The ketogenic diet has skyrocketed in popularity for good reason:
It can restore insulin sensitivity and help overcome diabetes.
It can fix abnormal brain activity and counteract epilepsy and other brain disorders.
It increases the body’s ability to burn fat and may raise energy expenditure.
It can improve body composition, reducing body fat and improving lean mass.
It improves cognition and brain function.
Despite these benefits, it’s easy to make mistakes when starting a ketogenic diet. As you probably know, a ketogenic diet is high in fat, moderate in protein, and low in carbohydrates—a dietary profile that is radically different from the way most people eat in the Western world. Because ketogenic diets remove many of the typical carbohydrate sources, they can impact health and function of the gastrointestinal tract.
Gut function is primarily regulated by the type and diversity of bacteria in the GI tract. These bacteria live off of the food we eat. Certain foods fuel the proliferation of beneficial bacteria, whereas others feed harmful bacteria that cause inflammation in the gut.
In theory, the ketogenic diet can have a healing effect on the gut for several reasons:
1. It eliminates the favorite food sources for inflammatory gut bacteria: Added sweeteners and artificial flavorings that fuel the proliferation of bad bacteria.
2. It removes gluten grains, which stimulate the release of zonulin, a protein that damages the intestinal lining, disrupting the ideal permeability of the gut.
3. It eliminates processed carbohydrates, which function similar to added sugar in the gut, feeding bad bacteria, especially Streptococcus, Enterococcus and yeasts such as Candida albicans.
Despite these anti-inflammatory benefits of the keto diet, most people make fatal mistakes when putting the diet to practice. When people go keto, they often eliminate all carbs including low-carb fruits and vegetables, effectively removing fiber from their diets. Why is this a problem?
The naturally occurring fiber in low-carb plants is a crucial source of fuel for good, anti-inflammatory gut bacteria. Incorporating leafy greens, cruciferous vegetables, and other low-carb plants will have a healing effect on the gut and help overcome some of the pitfalls of lower carb ketogenic diets.
First, the high-fat concentration required to induce ketone production and shift the body into fat burning may have a negative effect on the gut microbial community. One recent study found that a high-fat diet reduced the production of short-chain fatty acids that serve as a source of fuel for protective gut bacteria. This study also found a significant reduction in antioxidant levels, which could predispose dieters to increased inflammation, insulin resistance, diabetes, DNA damage, and aging.
Second, the higher animal protein content of ketogenic diets may lead to the growth of “bad” inflammatory gut bacteria that harm the delicate gut lining. These inflammatory markers are considered metabolic toxins that have been linked with adverse health conditions, including gastric cancer, obesity, and type 2 diabetes. Following one study that looked at the unfavorable effect of a higher protein intake on the gut, researchers recommended that anyone with a high animal protein intake should include protective low-carb plants, which will feed the beneficial gut bacteria and prevent inflammation.
Finally, including lower carb vegetables can help ensure that everything moves smoothly through the GI tract so that you avoid common gut problems, such as constipation or diarrhea.
Here is a ten-step action plan to ensure you don’t put your gut at risk when embarking on a ketogenic diet:
Shoot for adequate fiber from low-carb sources. This won’t be easy: Surveys show people on low-carb diets average less than 7 grams of fiber a day, but with a little planning you should be able to near the amount needed for optimal health and feed the good guys in your gut.
Include low-carb vegetables with every meal. By eating low-carb veggies, you improve digestion and reduce the inflammatory effect of protein. Load up on leafy greens (dandelion, collards, chard, mustard greens, kale, arugula, lettuce, spinach, parsley, basil), cruciferous vegetables (broccoli, cauliflower, cabbage, bok choy, brussels sprouts), alliums (garlic, onion, scallion, leeks), low-carb tubers (jicama, chicory, Jerusalem artichoke), and other low-carb veggies (eggplant, zucchini, asparagus, cucumbers, celery, mushrooms).
Load up on healthy fats that are also high in fiber. Good news is there are several high-fiber fats that should play a central role in any keto diet: olives, avocado, coconut, nuts (almonds, walnuts, pistachio), and seeds (chia, flax, sesame) all provide good gut-fueling fiber, without the insulin release of higher carb foods.
Up your omega-3 fat intake and de-emphasize omega-6 intake. Omega-3 fats are better when it comes to gut and metabolic health compared to omega-6 due to how they impact inflammatory pathways. Your goal is to have a balanced intake of omega-3 (from fish and wild or pasture raised meat) and omega-6 (from seeds and nuts) intake. Eliminating processed foods goes a long way to removing the lion’s share of omega-6s from your diet, however, it’s also important to remove omega-6 oils (canola, corn, soybean, sunflower, etc.) in the effort to reach a balanced 3 to 6 ratio.
Use resistant starch. A type of fiber that is highly effective at feeding beneficial gut bacteria, resistant starch can be gotten from prebiotic foods including oats, Jerusalem artichokes, green bananas, potatoes, and cashews. Of course, most of these foods have a higher carb content than is appropriate on most ketogenic diets, which means that supplementation may be helpful. Unmodified potato starch is the perfect solution, providing a great source of fuel for bacteria without calories or an insulin response.
Focus on unprocessed meat and fish. Most ketogenic diets are fairly high in meat and fish since these foods provide zero carbs but plenty of usable protein and healthy fat. It’s important to avoid processed meat, which often contains nitrates, antibiotics, or other compounds that feed bad bacteria and are associated with increased disease rates.
Get probiotics. You can promote the diversity of beneficial bacteria by supplementing with probiotics, the term for the “good” bacteria that promote a healthy microflora in the gut. Supplementation may be favored over relying on foods such as dairy and fermented vegetables because the live bacteria are unlikely to survive the food production and storage process. Additionally, the concentration of live bacteria is often too low to have an impact on the gut, and the type of bacteria used in many of these foods has not been shown to have beneficial effects on human health.
Get fiber from whole sources whenever possible. Many packaged foods advertise their “fiber” content; however, this is fiber that has been added after the fact, often to refined ingredients. Although studies show abundant benefits from naturally occurring fiber, the same cannot be said for processed foods with fiber added. Plus, most of these foods are high in carbs and/or omega-6 fats that you need to avoid.
Consider having a high-carb re-feed meal once every 5 to 7 days of super fibrous veggies or fruit. If you’re not getting the results you’d hoped for on a ketogenic diet, it may be worth it to incorporate occasional higher carb meals to supply additional fiber and get some mental relief from carb restriction. These foods can provide variety and give your gut some love: fruits (bananas, apples, pears, grapes, melons, mango, peaches, plums), legumes (lentils and beans), roots (carrots, sweet potatoes, potatoes, turnips, beets), and grains (oats, millet, buckwheat, amaranth).
Identify any food intolerances. On the one hand, ketogenic diets are good for reducing exposure to common food intolerances since they avoid soy and gluten. On the other, because keto diets are often repetitive, they may put you at risk of developing an intolerance to some other food you eat regularly. Intolerances are a problem because they harm the tight junctions that keep the gut lining healthy. Addressing food intolerances is out of the scope of this article, but the main point is to eliminate any offending foods, heal the gut, and then attempt to reinstate those foods, monitoring any symptoms and adjusting accordingly.
Final Words: You can set yourself up for better health with a ketogenic diet if you design your nutrition around a balanced array of whole foods in their most natural state. Hopefully, the strategies presented in this article will allow you to avoid undermining your efforts and optimize gut health.