Better brain health | DW Documentary


It’s impossible to avoid them! For decades we have been surrounded
by sweet and fatty foods. And the body has not been dealing
well with these eating habits. But what about the brain? Do our mental health, our
moods, and our brain abilities suffer from the wrong kind of nutrition? We know that junk food is making us fat, but science is telling us now that it
might also be shrinking our brains. Brain researchers have
joined the dining table? to study the effects of our eating habits. Diets that are high in fat
and sugar, in the long term, lead to changes in part of the
brain involved in memory. This is a recent field of research, a developing science that spotlights
a new facet of nutrition. Habitual intake of foods
high in fat and sugar results in a reprogramming of the brain. In short, our brain is affected
by what’s on our plates. It all starts with our very
first meals, even before birth. The brain is built up during pregnancy. How it functions later on depends
on how it has been nourished by the expectant mother’s
diet over nine months. A number of consequences of
poor nutrition during gestation have been known for a long time. Today, scientists in Australia are looking at the repercussions
of nutrition on brain function. Felice Jacka, a professor at
the University of Melbourne, examined the behavior of babies after following the eating
habits of 23,000 pregnant women. We measured their intake of
junk and processed foods, we measured their intake
of the healthful foods, foods with lots of fiber
and nutrients, etc. And then we looked at the emotional
health of their children over the first few years of
life from 18 months to 5 years. Of course, taking into account
things such as education, income, the mother’s mental health, parenting
practices, these sorts of things. And what we saw very clearly
was that mothers who ate more junk and processed foods, so sweet
drinks, and salty snacks, you know, cakes, biscuits, during their pregnancy, their children had more of these
behaviors such as aggression, and anger, and tantrums. This disquieting correlation
suggests that the mother’s diet impacts the mental development of the baby, though the link remains to be
demonstrated on the biological level. In any case, Felice Jacka is convinced. So what we also saw in
this large Norwegian study is that the children’s diet
seemed to be important as well, independent of what mum ate. If children were eating too
much junk and processed foods, and/or not enough of the healthful foods, they had more of these anger
and aggressive-type behaviors, but also sadness, anxiety,
worry, nightmares. Since then, Professor Jacka’s conclusions
have been confirmed by studies in Spain, the Netherlands, and Canada. Excess fat and sugar are now in the sights
of scientists working on the brain. Excesses and deficiencies. Junk food is often low on essential
nutrients, so it leaves the body, and especially the nerve cells, lacking. In this laboratory at the
University of Bordeaux, scientists are studying the consequences
of dietary deficiencies on mouse brains. This experiment is used to measure anxiety. The animal has the choice between exploring
the lighted area or hiding in the shade. A normal mouse takes the time
to examine the lighted area. But this animal was deprived of omega-3
fatty acids during its development. Omega-3s are called ‘good’ fats due to
their benefits to the heart and arteries. Instead of exploring the environment, the
mouse takes refuge in a dark corner. It is stressed, anxious. The experiment has been reproduced
many times on dozens of mice. For researchers, this strange
behavior can simply explained: without omega-3 fatty acids, the brain
does not develop and function normally. They are needed because
the brain‘s ‘gray matter’ is 90% fat which it cannot produce itself. The brain is the organ,
after adipose tissue, that is the richest in
polyunsaturated fatty acid? or omega-3. So omega-3 is indispensable
because the body can not make it. We have to ingest it. It has to come from the diet. Oily fish, organ meat, vegetable
oils, and seeds and nuts such as almonds have long been the
main sources of omega-3 for humans. But these foods have become scarce in the
cuisine of industrialized countries. The amount of omega-3 that
enters the brain is crucial for making brain cells more efficient. Because when these fatty
acids are incorporated into the membranes of nerve cells, they improve their electrical properties. In omega 3-rich neurons, the
signals propagate faster. The network is more efficient. Depriving the brain of omega-3 is linked
to a risk that it will function less well. The general population
is deficient in omega-3. We have insufficient intake of omega-3, so it’s important to pay attention to it. especially in the pre-natal
developmental period, when omega-3 is incorporated in
large quantities into the brain. Also, in adolescence, since adolescence
is a particular time of change of diet. And, during aging where
the incorporation of omega-3 into the brain tends
to be less effective, so we must increase its intake. The first rule for a brain
to run at full speed is: avoid deficiencies. But good nutrients and a varied
diet should be available. What happens to neurons when meals are
poor and, above all, always the same? That is a problem that is now affecting
the wild-living European hamster, which thrived for a long time in the
plains of France’s Alsace region. Since the 1960s, there has been a
decline in the hamster population, which is on the verge of extinction today. And, at the same time, what we have seen is an increase in the agricultural
