally or financially afford. For this reason, I am sharing the commentary I submitted to the USDA here in hopes that it may help shed light on the controversies at hand, and suggest a healthier way forward.
TOPIC: How well do USDA Food Pattern variations meet nutrient recommendations for children and adults?
Thank you for this opportunity to provide feedback about the US dietary guidelines generation process. I am writing not to take issue with any one dietary pattern, beverage, supplement, or nutrient, but rather to question (and make constructive suggestions about) the overall process by which the DGAC generates our national nutrition guidelines. The current process, by its very nature, interferes with the ability to arrive at meaningful recommendations with the power to improve public health, and leads to increased risk for nutrient deficiencies in children and adults of all ages.
As a psychiatrist specializing in college mental health who has studied and written about nutrition for the past ten years, I have grown increasingly concerned with the decline in mental health in our country and am convinced that the decline in the quality of our national diet is playing a major role in this growing epidemic. I am concerned that our nation’s dietary guidelines are part of the problem rather than part of the solution. Our current guidelines are convoluted, constantly changing, and so complex as to require 144 pages of explanation. This document confuses and frustrates even the savviest reader. We need guidelines that are clear, transparent, internally consistent, and easy to understand and implement. Approached properly, our national guidelines have the potential to serve as a source of knowledge and empowerment for all Americans striving to live long, healthy lives. It is my sincere hope that constructive, progressive change to the way the guidelines are generated would improve the public’s trust in the process, as well as improve public health.
Our current process for generating the national dietary guidelines fails the American people in that it:
1. Views nutrition from the outside in rather than from the inside out.
Currently, the Dietary Guidelines focus on a few arbitrarily-chosen dietary patterns hypothesized to be healthy by DGAC committee members. In human clinical trials, when compared to the modern “Standard American Diet” which is high in processed foods, each of these diets represents healthy improvements. However, this does not mean that these patterns represent the healthiest diets possible, only that they are superior to the unhealthiest diet one can imagine. There are countless other patterns just as worthy of study which are dismissed or not considered at all, thereby generating mistrust in the process among people who follow different diets which they experience as healthy. One could argue that the very focus on dietary patterns is unhelpful, given the myriad patterns possible. Wouldn’t it make more sense to approach questions about human nutrition from the inside out—by focusing on what the body needs to function properly and how it processes various foods, and using this information to determine which foods are best able to meet our common requirements? Truly valuable guidelines would go beyond recommending complicated, arbitrary patterns to educating and empowering people to make healthier choices within their chosen dietary patterns.
2. Prioritizes nutritional epidemiology over other scientific methods.
The vast majority of USDA guidelines are founded on hypotheses generated by epidemiological studies. Nutritional epidemiology is a notoriously flawed methodology, resting on inherently inaccurate food frequency questionnaires that generate weak, inconsistent, biased, and confounded associations. In stark contrast to cigarette smoking or infectious diseases caused by single agents—examples of public health problems which are well-served by epidemiological methods—there are simply too many variables in the modern human diet to properly account for with this approach.
Nutritional epidemiology is notorious for generating extremely weak, inconsistent associations between various foods and diseases. In fact, it has been determined that 80% or more of hypotheses generated by nutritional epidemiology are later proved false in clinical trials. By my count, of the 14 members of the DGAC, 9 are professional nutritional epidemiologists. Therefore, the majority, by virtue of their chosen professions, are likely to overestimate the value of observational studies. Fortunately, there is a wealth of high quality information to be found in other fields of science upon which to base our nutrition guidelines, including biochemistry, physiology, botany, anthropology, toxicology, and human clinical trials.
3. Places undue focus on isolated laboratory values rather than overall health.
An excellent example of how the over-reliance on epidemiological associations misinforms dietary policy is the focus on LDL. In medical school we were wisely taught to “treat the patient, not the lab test.” It is gradually becoming clear that the relationship between cholesterol tests and cardiovascular disease is complex, and that unfractionated LDL levels are the weakest predictors of future heart disease (compared to HDL and triglyceride levels). Tragically, our decades-long obsession with LDL reduction has distracted us from the search for root causes of cardiovascular disease such as inflammation, oxidation, calcification, insulin resistance, and endothelial dysfunction.
