One of the keystone discoveries of modern medicine is the relationship between systemic inflammation and a host of chronic illnesses, including cardiovascular disease, dementia, gastrointestinal disorders, type 2 diabetes, weight gain, and more. Virtually all specialties in the medical sciences recognize inflammation as a major player in the development of chronic disease states.
Inflammation is important, but in some ways it’s gotten a bad rap. It’s not inherently good or bad. It’s about balance—yin and yang; acute versus chronic; controlled versus uncontrolled. You hear a lot about how important it is to “cool down” or “turn off” the inflammatory response, and for most Americans, that’s essential. But to properly moderate inflammation, you need to know what it is, how it works, and how you got so inflamed in the first place. And, as we’ll see, the gut microflora are important factors.
When Your Immune System’s Sprinkler System Fails
Our immune systems are cellular forces that have evolved to protect us from infectious elements. When you get a splinter and the area turns red, swells, and becomes warm— that’s your immune system at work. When you have a fever and you feel like you’re about to burn up as you try to fight off a cold, it’s a sign your immune system is mounting a healthy response to clear the infection. Your immune system involves a lot of inflammation because immune and inflammatory reactions are basically the same thing. Virtually every aspect of your health operates on a spectrum from optimally balanced to completely out of control. Weight is like this—you could be a few pounds too big to look supersexy in this summer’s bikini, you could be morbidly obese, or you could be somewhere in between. The numbers on the scale (and your lab tests) creep in one direction or the other, depending on where you fall on this spectrum. And your gut controls your body curves. If you want to look sexy outside, start fixing the inside. Your immune system exists on the same kind of spectrum. When it’s optimally balanced, the immune system releases cells that attack foreign invaders when needed, but otherwise it rests. When it’s out of balance, it’s constantly sending cellular messengers that say “attack,” and in the worst cases, these cellular protectors turn on your body and start to beat up your own cells. This is called systemic inflammation. The condition may sound familiar. We talked about how the incidence of allergies, asthma, and other autoimmune (auto means “self,” so the term means “self-immune”) conditions is on the rise. Inflammation is at the very core of this process. Inflammation also leads to weight gain. Here are a few highlights illustrating the connection between runaway systemic inflammation and fat accumulation.
Inflammatory cytokines block insulin receptors, reducing your sensitivity to the hormone. As you become more resistant to insulin, your body has a more difficult time converting the calories you consume into energy. Instead, you pack on fat. That’s why metabolic syndrome, type 2 diabetes, and obesity are intimately interwoven conditions.
Visceral adipose tissue, also known as belly fat, is metabolically active and encourages further inflammation in the body. So fat makes you inflamed, which causes you to gain more fat in a vicious cycle.
Inflammation of the hypothalamus leads to resistance to leptin, the chief hormone that makes you feel full. When you’ve eaten enough, your body senses this and sends this hormone to your hypothalamus to tell you to stop. When you become resistant to leptin, you feel hungry more often and it’s difficult to satiate that hunger, so you eat more and you gain weight.
Remember, the flora you’re exposed to when you’re young train your immune system to differentiate friend from foe. If you don’t have the right bugs in your gut at an early age, the stage is set for immune imbalance, inflammation, and thus weight gain. But what if your immune system was properly trained when you were young? Is it still possible for your immune system to swing out of balance?
Absolutely. There are many dietary, lifestyle, and environmental factors that can lead to inflammation. Too much sugar in your diet (Americans eat about 150 pounds per person yearly—way too much), too little or too much exercise, stress, environmental toxins, food sensitivities, and more can all lead to chronic systemic inflammation. However, one overlooked player in this cycle of inflammation, weight gain, and disease is your gut microflora.
A sudden shift away from a healthy mixture of bugs reduces the biodiversity of our microbial friends and diminishes our ability to adapt. In the case of your gut microbiome, as biodiversity diminishes, the preponderance of pathogenic species of bugs tends to increase. This can be problematic, because certain strains of bacteria produce endotoxins (toxins generated inside your body) that, if absorbed into the bloodstream, can be harmful to human health.
Gerard E. Mullin MD is a board-certified internist, gastroenterologist and nutritionist. He is an associate professor of medicine and serves as the director of Integrative GI Nutrition Services at The Johns Hopkins Hospital.