area where corn is cultivated. Caroline Habold wondered
whether the collapse of the population was linked
to the sudden glut of corn. So she did a laboratory experiment,
feeding hamsters exclusively corn. During breeding, we observed
behavioral disturbances in females, which resulted in hyper-aggression
and hypersensitivity as soon as there was noise in the room. And above all, what we
did not expect is that these females would devour their
young the first day after birth. This behavior was observed
in more than 80% of females. A dietary deficiency was enough to
make a hamster devour its children. The cause? A simple vitamin. A lack of vitamin B3 is at the
origin of this abnormal behavior. When we supplemented
them with vitamin B3 in addition to their corn-based diet, they exhibited quite normal behavior. They began to nurse their young,
to raise them in the same way as the females that were
fed a diversified diet. The case of the cannibalistic
hamsters is disturbing. Could a unbalanced diet also trigger
aggressive, violent behavior in humans? Ap Zaalberg is a clinical
psychologist and political advisor to the Dutch Ministry of Justice. His specialty: nutrition and crime. He is convinced that enriching food with
vitamins, fatty acids, and minerals can reduce aggression. It’s a hypothesis that is difficult
to test in normal life because so many factors and circumstances can
influence our behavior and our impulses. In order to study nutrition without
the influence of the many parameters, he chose prisons as a nearly ideal setting. Here in the Netherlands, we conducted a study of young
prisoners in eight different prisons. For three months, we gave
them vitamins, minerals, and fatty-acid supplements. And then we looked at the
effect on their behavior. We measured it in two different ways. First, we asked the detainees
how aggressive they were and we asked the supervisors
for their views on the issue. Above all, we looked at the incident log. The number of times
detainees were punished. And we saw that solitary confinement
had fallen dramatically. In the group of inmates
whose meals were improved, the number of incidents
was reduced by one-third. What we eat may have the
power to change our moods, to stimulate certain impulses. But could the food on our plate
also influence our decisions? the ones we believe we
make using our free will? When people are asked if they
think that the food they eat has an impact on health,
most of them answer “yes.” But when asked if diet can also
influence tthoughts and decisions, very few people are willing
to believe this is the case. However, at the Institute of Psychology
of the University of Lübeck in Germany, Professor Soyoung Park has, for
the first time, proven it. Her work reveals the mechanism by which
food could influence our thoughts. And for that, the researcher has
developed a rather original experiment. Imagine that you face
the following dilemma. The money on the table is to
be divided into two sums. But it’s your partner, a stranger, who
decides how it is to be distributed. I‘ll give you two euros
and keep eight for me. If you accept the unfair offer, you leave with a little money but
much less than your partner’s. If you refuse, no one wins anything.
So what would you do? Do you accept the offer and take the
two euros, even if you feel cheated? Or, do you refuse, and leave with empty
pockets but your head held high? Well, it turns out, surprisingly, that whether you’ll take the money or
not depends on what you’ve just eaten. As part of this study, we follow 24
people who came to the laboratory twice to have two different breakfasts. We found that the same person made
completely different decisions based on what they ate in the morning. To the test person, the two
breakfasts look the same. In reality, one is far more
protein-rich than the other. The ratio of protein to sugar is
the only parameter that changes. A few hours after the meal, the subject
takes several tests on a computer. Today he tends to accept the offer. His self-interest outweighs
his anger at the unfairness, and he will leave with a
little money in his pocket. Last week he mainly refused
and won almost nothing. When the subjects consumed a
higher-protein breakfast in the morning, they were more tolerant
towards unfair offers. Conversely, when the subject had
consumed a high-carbohydrate breakfast, he was less tolerant in the
face of unfair offers. On average the subjects
who had little protein rejected unfair offers twice as often. But how can this surprising
result be explained? In their search for biological
evidence for this observation, the scientists carried out blood tests. We will send the blood to the lab
right away and they will analyse the level of hormones and
amino acids in the blood, especially the hormones insulin,
cortisol, adrenaline, and A-C-T-H. And for the amino acids
tryptophan and tyrosine. Of these substances, the
most important is tyrosine. The amino acid is one building-block of a
protein that is key to brain function: dopamine. This molecule ensures communication between neurons involved in
motivation and risk-taking. The results of the blood analysis show that subjects with higher levels of tyrosine in their blood are more willing
to accept the unfair offer. In other words, what we
eat can within hours subtly alter the chemistry of the brain, and thus the communication
between the neurons. Enough to guide some of our decisions. Experiments are continuing in
Lübeck to confirm this result. The implications are wide-ranging. Since we eat three times a day, every day, we realize that food has enormous
