A new study on the commonly used food additive, Propionate (frequently listed on food ingredients labels as ‘calcium propionate’) has demonstrated its potential for adversely affecting consumers’ metabolisms, as well as increasing resistance to insulin. Propionate occurs naturally (as in during the fermentation process) but depending on the product, the food industry may use the industrialized version (a lower cost, easier to use version chemically/synthetically altered in a lab) as a preservative and mold inhibitor for processed foods. Propionate (the salts and esters of propionic acid) is widely added to myriad of foods so many U.S. consumers are exposed to it on a regular, ongoing basis.
This was a two-part study with the first portion testing metabolic reactions to ingesting the food additive propionate on mice, and the second portion was a pilot study testing the impact of propionate on metabolic processes on a small group of humans*. The advantage of this two-part study design allowed the researchers to determine whether reactions in mice (which are known to have similar bodily processes to humans) are actually the same as the process that occurs when humans ingest this food additive.
*Study design: a randomized, placebo-controlled, double-blinded trial with 14 healthy volunteers.
Mice: Propionate lead to a surge of blood glucose in mice in the current study. More interesting was that a single dose of propionate increased the hormones in the body designed to stimulate glucose production from the liver. What does that mean? Well, if someone is starving or has a seriously low blood-sugar level, this is a good thing. However, under normal conditions, the results indicate that the food additive propionate (calcium propionate) actually tricks the body into producing more glucose–when it is not needed.
Additionally, over time, the mice that continued to be fed the food additive propionate gained weight.
Humans: The food additive propionate is converted by our metabolism into glucose. In the study it was discovered that even a very low dose of propionate stimulated the sympathetic nervous system which triggered the body to release norepinephrine. This, in turn, then resulted in an increase of the hormone glucagon (which stimulates glucose production) and the protein FABP4 (which moves propionate through our fat cells). There was also a rise in blood glucose. Given these results the researchers concluded that the food additive propionate is a “metabolic dysregulator”.
In the present study the food additive propionate triggered an increased resistance to insulin; chronic insulin resistance is known to help contribute to type 2 diabetes and other metabolic disorders like obesity. As the U.S. is experiencing what has been labeled by healthcare professionals as an ‘epidemic’ of diabetes and obesity, and as the food additive propionate is so pervasive in processed foods in the U.S., it would seem the results of this study merit future studies and further investigation to determine whether this additive should come with a warning label so that at-risk populations can be aware of the potential for adverse effects.
Journal Reference: Tirosh, A., et al. (2019). The short-chain fatty acid propionate increases glucagon and FABP4 production, impairing insulin action in mice and humans, Science Translational Medicine, Vol. 11, Issue 489, eaav0120.
Calcium Propionate: Where Found
The industrialized version of this food additive is commonly used as a preservative and can be found in processed meats, poultry and sausages, canned fish and shellfish, breakfast cereals, noodles/pasta, dairy products, yogurt, puddings, desserts,
processed cheeses and cheese spreads, packaged baked goods, bread products, pizza dough, biscuits, beer, malt and some alcoholic beverages, diet/low-calorie foods and drinks, sports drinks, mustard and other vinegar-based condiments, sauces, some processed vegetables and vegetable dishes, soups, almond butter and other nut-based butters, and packaged/processed salads (incl. potato salad/macaroni salad), etc.
Source: The Food Hacker’s Handbook
Calcium Propionate: Red Flags
In addition to the findings of the present study, this food additive has been the focus of previous studies, clinical trials, and consumer reports. Here is a compilation of some potential red flags for individuals who may be sensitive to this additive:
This additive may cause adverse reactions for people with gastritis, ulcers and other gastrointestinal problems. Additionally, commonly used bread preservatives (for which Calcium Propionate is one) are suspected of creating possible complications for individuals with bladder conditions such as interstitial cystitis (“painful bladder syndrome”), sensitive bladders, or who suffer from frequent bladder infections or irregularities. Other adverse reactions may include skin reactions, swelling, edema and subsequent weight gain, nasal congestion, headaches and migraines, insomnia/sleep disturbances, digestive problems (incl. diarrhea/IBS), irritability, agitation, difficulty concentrating, and restlessness, esp. among children, those who experience adverse reactions to fermented products and processed food items, and those individuals with other sensitivities to food additives.
Source: The Food Hacker’s Handbook