Amongst all the conflicting advice about what we should eat, it’s hard to argue with Mark Pollan: ‘Eat food. Not too much. Mostly plants.’ Drink more water, eat more vegetables and cut down on sugar. Even taking this into account, all calories are not created equal, and there is far more to the food in/energy out equation than meets the eye. When we eat, we aren’t just feeding ourselves, we’re feeding the vast number of tiny organisms that inhabit our gut.
The gut is the body’s second brain, and it has a hugely important effect on our overall health and happiness. The way food is processed by the body depends enormously on the make-up of the microbiome, which consists of bacteria, fungi, archaea, protists and viruses that play a huge role in the digestion of food, the immune system, the nervous system and a number of other vital bodily functions. Human cells are far larger by volume and weight, but by number account for only 10% of the cells in our body. Just like humans, these microscopic entities compete for space and resources, and they have the ability to send powerful messages to the brain by hijacking the vagus nerve, engendering cravings for certain types of food which will benefit them, even if that is at the expense of the host. They are also capable of synthesising hormones and provoking a feeling of dysphoria (generalised anxiety or unease), only satisfied when we eat their preferred type of food. They can manipulate our mood and behaviour, and in doing so they ensure that they receive a diet optimal for them and detrimental to their competitors, and if the foodstuffs they demand are not good for us, then tough luck: we pay the price by developing obesity, diabetes, sleep disorders, heart disease, cancer and a host of other diseases.
Fortunately, the microbiome can be manipulated. Our diet heavily determines microbe diversity, and we should ensure that we eat plenty of probiotics (beneficial ingested live microbes present in foods such as live yogurt, sauerkraut, kimchi, kombucha, and other pickled and fermented foods) and prebiotics, which are foods containing high amounts of fibre indigestible to the body in order to feed them: (oats, asparagus, apples, chicory, onions, garlic, cabbage, legumes, beans, bananas, apples, bran, barley, nuts, seeds and flaxseed, to name but a few.)
People who are obese have less diverse gut flora than those of a normal weight. The make-up of the microbiome determines which nutrients are extracted from food, heavily influencing health, weight and mood. An identical meal will affect two individuals very differently, depending on their microbiome, which are as individual as fingerprints. Being overweight is not a simple matter of lack of self-control. We are not merely people, we are holobionts, a collection of organisms forming an ecosystem, and we are kidding ourselves if we think we’re in sole control. The more diverse our microbiota, the less control individual species have over our behaviour. Instead of wondering what we would like to eat, we should think about what our microbes need. Positive food choices actively change the biome, and lead to a change in taste buds and eating behaviour beneficial to us and to our good microbes, and reduce the power of our chocoholic bugs to march us down to the nearest newsagents.
There are many factors which have led to a lack of microbiota diversity, but one of the most important has been the advent of antibiotics. Antibiotics changed the face of twentieth century health outcomes for humanity. Deadly diseases and infections were brought to heel, saving countless lives, but nothing comes for free: the use of such medicines can devastate the gut flora, leading to the rise of a host of twentieth century diseases. Doctors tend to overprescribe them on a ‘better safe than sorry’ basis, which is entirely understandable when they have a long queue of patients to see, but this has created antibiotic resistance, which is a real concern. Farmers give antiobiotics to their animals to fatten them up, so it’s not outrageous to posit that these drugs are fattening us up too. While routine antibiotic use has been outlawed in Europe, it is a widespread practice in the US. We ingest antibiotics when we eat meat from treated animals, and we also get a low dose from vegetables, which may have been grown in manure from treated animals. The widespread use of antibiotics provides a partial explanation for the epidemic of twentieth century diseases such as obesity in the Western world, which we are so kindly sharing with our brethren elsewhere thanks to the increasing global popularity of a Western diet.
Fresh air, exercise, yoga and meditation can all positively affect the biome. Intermittent fasting is highly beneficial to akkermansia, a microbe which does not rely on us for food; rather it feasts on mucus secreted by the gut, and it thrives when we cut down on eating, even temporarily. The higher the level of akkermansia, the better; it reinforces the bowel wall, preventing dangerous pathogens from invading. It is also associated with leanness: obese people have very low levels of it. When the guts of obese mice were colonised by akkermansia, they naturally slimmed down.
Another way to improve the biome is to come into contact with the soil; gardening not only gets your hands dirty, but it gets you out into the fresh air, allowing entry to billions of good microbes. Whether it’s a plant, an animal or a person, the act of nurturing is in itself incredibly beneficial.
Man does not live on bread alone. Food is central to sociability, to civilisation, to nurturing, to love. I don’t cook for my family simply to keep them alive, I do it to show my love. All civilisations worthy of the name put a high premium on hospitality, on showing generosity towards strangers, on opening up your house and sharing the bounty of your table.
Alcohol should be devastating to health and the microbiome, but in moderation, it isn’t at all. Red wine is a better choice than white, which in turn is a better choice than spirits and/or beer. Alcohol, like food, has the capacity to bring people together. If you drink alcohol, drink it with friends and with people you love, rather than by yourself.