How to feed your brain

Your brain's nutritional requirements were forged over millions of years. They are not about to change.

A client asked me the other day what I meant by the subtitle of my book on diet and brain health, How to Feed Your Brain.

The subtitle is Seven Evolutionary Steps to Transform Your Mental Health.

I explained that to understand the present you must understand the past. And the past stretches way back. We ignore our evolutionary history at our peril.

For that reason, and for further clarification (and blatant promotion), I thought I’d post an abridged version of the introduction to my book.

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How to feed your brain - the introduction

When I first set about writing this book, I assumed it would be a straightforward matter of detailing all the nutrients that make the brain function at optimal level.

I soon realised that the task I’d set myself was more complex than I’d anticipated. To understand the requirements of the modern human brain, I had to understand how it had grown, from small and unremarkable, to large and phenomenal, over the course of human evolution. No other animal has experienced brain growth on this scale. What on earth happened?

To answer that question, I had to go back. Way back, to when we were small-brained, tree-dwelling pre-humans, happy to munch on fruit all day and with little ambition to broaden our horizons. Although we lacked the cognitive wherewithal to dream of a different life, change was coming. We experimented with new foods, foods that reshaped not only our brains, but our whole bodies, from jaw to colon. Learning to control fire and cook our food also changed our physiology and drove brain growth even further.

What became clear from my research was that the food that triggered brain growth in those early days is the same food that makes it function at its best today.

In short, what sets us apart from other animals is the way we have evolved and the speed at which our brains have grown; no other animal can compete with our intellectual prowess. We are not the biggest, nor the strongest, but we have the smartest brains, brains that enable us to outwit all others. They are our superpower.

They are also our weakness, and the way things are going may turn out to be the architect of our demise. Mental health issues, from autism to Alzheimer’s, are more common than physical ailments. These issues are increasing exponentially across the globe, a phenomenon that cannot be attributed to genetics. Something else is harming our brains.

No one doubts that certain aspects of the modern diet can be detrimental to physical health. We know that a bad diet can influence the development of heart disease, cancer, type 2 diabetes, and other chronic diseases. Yet the idea that food affects brain function has not fully entered the collective consciousness.

Mental health issues are in the spotlight more than ever, and rightly so. Whereas those afflicted with mental ill-health were once also afflicted with the stigma that came with their illness, and were often treated in a derisory or dismissive manner, they are now afforded the same consideration and dignity as those suffering from any physical condition. Nevertheless, there is still little acknowledgement of the role of diet in the development of mental ill-health.

When the phenomenal Human Genome Project was completed in 2003, two years ahead of schedule and 50 years after the discovery of the structure of DNA, it looked like we had all diseases nailed. A simple DNA test would reveal the disease(s) most likely to get you, so you could pre-empt your nemesis. Forewarned is forearmed.

This project is a complete mapping of all the genes that form the blueprint for a human being. These genes, about 20,500 in total, are collectively known as the genome.

Your individual genome can now be analysed and the results plotted on charts. It can tell you what diseases you might inherit, who you are related to, and even where your ancestors came from.

Scrutinising the past is much easier than predicting the future. One unfortunate corollary of this genome-centric view of disease has been the widespread but mistaken belief that our genes dictate our diseases, like stars determining our fate, leaving us powerless to control its trajectory. You just sit back and await the inevitable.

Genetic testing represents a huge advance in the management and treatment of inherited conditions. Fortunately, most types of genetic mutation diseases are rare. Even so, a diagnosis can be invaluable. A well-known example of this is the BRCA1 gene. A mutation of this gene is an indication of high risk of developing breast cancer. Knowing you already have this mutation means you can work with your doctor to manage your risk, make lifestyle changes, or have treatment.

Nevertheless, finding out that you possess gene variants that are linked to common chronic diseases can cause unnecessary stress and anxiety. Those diseases that are now so prevalent across the globe include cardiovascular disease, type 2 diabetes, most cancers, and Alzheimer’s disease. Yet the truth is that genetic variants have surprisingly little influence.

