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It includes shopping tips and delicious recipes.
Draws on new research that shows that omega-3s can improve cognition at any age and help reduce the risk of cognitive decline in middle age and old age.
Consultant physician, and nutritionist, Dr Frank Ryan was co-author of The Eskimo Diet, a massively best-selling book, which began the omega-3 revolution. Where The Eskimo Diet dealt with heart attack prevention The Brain Food Diet does the same for preservation of brain health and cognition at any age. In particular it shows you how to reduce the risk of cognitive decline from middle age onwards. There is an important section on how to reduce the risk of Alzheimer's disease.
Written for the general reader, it sets out up-to-the-minute scientific evidence that show you how to plan your diet, improve your omega-3 intake and reduce your omega-6 and saturated fat intake.
Dr Frank Ryan
Frank Ryan is a consultant physician, with more than thirty years experience at the cutting edge of teaching hospital medicine. He helped set up the Nutrition Institute at the Northern General Hospital, in Sheffield. He is a member of the BMA, a fellow of the Royal College of Physicians, a fellow of the Royal Society of Medicine and a fellow of the Linnean Society of London. He is also a distinguished author whose books have been acclaimed worldwide and translated into many languages. His Tuberculosis: The Greatest Story Never Told was “Book of the Year” for the New York Times and Darwin’s Blind Spot was the “Chosen Book” for the distinguished financial expert Charlie Munger.
The Eskimo Diet, which he co-authored with Dr Reg Saynor, began the omega-3 revolution and was a massive best-seller in the UK.
The Brain Food Diet
Brain Food Diet
Stay Young in Mind with the Omega-3s
Dr Frank Ryan
First published in 2007
Declare the past, diagnose the present, foretell the future.
Hippocrates of Cos: Book 1, sect 11, Epidemics
This book will enable people to help themselves and their families. I am not advocating miracle cures or replacement treatments for people suffering from physical and mental disorders – or as a replacement for some treatment that people might be taking already. What I am advocating is that readers consider the facts and then decide for themselves whether or not their diet is deficient in the marine omega-3 fatty acids DHA and EPA, ingredients that now appear as vital to health as, say, vitamin C. Unfortunately the evidence suggests that many people’s diets really are deficient of these omega-3s. My aim, therefore, is to show you how to rebalance your diet, and that of your loved ones, and thus reduce the risk of the mental decline that is assumed to be a normal part of ageing.
People who have any special health queries about eating oily fish or taking fish oil or omega-3 supplements should take the advice of their family doctors. If a healthcare professional needs more detailed medical or scientific information they will find detailed references and resources at www.fprbooks.com.
Do you have days when you wake up feeling good about yourself? Days when the confidence of that inner sun is truly shining. There is a ready smile on your face when you greet people, a real zing about you – so much so that everybody wants to know what's making you feel so good about yourself. Well today I want to help you capture a little of that zing. And the reason I can say this with some confidence is because I have a scientifically proven message to give to you, an important message that will enable you to help yourself.
What will it cost me, I hear you ask?
I can assure you the cost, in terms of money, is very little. And if you anticipate cost in terms of punishment, frugality, starvation or fad diets, or doing without the things you love – those little things that make your life worthwhile – nothing at all. You see my message really is a happy one. It will not interfere with your day-to-day quality of life, except perhaps to make it even better.
Remember that one universal truth we all grasped a long time ago? The one thing we can count on is the fact we all grow older every day. That worries some of us, I know. There are aspects of it that worry me too. Some people get themselves into a tizzy and they go to extreme lengths to try to stave off the effects of ageing. Nobody wants to slow down, to get wrinkly and worn around the edges, to creak in the joints and, worst of all, to become forgetful and slowed down mentally. In fact, when it comes down to it, that’s what we fear more than anything – the fact that we might lose that zing. There’s a medical term for it, “age-related cognitive decline”, or “ARCD”, which in essence means the progressive loss of the ability to think, with its implicit erosion of memory and all of the important social graces and dignities that go with it.
