Heather Bedard, C.H.E.
This critique is based on the article titled, Your Vegetables Want to Kill You. This article was written by Keenan Ericksson and his article is based off of the work of Dr. Paul Saladino. The basic premise of this particular post by Ericksson was to enlighten people to the idea that plants contain very toxic and dangerous poisons which are contributing to the cause of autoimmune diseases and other physical ailments. He proposes, based on his experience, that adopting a carnivore diet (almost exclusively meat) is more along the lines of the type of diet that humans were designed to eat.
The points made by the author include the fact that a human’s stomach has more acidity than animals that eat a strictly herbivore diet.1 As a result, the assumption made is that humans weren’t designed to eat plants. His article goes on to explain how animals know how to avoid dangerous plants and humans don’t…so stick with eating the animals. According to Eriksson, plants contain “…chemicals that can cause you harm. If it isn’t a nutrient, it’s probably supposed to hurt you.” As we look into various plants and the chemical compounds they contain, we find that this statement is partially true; plants do contain compounds that are harmful in isolation and when consumed in copious amounts. Conversely, adverse effects can happen with almost any substance consumed in excess.
One example of a plant that is mentioned by the author, that contains a harmful compound, is broccoli, which contains sulforaphane. Sulforaphane is a sulfur-rich compound that causes adverse reactions when consumed in excess.2 Perhaps this fact is where the author acquires the information contributing to his claim. There are many things that contribute to the levels of sulforaphane available in broccoli. In one clinical trial, the availability of sulforaphane was three times higher when broccoli was raw than when it was cooked.3 If sulforaphane is a concern, cooking your broccoli could help alleviate any unease. Aside from this, sulforaphane does have potent anti-cancer properties. According to this paper, “Two clinical phase 1 studies showed that broccoli sprout extracts containing SFN (sulforaphane) were well tolerated and caused no significant adverse effects (toxicities) when administered orally by healthy volunteers at a dose of 15 μM for 7 days or women with breast cancer received 200 μmol of on average 50 min prior to the surgery”.[4,5,6] Overall, more studies need to be done to show the effect of sulforaphane on humans as most studies are done on animals or in vitro.7 No studies have been done to show what the optimal level of sulforaphane intake is, or what the exact toxic level would be in humans. The few studies that I could find were on mice, which is not an exact cross-over in regard to human expression.8 , 9
Eriksson proposes that the most important poisons or toxins to watch out for are lectins, oxalates, and polyphenols. A deeper look reveals the truth behind these misunderstood compounds.
Beans of all types contain lectins. Lectins are a carbohydrate-binding protein which can permeate the gut causing inflammation.10 Despite this fact, studies have shown that some lectins can actually decrease inflammation in the body.11 In a randomized cross-over feeding trial that assessed 64 men who ate a low GI (glycemic index) high bean diet, the men had reduced inflammation and biomarkers for cancer.12 While some studies shows that lectins can increase the pathogenesis of some autoimmune diseases, more studies support the fact that cooking beans properly reduces the load of lectins on the body and the health benefits far outweigh any potential side effects.13
Likewise, although they can be dangerous in high amounts, high oxalate foods eaten as part of a whole food plant-based diet carry plentiful vitamins and minerals that counteract many negative effects caused by this naturally-occurring molecule.14 Some examples of high oxalate foods are spinach, potatoes, raspberries, and dates. Knowing the possible dangers of consuming these foods, the rationale behind the regular consumption of high oxalate plants is possibly attributed to the interdependent effects of phytate, potassium, calcium, and other phytochemicals readily available in these foods. For example, despite the fact that tea is an immense source of oxalate, it is believed that the polyphenols and other antioxidant phytochemicals in tea, may help to prevent kidney stone formation.15 In regard to oxalates and kidney stones, although there is a connection between oxalates and stone risk, many health professionals believe that the association may be more complex than once understood. Furthermore, there is a relationship with a diet high in animal foods and kidney stone formation.16
Lastly, another toxic compound found in plants are polyphenols. Examples of plant polyphenols include resveratrol, quercetin, flavonoids, and tannins. The author states, “these compounds serve no purpose in plant metabolism. They do not help the plants stay healthy. Instead, polyphenols are either pigments or plant defense mechanisms.” Are we to assume then, that polyphenols would not help humans stay healthy? Studies consistently show this is not the case. This review titled, The Immunomodulatory and Anti-Inflammatory Role of Polyphenols, shows the mechanism of action that polyphenols take in being anti-inflammatory.17 Moreover, I could not find any studies that stated that polyphenols actually caused inflammation as the author implies or that consuming them in regular amounts would cause damage. Plants and humans are genetically different and inversely, human’s stomachs are made to handle and transform those compounds into something useful for the body. Polyphenols also regulate and are affected by the gut microflora in a positive way.18, 19
In conclusion, my understanding would be that although plants do contain some compounds that are toxic in high amounts, the amount you’d have to eat to see a negative result would be too high for the average person to consume. Many of these plant products are used by the body defensively and are excreted if not needed. Based on the studies that I read, it seems that because these dangerous poisons are not ingested as isolated compounds, and all of the thousands of compounds that make up a single food work together inside of the body to produce a variety of helpful acids, enzymes and nutrients, the effects of a singular “bad” compound would be counteracted.20 The majority of people are not eating enough of one particular plant to allow a build-up in the body of toxins (think eating 4 cups of broccoli every 3 hours!).
Not mentioned in the article is that animal foods also contain lectins and oxalates. The effects of these compounds found in animals should be addressed as they relate to the human body before making sweeping claims about the dangers of isolated plant compounds. If someone is concerned with how they feel after eating specific plants, they would benefit in observing how their bodies interact with those plants and adjust their preparation of them to allow for optimal digestion.