Take Alzheimer’s disease. Cases of this neurodegenerative disease are rising exponentially and are expected to double every 20 years, something that already suggests that ‘bad’ genes are not the cause. Mutations of the APOE (apolipoprotein E) gene are associated with Alzheimer’s, but the association is weak, because mutations are quite common and also occur among people who don’t go on to develop the disease.

As the UK Alzheimer’s Society website states: ‘Many people fear that Alzheimer’s disease in the family may be passed on to children and grandchildren. In the vast majority (99 per cent) of cases, this is not so.’ What this means is that although genes may suggest susceptibility to common chronic conditions, they are not determinants of disease.

This is something that has been confirmed by research. Scientists at the University of Alberta, Canada, analysed the data from almost 600 studies that examined the relationship between genetic variants and over 200 common conditions. According to senior study author David Wishart, ‘Most common, chronic diseases have little to do with genetics or to do with your parents or the genes you inherited from them.’

Human genes evolve very, very, slowly. It would be an exaggeration to describe the pace as glacial. Our ancient genome has an average mutation rate of 0.5 per cent per million years, meaning that it ‘..still resides for the greater part in the Paleolithic era’. In other words, you have a Stone Age body. You have passed down the evolutionary chute from your ancient ancestors and landed in the modern age, virtually unchanged.

The Palaeolithic lasted 2.6 million years and ended just 10,000 years ago. For the last 10,000 years, our genes have changed by just 0.005%. The processed, junk food industry took off less than a hundred years ago, meaning that in a flash our diets and lifestyles have been transformed beyond all recognition, but our bodies have not.

However – and this is a big however – the fact that our genes don’t really change doesn’t mean that they are not affected by external factors. The study of environmental influences on genetic expression is known as epigenetics. Epigenetic influences include diet, stress, and exposure to sunlight, chemicals, and infection. These influences are able to switch genes on and off, creating changes in gene expression, within just a few generations. These changes can be passed on to offspring. The risk of acquiring a chronic disease, mental or physical, is influenced by the interactions between genes and environmental factors.

If you want to influence your genes, and therefore the risk of diseases you may be susceptible to, diet is a powerful way to do so. Dietary interventions can alter the course of certain diseases, via crosstalk between diet and genome. Genetics show only susceptibility, but environmental factors determine ‘which genetically susceptible individuals will be affected.’

The Global Burden of Disease Study is a comprehensive, worldwide examination of trends in death and disease, from 1980 to the present time. Between 2005 and 2015, total deaths from non-communicable, chronic diseases across the globe increased by over 14 per cent. During this period, deaths from breast cancer increased by over 21 per cent; from cardiovascular disease by over 12 per cent, and from ischaemic heart disease by over 16 per cent. Death from chronic kidney disease, as a result of diabetes, saw an increase of over 39 per cent. For some cancers, total deaths increased by 20 per cent or more. The leading cause of non-communicable deaths, in 2015, was cardiovascular disease, followed by cancer and chronic respiratory diseases. The death rate from infectious diseases declined significantly during this same period.

Today, incidence of these diseases ‘of civilization’ continues to snowball. Cancer, heart disease, obesity, type 2 diabetes…. And now we can add mental health disorders to that list. Mental illnesses have increased in line with physical chronic diseases since 1960. Brain disorders strike from birth to old age: ADHD, autism, depression, schizophrenia and dementia.

You have exactly the same dietary requirements as your ancient forebears. Those requirements were forged during the Palaeolithic era, a mere heartbeat ago, in evolutionary terms. Although they have not changed since then, those requirements are not being met. Major changes to our diet have occurred, not least of all a pronounced reduction in vitamin and mineral intake, which was up to eight times higher during the Palaeolithic than it is today.

This book is for anyone with a mental health disorder who wishes to explore dietary connections and solutions. It is also ideal for anyone interested in maintaining optimum mental health, especially if concerned about developing dementia or some other neurodegenerative condition in later life. People caring for others with mental health issues will also find it a useful guide. Because of the rich recourse to the scientific literature, this book will be of interest to students and practitioners of health-related professions.