Focus on LDL reduction has also led to the strange and dangerous recommendation by the USDA to replace natural saturated fats with industrially-produced, refined seed oils, such as soybean and cottonseed oils. These modern oils tend to be extremely high in linoleic acid (LA), the essential omega-6 fatty acid necessary for mounting an inflammatory response to injuries and infections. Linoleic acid is readily obtained from both plant and animal foods, so there is no need to go out of our way to obtain more of it by consuming refined seed oils.
Furthermore, it is well-established in the scientific literature that an excess of omega-6 fatty acid competes with and reduces the availability of precious omega-3 fatty acids (namely, EPA and DHA). EPA generates anti-inflammatory molecules necessary for resolving and healing cellular damage. When EPA products are outnumbered by LA products, inflammation—the cornerstone of most chronic disease—predominates. DHA comprises 20% of the brain’s fat content and is critical to cortical development and myelination, as well as to the structure and function of retinal photoreceptors, cardiac cells, and mitochondrial membranes throughout the body. EPA and DHA are far more challenging to obtain from most standard omnivorous diets in that they are found in seafood and pastured animal organs/fats and do not exist in plant foods. It is well-established that the human body converts very little, if any, plant-sourced omega-3 fatty acids into the EPA and DHA our bodies require, therefore we must consume pre-formed sources of these essential fatty acids directly from animal foods (or take supplements). Misplaced focus on LDL and unnecessary avoidance of saturated fat has resulted in guidelines that inadvertently contribute to depletion of DHA from our hearts and brains and EPA from our immune systems, setting the stage for widespread inflammation and chronic disease.
4. Displays clear evidence of pro-plant bias.
The most recent DGAC was too homogeneous in that plant-based dietary philosophies were over-represented at the expense of other viewpoints. Of the 14 DGAC members, 9 had conducted studies focusing on the health benefits of plant ingredients and/or plant-based diets, and two had written books promoting plant-based diets. Therefore, most of these researchers had staked their careers at least in part on the theory that plant foods are superior to animal foods. Pro-plant bias (whether conscious or unconscious) within the committee likely clouded its ability to objectively evaluate and compare the nutritional qualities of plant and animal foods, resulting in guidelines that imply we should limit animal foods and strive to consume large quantities of plant foods.
Thus, the committee found itself in the shameful position of explicitly recommending that up to 50% of our daily grain intake be in the form of enriched refined grains, despite overwhelming evidence that refined carbohydrates are exceedingly unhealthy. The rationale for this absurd position is that without these fortified processed foods the “healthy” dietary patterns put forth in the guidelines would be lacking in key essential nutrients that are difficult to obtain from plant foods, yet easy to obtain from animal foods, such as B vitamins. How did human beings obtain essential nutrients prior to the invention of processed foods? This is the kind of common-sense question not being asked as part of the current process.
The consumption of refined carbohydrates can lead to chronically elevated insulin levels, which promote inflammation, oxidation, and insulin resistance throughout the body, including at the blood-brain barrier. Insulin resistance, which now affects more than 50% of Americans, is a driving force behind many chronic diseases, including obesity, type 2 diabetes and Alzheimer’s disease.
Additional problematic evidence of pro-plant bias is the lack of responsible acknowledgment of and warnings about risk of serious micronutrient deficiencies inherent in vegan diets unless properly and carefully supplemented. The 144-page dietary guidelines for 2015-2020 devote just a single sentence to vegan diets: “This [healthy vegetarian] Pattern can be vegan if all dairy choices are comprised of fortified soy beverages (soymilk) or other plant-based dairy substitutes.” This simple statement sanctioning a vegan diet does not clearly state that plant-based dairy substitutes must be fortified with B12 and neglects the importance of proper supplementation of long-chain omega-3 PUFAs (DHA and EPA) and vitamin K2, which are not found in plant foods. It also includes no warnings about the risks of serious nutrient deficiencies which are more common among vegans than omnivores, including: B12, B2, iodine, zinc, EPA and DHA deficiencies.