power, modifying and shaping us. So it’s important to think
about how we can use food to promote our well-being and
optimize our mental state. Not only does an unbalanced diet affect
our brain functions and behavior, and our meal plan interfere
with everyday decisions, it is also becoming increasingly clear that
diet plays a decisive role in our mood? and, possibly mental health. But what about junk food,
dripping with sugar and bad fats? What would happen if we ate more of that? This is the focus of research here in
Australia at the University of Sydney. Margaret Morris runs a laboratory where
rats are fed the kind of junk food that you find in supermarkets or
cheap, fast-food restaurants. Our experiments use a range of Western
foods, of the type eaten by all of us. So we feed ouf rats meat pies,
chips, cakes, and biscuits. The sort of foods that are
readily available and cheap. So we are modelling the Western world. The first consequence of this diet: the rat doubles its food rations. The animal seems never satiated. But that is not the most
surprising outcome. One of our chief interests is the impact
of this diet on the animal’s memory. And we can measure this
easily in the rat by using a task known as the novel
object and novel place task. In this test, the researcher
places objects in the rat’s cage. The animal comes over
immediately to examine them. Rodents are very curious by nature. Once it has completed its examination
and memorized its surroundings, it is temporarily removed. We then place the animal in the arena
with one object that has been shifted. On its return, the rat spends more time
examining the object that has changed places because it already
knows the other objects. They are engraved in its memory. The rats stuffed full of bad
foods behave differently. What we observe is that animals eating
a high fat diet or a high sugar diet, or the combined high fat? high sugar foods, were
less able to recognise, to remember that that object had moved, they explore the two
objects about the same, that shows an impairment of spatial memory. The overfed rats have not
only damaged spatial memory, but also other malfunctions that sound
a warning signal for the scientists. They point to changes to the hippocampus, a small region nestled in
the center of the brain. It is essential for learning and
the consolidation of memory. Recent studies show that in
humans a too energy-rich diet also interferes with the hippocampus. We see for example, that the
quality of people’s diets is related to the size
of their hippocampus, to the size of their grey
and white matter volume. And there are starting to
be intervention studies, so for example we see that only
four days on a junk food-type diet will have an impact on cognitive functions that are related to the hippocampus. Margaret Morris is now seeking to
understand how sugary and fatty foods disrupt the brains of her rats to the
point of affecting their performance. She has a
hypothesis, namely: Eating too much fat and sugar
triggers an inflammatory reaction that spreads to the neurons. So, in response to these foods, there is a general inflammatory
response all around the body. This has been well described in obesity, but it now appears to be quite
an acute response as well. And what we find is that inflammatory
molecules such as cytokines are increased in response to the diet. An overly rich diet
confuses the immune system. It reponds by triggering an inflammatory
reaction, especially in fatty tissues. Our fat masses release substances
that then propagate this inflammation throughout the body. Neurons were thought to
be spared this effect behind the protective blood-brain barrier, the semi-permeable membrane that separates the circulating blood
vessels from the brain. So there is increased inflammation
in the whole of the body, and we think this may spread to the brain. That’s because the blood-brain barrier
which normally protects the brain from inflammatory molecules
may be impaired in fact by the diet and become leaky, allowing traffic of
molecules into the brain. The inflammation infiltrates the meninges
and then triggers a surprising phenomenon. In her laboratory, Sophie Layé
has shown in her overfed mice that certain immune cells in the brain, the microglial cells,
begin to devour neurons. These microglial cells within
the brain are important because they can eat dead neurons. But when they are deregulated? especially in a situation
of unbalanced nutrition? they start to eat neurons that are alive. Therefore, by consuming these
neurons in excessive numbers, eventually they will destroy or participate
in the destruction of neural networks. That includes neurons that are alive
and that should be functional. This reaction of the microglial
cells could be filmed in-vitro. The images show how
energetically they move. The red objects are fragments
of neurons that they ingest. In an obese mouse, the
activity becomes frenetic. This phenomenon is suspected
of significantly affecting the functioning of the brain. We’ve been saying to people for
30 years, don’t eat these foods, you might have a heart attack, you
might get cancer and diabetes. It hasn’t worked to
change people’s behavior. We hope that if people understand that
what they put in their mouth is actually really essential to the health of their
brain and that of their children, that might have a more profound
impact on people’s dietary choices. Microscope, micromanipulator,
and ultra-sensitive recorder: Xavier Fioramonti is at
the helm of an apparatus that can record the electrical
