Sometimes, treating digestive disorders can require unraveling a complex tangle of interrelated psychological, immunological, and gastroenterological factors. It can involve identifying and addressing such problems as hypochlorhydria, histamine intolerance, hiatal hernia, microscopic colitis, ileocecal valve dysfunction, or a microbiome devastated by multiple rounds of antibiotics.

Other times, the most intractable digestive disorders can be effectively addressed by simply eliminating one particular food trigger from the diet. It tends to be taken for granted in a modern, cosmopolitan, melting-pot culture such as our own that food is our freedom and our choice, and we should have every food item in the entire world’s vast array of different cuisine to choose from. If someone consumes it anywhere, there is no reason why all of us should not be able to consume it here.

This notion contrasts with most of human history, where geography, climate, and season would strictly limit the choice of foods available, and hard times were of necessity survived by finding clever ways to render poisonous, often borderline-nutritive aspects of the local environment somewhat edible. Several of the world’s staple foods, like soy and pinto beans for instance, are toxic and frankly injurious unless subjected to careful methods of preparation.

In America, it would be considered a great tragedy if someone was unable to eat pizza due to a health condition, even though the tomato was wholly unknown outside of Mexico until the 16th century, and there are many people in America today whose immigrant ancestors would never have consumed tomatoes at all until 400 years ago, 200 years ago, or even a single generation ago. While tomatoes seem harmless to most and were enjoyed by the Aztecs before finding their way into Spanish and later, Italian cuisine, they have been known to cause heartburn and even joint inflammation in people with nightshade sensitivities.

Whenever a novel food is introduced to the diet of an entire people, it has the potential to cause health problems in at least some sensitive individuals. This is especially likely if the population is genetically diverse, as is the case in America, and especially true if the food is something entirely novel that no human anywhere has ever consumed before.

Healthcare practitioners, especially those treating digestive disorders, should be aware of emerging food trends and alert to culture-wide dietary changes, as these may well be culprits in a patient’s emerging digestive upset. Certainly, not all digestive problems can be solved so easily, but when people take it for granted that any food which can be legally marketed to them can be eaten by them with impunity, ruling out simple food triggers becomes an important part of evaluating any digestive complaint. Anything novel or recently introduced should of course top the list of suspicion, hence the importance of staying current with emerging food trends. One of the latest and most popular food trends is the new generation of plant-based meat alternatives, which are now being offered as options in several fast-food chains. Due to some technological innovations, these new plant-based meats provide a sensory experience closer to eating real meat than ever before, and therefore appeal to more and more people, but they are also being identified by some as a culprit in new-onset digestive complaints.

When perusing the ingredient list of one of these plant-based burger patties, their synthetic and highly processed nature at once becomes apparent, although for many people this alone would hardly be a radical departure from their normal diet. Most of the protein content of these burgers is provided by pea protein, which is considered to be relatively well-digested, especially compared to soy protein. The theories as to why these plant-meats are causing some people to have indigestion boil down to three things. The first is these burgers’ high-fat content, which is mostly canola oil but also includes coconut oil, providing some saturated fat as one would find in a ground beef patty. Some people who have been used to consuming a low-fat vegan diet have found these burgers much greasier than anticipated, or at least greasier than other plant-based meat alternatives they are used to, and attribute their indigestion to this high-fat content. Too much fat can cause indigestion in some people, especially those with pancreatic insufficiency or gallbladder disorders. Another ingredient being blamed is methylcellulose, a type of dietary fiber used to provide texture to the burgers, and which is also commonly sold as an over-the-counter laxative. But the most suspicious ingredient of all is in fact the key to these new burgers’ strikingly improved semblance to meat, a soy-based compound called leghemoglobin.