5. Displays clear evidence of anti-meat bias.
As a psychiatrist I was curious to understand the reasoning behind the DGAC’s conclusion that diets lower in red meat reduced risk for depression. There is clear evidence that the DGAC not only cherry-picked studies to support its stance against red meat, but that it misrepresented the studies it chose to review. I took the time to read every study the DGAC cited in support of its findings and was appalled to find that they did NOT support the notion that red meat increases risk for depression (!). My complete analysis of the studies concludes:
“In summary, 16 studies look at meat. One of them suggests meat increases risk for depression, six of them suggest that meat mixed with junk foods increases risk for depression, NINE studies specifically exonerate meat, including BOTH of the RCT’s, and one of the RCT’s found that eating MORE red meat was actually PROTECTIVE against depression.”
Anti-animal food bias clearly prevented the committee from objectively and honestly evaluating all of the available science.
6. Fails to properly and critically evaluate the nutritional quality of whole foods.
The guidelines are inconsistent in taking bioavailability concerns into account when comparing the nutrient content of plant and animal foods. Just because a food contains a nutrient does not necessarily mean we can access it. It is well-known that many plant foods naturally contain compounds which interfere with our ability to digest, absorb, and utilize many essential nutrients from plant and animal foods.
For example, the committee assumes human beings need to consume whole grains and legumes to be healthy, yet there is no scientific evidence I’m aware of demonstrating a nutritional requirement for grains of any kind in the human diet. Whole grains are presumed to be healthy because of the plethora of studies demonstrating that diets including whole grains are healthier than diets including refined grains, not because there are any studies demonstrating that diets including whole grains are healthier than diets without any grains at all. When one looks closely at the components of grains, one finds very little in the way of nutrients (to the point that we go out of our way to fortify them) and significant amounts of anti-nutrients and natural toxins including phytates, lectins, and protease inhibitors not found in animal foods. Nutrition experts must do the hard work of studying not just nutrients within foods but all components within foods that affect our health.
My own health deteriorated following the USDA guidelines; it was only by abandoning the guidelines and starting from scratch to learn nutrition on my own, from the ground up, that I was able to restore my own good health.
To generate truly meaningful dietary guidelines, future committees must start from scratch as well. To continue to make modifications to an inherently flawed foundation composed of weak epidemiological associations, biased assumptions, and arbitrarily-chosen dietary patterns will not significantly improve the quality of the final product. We need a more diverse, less entrenched, more scientifically rigorous committee that openly declares its personal, professional, and financial biases. There is nothing inherently wrong with bias—all humans have their biases—it is in acknowledging them that we stay honest with ourselves and others about our blind spots.
If we choose as a nation to publish highly influential nutrition guidelines that dictate how our hospitals, schools, and other institutions feed people, then it is my sincere hope that future committees be comprised of individuals representing a diversity of (declared) nutrition philosophies—so that we avoid the appearance of dietary favoritism—as well as a diversity of scientific disciplines—even from outside of the nutrition sciences, perhaps even several representatives from non-biological sciences—so that we avoid the risk of building our guidelines on unrecognized assumptions about foods that may need to be questioned.
A responsible committee would openly acknowledge areas of nutrition controversy and doubt to foster ongoing research. If we truly care about the health and well-being of our fellow human beings, we owe it to ourselves and others to stay curious and open-minded. We must take the time to learn and appreciate how the foods we choose to eat operate within the human body, to understand and be honest about the real risks and benefits of the diets we personally eat and professionally recommend, and to acknowledge the limitations of our knowledge. The healthier the process is, the healthier our nation will be.