Brain On Junk Food

Scott C. Anderson

Many highly processed foods are potentially dangerous, partly because they disregard the fate of gut microbes. It is pure folly to ignore those microbes, especially since they are so crucial to our physical and mental health. How important? A new study from Tufts University, supported by the Rockefeller Foundation, says that better diets “could avert approximately 1.6 million hospitalisations and result in an estimated net savings of $13.6 billion in health care costs in the first year alone.”

The microbes in your gut differ from mine, and they vary daily. The diversity of gut microbes gives rise to an astonishing number of genes, outnumbering our genes by a factor of 100. Good bacteria produce nourishing substances that feed and heal the cells lining your gut. If you don’t support those good bacteria, your gut cells may become hungry and disease-prone. Your gut may become leaky enough to allow bacteria and toxins to pass through. Once bacteria breach the gut lining, the heart will pump them to every organ in your body, including your brain. This can lead to depression, anxiety, paranoia, psychosis, cognitive difficulties, and dementia.

Other foods are so highly processed that it’s difficult to identify the source material. Think of cheese puffs, twinkies, or vegan burgers. Delicious, yes, but what are they made of? These foodstuffs can be problematic since one of the first steps in processing them is to remove the fibre. After all, the thinking goes, fibre is indigestible and makes products brown. Take the fibre out, and you have beautiful white foods that are easy to colour any way you wish.

But fibre, an important macronutrient, is meant for your gut microbes, not you. That single elimination may be the worst thing that has happened to our diet over the last 60 years. Our gut microbes are changing composition, and some species are even becoming extinct.

Processed foods often contain emulsifiers, which improve texture, extend shelf life, and keep ingredients mixed. Some of them, like carboxymethylcellulose and polysorbate 80, can significantly impact intestinal microbiota and lead to gut inflammation. Modern diets are failing us. Your diet and intestines have a clear connection, but how does that affect your brain? 

Amazingly, bacteria in your gut can produce neurotransmitters, including dopamine and serotonin. These can communicate with your brain via the vagus nerve. These neurotransmitters are the same ones targeted by psychoactive drugs, so these microbes may be just as effective as Prozac but without the side effects. On the downside, a leaky gut caused by sugar-pumped pathogens can lead to systemic inflammation. Over time, that can adversely affect our cognition and mood. There are several more channels of communication between the gut and the brain, but these two are extremely important from a dietary point of view.

The good news is that you can fix gut-brain problems by cutting back on processed food and replacing it with fibre-filled veggies, like onions, broccoli, artichokes, and beans. Good fibre and beneficial bacteria sources can be found in ferments like sauerkraut, kimchee, kefir, and yogurt. If you can’t flip the script, try probiotic or prebiotic fibre supplements to give you a concentrated dose of the good stuff.This isn’t an all-or-none life change. But every step you take toward increasing fibre in your diet is a step toward rejuvenating your gut bacteria. Your microbes will make you feel better in return.

- Psychology Today