Overall score
Scientific accuracy
Reference accuracy
Healthfulness
How hard would it be to apply the book's advice? Very difficult
The Plant Paradox, by Steven R. Gundry, MD, describes a diet and lifestyle program intended to prevent and reverse obesity and most chronic diseases by eliminating their supposed root cause: plant lectins. These are naturally-occurring substances found in many common plant foods and certain types of dairy. To solve this perceived problem, the book presents the Plant Paradox Program, which focuses on avoiding foods rich in lectins. Other recommendations include limiting the consumption of red meat, regular intermittent fasting, getting sufficient sleep, avoiding certain chemicals such as the herbicide roundup, avoiding genetically modified foods, and taking a large number of supplements.
Key points from our review
- The book’s strong claims that the plant paradox program can prevent and reverse obesity and most chronic diseases are poorly supported by scientific evidence.
- We were unable to identify even modest evidence that lectins may be a root cause of obesity or any of the chronic diseases mentioned in the book.
- While some claims are well supported by the references cited in the book, others are not, or only partly.
- The diet portion of the program is extremely restrictive, quite expensive, and would be very hard for most people to follow for more than just a few weeks.
- For those who are able to follow the book’s recommendations in the long-term, we think the nutrient-dense whole foods the book recommends, and the exclusion of most junk foods will likely provide health benefits.
- Because current scientific evidence on the health effects of lectins in humans is very limited, it is not entirely out of the question that plant lectins could play a role in the development of certain diseases in at least some individuals.
Bottom line: While the diet recommended in The Plant Paradox probably has general health benefits for people who can stick with it, it’s not clear whether avoiding common dietary lectins is beneficial.
Book published in 2017
Published by Harper Wave
First Edition, Hardcover
Review posted March 30, 2019
Primary reviewer: Mario Kratz
Peer reviewer: Stephan Guyenet
If you like what we do at Red Pen Reviews, please consider donating. To continue bringing you the most informative and objective book reviews available, we have to be able to pay our expert reviewers for their time, and you can make that happen.
Table of contents
Introduction
In The Plant Paradox, Steven R. Gundry, MD, argues that lectins from certain plant foods including grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables are the cause of obesity and numerous chronic diseases, including autoimmune disease, cancer, cardiovascular disease, diabetes, and certain neurodegenerative diseases. Lectins are a diverse class of sugar-binding molecules that can be found in many foods, capable of binding to the sugars on the outside of cells. The author argues that at least some humans may not be well adapted to consuming large quantities of lectins from foods that were introduced into the human diet only in the last ~10,000 years. In the Plant Paradox Program, the author recommends that individuals may want to completely eliminate (phases 1 and 2 of the program) or dramatically limit (phase 3) those foods that are rich sources of supposedly problematic plant lectins. The program has a few other components, such as the recommendation to limit animal protein, to avoid certain drugs such as non-steroidal anti-inflammatory drugs (NSAIDS, such as aspirin, ibuprofen, etc.) or stomach acid-blocking drugs, to use certain supplements, to fast intermittently, and to avoid exposure to blue light at night, but the key distinguishing feature of the program is clearly the strong emphasis on avoiding plant lectins.
The author claims that the Plant Paradox program can reverse numerous medical conditions, including obesity and autoimmune disease. The book is written for a general audience, but may be particularly appealing to individuals suffering from one of the conditions the author links to plant lectins. The book has been extremely popular since its publication in 2017. I chose to review it primarily because I am personally and professionally interested in the potential health effects of plant lectins, and because of its popularity.
Scientific Accuracy
The author makes numerous very strong claims throughout the book. However, because the most defining characteristic of the Plant Paradox Program is the avoidance of lectins from grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables, I decided to focus on key claims made about health effects of lectins from these foods.
Claim 1: Lectins from grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables cause an increase in intestinal permeability (“leaky gut”).
Claim 2: Grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables are fattening foods because their high content of lectins stimulate energy storage and appetite.
Claim 3: Inside the body, lectins from grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables cause chronic autoimmune or other inflammatory reactions leading to a wide range of chronic diseases.
It is noteworthy that the author repeatedly emphasizes that his claims and his program are based on scientific evidence. For example, in the introduction (page XV), he states that he has published his research in “peer-reviewed medical journals” (only true with major reservations, as the cited article is a conference abstract, i.e., very short and not rigorously peer-reviewed). However, most of the major claims made, such as the three chosen here, are not at all or only very poorly supported by cited literature. In each case, we conducted a literature review to assess the degree to which the claims are supported by published peer-reviewed evidence.