Well, here’s the wonderful truth of my message. I am convinced that, thanks to some very recent advances in medical knowledge, there really is something we can do to help ourselves.
Some of you might even remember how this story began, back in 1990, when Reg Saynor and I co-authored The Eskimo Diet. This brought about a nutritional and medical revolution in the UK and Ireland. At the time it was also highly controversial. I was working as a consultant physician in a major teaching hospital, which was also the regional cardiac referral centre. I had twenty years of experience treating heart attacks, and indeed all of the common and serious medical conditions I shall be talking about in this book. Up to then patients who had suffered heart attacks, or who were thought to be at high risk of a heart attack because they had angina or high cholesterol levels in their blood, were told to avoid oily fish. Reg Saynor had been running a blood fat clinic at the hospital for years and had pioneered the study of fish oil in treating abnormal blood fat levels. He believed he had more than enough evidence to prove the very opposite – that fish oil had properties that reduced blood fats and reduced the risk of heart attacks. We combined experiences to write The Eskimo Diet, which proved to be a runaway bestseller that caught the attention of the media and helped to change dietary habits for the better.
This was the beginning of the Omega-3 story. Little did I realize that what we knew then, revolutionary as it seemed, was merely the tip of the iceberg in a remarkable chapter of discovery with major biological and medical implications, many of which are related to ageing. In this book, the happiest I have had the privilege of writing, I shall examine this expanding story and focus down onto one area of discovery in particular. I shall explain how fish oil, and the omega-3s that come with it, helps to slow down, in some ways even to prevent, the loss of memory, and all of the other important mental powers, that we regard as the inevitable indignity of ageing. Indeed, as some recent studies suggest, fish oil may help to reduce the risk of getting Alzheimer’s disease – and it may even help some people who have already developed milder forms of the disease. There is growing evidence it may even help to lighten your mood.
So you see it really is a zing thing.
These are major claims. How could a natural ingredient in our diet do all of these things? This is such an important question it needs to be looked at closely, without hype or the rose-tinted spectacles of wishful thinking. Yet the exciting thing is that over the last few years this message has become increasingly credible through good quality scientific and medical research. I don’t expect you to just take my word for it. In this book I shall give you the evidence in simple English so you can make up your own mind. Then if, like me, you are convinced, I shall go on to show you how to add that zing to your life.
Old Wives Tales and Eccentric Oxford Dons
Isn’t it curious that old wives’ tales had it that fish was brain food long before medical science took this seriously! Indeed when The Eskimo Diet was first published I recall some of my colleagues joking about cod fathers and briny old tales of the sea. Belief in the health-giving properties of fish oil is very old indeed. The Romans knew about it, as, very likely, did earlier folk. Somehow, and perhaps it really was old wives, began to notice that fish oil was good for their health. And then, thousands of years later, doctors became very interested in rickets.
Rickets is a serious disease that stunts the growth and development of children. In the late nineteenth and early twentieth century it reached plague proportions in Northern Europe and America. It was also proving bad for the war business because somewhere between twenty and thirty percent of young men failed their army medicals because of the effects of childhood rickets. Something had to be done about it! Government health advisors knew exactly what to do. Rickets was caused by a lack of vitamin D in the diet. The reason it was common in northern climates was the fact we manufacture a little vitamin D in our skins, under the beneficial action of direct sunlight. But in the cloudy and polluted atmosphere of the northern hemisphere, there wasn’t enough direct sunlight to make it happen. Cod liver oil is rich in vitamin D. So governments set up health programmes aimed at mums.
Get your kids to take a spoonful of cod liver oil a day!
Mums got the message. Whole generations of children, including my own, grew up with the taste of cod liver oil, often downed under threat or with the taste masked by the more pleasant flavours of malt or lemon. The wonderful thing is that it worked. The plague of childhood rickets was abolished in a single generation. And that was thought to be that. Nobody imagined there was more to the story until the Oxford Don, Hugh Sinclair, took it into his to prove otherwise.
