Personalized nutrition - Could genetic tests improve your health and your figure? | DW Documentary

My food and myself what's good for me? An experiment What does ideal nutrition look like? Are fruit and vegetables best for everyone?

Sugars and fats unhealthy for everyone? Our test subjects are in for a few surprises. Something's happening in the body there.

. . Getting fit and strong, or staying in shape.

Many count on current nutritional advice to get there. But why do most fail? We're beginning an experiment.

Hello! You're the first You can take a seat there at the table. Ok, thanks.

Welcome! Our four test subjects are between 30 and 60 years old and have differing lifestyles. Their goals are similar to most people's: Some want to lose weight and improve their fitness, and all of them want to keep healthy.

Christian Sina is head of the Institute of Nutritional Medicine in Lübeck, Germany and leads our experiment. So, I come from a medical background, specifically gastroenterology, which has looked at personalized medicine for a long time. We know that prescription drugs aren't equally effective with everyone.

With nutrition these aspects haven't been well researched, but the same principles could also apply. Welcome! It's great that you're here and participating in our little experiment.

What we're aiming for is to take a little journey into your own metabolism. . .

to really find out which of these things might lead to an increase in your blood sugar levels and I'd like to put forward the hypothesis at the outset of this experiment that you will all react very, very differently to the same foods. Sugar plays a pivotal role, as it’s the most abundant source of energy our body can use for our metabolism. A small amount of it can always be found in the blood of any healthy person.

We get this essential sugar from our diet in the form of carbohydrates. Carbohydrates are made up of varying lengths of sugar molecules. Enzymes in the small intestine break up longer chains of molecules, releasing glucose.

The glucose then passes through the wall of the intestine, entering the bloodstream. With that, blood sugar increases after a carbohydrate has been consumed. The body reacts by secreting insulin.

That enhances the body's glucose uptake, transporting it from the blood into the individual cells. They then burn the sugar up, and the blood sugar level lowers once more. Up until now, some carbohydrates have been considered good for blood sugar levels, others bad but can we really speak in such generalized terms?

Minor fluctuations in blood glucose levels are normal. If there is a sharp rise, however, the body secretes more insulin. After that, the blood's glucose levels typically swiftly drop off again, with the result that we become tired, or get cravings.

If our blood glucose levels remain elevated over a long time, our blood will also contain higher levels of insulin. Insulin is known to be a fat storage hormone people who produce a lot of it are prone to weight gain, and may develop type two diabetes. Extreme fluctuations in blood sugar {\an8}also increase the risk of cardiovascular disease.

and, if I now know which of these foods is more likely to produce this flatter curve, and I know what things in my own diet lead to a sharper response, I can adjust my diet accordingly. Before the experiment begins, Christian Sina wants to know from everyone what their regular diets look like. I do try to incorporate things that seem healthy to me but I definitely won't be passing on the chocolate.

Vegetables are great, an apple as well, but meat is also really nice. Wherever we have to make changes, it gets hard to stick with it. We know that over 80% of all study participants have dropped the diets we recommend after one year at the most.

For us, it's more about adapting the existing diet. The participants have each been given a blood sugar monitor. An applicator is then used to place a thin, flexible thread under their skin.

The monitors will remain in their arms for two weeks. It will record sugar fluctuations in the tissue. Despite lagging some ten minutes behind glucose levels in the blood, it's still the simplest way to gather uninterrupted data.

I'm very excited. I hope you're excited too. The idea for this experiment has its roots in Israel.

The Mediterranean country is a melting pot of cultures and eating habits. Mediterranean diets are considered especially healthy, and are often recommended for people living with diabetes. However, around half the people who live here are nonetheless overweight.

As such, researchers in Israel are also looking for more precise guidelines on what makesa healthy diet. An important reference point is the glycemic index. While the calorific value - the number of calories any food contains can be chemically determined with great precision, the glycemic index is not as simple.

The glycemic index describes how high, and how fast blood glucose will rise within two hours of eating a food containing carbohydrates. The reference point is 50 grams of glucose; with an index set at 100%. If the glycemic index is over 70%, it's considered high.

Under 70 and down to 50% is considered an average value. Below that is a low glycemic index value. Each person metabolizes their food differently,though, so the glycemic index can only offer an average value.

How indicative, then, can the index really be? In 2015, Israeli researchers recruited around 800 test subjects for what was at the time the largest study of blood glucose levels to date. Over the course of a week, the team at the Weizmann Institute of Science recorded the blood glucose responses of each participant just as in our experiment.