Claim 1
Lectins from grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables cause an increase in intestinal permeability (“leaky gut”).
On numerous occasions, the author states that plant lectins cause a syndrome that is commonly referred to as “leaky gut”, the scientific term for which is “increased intestinal permeability”. Leaky gut is relevant, the author argues, because it allows lectins and other molecules to enter the bloodstream and interact with the immune system. This would be expected to lead to inflammation, and may also pave the way for autoimmune diseases in which the immune system mistakenly attacks the body’s own cells and tissues.
Supporting quote(s) and page number(s)
Page 22: “Lectin attack strategy #1: Get through the gut wall. The first mission of lectins is to pry apart what are called tight junctions between the cells in the mucosal wall lining your intestine.”
Page 23: “[…] lectins can pry apart the tight junctions in the intestinal wall by binding with receptors on certain cells to produce a chemical compound called zonulin. Zonulin opens up the spaces between the cells of the intestinal lining, which enables lectins to access the surrounding tissues, lymph nodes and glands, or bloodstream, where they have no business being.”
Pages 79-80: “Lectins are adept at prying apart the tight junctions between the cells that make up your intestinal mucosal border”.
Criterion 1.1. How well is the claim supported by current evidence?
2 out of 4
This claim received a score of 2, indicating that it is weakly supported by current evidence. The author does not cite any references in support of this claim. While we were able to locate several studies that demonstrated increased intestinal permeability in response to the oral intake of lectins, all of these were rodent studies using high doses of lectins, for example using isolated lectins or uncooked beans. It remains unclear whether an increase in intestinal permeability would result in humans consuming much smaller amounts of lectins from lectin-rich foods that will almost always be consumed in their cooked form.
While the current evidence only weakly supports the claim made by the author, there is evidence that lectins can be found in human blood, as has been described for peanut lectin. Also noteworthy in this regard is that lectins are generally considered to be resistant to digestion, based on studies with some specific lectins such as the garlic lectin and the tomato lectin. Thus, the general argument the author makes that lectins can enter the human body is to some degree supported by the scientific literature. Whether this requires an increase in intestinal permeability, however, is not clearly supported by current evidence.
Criterion 1.2. Are the references cited in the book to support the claim convincing?
1 out of 4
This claim received a score of 1, because the author did not cite references to support it.
Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?
2 out of 4
While there is some evidence that lectins may increase intestinal permeability, the author does not appropriately discuss the qualifiers, i.e. that effects thus far have been seen only in animal models, and only using doses that may be substantially higher than what humans typically ingest.
Overall (average) score for claim 1
1.7 out of 4
Claim 2
Grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables are fattening foods because their high content of lectins stimulate energy storage and appetite.
Throughout the book, the author repeatedly argues that lectins from foods that were introduced into the human diet only in the past ~10,000 years trigger excessive food intake and energy storage, leading to weight gain and obesity. A whole section (starting on page 144) is devoted to the author’s theory that a specific lectin, wheat germ agglutinin (WGA), stimulates fat storage by mimicking insulin-binding to fat cells. In another section (“Fruit might as well be candy”, pages 170-171), the author argues that most fruit is fattening.
Supporting quote(s) and page number(s)
Page 142: “And as with pigs, eating corn fattens up us humans.”
Page 142: “Yes, when everything else failed to restore their lost weight, grains and beans did the job”
Page 143: “Here, then, is the reason grains and beans took over the world. It wasn’t because they were ‘healthy’. It wasn’t because they could be stored. No, it was merely because such foods promoted greater fat deposits per calorie than any other food source.”
Page 143: “You’ll recall that it isn’t just grains and beans that turbocharge fat storage, but also milk products.”
Page 171: “If it has seeds, it is a fruit! That means that a zucchini, a tomato, a bell pepper, an eggplant, and a pickle are all fruits! And when you eat them, they deliver the same chemical message to your genes and your brain as a more obvious fruit, such as an apple, does: store fat for the winter!”
Criterion 1.1. How well is the claim supported by current evidence?
1 out of 4
This claim received a score of 1, because there is little in the scientific literature to support this claim, and the author did not provide references to support most of the statements made in this regard.
