A food thickener is defined as an "agent that increases the viscosity of a liquid mix without interfering with its other properties." Thickening agents are in most processed and packaged foods generally used to mimic a smooth, creamy texture. Think ice cream, milks, pre-made smoothies etc. But they can also be found in breads, cakes, sauces, fillings, sweets and pudding.
There are three classes of food thickeners:
polysaccharides which consists of:
Maltodextrin: from the chemical degradation of corn, potato or rice starch used as a filler and thickening agent in food processing. (To note, the majority of negative effects on the GI system were studied in mice).
starches: thick flour, cornstarch, potato starch, arrowroot and tapioca
vegetable gums: think acacia, lecithin, guar and gellan as well as carboxymethylcellulose (CMC).
pectin: from peels of citrus fruit plants, used to make a gel and is considered a soluble fiber.
proteins - eggs, collagen (when cooked, it will dissolve and thicken sauces), gelatin (extracted from boiled bones, connective tissues, organs from animals) and albumin
fats - butter, oils and lards
"The use of additives in food processing is regulated by specific laws and must be authorized by the Food and Drug Administration (FDA) in the United States and the European Food Safety Authority (EFSA) in the European community." (source). They establish an acceptable daily intake (ADI) level that is safe for human consumption. There are three main factors these governing bodies assess when determining safe consumption levels: frequency of the food consumed, portion sizes generally consumed and concentration of the ingredient in the food item.
This should make us feel confident when eating foods that contain these added agents but "researchers have recently hypothesized that emulsifiers in processed foods may increase the translocation of bacteria through the epithelium in the gut barrier, thereby inducing inflammation" (source). Meaning, thickening agents and emulsifiers may be breaking down the mucus layer in our guts causing leaky gut and inflammation which can lead to other serious GI conditions like IBD and IBS.
Emulsifiers have been shown to stimulate chronic inflammation in the gut microbiome of animal models and in in-vitro studies as well as predispose to subject to developing metabolic syndrome, but what about in human studies? (I'm already making Layne Norton proud). Chassaing et. al. performed a randomized, double-blind, controlled-feeding study (can't get much better than that) in healthy adults. One group consumed a diet free of emulsifiers and another group consumed an identical diet but with 15 grams of carboxymethylcellulose (CMC, a dose higher than generally thought to be consumed on a daily basis but represents an ultra-processed diet) for 14 days. "Data analyses found that adding CMC to a healthy additive-free diet increased postprandial [after eating a meal] abdominal discomfort and altered intestinal microbiota composition. In addition, CMC reduced microbiota richness and diversity" (source, more studies and information can be found at this link).
The main food thickeners that we seen in packaged foods are listed below in ranking order from least agitating to the gut to the worst:
Propylene Glycol- can be derived from petroleum, natural gas or vegetable sources and the component added to food is not going to be from the first two (but uninformed wellness zealots on social media will scare you into thinking your eating petroleum). It can come from soybeans or brown seaweed and is commonly used in dressings, beer, frozen foods, bakeries and jelly. The FDA has established levels ranging from 0.4 - 1.7% as safe and the EFSA defined an ADI of 55 mg/kg body weight as safe.
Agar gum - from the cell walls of red algae, mainly used in desserts. The FDA deemed the ADI for this ingredient is 0.25 - 1.2% depending on the food it's added to. The EFSA did not establish a ADI level.
Arabic/acacia gum - comes from the sap of trees of the Acacia and commonly found in paints, glues, cosmetics, inks and food. Acacia gum is unlikely to be absorbed intact and is slightly fermented by the gut and therefore, no ADI level was needed.
Guar gum - processed from guar beans but also chemically derived from the sugars galactose and mannose. It has 8 times the water-thickening potency of cornstarch. "Thus it can be used in various multi-phase formulations: as an emulsifier because it helps to prevent oil droplets from coalescing, and/or as a stabilizer because it helps to prevent solid particles from settling." (source). Guar gum is noted to be well tolerated in adults, but GI symptoms should be monitored in infants and children. No ADI level was established.
Gellan gum - produced from a bacteria that helps with stabilization, suspension and thickening/texturizing.
Carob/locust bean gum - comes from the seeds of carob plants.
Lecithin gum - derived from the fats in soybeans, sunflower and egg yolks, improves texture and shelf life of foods. For sunflower lecithin, "The EFSA Panel concluded that there is no need for a numerical ADI."
Carrageenan - derived from edible red seaweed that is dried and processed with an alkali solution. "The EFSA has established a temporary ADI of 75 mg per kilogram of body weight. At the same time, in the United States, carrageenans are permitted by the FDA for use as a food additive when used in the amount necessary for the intended effect."
Xanthan gum - comes from a bacteria that ferments in sugar generally from wheat, corn, soy and/or dairy. It's extracted using isopropyl alcohol and then ground into a powder. It helps prevent oil separation (think salad dressings) and can help suspend solid particles (think spices). In large amounts, this gum has a laxative effect which means in smaller to moderate amounts, it can also cause digestive issues like gas, bloating and discomfort. However, "There is no need for a numerical ADI, and there is no safety concern for xanthan gum."
It appears that "most emulsifiers do not have daily quantity restrictions" however, "their cumulative quantities and the synergic effects of each other have not yet been assessed." Meaning, we could be eating a bunch a foods daily that contain various thickening agents and consume a large dose not studied or deemed as safe. The table below outlines the ADI for some thickening agents.
It's important to note that "not all emulsifiers should be considered equal" and studies show that some may even have beneficial probiotic effects to our gut. In general, I like to stick with the ones derived from plants, beans and food sources rather than bacteria or synthetically made. For example:
Agar gum shows anti-inflammatory, antioxidant, and immunomodulatory properties in vivo animal models.
Lecithin increased postprandial omega 3 fatty acids and induced beneficial modifications in bile acid profile.
IN CONCLUSION: I generally avoid xanthan gum at all costs mainly because I know it agitates my gut. Other than that, the less ultra-processed foods you eat (meaning fried and packaged foods), the less likely you are to consume high amounts of these thickening agents. But know that they are generally recognized as safe (GRAS) in the ADI levels.
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