Sinclair was in the best tradition of the dons of his day in combining intellectual brilliance with British eccentricity. Fascinated by nutrition, in 1944 he travelled to Canada, where he took advantage of the opportunity of the opportunity to visit the Eskimos. These people, today called the Inuit, ate a diet so high in fat it would give a cardiologist nightmares. Indeed, their diet contained the highest amount of saturated fat in the world, yet they didn’t appear to get heart attacks. It was an enigma too exciting to be ignored. In time Sinclair confirmed that Eskimos had no word for heart attack, although they had dozens of words for different types of snow. In 1976, together with two Danish scientists, Dyerberg and Bang, Sinclair travelled to meet the Eskimos in Greenland where they found that their blood cholesterol levels were no different from our own. Meanwhile another blood fat known as triglyceride, which is also linked to heart attacks, was astonishingly low. Given their high blubber diet, this was astonishing. Sinclair could think of only two possible explanations: either the Eskimos had bred a population resistant to the bad effects of a very high fat diet, or there was something else in their diet that was at one and the same time protecting them from the effects of their high fat diet.
Three years later he had the brainwave of putting himself on the Eskimo diet. He imported a frozen seal, whose blubber would supply him with a high fat diet, and he otherwise ate just fish and shellfish. I should point out that this is a good deal less balanced than the real diet of the Eskimos. Over three months or so, his weight fell by a couple of stones, though it’s hardly a diet I would recommend for weight reduction. His blood fats turned to the same pattern as the Eskimos, suggesting that their astonishing blood fats and lack of heart attacks was indeed linked to their diet. But there was another, and wholly unpredicted, effect of this extreme marine diet. He developed extensive bruising over his body, blood showed in his urine and the clotting ability of his blood became impaired. It suggested that not only did a fishy diet protect against the dietary effects of saturated fat, it also lessened the possibility of a blood clot – a major factor in the causation of heart attacks.
In an experiment confined to himself Sinclair drew conclusions that would, in time, have monumental medical implications.
That same year, my colleague Reg Saynor saw Sinclair being interviewed on television. Reg, who ran the cardiothoracic laboratory at our hospital, was worried about his own high cholesterol. But instead of trying Sinclair’s extreme diet, Reg went out the chemist’s and bought a bottle of cod liver oil. He soon discovered that a spoonful of cod liver oil had much the same effects on his blood fats, though not so extreme as to threaten his health. He began a series of experiments, testing various types and doses of fish oil for beneficial effects on cholesterol and triglyceride – and further in preventing heart attacks. All of his experiments pointed to protection against heart attacks, even in patients with bad blood fats who had bad angina or who had already suffered a heart attack.
This was the birth of the omega-3 story. When Reg and I combined to co-write The Eskimo Diet with him, I added my experience in dealing with heart attacks and my background knowledge of nutrition. In a later chapter, I shall bring this story up to date, and extend it to the rainbow of benefits it offers sufferers from many different illnesses. But it is time I returned to the all-important question of reining in the unwanted memory loss and other indignities of ageing.
Mums and Babies
In Gulliver’s Travels the Immortals from Luggnagg never bothered with reading books because their memories were so poor they had forgotten the beginning of a sentence before they got to the end. The author, Jonathan Swift, might have been describing Alzheimer’s disease, that tragic affliction that affects increasing numbers of the population in the UK today. There can be little doubt that anything that reduces the danger of getting Alzheimer’s disease, or that might even help mitigate the effects when the illness first begins, is worth knowing about. However, lesser “Luggnaggian” problems afflict most of us sooner or later – and long before what we would consider old age. We all have embarrassing memory lapses, when we head for the shops or meet somebody and can’t recall his or her name.
The sad fact is that, sooner or later, most of us are destined to suffer the effects of the dreaded age related mental decline.