Let’s first look at the current state of scientific knowledge supporting the claim that lectins such as WGA promote overeating and obesity. There are indeed several publications that describe insulin–like effects of WGA and another lectin, concanavalin A, so these statements of the author are technically not incorrect. However, this particular point is also a good illustration of where the author goes wrong in his synthesis and interpretation of the literature. The existing literature shows fairly consistently that WGA in low concentrations increases the sensitivity of cells to insulin. This would certainly be a potentially beneficial effect of WGA, as improved insulin sensitivity would lower circulating insulin concentrations and reduce the risk of glucose intolerance and type 2 diabetes. At high concentrations, WGA inhibits the binding of insulin to its receptor on fat cells, which would be expected to reduce insulin sensitivity. These divergent effects of WGA on fat cell insulin sensitivity and signaling illustrate that a simple conclusion such as “WGA locks on for good and continues to instruct the cell to make fat from any sugar floating by” (page 146) cannot possibly be correct. Whether WGA concentrations in blood are more similar to the low or the high dose tested in these experiments cannot be determined at this point, because to our knowledge no one has confirmed that WGA is actually present in human blood, and at which concentration. Further, even if WGA acted on fat cells just like insulin does, the net effect on body fatness is far from certain. While it is true that insulin stimulates fat storage in fat cells, its overall role in regulating body weight is much more complex, and it is far from clear that some additional insulin activity through a compound such as WGA would induce overeating and weight gain. And, possibly most importantly, the author fails to mention that everything we know about these insulin-like effects of WGA is based on cell culture experiments, which may not at all apply to the situation in a human tissue. To this point, an early paper on the topic clarifies that “all of the effects observed with the plant lectins are reversed by simple sugars that bind specifically to these plant proteins”. Thus, any simple sugars that are present in a live tissue would possibly negate the insulin-like effects of WGA on cells. Taken together, while there is evidence from cell culture that WGA can affect insulin signaling in fat and other tissues, and can even mimic insulin actions, it is unclear whether these cell culture findings apply to humans, and whether such WGA action would even be fattening. To our knowledge, there is also no convincing scientific evidence that other plant lectins may affect calorie intake or expenditure in a way that could be seen as fattening. Thus, the author clearly and substantially overstates the strength of the evidence in this regard.
But maybe there is evidence in the literature supporting the claim that the consumption of these lectin-rich foods leads to weight gain and obesity? Mostly, there is not. In fact, there is clearly some support for suggestive protective effects againstweight gain for fruit and legumes, and mostly no or only weak associations with weight gain for grains and dairy. Specifically, the consumption of fruitis consistently inversely associated with weight gain in cohort studies, and experimental studies demonstrate a reduction in calorie intake in individuals who increase their fruit intake. The consumption of whole grains (which are particularly rich in lectins compared to refined grains) is mostly associated with leanness in observational studies, while intervention studies in which people were randomized to consume more whole grains mostly show weight loss or no effect on body weight. Higher consumption of legumes is associated with lower body weight in most studies. The only one of these factors that may be associated with a modest increase in body weight is dairy, based on some intervention studies. Thus, the scientific literature mostly undermines the author’s proposed fattening effects of grains, legumes, fruit, and dairy.
Criterion 1.2. Are the references cited in the book to support the claim convincing?
1 out of 4
The book received a score of 1 for its use of references to support this claim because the author does not provide references to support this claim.
Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?
0 out of 4
As outlined above, there is little in the scientific literature to support this claim. In fact, the existing evidence, while not particularly strong or conclusive, undermines the author’s claim when considered in its totality.
Overall (average) score for claim 2
0.7 out of 4
Claim 3
Inside the body, lectins from grains, legumes, certain types of dairy, fruit, and nightshade and cucumber-family vegetables cause chronic autoimmune or other inflammatory reactions leading to a wide range of chronic diseases.
Throughout the book, the author repeatedly claims that specific plant lectins cause inflammatory or autoimmune responses, thereby causing or contributing to major chronic disease. He does state that lectins are “in cahoots with” (page 129) other factors, such as use of antibiotics, NSAIDs, stomach acid-blocking drugs, certain chemicals, and a deficiency in certain micronutrients or plant phytochemicals, but the core of his argument centers around the pro-inflammatory actions of lectins in the body.
Supporting quote(s) and page number(s)
Page 38: “[…], certain lectin-heavy foods are the cause of so-called autoimmune diseases, while lectin avoidance in my patients and as reported in the scientific literature has been found to cure autoimmune diseases.”
On page 70, after listing about 50 different diseases, including “allergies”, “arthritis”, “asthma”, “autoimmune diseases”, “cancer”, “dementia”, “depression”, “diabetes”, “headaches”, “heart disease”, and “Parkinson’s disease”, the author states “Twelve years ago I myself would have tossed this book out the window if you had suggested that everything on this list was caused by consuming lectins, in collaboration with chemical and other disruptors that have infiltrated our bodies. However, my experience with tens of thousands of patients is proof that this is in fact the case – and that following my protocol will heal what ails you.”
Criterion 1.1. How well is the claim supported by current evidence?