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1. Beasley DE, Koltz AM, Lambert JE, Fierer N, Dunn RR. The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome. PLoS One. 2015;10(7):e0134116. Published 2015 Jul 29. doi:10.1371/journal.pone.0134116
2. Chartoumpekis DV, Ziros PG, Chen JG, Groopman JD, Kensler TW, Sykiotis GP. Broccoli sprout beverage is safe for thyroid hormonal and autoimmune status: Results of a 12-week randomized trial. Food Chem Toxicol. 2019;126:1-6. doi:10.1016/j.fct.2019.02.004
3. Conaway CC, Getahun SM, Liebes LL, et al. Disposition of glucosinolates and sulforaphane in humans after ingestion of steamed and fresh broccoli [published correction appears in Nutr Cancer 2001;41(1-2):196]. Nutr Cancer. 2000;38(2):168-178. doi:10.1207/S15327914NC382_5
4. Su X, Jiang X, Meng L, Dong X, Shen Y, Xin Y. Anticancer Activity of Sulforaphane: The Epigenetic Mechanisms and the Nrf2 Signaling Pathway. Oxid Med Cell Longev. 2018;2018:5438179. Published 2018 Jun 6. doi:10.1155/2018/5438179
5. Shapiro TA, Fahey JW, Dinkova-Kostova AT, et al. Safety, tolerance, and metabolism of broccoli sprout glucosinolates and isothiocyanates: a clinical phase I study. Nutr Cancer. 2006;55(1):53-62. doi:10.1207/s15327914nc5501_7
6. Cornblatt BS, Ye L, Dinkova-Kostova AT, et al. Preclinical and clinical evaluation of sulforaphane for chemoprevention in the breast. Carcinogenesis. 2007;28(7):1485-1490. doi:10.1093/carcin/bgm049
7. Conzatti A, Fróes FC, Schweigert Perry ID, Souza CG. Clinical and molecular evidence of the consumption of broccoli, glucoraphanin and sulforaphane in humans. Nutr Hosp. 2014;31(2):559-569. Published 2014 Nov 30. doi:10.3305/nh.2015.31.2.7685
8. Socała K, Nieoczym D, Kowalczuk-Vasilev E, Wyska E, Wlaź P. Increased seizure susceptibility and other toxicity symptoms following acute sulforaphane treatment in mice. Toxicol Appl Pharmacol. 2017;326:43-53. doi:10.1016/j.taap.2017.04.010
9. Walsh NC, Kenney LL, Jangalwe S, et al. Humanized Mouse Models of Clinical Disease. Annu Rev Pathol. 2017;12:187-215. doi:10.1146/annurev-pathol-052016-100332
10. Ryder SD, Jacyna MR, Levi AJ, Rizzo PM, Rhodes JM. Peanut ingestion increases rectal proliferation in individuals with mucosal expression of peanut lectin receptor: study. American Gastroenterological Association. 1997 July 25; doi.org/10.1016/S0016-5085(98)70631-6
11. Pires AF, Marques GFO, Alencar NMN, et al. Inhibitory effect of Lonchocarpus araripensis lectin in rat acute models of inflammation. An Acad Bras Cienc. 2019;91(2):e20180991. Published 2019 Jun 19. doi:10.1590/0001-3765201920180991
12. Hartman TJ, Albert PS, Zhang Z, et al. Consumption of a legume-enriched, low-glycemic index diet is associated with biomarkers of insulin resistance and inflammation among men at risk for colorectal cancer. J Nutr. 2010;140(1):60-67. doi:10.3945/jn.109.114249
13. Vojdani A, Afar D, Vojdani E. Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to Autoimmunity. J Immunol Res. 2020;2020:1438957. Published 2020 Feb 11. doi:10.1155/2020/1438957
14. Taylor EN, Fung TT, Curhan GC. DASH-style diet associates with reduced risk for kidney stones. J Am Soc Nephrol. 2009;20(10):2253-2259. doi:10.1681/ASN.2009030276
15. Zhuo D, Li M, Cheng L, Zhang J, Huang H, Yao Y. A Study of Diet and Lifestyle and the Risk of Urolithiasis in 1,519 Patients in Southern China. Med Sci Monit. 2019;25:4217-4224. Published 2019 Jun 6. doi:10.12659/MSM.916703
16. Breslau NA, Brinkley L, Hill KD, Pak CY. Relationship of animal protein-rich diet to kidney stone formation and calcium metabolism. J Clin Endocrinol Metab. 1988;66(1):140-146. doi:10.1210/jcem-66-1-140
17. Yahfoufi N, Alsadi N, Jambi M, Matar C. The Immunomodulatory and Anti-Inflammatory Role of Polyphenols. Nutrients. 2018;10(11):1618. Published 2018 Nov 2. doi:10.3390/nu10111618
18. Ozdal T, Sela DA, Xiao J, Boyacioglu D, Chen F, Capanoglu E. The Reciprocal Interactions between Polyphenols and Gut Microbiota and Effects on Bioaccessibility. Nutrients. 2016;8(2):78. Published 2016 Feb 6. doi:10.3390/nu8020078
19. Westfall S, Pasinetti GM. The Gut Microbiota Links Dietary Polyphenols With Management of Psychiatric Mood Disorders. Front Neurosci. 2019;13:1196. Published 2019 Nov 5. doi:10.3389/fnins.2019.01196
20. Petroski W, Minich DM. Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients. 2020;12(10):2929. Published 2020 Sep 24. doi:10.3390/nu12102929