‘Heck,’ I hear you exclaim, ‘I’m half way there already!’
‘Me too,’ I have to admit, ‘at times!’
But then isn’t there an important clue in that everyday observation of our ordinary experiences?
Some days we feel less than sharp, while other days we’d shave the head off a new pencil. In fact a similar situation applies in Alzheimer’s disease, particularly in the earlier stages, where the unfortunate sufferers have moments, or even days, when they appear to recover their faculties. This suggests that whatever is blunting the normal clarity of their memory and thinking doesn’t have to be progressive or permanent – thank goodness it isn’t permanent in our ordinary lapses! How much more so does this apply to our moods, whether happy or sad. If a chemical change in our brains can influence memory, wit and even that elusive inner sense of peace and happiness, this, it suggests that there may be ways in which we can influence that brain chemistry to improve and protect those blessings.
Even when The Eskimo Diet was first published we knew that DHA, one of the key ingredients of fish oil, plays an important role in the development and health of the human brain. In the intervening years, and particularly so in the last decade or so, this evidence has become overwhelming. What then are the omega-3 ingredients, and why should they have proved to be so important?
You could compare fatty acids to a string of beads, made of carbon, with chemical links between each bead. If all the links are rigid wires (a single bond), the fatty acid is called a “saturated” fat. If one of the links is mobile, like a flexible joint between any two of the beads (a double bond), it is a “monounsaturated” fat – like the oleic acid in olive oil. If two or more of the links are flexible, it is called a polyunsaturated fat, also called a polyunsaturated fatty acid, or PUFA. All of the fatty acids that are essential to human health are polyunsaturated fatty acids, or PUFAs.
DHA is one of these, with multiple flexible joints between the carbon beads. The letters DHA stands for “docosahexaenoic acid” – so you can see why even chemists refer to it as DHA! Because the first of the flexible joints is on the third bead or carbon from the distant (omega) end of the string, it’s called an “omega-3 polyunsaturated fatty acid”. Fat accounts for roughly 55% of the substance of our brains, but this is a very special type of fat, not the kind we gather around our waists, hips and thighs. This so-called “structural fat” is an integral part of the membranes of the nerve cells. DHA is the main fatty acid found in these structures and it is especially rich in the vast proliferation of nerve-to-nerve junctions, known as synapses, that ramify throughout the cortex, or “thinking part” of our brain. The highest concentration of all is found in the retina – the nerve lining at the back of the eyes – where it plays an important role in vision. In men it also plays a role in the tail-wagging movement, or motility, of the sperm.
I shall begin by explaining how DHA is critical for normal brain development in the baby in the womb, and also during the first year or two of life after birth. I also propose, for the first time in a book of this sort, to explain why it is every bit as crucial to normal brain function in adults. In my opinion, there is no longer any controversy to our original proposal that it helps to maintain a healthy heart. Yet another beneficial role is in the reduction of inflammation that plays a part in arthritis and other conditions.
Eicosapentaenoic Acid, or “EPA”, is another omega-3 polyunsaturated fatty acid that comes from fish. Unlike DHA, this is not stored in any great amount in the brain or retina, but it plays an important part in the health of our hearts and circulation and is important also in reducing inflammation. While there is no convincing evidence that EPA is critical to brain development, some experts believe that it may play a beneficial role in mental disorders.
It is important to grasp that DHA and EPA are only found in any significant quantity in marine foods, especially the edible flesh of oily fish, such as herrings, salmon and mackerel, and the livers of white fish, such as cod and haddock. Other essential fatty acids include the omega-6 arachidonic acid (ARA). As you will now have figured out, it is called an omega-6 because the first flexible joint is on the sixth carbon from the distant, or omega, end of the string. Our bodies readily form ARA from dietary sources of linoleic acid, an omega-6 which is abundant in plants, particularly their seeds. We shall hear more about ARA later, but it is worth noting that given the many sources of linoleic acid in the diet, deficiency of ARA, unlike DHA, is unlikely in otherwise healthy people. Meanwhile another important source of DHA, and the only significant vegetarian one, is certain marine algae, which provides the DHA that is now used to fortify infant formulas.
