For over three decades, Dr. Tim McCullough has helped thousands of patients find their way back to health by diagnosing and treating the most common root cause of symptoms: Leaky Gut. Written for patients and doctors from any background, Inside Is Outside offers an approachable guide to how the breakdown of the digestive system is often the key driver of chronic illness, why stomach acid plays an essential role in gut health, and how to heal and repair Leaky Gut.

Much like our skin protects us from the outside world, our intestinal wall keeps the “outside” world (such as food, viruses, and toxins) separate from “inside” our bodies. Without sufficient stomach acid, the body cannot properly break down food or eliminate dangerous pathogens, such as viruses and toxins. Over time, this damages the intestinal wall, allowing substances to leak into the bloodstream and triggering the body’s immune system, which launches an attack. If this keeps happening day after day, week after week, and year after year, the result of this dysfunction is illness, often in the form of varied and seemingly unrelated symptoms from fatigue and digestive problems to rashes and pain.

Medical schools teach doctors the dangerous myth that patients often have too much stomach acid and that antacids are the cure for conditions such as reflux or indigestion; in reality, most people make too little stomach acid. Few doctors actually test stomach acid levels because, until recently, diagnostic testing was expensive and time-consuming or simply unavailable. Now, the Gastro-Test® can provide direct measurement of stomach acid levels in under 20 minutes. This simple, inexpensive, and easy-to-use test is the missing link to the accurate diagnosis and treatment of one of the most overlooked causes of illness: deficient hydrochloric acid in the stomach.

The bottom line is that you cannot feel well if you do not have a properly functioning digestive system—this is the key to health. Rather than suppressing or covering up symptoms, we can correct underlying dysfunction and support the body in healing itself, starting in the gut. For those who have been suffering from debilitating symptoms or who are looking for relief for patients or loved ones, don’t lose hope; there is always an answer. Free on Kindle.