Your Personal Paleo Code: The 3-Step Plan to Lose Weight, Reverse Disease, and Stay Fit and Healthy for Life (19 page)

Preliminary research suggests that some environmental toxins, such as bisphenol A (BPA), may cause intestinal permeability.

The Greek physician Hippocrates said that all disease begins in the gut. By now, I’m sure you realize how true those words are. Let’s look even more closely at the gut-disease connection.

The connection between the gut and the brain is apparent in our language; we all say things like “I have a gut feeling” and “I have butterflies in my stomach.” Long before scientists understood how the gut and the brain influence each other, people experienced it firsthand: a nervous stomach before an important speech, or perhaps heartburn during a stressful financial situation.

While most people are aware that stress and emotional states like anxiety affect the gut, fewer people realize that problems in the gut can affect the brain. For example, SIBO (see above) is strongly associated with depression and anxiety in observational studies. Other research indicates that inflammation in the gut can alter mood and cause depression. Inflammatory molecules produced in the gut travel through the bloodstream, cross the blood-brain barrier, and activate specific cells in the brain, known as microglial cells. The microglial cells play an important role in repairing brain cells, but when they are chronically activated, communication among neurons (the functional brain cells) is impaired and depression results. Finally, increased intestinal permeability is much more common in autistic children and may contribute to the development of autism spectrum disorders.

I’ve found in my work with patients that SIBO, gut dysbiosis (an imbalance between the good and bad bacteria that colonize your gut), and gut inflammation are the most common causes of anxiety, depression, and other psychological and behavioral problems. This is especially true in children.

One of the hottest topics in the scientific community over the past few years has been the connection between the gut microbiota and metabolic health. There are several reasons for this link. The gut microbiota is a source of bacterial toxins that provoke inflammation and insulin resistance, both of which contribute to obesity. Changes in the gut microbiota have been shown to increase appetite, increase the rate at which we absorb
fats and carbohydrates, and increase the storage of calories as fat. Bad bacteria in the gut can also cause insulin resistance and inflammation of the hypothalamus in the brain, both of which are associated with obesity.

Other gut problems have also been shown to cause obesity and metabolic disease, including bacterial overgrowth in the small intestine, increased intestinal permeability, gallstones, and changes in the enteric (gut) nervous system.

Gut dysfunction is an emerging focus in the study of autoimmune disease. In fact, as I mentioned above, some researchers believe that intestinal permeability is a
precondition
for developing autoimmune disease. In this theory, an environmental antigen (such as a protein from a food) leaks through the permeable gut barrier and initiates an immune response. Though this immune response is designed to protect the body from foreign invaders like bacteria and viruses, when it’s continually triggered by food proteins and other environmental antigens penetrating the gut barrier, it can become overzealous and begin attacking human tissue. That’s what autoimmune disease is: the body attacking itself.

In addition to contributing to autoimmune disease, disruptions in the gut barrier have also been shown to increase susceptibility to infection and weaken our immune defenses.

There are clear associations between gut disorders and skin conditions in the scientific literature: 14 percent of patients with ulcerative colitis and 24 percent of patients with Crohn’s disease have skin rashes, and 25 percent of patients with celiac disease have a skin condition called dermatitis herpetiformis. Celiacs also have a higher frequency of oral mucosal lesions, alopecia, and vitiligo.

One fascinating study found that SIBO is ten times more prevalent in those with acne rosacea than in those without it, and the correction of SIBO in these patients led to either a complete clearing or a significant improvement of lesions in 92 percent of patients. Altered gut microbiota
also promotes the release of substance P, a potent neuropeptide that is produced in both the gut and skin and plays a major role in skin disorders. Finally, probiotics have been shown to improve intestinal-barrier function, reduce inflammation, and improve skin conditions. One Italian study involving forty patients with acne found that probiotics plus standard care were more effective than standard care alone.

Now that you know how important the gut is to overall health, let’s discuss some basic strategies for maintaining your digestive health.

The basic Paleo approach is an excellent starting place for maintaining gut health. Refined flour, sugar, and industrial seed oils—the staples of the industrialized diet—are harmful because they cause undesirable changes in the gut microbiota and may disrupt the integrity of the intestinal barrier.

Excess alcohol has been shown to cause intestinal permeability, so I recommend limiting alcohol consumption to four to six drinks per week (and eliminating alcohol altogether if you have significant gut issues). Certain foods (such as those in the nightshade family) and nutrients that are well tolerated by most people can be harmful for people with digestive problems. I will discuss these in more detail in the bonus chapter on digestive disorders, available on my website.