Alpha-linolenic acid, or ALA, is another omega-3 fatty acid of plant origin, being found for example in flaxseeds, walnuts, and soy nuts and soybean oil. It acts as a source of energy for the body. It can also be used by the body as a building block for DHA and EPA. But this conversion process is slow and inefficient, with only 5-10% of ALA being converted to EPA and even less being converted to DHA. This means that the only reliable way we can get hold of enough of these essential dietary ingredients is to consume DHA and EPA in our diets. We are faced with a simple choice – either we eat a meal of oily fish at least twice a week, or we supplement our diet with a high quality omega-3 source, such as cod liver oil or an omega-3 concentrate in capsule form.
The key question, then, is just how important are these omega-3 dietary ingredients to our mental health?
An important clue came from studies of babies in the womb, and also of the continuing development of babies after birth. During this time the brain accumulates large amounts of DHA and ARA. The question, then, was how vital a role did DHA play in brain growth and development.
In Bristol a far-sighted medical and nutritional team has long been conducting a long term study aimed at improving the health and development of children. Known as the “Children of the 90s”, they looked in particular at the role of diet. Most of the baby’s brain maturation takes place during the last three months of pregnancy and, after birth, in the next year or two of life. But, as you might imagine, it’s difficult to measure brain function in young infants. But one thing we can measure is the ability of children to recognise depth in three-dimensional images, an ability we call “stereopsis”. The Bristol experts arrived at two conclusions. Children who were breast-fed for 4 months or more were more likely to have high-grade brain function on this test. Moreover, children born of mums who ate oily fish, were also likely to have higher grade brain function on the test.
This was a far-reaching discovery. Human breast milk contains DHA but, until recently, milk formulas for artificial feeding did not. So it was inevitable that breast-fed babies had higher levels of DHA in their brains than those who, at this time, were bottle fed. The Bristol results were confirmed in many other studies in different countries. Indeed when other experts compared reading, visual interpretation, sentence completion and even mathematical ability, the breast-fed children performed better.
Some sceptics still argued that the better performance didn’t necessarily mean that DHA was the magical ingredient. There were alternative explanations, like the fact breast-feeding was more often associated with higher socioeconomic class, and thus perhaps the breast-fed kids enjoyed a better general level of nutrition, and maybe also a better level of healthcare and welfare.
In Norway Ingrid B Helland, and her colleagues, put it to the test. They studied the effects of two different food supplements in 590 pregnant and lactating mothers, giving half of them corn oil (vegetable type omegas) and the other half cod liver oil (DHA omega-3). When they subsequently tested the babies of the pregnant mothers, the infants of the mothers given cod liver oil were bigger in body length and had better brain maturation at birth. Of course babies’ brains continue to develop after birth. When the same experts conducted an IQ test in children aged four years, they found higher scores in those whose mothers had taken cod liver oil in pregnancy or during lactation. In their words: “Maternal intake of [cod liver oil] during pregnancy and lactation may be favourable for later mental development of children.”
Ricardo Uauy, Professor of Public Health Nutrition at the London School of Hygiene and Tropical Medicine, took this conclusion a step further. Comparing brain and eye function in breast-fed babies with babies fed on the bottle, he found that when the bottle-fed babies received supplements of fish oil, they had the same scores as the breast-fed infants.