Much of the unique sensory experience of eating meat comes from hemoglobin and myoglobin. These iron-containing proteins, found only in the blood and muscle of animals, account for much of red meat’s redness and distinctive taste. While the umami attribute of meat is easy to replicate with plant-based ingredients, it was capturing the slightly metallic, slightly bloody taste of real meat that remained elusive with only plant-based ingredients, until recently. Part of meat’s unique taste is provided by heme, an extremely complex molecule that is difficult to synthesize and virtually unknown to the plant kingdom. The key innovation behind these new meat alternatives is the addition of leghemoglobin, a rare vegan source of heme produced by nitrogen-fixing bacteria and discovered in the rootlets of soybeans. It provides not only the flavor, but also the bloodiness of beef to these plant-based foods, duplicating the visceral sensory experience of pressing the blood from a sizzling patty on the grill or tasting it running as juice from a burger cooked medium-rare. The only problem with leghemoglobin is it’s an entirely novel food ingredient that has never been consumed by humans, and while the FDA has approved it as safe, this decision came not without some controversy.

While leghemoglobin can be obtained from the roots of soy, it can only be obtained naturally in very small quantities, through processes that are not cost-effective.

The leghemoglobin in these new meat substitutes is obtained from yeast, which has been genetically modified to produce leghemoglobin. The companies behind this innovation first attempted to obtain GRAS status from the FDA by arguing that soy and yeast are both existing parts of the food supply, ergo leghemoglobin is not a novel food ingredient. The FDA expressed major concerns however, and argued that leghemoglobin is only found in the roots of the soy plant, which are not consumed by humans, and even so would never have been consumed before in such high amounts. Soon after, the FDA changed their mind and approved the ingredient, and this hasty decision is currently the object of a lawsuit being brought against the FDA by the Center for Food Safety, an anti-GMO group[i].

Although a study[ii] was published declaring leghemoglobin to be non-toxic, which became the basis of the FDA’s approval, opponents of the FDA’s decision have cited the following complaints: first, the study was funded by the very financial interests backing leghemoglobin, second, the feeding trial, performed in rats, only lasted for 28 days, which would not be sufficient to uncover potential long-term effects in humans, and third, the rats in the leghemoglobin group actually did experience statistically significant adverse effects, which the study’s conclusion dismissed as trivial.

These changes included failure to gain weight despite adequate food intake, decreased blood clotting, decreased reticulocyte count, and changes in serum markers suggestive of anemia, malnutrition, inflammation, and kidney disease[iii]. The decreased reticulocyte count is especially interesting, as this can indicate problems synthesizing new red blood cells in the bone marrow. The recycling and incorporation of iron-containing heme groups is an important step in red blood cell synthesis, and this process seemed to be disturbed in rats that were being fed this GMO yeast-derived leghemoglobin. It should also be noted that subjective symptoms like fatigue, muscle weakness, and indigestion would be difficult to ascertain from a rat-feeding study, so the true effects in humans of consuming leghemoglobin remain largely unknown.

While this is not meant to be a condemnation of these new plant-based burgers, a healthy diet remains among the foundations of health, and it is important for healthcare practitioners to fully understand exactly what their patients are eating.

This is especially true for holistic practitioners, who are often the first to detect when some new dietary ingredient is causing widespread problems with the population’s health. The true effects of leghemoglobin consumption are still unknown, but in the short-term these new foods should at least be considered as a potential cause in any new-onset digestive complaint, or a possible contributing factor to an existing one.

• [i] Claire Robinson and Michael Antoniou. “Rat feeding study suggests the Impossible Burger may not be safe to eat.” June 25, 2019. Accessed online 7/30/21 at https://www.gmoscience.org/2019/06/25/rat-feeding-studies-suggest-the-impossible-burger-may-not-be-safe-to-eat/
• [ii] Fraser RZ, Shitut M, Agrawal P, Mendes O, Klapholz S. Safety Evaluation of Soy Leghemoglobin Protein Preparation Derived From Pichia pastoris, Intended for Use as a Flavor Catalyst in Plant-Based Meat. Int J Toxicol. 2018;37(3):241-262. doi:10.1177/1091581818766318
• [iii] Robinson and Antoniou 2019.
• Any homeopathic claims are based on traditional homeopathic practice, not accepted medical evidence. Not FDA evaluated.
• These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.