1 out of 4
This claim received a score of 1, indicating that existing evidence does not convincingly support this claim. While the author claims repeatedly throughout the book, in no uncertain terms, that lectins cause or contribute to a large number of chronic diseases, he almost never cites any pertinent literature to support this claim. On one occasion the author supported the very strong statement “while lectin avoidance in my patients and as reported in scientific literature has been found to cure autoimmune disease” with a reference to a conference abstract he himself had submitted. While conference abstracts are commonly peer-reviewed, the level of rigor in this review process is much lower than in quality biomedical journals, and short abstracts provide very little detail on the work. Thus, basing such a strong claim on a conference abstract alone is not appropriate.
Because the author failed to cite appropriate peer-reviewed literature to support his claim, we conducted a literature review of the evidence on the relationship between plant-lectins and autoimmune disease, diabetes, cancer, and cardiovascular disease. For cancer, the author fails to mention that active current research is more focused on anti-cancer properties of a number of plant lectins. There are some publications that weakly suggest that immune responses to plant lectins may play a role in the development of certain autoimmune disease, but even those are not particularly convincing. For example, two studies report that binding sites for plant lectins are altered in intestinal tract cells of patients with ulcerative colitis or Crohn’s disease compared to healthy controls. We also found two review articles proposing the hypothesis that plant lectins may play a role in the development of certain diseases, but neither provides any real evidence in support of this hypothesis. Thus, at this point, the idea that plant lectins are a major factor in the development of obesity or chronic diseases is highly speculative.
Criterion 1.2. Are the references cited in the book to support the claim convincing?
1 out of 4
In most instances, the author does not cite any evidence for this claim, or cites inadequate sources (conference abstract by the author himself).
Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?
0 out of 4
The available data from peer-reviewed literature does not even weakly support the claim that lectins cause any of the diseases mentioned.
Overall (average) score for claim 3
0.7 out of 4
Overall (average) score for scientific accuracy
1.0 out of 4
Reference Accuracy
I randomly selected ten references in The Plant Paradox and checked them for accuracy. The overall reference accuracy score was 2.8 out of 4, with most references receiving either a 4 (reference offers strong support for the claim) or a 1 (reference does not convincingly support the claim). Mostly, I would describe the use of references in this book as problematic. For example, the author cited a conference abstract submitted by himself as the only reference in support of an extremely strong statement (“cures autoimmune disease”, see reference #3 below), or cited references not at all related to the stated claim (see references #2, 7, and 9). Other claims are well supported by the references cited. However, even in those cases the author’s tendency to use hyperbolic language often feels like he is overstepping the evidence.
Reference 1
Reference
Monahan, P. 2016. Plants defend themselves with armor made of sand. Accessed 12/10/2016
Associated quote(s) and page number(s)
“Plants may use a variety of physical deterrents, such as color to blend into their surroundings; an unpleasant texture; sticky stuff such as resins and saps that entangle insects, provide protective cover by making sand or soil clump, […]” (page 6).
Criterion 2.1. Does the reference support the claim?
4 out of 4
The claim that plants secrete ‘sticky stuff’ which makes sand stick, making them less attractive as a food for herbivores, is supported by a popular science article in Science Magazine. This article is based on a scientific paper published in the journal Ecology by LoPresti and Karban, and while it would have been preferable to cite the original source, the claim is supported by the evidence cited.
Reference 2
Reference
Associated quote(s) and page number(s)
“For example, the lectin WGA bears a striking resemblance to insulin” (page 25).
Criterion 2.1. Does the reference support the claim?
1 out of 4
The book cites three scientific articles to support his claim that wheat germ agglutinin (WGA) resembles insulin. While none of these articles suggests that WGA is actually structurally similar to insulin, the paper by Livingstone and colleagues demonstrates that WGA affects insulin binding and insulin sensitivity in fat cells, so this publication at least somehow links WGA and insulin. The other two publications cited here don’t even contain the word ‘insulin’, and the paper by Hollander et al. also doesn’t cover ‘WGA’. There are several publications demonstrating that WGA can mimic insulin actions on a number of cell types; however, none of these are cited by the author to support this claim.
Reference 3
Reference
Gundry SR. Curing/remission of multiple autoimmune diseases is possible by manipulation of the human gut microbiome: the effect of a lectin limited, polyphenol enriched, prebiotic/probiotic regimen in 78 patients. Journal of International Society of Microbiota 2016; 3(1).
Associated quote(s) and page number(s)
“[…], certain lectin-heavy foods are the cause of so-called autoimmune diseases, while lectin avoidance in my patients and as reported in scientific literature has been found to cure autoimmune diseases” (page 38).