In America, Eileen E Birch and her colleagues looked at infant brain development after the breast-feeding period, taking as their measure the eyesight of 65 healthy babies after they had been weaned, at six weeks, from the mother’s milk. They were interested in the fact that the part of the brain responsible for vision – the “visual cortex” – matures after the six week period. The infants were divided into two groups. One group was weaned on a standard formula feed (which contained the vegetable omega-6 and vegetable omega-3 but contained no DHA) and the other group was weaned on the same formula fortified by DHA and ARA. In spite of the fact both groups enjoyed the same good supply of omega-3s from the mother’s milk for the first six weeks, infants weaned on bottle milk that was not fortified with DHA had significantly poorer eyesight when it was measured at 17, 26 and 52 weeks after birth. In the experts own words, ‘Better acuity at 52 weeks was correlated with higher concentrations of docosahexaenoic acid [DHA] in plasma and red blood cells’. Their conclusions were inevitable: DHA continues to influence brain maturation and function long after birth.
The implications were so important that Japanese health authorities, concerned about a possible intellectual decay in the community by changing traditional Japanese dietary habits rich in seafood and vegetables to Western-style junk food, launched a campaign to increase the intake of DHA in Japanese children.
Perhaps I should let Professor James A. McGregor, in his advice to American obstetricians, speak for me:
“[First-class scientific studies]… have shown us that polyunsaturated fatty acids have the potential to improve pregnancy performance and measures of neurocognition in babies and children. The results of [these studies] suggest that both reduced rates of prematurity and increased childhood neurocognition can be provided by improving omega-3 fatty acid nutrition in pregnancy, lactation and early childhood. Mothers also benefit from optimized PUFA nutrition during pregnancy.”
To put it into simple English, omega-3 fatty acids are vital not only to brain development in the baby in the womb but also for the first year after birth. And they are also a healthy requirement for the mother herself. If this message isn’t already clear as day, Professor McGregor went on to explain what he was recommending in more detail:
“All sources of omega-3 fatty acids are not equal. Fish is the only source of easily available Eicosapentaenoic acid (EPA) and DHA.”
Mums who rarely or never eat oily fish, or other rich marine sources, should be concerned about Professor McGregor’s conclusions. This also applies to mums who happen to be vegetarians, and who tend to assume that their bodies can convert the omega-3s found in vegetable sources to sufficient quantity of those that come exclusively from marine sources. But there are ways in which they can get hold of the essential omega-3s. I would recommend they take the advice of their doctors and the national vegetarian society. Indeed, by now there is a large and growing library of information derived from trials in many different countries that confirms the importance of the fish oil type of omega-3 ingredients in the development of the infant’s brain.
Could it be that the omega-3s, and DHA in particular, also play a vital role in the health and function of our brains no matter what our age?
Rats, Fats and Brainwave Patterns
In Shakespeare’s A Midsummer Night’s Dream, Snug declares, ‘Give it to me, for I am slow of study.’ Who isn’t, you might well declare! We associate memory decline with the passing years, but, while some slowing down is probably inevitable, severe memory loss sufficient to undermine the quality of life and health is not.
I encountered much the same false assumption at the time of publication of the Eskimo Diet, when some of my medical colleagues thought heart attacks were a natural process. Nobody these days regard heart attacks as natural – rather we rightly regard them as the manifestations of a disease. And this is exactly how we should regard age-related cognitive decline, much as we now regard dementia, such as Alzheimer’s disease.
Indeed, the world of medicine might be accused of being Snug’s bedfellow when it came to appreciating the importance of the omega-3 fatty acids, such as DHA and EPA. When you consider that the long chain fatty acids, which include them, were found to be “essential” to growth and health by the husband and wife team of Burr and Burr as long ago as 1929, it has taken us rather a long time to wake up to their true nutritional role in human health and wellbeing.
So slow has been the general realisation that some colleagues still misunderstand the central message of this book – the omega-3s I recommend are not a drug. They’re a normal and essential part of our diet. From an evolutionary point of view, humans have evolved from ancestors that consumed fish, and shell fish, regularly. I would hazard the guess that our ancestors consumed them daily, perhaps several times a day over such vast time periods that they became central to their physical development and day-to-day health. As Professor Michael A Crawford, from the Institute of Brain Chemistry and Human Nutrition at the University of North London, has abundantly demonstrated, the omega-3s may well have played a central role in the evolution of our large and sentient human brains. Whether we take them as fish, or as a fish oil or omega-3 supplement, we are not doing something artificial. We are restoring the normal nutritional balance to our diets and by doing so helping to prevent developmental stagnation in infants and illnesses in older children and adults that, in variable degree, result from the deficiency or lack of these essential dietary ingredients.