How to Feed Your Brain is divided into three parts. In part one, I outline seven approaches to improving mental health, and avoiding mental ill-health, with a particular focus on the more common brain disorders, from depression to dementia. You will learn about the key nutrients that make the brain work, where to find them, and how to spot the signs of deficiency. Those signs can be both mental and physical. You will also learn about the role of carbohydrates, fat, cholesterol, and protein, why exercise and fasting are so important, and how the gut microbiome is able to control your mind.

Part two is for those of you who want to delve more deeply into the science and evolutionary background of the dietary requirements of the human brain. It’s a fascinating story, one that links the past with the present and makes sense of the cause-and-effect relationship between nutrition and mental health.

In part three, I offer simple meal suggestions to help ensure your diet contains all the key brain nutrients. You will learn how to put together a meal containing the specific nutrients you are aiming to increase in your diet.

Some nutrients play a greater role than others. In this book, I will focus on those that we know to be key, and for which we have the most robust evidence. But brain health isn’t just about what you include in your diet; it’s also about what you leave off your plate, how you look after your digestive system, and knowing when to give food – and your gut – a break.

The human brain may not be much to look at — dissect it, and it has all the charm of a cleaved cauliflower — but it is as complex as any galaxy in the universe. Not for nothing are celestial comparisons often made. There are at least 200 billion stars in our galaxy alone and nearly as many neurons and glial cells in the brain. The universe is always expanding, as old stars collapse, new stars are born. The brain constantly reorganises itself: old neurons die, new ones grow and rewire, forming new synapses.

Your brain is made of matter that is fuelled by the nutrients you obtain by eating plants and animals that feed on the sun, each other, and soil — mineral-rich soil that is the accumulation of dust and particles that came together after the Big Bang and formed the earth 13.8 billion years ago.

You don’t have to go outdoors to appreciate the ineffable wonder of the universe. It’s right there in your head. But your sophisticated, highly evolved brain needs careful nurturing, in accordance with its evolutionary biology, if it is to achieve its full potential. How to Feed Your Brain is a guide to doing just that.

I hope you find the story of the human brain as fascinating as I do. I’ve worked in nutrition for thirty years, as a nutritional therapist, university lecturer, and author. I see clients with all manner of health issues, but what is clear to me is how everything is connected. How to Feed Your Brain is about how food affects mental health. This is the area of nutrition that I find most intriguing, though in reality, nutrition and the brain cannot be separated from nutrition and any other part or system of the body. To understand diet and mental health is to understand diet and the gut; to understand the gut is to understand the immune system. You can’t separate the immune system from the hormonal system, or metabolism from muscle. The body works as a complete ecosystem, and the whole is always greater than the sum of its individual parts.

One of the first questions I always ask my clients is: What is the main health issue you would like to address? Usually the answer relates to digestion, or energy, skin problems or hormonal imbalances. But almost always, lurking in the background, is one or a combination of symptoms that include anxiety, brain fog, depression, poor memory and concentration.

I know this from personal as well as professional experience: I became interested in nutrition after years of frustration at not being able to find solutions for my own health issues.

I had the irritable bowel from hell. For nigh-on 15 years I had lived with almost daily, often excruciating abdominal pain, accompanied by some extraordinary bloating and gas.

I could have put up with all that. But as a sensitive young adult, I could have done without the spots. And the brain that didn’t work properly: poor memory and a persistent fog. At times, I just couldn’t focus. In my early, pre-nutrition student days, I lurched from one bad lead to another in my quest to resolve all these issues. I saw a succession of experts who turned out to be as clueless as I was. At the time, I was a nutrition philistine, and had no idea that all my problems were connected.

Studying nutrition, it turned out, was to be my salvation. I was able to fit the pieces together and recalibrate mind and body. Health and normality were restored.

Your skin is often a reflection of what is going on in your gut. What is going on in your gut is often a reflection of the stress that is affecting your brain. Your brain is in charge of hormone production. My role as a nutritionist is to connect dots, trace imbalances back to their root causes. With this book, I aim to help you trace the origins of your own mental health issues.