Criterion 2.1. Does the reference support the claim?
N/A
The article is not indexed in either PubMed or Google Scholar, and could also not be obtained from the International Society of Microbiota. It could therefore not be reviewed, and was not scored. It is fair to say, however, that the peer-review process for conference abstracts is not considered to be particularly rigorous. Abstracts are almost always very short, almost always accepted for at least a poster presentation, and there is no back-and-forth between reviewers and authors to address problems. Thus, a conference abstract that provides little detail and that is not accessible to the public or even peer researchers is not a suitable reference for such a strong claim.
Reference 4
Reference
Associated quote(s) and page number(s)
“Copious research published over the last half century reveals that gulping down apparently harmless NSAIDs is like swallowing a live grenade. These drugs blow gaping holes in the mucus-lined intestinal barrier. As a result, lectins, LPSs, and living bacteria are able to deluge the breaks in your levee, flooding your body with foreign invaders. Inundated by these foreign proteins and other invaders, your immune system does what it does best, producing inflammation and pain. This in turn prompts you to down another NSAID, promoting a vicious cycle, which can ultimately result in your seeking out prescription-level pain relievers. In other words, that harmless Aleve or Advil is the pharmaceutical industry’s gateway drug” (page 84).
Criterion 2.1. Does the reference support the claim?
4 out of 4
The reference is a review article, summarizing good-quality evidence that NSAIDs indeed cause gastrointestinal injury and increased intestinal permeability (whether this should be referred to as a “grenade”, however, is a different question).
Reference 5
Reference
Whiteman H. CDC: Life expectancy in the US reaches record high. Accessed 11/28/2016.
Associated quote(s) and page number(s)
“In 1960, the average life expectancy for American men was 66.4 years; by 2013 it was a full ten years longer” (page 94).
Criterion 2.1. Does the reference support the claim?
3 out of 4
The cited article is a summary for the general public based on a study by the Centers for Disease Control and Prevention (CDC). While it would have been preferable to cite the original source, the article does state that the life expectancy of men born in 2012 is 76.4. No data are given for 2013, and the article does not provide data for 1960.
Reference 6
Reference
Associated quote(s) and page number(s)
“One study showed a 44 percent increased risk of dementia among 74,000 people aged seventy-five and older who had used these drugs, compared with those who did not” (page 105).
Criterion 2.1. Does the reference support the claim?
4 out of 4
The cited article is an observational study of good quality that describes an increased risk of dementia (by 44%) in older individuals who were using proton pump inhibitors compared to individuals who did not.
Reference 7
Reference
University of California San Francisco. UCSF presentation reveals glyphosate contamination in people across America. Accessed 11/29/2016
Associated quote(s) and page number(s)
“A growing number of scientists are risking attack by the biotech industry by releasing studies that link glyphosate to cancer, kidney and liver failure, birth defects, infertility, increased risk of allergies, and digestive issues, among other chronic illnesses” (page 124).
Criterion 2.1. Does the reference support the claim?
1 out of 4
This citation does not support the claim, and is also misleading. First, the article discusses glyphosate levels in urine as well as potential health effects, and does not mention attacks on scientists by the biotech industry. Second, the reference suggests that the source origin is the University of California San Francisco, which is not the case, as the URL links to an article on the web site of the Organic Consumers Association.
Reference 8
Reference
Associated quote(s) and page number(s)
“You may have a small serving of nuts, guacamole, or simply half a Hass avocado as a snack” (page 179).
Criterion 2.1. Does the reference support the claim?
N/A
The reference belongs to a recommendation of the author, not a claim that needs to be supported by a reference. It was therefore not scored.
Reference 9
Reference
Associated quote(s) and page number(s)
“Unlike other polyunsaturated fats, long-chain fish oil omega-3s also block the entry of LPSs past your gut wall” (page 216).
Criterion 2.1. Does the reference support the claim?
1 out of 4
The cited reference describes the effects of fish oil supplementation on measures of endothelial function and arterial stiffness, and does not mention any of the words “LPS”, “lipopolysaccharide”, or “endotoxin” (commonly used term for lipopolysaccharide) anywhere. It is not a suitable reference for the claim made.
Reference 10
Reference
Associated quote(s) and page number(s)
“In fact, because the lectins in grain bind to joint cartilage, Italians overall have significantly high rates of arthritis” (page 240).
Criterion 2.1. Does the reference support the claim?
2 out of 4
The reference clearly confirms that joint cartilage has binding sites for certain lectins. However, the reference does not provide any evidence that Italians have high rates of arthritis, or that this is related to their intake of lectins.