Vegetables are one of the few foods that every diet philosophy agrees are healthy. That said, vegetables (particularly nonstarchy vegetables) tend to be high in insoluble fiber, which can irritate an inflamed gut. If you have irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or other digestive disorders, you may benefit from reducing your intake of vegetables that are high in insoluble fiber. These include:

However, vegetables that are higher in soluble fiber and lower in insoluble fiber tend to have a soothing effect on the gut. These include:

In addition to reducing your overall intake of vegetables high in insoluble fiber, you should also reduce the variety of vegetables you eat at any given meal. Instead of stir-fries with six different vegetables, for example, have a single steamed or roasted vegetable as a side dish.

Note that I’m not suggesting you completely avoid vegetables that are high in insoluble fiber; I’m just suggesting that you limit them. Moreover,
there are steps you can take to make these foods more digestible and less likely to irritate your gut:

Finally, fermenting vegetables that are high in insoluble fiber is another option for making them more digestible, since fermentation is essentially a process of predigestion. Many of my patients who can’t tolerate unfermented cabbage (raw or cooked) are able to eat fermented cabbage (like sauerkraut) without a problem. See my website for more information about how to make fermented foods. If you choose to buy fermented foods, make sure that they’re raw and that they’re in the refrigerated section. The sauerkraut you can buy in the condiments section has been pasteurized and won’t have the same beneficial effect as raw or unpasteurized sauerkraut. (For more on fermented foods, see below.)

In addition to avoiding foods that harm the gut, it’s important to focus on foods that nourish the gut. These can be broken into three categories: bone broth, fermentable fibers, and fermented foods.

Bone broth is made from water and the meat and bones of animals (it may also contain vegetables and seasonings). It’s considered a healing food in many traditional cultures, and it’s rich in glycine and gelatin,
both of which support digestive health. The nutrients in bone broth are particularly helpful for restoring the integrity of the gut barrier when it’s damaged. I recommend consuming one-half to one cup of bone broth per day in the form of soups, stock, stews, or sauces (bone broth makes an excellent base for sauces and stews).

Soluble fibers naturally found in fruits, vegetables, starches, nuts, and seeds provide a food source for the beneficial bacteria in the gut. These bacteria ferment the fiber and produce short-chain fatty acids such as butyrate, which has anti-inflammatory properties, promotes the development of healthy cells in the colon, and may protect against colon cancer. Starches like potatoes, sweet potatoes, plantains, taro root, and yuca are particularly good sources of soluble fibers.

Another option for fermentable fiber is resistant starch. The suggested amount is between twenty and forty grams a day. Unfortunately, it’s not easy to come by in whole foods, because cooking tends to destroy it, and foods that contain it in large amounts can’t be eaten raw. With this in mind, here are a few ways to add resistant starch to your diet:

Note: Some people with gut issues may benefit from reducing intake of fiber for a time.

These include fermented vegetables, like raw (unpasteurized) sauerkraut, kimchi, and pickles; fermented dairy, like yogurt and kefir; and fermented beverages, like beet kvass, kombucha, and water kefir. Fermented foods contain beneficial microorganisms that have positive effects on several different aspects of gut health. I suggest consuming one to two tablespoons of sauerkraut or other fermented vegetables with each meal and eating additional fermented foods, like yogurt, dairy kefir, water kefir, or beet kvass, throughout the day. (Note that while cheese, sour cream, and alcohol are fermented, they do not have a therapeutic effect like the fermented foods I’ve listed above do.)

We’ve known for some time that antibiotics kill beneficial bacteria in the gut. However, more sensitive DNA-sequencing technology developed in the past few years has increased our understanding of just how far-reaching the effects of antibiotic use on the gut microbiota can be. For example, two separate studies published in the past five years have shown that a single course of antibiotics may cause irreversible, permanent changes to the gut microbiota. The clinical significances of these changes are not yet well understood, but given what we know about the importance of the gut microbiota to health, it’s likely such changes aren’t harmless.

Antibiotics are potentially lifesaving and certainly necessary in some cases, and I’m not suggesting that you avoid them then. But they are often prescribed (or requested by patients) when there’s no evidence that they help, such as for colds and flus and other infections that are viral in origin.

Gut infections are far more common than most people believe, and you don’t have to travel to a foreign country to get one (though that can help!).
Helicobacter pylori,
the bacterium that causes gastritis and ulcers,
is thought to infect up to half the global population, with significantly higher rates in developing countries. Parasite infections are more difficult to track because conventional testing does a poor job of identifying them. But using more sensitive lab methods in my practice, I’ve found them to be quite common. See my website for information on how to find a clinician that can help you test for and treat gut infections.

Chronic stress can cause bacterial overgrowth in the small intestine, inflammation, and intestinal permeability. It also increases disease symptoms in IBS and IBD. However, mindfulness-based stress reduction, hypnotherapy, biofeedback, and other stress-reduction techniques have been shown to improve gut function and reduce gut symptoms. Please see
chapter 14
for specific recommendations for stress management.