activity of a single neuron. The principle is simple, a slice of mouse brain is immersed
in a liquid that keeps it alive. The researcher approaches it
carefully with an electrode. It’s a meticulous operation. Here, I lower the pipette
into the slice of brain and now we will approach this
recording pipette near the neuron to make contact. That’s it, we’ve made contact and now we will be able to measure the
electrical activity of the neuron. The upper peaks that we see are
ares for potential action. This is how neurons encode information. The time that elapses between the peaks
is the message sent by the neuron. Now we will raise the glucose
concentration in the bath. And we will see if this cell
responds to this increase in the concentration of glucose. As can be seen here, this cell responds to the increase
with more electrical activity. There is more potential for
action than we saw here before the increase in
glucose concentration. This signal comes from a single cell. But in the brain, the neurons are
all connected to each other. That makes the scientists suspect
that glucose has the ability to modify the activity of entire brain areas
that control emotions and pleasure. Is this how sugar ensures
its grip on our will? This is, for the moment, only a hypothesis. But today, sugar addiction is the subject
of intense research in laboratories. And what appears more and more clear is that the power of sugar is
similar to that of a drug. Serge Ahmed was one of the first to provide
proof with a very simple experiment. Step one, he raised rats,
giving them cocaine and sugar. Then after weeks of this diet, he
presented the animals with a choice. We have the situation in which the
animal has the choice between a lever that is connected to a syringe
that contains a drug solution. And, the drug in question is a
hard drug like cocaine and heroin. And on the left, a lever allows
him to control a syringe that contains a sweet drink. And, there we see that the animal
chooses to take the sweet drink. The rats selected the sugar water
four times more often than the drugs. It can’t be called a glucose overdose, but
the irrepressible desire is plain to see. So this experiment simply shows that
sugar has more addictive potential than we had imagined and it is, perhaps, even stronger than the pull of hard
drugs, such as cocaine and heroin. Today, we live in a food environment
that is a little crazy. We find sugar in a lot of foods, as
we would expect, in sugary drinks. But we also find sugar in foods
that are not meant to be sweet, such as ham and soup. We could cite other examples, but
it is adding sugar to these foods that contributes to the fact that
we make people addicted to them without their knowing it. Here at the Oregon Research Institute, the influence of sweet food on the
human brain is being investigated. What this program of research has revealed is that habitual consumption of
energy-dense food alters your neural circuitry in exactly the same way
as consumption of drugs of abuse. Eric Stice recruited about
a hundred students, half of whom regularly eat ice cream,
while the others never eat it. They all came to the laboratory to
drink a milkshake inside an MRI device and give the researchers a peek
into their brain activity. Great, Casey, so what we’re going to do
today is give you a chocolate milkshake and record the brain activity
in your entire brain, as you receive and anticipate
receiving the chocolate milkshake, to look at the neural basis of
consuming energy-dense foods. The test subjects can sip the
milkshake through the tubes without moving their heads. What we found out is that the
people who never eat ice cream, you could trace the reward circuitry? everything lit up just beautifully, and
it activated things very strongly, but in contrast the people
who ate ice cream every day showed a very diminished response, there
was hardly any activation whatsoever, illustrating that regular
intake of an energy dense food really reduces the pleasure you
experience when you consume those foods. The reward circuit is a region of the brain
that controls the feeling of pleasure. It is particularly responsive
to sugar consumption. But eating too much ends up
weakening its responsiveness, so that at the same dose, the sensations
of pleasure are ultimately reduced. And Eric Stice’s experiment
reveals another more subtle, and perhaps more pernicious, effect. After a diet too rich in sugar, the brain becomes hyper-sensitive
to images of food. The more and more you eat ice cream, the less and less the reward circuitry
is recruited when you consume ice-cream, but the more your reward circuitry
is activated when you see cues that say you might get ice cream. So your reward circuitry fires up
when you see an ice cream store as you’re driving down the street, or you see a commercial for
ice cream on the television, and the reward circuitry activates
much more for people who eat ice cream all the time than it does
for people who don’t. And that prompts eating in the absence of
hunger that drives obesity and weight gain. This direct influence of food on
our brain plays a crucial role in what we choose to eat each day. What happens in the brain at the
moment we pick a dessert rather than an appetizer, or fish
rather than red meat? Who is really pulling the strings? Carlos Ribeiro and his team are
leading researchers on food choices. What we really want is to find all the
components, all the genes, the molecules, the neurons, which direct
feeding decisions, and for that we have to be able to
look at very fine and small effects. The simplicity of this