Overall (average) score for reference accuracy
2.5 out of 4
Healthfulness
The target audience ofThe Plant Paradox is not well defined in the book. Given that the book makes strong claims about preventive and therapeutic effects related to a wide range of medical conditions, it seems to address both the general public interested in health and prevention of chronic disease, as well as those with conditions ranging from obesity to autoimmune diseases, cancer, cardiovascular disease, and neurodegenerative disease.
The Plant Paradox Program presented in this book consists of three phases. Phase 1 is called the ‘3-day cleanse’, and is intended to ‘repair’ dysfunctional gut microbiota. The phase 1 diet is entirely free of foods that contain supposedly problematic plant lectins, and includes mostly organic vegetables, wild-caught fish or pasture-fed chicken, and certain foods rich in fat such as olives, avocado, and certain nuts. A green smoothie is encouraged every morning. The author also recommends a laxative and other supplements that are said to “kill parasites, fungi, and other bad gut flora” (page 196).
The overarching goal of phase 2is to reduce the consumption of lectins that have been introduced into the human diet only in the last ~10,000 years. This phase should be followed for 6 weeks, but could be followed much longer or forever. For the first 2 weeks, the recommendation is to follow a very low-fat diet, and to limit the intake of animal protein-rich foods and eat abundant fiber, among other fairly specific guidance. Finally, it strongly suggests eliminating any antibiotics, stomach-acid blocking drugs, and non-steroidal anti-inflammatory drugs (NSAIDs).
Once the gut health has been restored, weight has normalized, and any symptoms of chronic disease have disappeared, readers can consider transitioning into phase 3. This phase is the long-term, new ‘lifestyle’ to be followed forever. During this phase, they can consider re-introducing some lectin-rich foods as long as they are prepared properly. For long-term health, it also recommends dramatically limiting animal foods rich in protein and intermittent fasting, among other things.
For individuals who already suffer from major disease, the book recommends a very-low carb low-protein diet rich in specific oils and fats called the Keto Plant Paradox Intensive Care Program. Here, the author argues that such a ketogenic lectin-free diet will correct mitochondrial dysfunction, and through this mechanism (no reference cited) cure diverse diseases including type 2 diabetes, cancer, kidney disease, and amyotrophic lateral sclerosis. As for the normal Plant Paradox Program, foods rich in problematic lectins are strongly limited or eliminated, animal protein is limited, and certain oil- or fat-rich foods are encouraged.
In addition to these dietary changes, the author recommends a long list of supplements (many of which are sold on the author’s web site), including a ‘lectin shield’.
Summary of the health-related intervention promoted in the book
The book promotes the Plant Paradox Program for the prevention of obesity and chronic disease, consisting of a low-protein, largely whole foods-based low-lectin diet in combination with supplements to enhance the consumption of certain nutrients and plant phytochemicals. Other components of the program are limited red meat intake, avoidance of blue light at night and regular, sufficient sleep, intermittent fasting, avoidance of non-steroidal anti-inflammatory drugs (NSAIDs) and stomach acid-blocking drugs, and avoidance of certain environmental exposures including the pesticide roundup and genetically modified foods.
Condition targeted by the book, if applicable
Obesity and most chronic diseases, including but not limited to autoimmune disease, cardiovascular disease, diabetes, cancer, and certain neurodegenerative diseases
Apparent target audience of the book
Healthy general population interested in prevention, obese individuals, and individuals with chronic disease.
Criterion 3.1. Is the intervention likely to improve the target condition?
2 out of 4
Because there is very little published evidence on this diet, there are little to no scientific data available to provide guidance in answering this question. The truth is that it is currently unknown whether avoidance of certain lectins, or most of the other components of the Plant Paradox Program, are effective in preventing or treating any of the conditions this program aims to target. It is also likely that the effectiveness of the Plant Paradox Program will differ across the wide variety of conditions targeted by the program. What is clear, however, is that the program as a whole and the recommendation to dramatically limit the consumption of certain lectin-rich foods in particular is not based on scientific evidence at this point. While evidence exists that lectins can pass through the gastrointestinal tract, can have toxic effects on the gut, can be absorbed and detected in human blood, can bind numerous structures inside the human body, can mimic certain hormones such as insulin, and are able to trigger an immune response, it is currently unknown whether they play a role in any chronic disease. It is possible and in fact may be considered plausible by some, however, that lectins are involved in the development of some chronic diseases, and that at least some individuals may benefit from the proposed lectin-limited diet.