In 1982 an American doctor, Ralph T Holman, reported the case of a six-year-old girl who had been shot in the stomach. Let us, for simplicity’s sake, call her “Jenny”. Jenny’s injury resulted in severe bowel damage and so she had to be fed through an intravenous drip instead of eating food in the normal way. By 1982 doctors were already aware that humans needed a regular intake of essential fats, but they were unaware that DHA and EPA were “essential” in this strict medical sense. So the drip fluid was fortified with safflower oil, which is high in the omega-6 linoleic acid (which the body converts into the essential arachidonic acid, or ARA), but almost devoid in omega-3. After five months of drip feeding Jenny developed numbness and tingling of her hands and feet, weakness and then the complete inability to walk, blurred vision and psychological disturbance. These symptoms suggested combined brain and peripheral nerve damage. At this time experts were beginning to realise the importance of omega-3 fatty acids in the normal diet, but they still though of this as exclusively the plant-derived linolenic acid. They checked Jenny’s blood, which showed gross omega-3 deficiency. This was the first time omega-3 deficiency had been demonstrated by formal testing in humans. When they swapped safflower oil for soybean oil, high in alpha-linolenic acid, or ALA, the little girl’s condition slowly returned to normal.
In fact we would now assume that the key deficiency was of DHA and EPA. As we saw earlier, the human body can convert linolenic acid to DHA and EPA, albeit slowly and somewhat inefficiently. Had they known this and given her DHA and EPA, her response might have been quicker, but this is not to detract from their very precious achievement, which was to save Jenny’s life.
Of course the rapid brain growth and development that happens in the womb, and extending into the first year of baby life, is long over in a little girl of six. Yet it would appear that the lack of omega-3s, and very likely DHA in particular, was still critical to the health of her brain and peripheral nervous system. Her story became a milestone in our understanding of the role of omega-3 fatty acids in day-to-day brain function, and it triggered a great deal of investigation.
In fact even at the time Dr Holman was treating Jenny, tests were being conducted in laboratory animals, such as rats and mice. It may strike some people as odd to test cognition in animals, but all mammals use problem-solving and learning behaviour in their day-to-day attempts to find food and survive in nature. Indeed the brains of rats and mice are composed of the same types of nerve cells and nerve junctions as humans, and DHA is the single most important component of the structural fats in their brains and in the backs of their eyes. One of the reasons why Dr Holman tried omega-3 supplementation in Jenny’s case was a test conducted in rats some five years earlier by Lamptey and Walker. They fed safflower oil, high in omega-6 but low in omega-3, to one group of rats while feeding a diet containing a good supply of omega-3 in the form of linolenic acid to another. When they compared their performance in finding their way out of a maze, those rats fed exclusively omega-6 found their way out of the maze only 60% of the time, meanwhile those fed omega-3s found the way out 90% of the time.
Since then a range of tests have been conducted in rats, mice and baboons, confirming that omega-3s, and most particularly DHA, really do enhance problem-solving performance. When the diets of animals are deficient in DHA, problem-solving and learning ability falls dramatically. And, yes – you might have guessed it – they have even looked at the effects of DHA in older rats.
Ageing in rats is, of course, relative. Two years in rats, for example, might equate to pensionable age in humans. In one such study, by Gamoh and colleagues in Japan, the administration of DHA to such “older” rats significantly improved tests of memory, including “working memory” – or at least what passes for it in rats. The question, then, is do these tests on brain function in animals really extrapolate to you and me?
