But new research suggest another scenario: Inflammation might not be a symptom, it could be a cause. According to this theory, it is the immune activation caused by lousy food that prompts insulin and leptin resistance. Sugar builds up in your blood. Insulin increases. Your liver and pancreas strain to keep up. All because the loudly blaring danger signal—the inflammation—hampers your cells' ability to respond to hormonal signals. Maybe the most dramatic evidence in support of this idea comes from experiments where scientists quash inflammation in animals. If you simply increase the number of white blood cells that alleviate inflammation—called regulatory T-cells—in obese mice with metabolic syndrome, the whole syndrome fades away. Deal with the inflammation, it seems, and you halt the dysfunction.
Now, on the face of it, it seems odd that a little inflammation should have such a great impact on energy regulation. But consider: This is about apportioning a limited resource exactly where it's needed, when it's needed. When not under threat, the body uses energy for housekeeping and maintenance—and, if you're lucky, procreation, an optimistic, future-oriented activity. But when a threat arrives—a measles virus, say—you reprioritize. All that hormone-regulated activity declines to a bare minimum. Your body institutes a version of World War II rationing: troops (white blood cells) and resources (calories) are redirected toward the threat. Nonessential tasks, including the production of testosterone, shut down. Forget tomorrow. The priority is to preserve the self today.
This, some think, is the evolutionary reason for insulin resistance. Cells in the body stop absorbing sugar because the fuel is required—requisitioned, really—by armies of white blood cells. The problems arise when that emergency response, crucial to repelling pillagers in the short term, drags on indefinitely. Imagine it this way. Your dinner is cooking on the stove. You're paying bills. You smell smoke. You jump up, leaving those tasks half-done, and search for the fire before it burns down your house. Normally, once you put the fire out, you'd return to your tasks and then eat dinner.
But now imagine that you never find the fire, and you never stop smelling the smoke. You remain in a perpetual state of alarm. Your bills never get paid. You never eat your dinner. Your house smolders. Your life falls into disarray.
That's metabolic syndrome. Normal function ceases. Aging accelerates. Diabetes develops. Heart attacks strike. The brain degenerates. Life ends early. And it's all driven, in this understanding, by chronic, low-grade inflammation.
Where does the perceived threat come from—all that inflammation? Some ingested fats are directly inflammatory. And dumping a huge amount of calories into the bloodstream from any source, be it fat or sugar, may overwhelm and inflame cells. But another source of inflammation is hidden in plain sight, the 100 trillion microbes inhabiting your gut. Junk food, it turns out, may not kill us entirely directly, but rather by prompting the collapse of an ancient and mutually beneficial symbiosis, and turning a once cooperative relationship adversarial.
by Moises Valasquez-Manoff, Mother Jones | Read more:
Image: Eye of Science / Science Source