animal model, the fly, makes it possible to explore new
avenues and new hypotheses. To understand the feeding
behavior of the fly, Carlos Ribeiro has developed a machine that monitors the insect’s
choices in great detail. When it’s touching the food, which is
in the other electrode with its tongue, the proboscis, then we can
measure with the sensor here, which is the same sensor which you
use on your iPad or your iPhone to detect touch on the screen. Just that here, we don’t
detect the touch on screen, we detect the touch of the food and so, we can really now dissect and analyse the
choice of the fly for protein or sugar. But also when it is eating from
the different foods, how it eats, how much it eats, how fast
it eats, and how often. We can really dissect all the
details of the decisions which are controlled by the brain. Thanks to this technique, he
has been able to prove that the main reason for choosing food
is first of all deficiencies. Naturally, flies that lack protein
will choose protein-rich food. But looking more closely, Ribeiro observed
that this is not always the case. But sometimes actually we had
some flies which didn’t have this strong urge to eat protein. And then we were wondering why that
was the case, and so when we looked, it turned out that the flies which had
no craving for protein had gut microbes. And so following up on many experiments, we showed that there are two specific gut
microbes which, when they are in the fly, they suppress protein appetite, and
therefore these two microbes have a very important influence on
protein cravings in flies. Flies, when choosing their diet, are
influenced by the bacteria in their gut. This unexpected discovery
raises an important question. Does the human intestinal flora, called
the microbiome, also act on our brains? Do our gut bacteria play a
role in our food preferences? At University College Cork in Ireland, John Cryan does pioneering
research on the microbiome. He has been able to prove that
gut bacteria can influence certain behaviors in animals as well. When you take microbes
from highly anxious mice and transplant them to normal anxious mice, they become much more
anxious, and vice-versa. Even when you take them from normal you can normalise the stress
response and the anxiety. Scientists now even consider the
microbiome to be a kind of intermediary, a link between food and the brain. The main factor that influences the
composition of microbes is the food we eat. Diet and the diversity of the diet is really important from the
moment we’re born until we die, in shaping the composition of the microbes. So we’re beginning to realise
the importance of what we eat has on what’s in our microbes, and how that’s influencing
what’s going on in our brain. Our well-being depends, in one way
or another, on our microbiome. A diet that is good for our
mood is first and foremost a diet that is suitable for the
bacteria in our intestines. This has led to the idea of using food to pamper the brain and
maintain mental health. And it is the famous Mediterranean
diet that has the scientists excited. The traditional Mediterranean diet is
high in a diverse range of plant foods, so lots of different leafy greens,
and different colored vegetables, but also fruits. Very importantly, legumes. So this is your beans, and
lentils, and chickpeas. Nuts and seeds, fish, and
of course olive oil. Olive oil is a very important
component of the Mediterranean diet. And we think that that diversity leads
to more diversity in the gut microbiota. The microbiota that live in our gut. And that diversity in the gut has
been linked to good health outcomes. We ran the first study last year
where we recruited 67 people with major depression, they received
dietary support with a clinical dietician. Now over a three-month period
this trial took place, and at the end of that when we
measured their depression again we saw that the degree of change
in their diet correlated with the degree of change in their depression. So the more they moved towards
a Mediterranean diet, the more their depression improved. Using diet to serve the brain? it‘s an idea that’s catching on. Scientists are now exploring
all kinds of clues. Spices used for centuries in
traditional Indian medicine are now being studied in labs for
their benefits for mental health. Red fruits and berries have
awakened high expectations. The polyphenols they contain might be able
to rejuvenate neurons on the decline. Are red fruits and spices the miracle
ingredients for eternally-young neurons? It is still too early to say for sure. Researchers are only just beginning
to uncover the secrets of the remarkable relationship
between nutrition and the brain. The ideal menu for our little grey
cells is still largely unknown. But a balanced, diverse diet which
does without processed food and sugar, and favors fruits and vegetables, seems so far to be the best recipe
for preserving the mental faculties. My grandmother said “You are
what you eat, so eat well.” And what we’re
realizing is that science is beginning to
understand how true she was. If we limited the deficiencies,
would that reduce crime? Too early to say. What we do know is that when
you bet on healthy eating, it has effects on behavior. The more we over-eat Snickers bars, we
become hyper-vigilant to Snickers cues, and we eat a lot of Snickers. And we create that monster in ourselves. So the best thing to do if you have kids is feed them healthy foods and not get
them used to eating this kind of crap. I can’t believe I just said “crap,” sorry!

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