Another aspect we considered is that the proposed whole foods-based program and many of the other recommendations, such as regular intermittent fasting, avoidance of certain environmental exposures, regular and sufficient sleep, and even some of the recommended supplements, will likely lead to a healthier diet and lifestyle than that of average Americans, and are likely to improve at least some of the target conditions at least modestly. For example, dramatically reducing variety in food choices, and avoiding the most highly rewarding types of foods, two changes that adherence to this program would clearly enforce, will reduce calorie intake and body weight in the short to medium term in most people. Similarly, the program would very substantially limit the consumption of empty calories from refined grains and added sugars, which would make the diet less energy dense (i.e., fewer calories per weight of food eaten) and more nutrient dense (more nutrients per calorie eaten), both changes that likely offer health benefits.
Criterion 3.2. Is the intervention likely to improve general health in the target audience?
2 out of 4
Given that the intervention targets obesity as well as almost all major chronic conditions, our response to this question is identical to that of the previous one (criterion 3.1).
Criterion 3.3. Does the diet portion of the intervention promote an adequate nutrient intake for general health in the target audience?
3 out of 4
A major benefit of the main Plant Paradox Program is that the recommended diet eliminates all ‘junk’ foods that are high in energy density and very low in micronutrients and fiber, such as cakes, cookies, muffins, donuts, chips, or candy. Even though some nutritious foods are very much limited or entirely eliminated, the allowed foods include whole, nutritious foods across most categories. With the focus on lots of leafy green and other vegetables, certain fruit such as avocado, nuts and seeds, fish and shellfish, complemented with smaller quantities of other animal foods such as certain types of dairy, meat, and eggs, we don’t see any risk of major micronutrient deficiencies on this plan. In fact, the diet will likely have a substantially higher content of most vitamins, minerals, and trace elements than the diet of average Americans, or even individuals following the prevailing Dietary Guidelines for Americans. Similarly, the diet will almost certainly be higher in most plant phytochemicals, even though the recommendation to limit intake of out-of-season fruit hurts in this regard.
The one dietary factor we are slightly concerned about is fiber. In the US diet, fiber is mostly consumed in the form of whole grains, legumes, fruit and vegetables, and three of these four categories are severely limited or entirely eliminated on the Plant Paradox diet plans. For example, grain foods alone provide 55% of all fiber consumed in the US diet. While in theory individuals could meet their daily fiber requirements with the allowed foods, in practice this will be very hard for many. The recommended fiber supplement may help, however, and reintroduction of some lectin-rich foods such as certain properly prepared grains or legumes in the long-term phase 3 of the program may also be particularly advantageous in this regard.
We are a bit more concerned about adequate nutrient and particularly fiber intakes on the ketogenic Plant Paradox Program that is recommended to individuals with pre-existing major chronic disease, particularly because it is emphasized that this diet may be ‘for life’ (page 268). To be ketogenic, this diet will need to be particularly high in fat while limiting both carbohydrate and protein intakes. Few foods are naturally very high in fat and low in protein and carbohydrate, and most individuals can eat only limited amounts of these foods. Thus, there is a risk that this specific diet would be richer in added fats and oils, or particularly fatty cuts of meat or fat-enriched dairy products. Those particular foods are much lower in nutrient density and higher in energy density, which partly negates the positive benefits of the regular Plant Paradox Program outlined above.
Overall (average) score for healthfulness
2.3 out of 4
Most unusual claim
There are numerous unusual claims in this book. I chose to discuss the claim that consumption of fruit leads to weight gain and obesity. Repeatedly throughout the book, and particularly in a separate section on pages 170-171, the author claims that fruit is highly fattening, and that our bodies evolved to store excessive amounts of fat when eating fruit because before the advent of agriculture fruit was only ripe in the summer and particularly fall, i.e. before periods of low food availability in winter.
Relevant quotes:
- Page 170: “As you’ve learned, eating fruit in season allowed our ancestors to fatten up for the winter, but now fruit is ubiquitous 365 days a year”
- Page 171: “If it has seeds, it’s a fruit! That means that a zucchini, a tomato, a bell pepper, an eggplant, and a pickle are all fruits! And when you eat them, they deliver the same chemical message to your genes and your brain as a more obvious fruit, such as an apple, does: Store fat for the winter.”
The argument centers around lectins present in fruit, and also the high fructose content of most fruit. The book cites no evidence to support the claim that fruit causes weight gain and obesity, or that fruit lectins impact the body in a way that would trigger overeating. We do not believe such evidence exists. In fact, the consumption of fruit is consistently inversely associated with weight gain in cohort studies, and experimental studies demonstrate a reduction in calorie intake in people who increase their fruit intake.
