How Processed Food Causes Disease. 

Last fall I attended the Harvard School of Nutrition’s Symposium on Gut Health, Probiotics and the Microbiota. It’s an exciting meeting of researchers who are defining the role and medical uses of probiotics. They talk about what they have already found and published, and what they have happening now in the lab.

Most of the probiotic research right now is focused on taking a head count of bacteria in the gut under different conditions. Researchers showed graphs of bacteria in a healthy rodent, then compared it with the bacteria present in a rodent who has obesity/ heart disease/ depression, etc. Comparing them teaches us which bacteria are helpful and which ones show up when there is disease present. There is some research in humans, but using rodents lets researchers look at multiple generations in just a few years’ time. They also help us study whether simply putting bacteria in the GI tract causes these symptoms, even if nothing else has changed (spoiler alert: it does, but we’ll talk more about that in another post).

In the midst of these beautiful fluorescent graphs of bacteria found in the GI tract, one brave researcher, Dr. Gerwitz, showed a slide of actual rodent intestines*. Yes, it was kind of gross. The intestines had been removed from the rodents and were stretched out beside rulers to measure their length. One was much shorter than the other. Both rodents had been healthy; they were simply fed different diets. One had been given purified diets of carefully measured and controlled nutrients. The other one had been given a nutrient-rich diet of raw food scraps.

The rodent that had been given a purified diet of exactly what a rodent would need to be perfectly healthy, had a shorter intestine. The rodent who had eaten a balanced diet of diverse nutrients given to him as raw food scraps, actually had more intestine. The researcher also showed a change in the absorptive area of the intestines, called the villi. It was reduced in rats fed purified diets. The villi, or finger like projections that create absorptive area in the GI tract, were shorter in the rodents who ate a purified diet. We expect to see this when people with Celiac disease are eating gluten, but not simply from eating a purified or processed diet.


The Colitis and Metabolic Syndrome Connection

After Dr. Gerwitz amazed us with the truth that processing the diet changes the actual intestine, he said, “And we know when we give them these emulsifiers, we give them colitis. That always happens.”


Scrrreeeechhh. What??????????


The emulsifiers he was referring to were Polysorbate-80 and Carboxymethylcellulose. I found his paper on this topic to learn more.[1] It is not only colitis (Crohn’s Disease and Ulcerative Colitis) that is caused by these common additives in processed foods… it is obesity and metabolic syndrome.

Emulsifiers are added to most processed foods to make them smoother, creamier and overall better looking for longer. Think about the difference between homemade oil and vinegar salad dressing that begins to separate before it gets to the table, and a store-bought Italian dressing that stays perfectly blended for months. The difference is that emulsifiers help the water and the oil mix and stay mixed. When they get to the intestine, they cause enough damage that the absorptive surface is compromised and the actual length of the intestine shortens.


What can we do about this?

When emulsifiers reach the protective layer of the GI tract, they cause damage that creates ongoing, low-grade inflammation. For some people, this erupts into colitis, and for other people, this changes the protective bacteria in the GI tract that help manage weight and blood sugar.

The first step towards using this information is avoiding food with emulsifiers in them. This can be hard! Emulsifiers keep baked goods from going stale, keep dill oil dissolved in bottled dill pickles, help coffee whiteners dissolve in coffee, and prevent oil from separating out of artificial whipped cream.[2] Make sure you read labels and avoid all Polysorbate-80 and Carboxymethycellose. Carboxymethylcellulose can be lumped in with “dietary fiber” on the label, so if you are really trying to get ahead of Ulcerative Colitis, Crohn’s disease, obesity or metabolic syndrome, it’s worth working towards making more and more of your food at home.


There is something else we can do. Another interesting thing this research found is that inulin[3] repaired the damage! Rodents fed purified, or processed, diets with inulin added to them had normal length intestines and healthy villi. Inulin is a prebiotic that helps feed the helpful bacteria in the Bifidobacter genus. These helpful bacteria repair damage to the intestine, fight bad bacteria and create a healthy environment in the gut.

So, when you do eat processed food, take a good probiotic with a variety of the beneficial bacteria that may be disrupted by the emulsifiers, along with a good prebiotic. It will help restore your healthy flora faster and support the good bacteria in your body that work to manage the inflammation.


(*It’s worth noting that these labs take many steps to treat the rodents humanely throughout their time in the lab, keep them comfortable and let them live as full a life as possible.)

[1] Chassaing, B., Koren, O., Goodrich, J., Poole, A., Srinivasan, S., Ley, R. E., & Gewirtz, A. T. (2015). Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature, 519(7541), 92–96. http://doi.org/10.1038/nature14232

[2] https://cspinet.org/eating-healthy/chemical-cuisine#polysorbate

[3] Chassaing, B., Miles-Brown, J., Pellizzon, M., Ulman, E., Ricci, M., Zhang, L., … Gewirtz, A. T. (2015). Lack of soluble fiber drives diet-induced adiposity in mice. American Journal of Physiology – Gastrointestinal and Liver Physiology, 309(7), G528–G541. http://doi.org/10.1152/ajpgi.00172.2015