As protein cannot be stored, the average adult needs to eat 45-60g of it a day. However, unless you are doing very physical work or extreme amounts of exercise, more is not necessarily better. This is a moderate-protein diet, not a high-protein diet.
Variety is all when it comes to gut health, so eat as broad a range of protein as you can. Quality proteins include meat, fatty fish, eggs, seafood, tofu, and cheese. Other good sources include edamame, Quorn, nuts, and tempeh. There are strong ethical reasons why you might want to avoid meat, but it is undoubtedly an excellent source of protein and important nutrients such as iron. We recommend eating free-range meat if possible. Eat less, but better quality—ideally red meat no more than twice a week. It is advised to restrict processed meats (such as salami and bacon) as they are more likely to contain additives, preservatives, or hydrogenated oils.
These are found in plant foods, such as nuts, seeds, olive oil, and avocados, and in dairy products, as well as meat and seafood—fatty fish being one of the best sources. Increasing the proportion of healthy fats you eat helps to reset your metabolism and reduce blood sugar. Fat slows the release of starchy carbohydrates and sugars (hence the baked potato conundrum at the end of the last section). Being slow to burn, it provides a steady source of energy that doesn’t stimulate the release of insulin (the fat storage hormone). That said, there are fats that you should try to avoid—the trans and partially hydrogenated fats that are mainly present in spreads and processed foods, such as cookies and pastries.
Foods such as yogurt and cheese are an excellent source of calcium and protein, and are not the demons responsible for increasing the risk of developing heart disease or type 2 diabetes that we once thought they were. However, dairy products contain the sugar lactose, which can cause digestive symptoms, such as bloating, cramps, and diarrhea. Around 75 percent of the world’s population are lactose-intolerant, and if you have it mildly you may not have identified it as the cause of your symptoms. If this is the case, it may be worth trying a brief exclusion diet to see if it helps (as described in Phase 1—see page 25). We do include dairy products in many of the recipes, but suggest alternatives, such as nut or soy products, wherever possible.
We are not anti-grain by any means; in fact, whole grains are found to be beneficial. But because many grains contain gluten, which can irritate the gut and in some people cause problems, we have tried to minimize using it in our recipes. We have used traditional, lower-gluten grains, such as rye or spelt, and “artisan” bread-making techniques such as sourdough, where the fermentation process breaks down much of the gluten, making it easier to tolerate.
For those who are avoiding gluten altogether, many gluten-free flours are now available. They are made with a blend of ingredients, such as rice flour, potato flour, and tapioca, and are designed for baking. However, they are often white and highly refined, and tend to lack the healthy fiber needed by your microbiome. We would urge you where possible to use whole grain alternatives such as buckwheat flour, which, despite the misleading name, is gluten-free, or whole grain chickpea flour, also known as gram flour or besan, or indeed nut flours or ground almonds, which are also high in protein and healthy natural oils. There are lots of tricks to help produce a bread-like texture or softer cakes, such as adding xanthan gum.
Fiber acts like a broom for the digestive system, helping the gut to push waste through the intestine. It is broadly made up of non-digestible carbohydrates and acts as a source of energy and nutrients for the creatures that live in your gut. We should all be aiming to eat at least 35g of fiber a day; unfortunately, the average Western diet contains less than half of that.
Most foods contain a mix of soluble and insoluble fiber. Soluble fiber attracts water and partially dissolves, forming a thick gel which helps to create the stool and move it through the intestines. It can also help reduce heart disease. Soluble fiber is found in foods like oatmeal, barley, lentils, beans, potatoes, carrots, bananas, avocados, and okra. Insoluble fiber doesn’t dissolve; it is more “scratchy” and adds bulk to the stool. Two of the most important types of it, as far as your gut is concerned, are inulin and fructooligosaccharides. These are prebiotics, which are not digested in the small intestine, but continue on down the gut to become an important source of nutrients for the microbiome, promoting the growth of beneficial bacteria. These bacteria, through fermentation of fiber in the colon, produce the vital short-chain fatty acids, such as butyrate, propionate and acetate, which in turn play an important role in health and disease. Fructooligosaccharides are also a natural sweetener.
Insoluble fiber is found in foods such as asparagus, chicory, Jerusalem artichokes, onions, string beans, wheat bran, celery, and tough stems of cabbage or kale. In some people it can exacerbate symptoms of IBS, so we include less of this in Phase 1 recipes.
Prebiotics are non-digestible carbohydrates, usually fiber, that have beneficial effects, particularly through encouraging the growth of gut-friendly micro-organisms. They are like the fertilizer that helps the grass grow in a lawn.
Probiotics are like the seeds that you scatter on the lawn to keep it lush and compete with the weeds. They are “friendly” live bacteria, found naturally in fermented foods such as sauerkraut, kefir, and yogurt (see chapter 6), which work in a variety of ways along the digestive tract, boosting healthy microbes and driving down numbers of the harmful ones. We love them!
Polyphenols are the most common antioxidants in our food and tend to be found in plant fiber. They have anti-inflammatory properties and are good for your gut health as well as for your brain and heart. As much as 90-95% of the polyphenol-rich foods you take in make it down to the colon, where they are processed by microbes and encourage the growth of beneficial bacteria. Herbs, spices, nuts, seeds, berries, teas, red wine, and dark chocolate contain high quantities of polyphenols, and we have included many of these in our recipes.
Phytonutrients are natural components of plants that keep them healthy, protecting them from disease and damage. Their antioxidant and anti-inflammatory properties also provide significant health benefits and help to preserve a healthy microbial balance in the gut. Phytonutrients are concentrated in the pigments in the skin of fruit and vegetables, so the key is to eat a wide variety of colors—aim for two or more of each per day.