The claim that fructose in the form of fruit is fattening deserves a bit of a more thorough discussion, as it is not entirely groundless. Fructose is metabolized differently than most other carbohydrates. Specifically, fructose is converted into fat in the liver, potentially contributing to excessive fat storage in the liver. In contrast to glucose, fructose also does not trigger changes in key hormones known to regulate appetite and body weight, including leptin, insulin, and ghrelin, which has caused some investigators to propose that fructose may be the most fattening type of carbohydrate. This seemed to be supported by the consistent findings that sugar-sweetened beverages, which are rich in fructose from either sucrose or high-fructose corn syrup, increase calorie intake and promote weight gain. However, the degree to which individuals overconsume calories when they drink sugar-sweetened beverages is not different when these beverages are sweetened with glucose vs. fructose, suggesting that people overconsume calories when drinking sugary drinks because they are liquid calories, not because they are rich in fructose. To our knowledge, it has also never been shown convincingly that fructose consumed in the form of normal household sugar (sucrose) or high-fructose corn syrup in solid foods, or present naturally in fruit, leads to overeating or weight gain.
It is also worth pointing out that from a nutritional point of view, seeing fruit only as a vehicle for lectins and fructose, and suggesting they are “the same poisonous stuff” as “Skittles candy” (page 171), is a case of reductionism that has rarely been helpful in evaluating the health properties of whole foods. Fruit is exceptionally rich in fiber, and characterized by a low calorie density of only ~50-60 kcal per 100 grams (1/4 lb) for most types of fruit. Thus, you could eat, say, two apples (~370 g, ~190 kcal) and get the same calories as you’d get from one donut (~40 g, ~190 kcal). Even if the fructose and lectins in fruit caused you to overeat, you’d have a hard time eating so many apples that you’d start gaining weight.
Other
I was interested in reviewing this book because I had repeatedly stumbled upon scientific publications that described potentially negative health effects of plant lectins, such as their gastrointestinal toxicity. My hope was that the book would provide a thorough overview of what is—and is not—currently known about the health effects of plant lectins. It did not. While the author emphasizes repeatedly that the Plant Paradox Program is based on scientific evidence, this is clearly not the case. The available literature on the effects of plant lectins on biological processes related to health and disease are almost entirely based on experiments in cell culture or animal models, and no human studies that we are aware of convincingly link lectin intake to obesity or any chronic disease.
We can give the author some credit that he has tried to publish the anecdotal evidence from his clinics in the scientific literature, albeit so far only as conference abstracts. If we assume that the data are as convincing as the ‘Success Stories’ throughout this book suggest, however, it is astonishing that he has not yet published an actual peer-reviewed paper in a higher-quality biomedical journal to date. As it is, the book makes a lot of strong claims based on almost no scientific evidence whatsoever, while at the same time claiming that the program is based on scientific evidence. The extensive list of supplements that are recommended, all available from the author himself at a price tag of several hundred dollars per month, does seem to constitute a major conflict of interest. If a service to patients were truly the mission here, then the proposed mechanisms behind the Plant Paradox Program could easily have been presented as a hypothesis, which is what they are at this point, rather than repeatedly making statements that are not backed by evidence. Had the author presented this correctly as a speculative hypothesis, backed by the anecdotal evidence from his clinical work, this could have opened the door to investigate the relationship between plant lectins and chronic disease further. The lack of scientific rigor in this book will, unfortunately, make it hard for those of us interested in studying the impact of plant lectins on health because it will be seen by many in the field as just the latest diet fad.
Conclusion
In The Plant Paradox, Steven R. Gundry, MD, claims that he has “found there is a common cause for most health problems”, namely lectins from certain plant foods including grains, legumes, most fruit, and certain vegetables and dairy products. He repeatedly emphasizes that The Plant Paradox Program is based on scientific evidence, for example when he states that “lectin avoidance in my patients and as reported in the scientific literature has been found to cure autoimmune diseases” (page 38), or “now that you know the science behind the Plant Paradox Program” (page 167). Based on our review, the proposed link between plant lectins and obesity as well as chronic disease is not supported by even suggestive scientific evidence. The proposed diet and lifestyle program is very restrictive and likely not feasible for most individuals in the long-run, but its low calorie density and very high nutrient density would certainly make it nutritionally adequate and likely offer some health benefits even when compared to the diet currently recommended to Americans. Only time, and a lot more research, will tell whether the recommendation to eliminate major food groups such as grains, legumes, and fruit to limit the intake of certain lectins indeed offers any health benefit for at least some conditions or in some individuals. We believe the ideas in this book should have been presented as hypotheses to be tested rather than as scientific findings.
Updates
Write your updates here