We’ve seen how important DHA is to infants, both in the womb and the milk-feeding newborn when the brain is very actively growing and developing. In Jenny’s case, we saw how it remained important for long after the brain had gone through its phase of rapid growth and development. In the mid 1990s, Stephens and colleagues at Purdue University in America wondered if omega-3 fatty acid deficiency might play a part in attention deficit hyperactivity disorder (ADHD), a condition in which children are unusually inattentive, impulsive and hyperactive. When they measured blood concentrations of three essential fatty acids, the omega-6 arachidonic acid the omega-3s, DHA and EPA, they found a significant association between ADHD and low blood levels of all three.
Just because these levels are low in ADHD, it doesn’t necessarily follow that this is the cause of the condition. Even today the cause of ADHD remains elusive, but it is likely that the condition is caused by several different factors, so a single line of therapy is unlikely to work for all affected children. When the same experts tried treating the children with omega-3 supplementation, parents and teachers reported some improvement in behaviour. But we shouldn’t get carried away with this. What these studies suggest is that it might at least be worth looking further into this – meanwhile it would appear reasonable to look for DHA deficiency by dietary and blood analysis and correcting this if it is found.
The same group went on to study learning problems in one hundred boys aged from six to twelve. They found that the children with the highest levels of omega-3 fatty acids in their blood had the fewest learning difficulties.
Here in the UK, Richardson and her colleagues, found evidence that dietary fatty acid deficiency, or imbalances, may contribute to the severity of dyslexia, while also contributing to dyspraxia, ADHD and autism. Meanwhile, in America, Zhang and colleagues looked at whether polyunsaturated fat deficiency might be linked to abnormal behaviour and learning difficulties. When they analysed the diet of 3,666 children aged 6-16 and measured achievement scores and intelligence tests, the total dietary fat intakes had no significance, but when they looked at polyunsaturated fats there appeared to be a dose-related link between poor intake of polyunsaturated fats and poor performance. Dose-linked findings like this are very suggestive. But unfortunately the polyunsaturated fatty acids were not broken down into the various omega types, nor were blood levels of omega-3 taken, so the singular impact of DHA could not be extrapolated.
So what about adults – and in particular adults over the age of fifty? Do these remarkable findings in children extrapolate to maturity?
One way in which you can measure the efficiency of brain function is to look at the transmission of brainwave patterns during tests involving learning and memory. The faster the transmission of the brain wave, the more efficiently the brain is working. This rate of transmission has been shown to decline with age and it is significantly slower in people with dementia. After an initial set of tests, a group of 26 healthy adults were given supplements of either DHA or EPA and tested again. Just two hours after taking DHA, the volunteers showed a significant improvement of their brain wave patterns.
This suggests that DHA has an almost immediate beneficial effect on brain chemistry, a role that would appear to be specific and separate from its effect on brain development in infants. It would appear to me to confirm my earlier guess that our ancestors consumed fish or shell fish daily, since the effect is rapid and short term. It also fits with the evidence from other animal studies in which DHA has been shown to help signalling between nerves in the brain.
When I was a medical student, I was taught that our brain cells stopped dividing in youth. This was assumed to explain the mental decline as people got older. In fact the picture is far more complex. Brain cells do have some capacity to divide in adults. And of vital importance is the potential to set up new and better connections between different brain cells, and between different parts of the brain as a whole. This function remains highly active right into old age. Not all of the effects of DHA are immediate and short term. One of the interesting results of the studies in animals was the fact that it took at least a month for mice on DHA supplementation to make significantly fewer mistakes on threading their way through mazes – and by this time the supplemented older animals performed even better than younger ones whose diet did not contain DHA. This could not have resulted from rapid changes in nerve chemistry, as seen in the human volunteers in the brain wave experiment. It suggests additional uses and nerve pathways where DHA may be important.
And this in turn leads us to the key question. Will supplementing our diet with omega-3s, such as EPA and DHA, protect us from the mental decline that people assume is just part of the process of ageing?