Eran Elinav co-authored the study. The data confirmed the validity of the glycemic index but only its average values. The subjects' individual blood glucose reactions to the same foods varied more widely than had been expected sometimes even behaving in opposite ways than predicted.

This was mind blowing for us, very surprising, and it took us a long time to to really believe our data and believe ourselves. Because you know, when you think about it, it tells us that the food pyramid posters that are hanging in our children's classrooms are not correct because it's not just, you know, following a class of diets that would make you healthy. It is measurements of yourself and your responses to different foods, that is even more important and we disregarded it for, for decades of research.

Why then does one person's blood sugar shoot up while nothing happens to another person even though they're both eating the same thing? To find the answer, the researchers considered a number of parameters. They performed DNA analyses, and examined stool samples, and then had an algorithm evaluate the data.

The artificial intelligence was tasked with finding out what most strongly influences the blood sugar response. The result: Genes play a secondary role; it's the microorganisms in our bodies that make the crucial impact. The microbiome describes all microorganisms in the intestine.

In total there are almost 40 trillion of them. {\an8}Most of them are bacteria, with over 1000 different species. They live mainly in our large intestine; protecting us from pathogens and aiding digestion.

Their diversity is important for healthy intestinal flora. The exact function of certain intestinal bacteria is still largely unexplored. The makeup of the microbiome varies from person to person depending upon diet and medication.

The microbiome is as unique as a fingerprint. Based on microbiome analyses from stool samples, the algorithm can with a high degree of probability predict how a person's blood sugar will react to certain foods; even if the process itself still puzzles researchers. .

. We don't, to be honest, yet know why the algorithm chooses one feature over the other. The mechanism remains a very big black box, So we use artificial intelligence in order to bypass this huge black box and to reach actionable conclusions, even without yet understanding the mechanisms by which the microbes in the host interact in determining our blood sugar responses.

The microbiome can have a strong influence on food tolerances, as Elinav's laboratory studies on artificial sweeteners have shown. The sugar substitutes contain no calories, and as such should have no major effect on metabolism. Nevertheless, it's suspected that they promote obesity and diabetes.

In a study, Eran Elinav found that after consuming the sweetener saccharin, around half of the test subjects developed a glucose intolerance often a precondition of type two diabetes. Analyses revealed that the test subjects with negative reactions had consistently different intestinal bacteria. There are world-wars between researchers and physicians on what is good and what is bad.

And what we strongly believe in, and we have a lot of evidence showing it, is that by disregarding the personalized responses of different individuals or different subsets of participants in these studies, we are missing a very important parameter that may explain and even reconcile the differences between studies. Researchers in Israel hope that further studies will help them better understand the links between the microbiome and diet. Our test subjects have begun their experiment.

Will their blood sugar really react so differently to the same foods? Christian Sina developed the program the test kit can be purchased for 250 euros. During the two weeks, the four must note down exactly what they eat.

Mealtimes have to be at least two hours apart, so that blood glucose levels can return to their baseline values. With a few exceptions, they're to eat what they usually would. Joachim works in sales, he's self-employed and often on the road.

Nevertheless, he pays careful attention to his diet, even documenting which nutrients he's eating but he has yet to figure out how and why he reacts as he does to them. That's my goal - to have my eating habits more under control, and then I'll also be shedding a few kilos too. Natalie is also curious.

She's a teacher, and in her free time is involved in many projects leaving her little time to prepare healthy food. Because I don't have much time, I often eat convenience food, especially during stressful periods. I'd like to know what that does to my body.

Matthias volunteers as a coach for two soccer teams, and himself also plays sports three times a week. He's very fond of eating meat. I hope with the analysis I'll be able to curb disease in my old age, and have more energy in daily life and for sports.

The fourth member of the group, Ute, has a weakness for sweets. Her wish: to lose a few kilos on the scales. I've already tried everything - it all only worked for a short time, I would lose weight but then put it back on again.

I feel that diets don't make sense for me anymore. The blood sugar experiment will lead to surprising insights for all of them. Do they need to change their eating habits?

Despite the scientific community's numerous recommendations on weight loss, the number of overweight people is rising worldwide. Could genetics be to blame? That's what's they're investigating at the Technical University of Munich.

Christina Holzapfel is an expert in genetics and is leading a large study in which 272 participants have to follow a specific nutritional regime. For eight weeks, a formula diet helps them to lose weight, and at least one daily meal is replaced by protein-rich shakes and powders. To maintain the weights they attain, one group is to reduce carbohydrates in their diet, the other fats.

The end goal of the study is to in the end identify the parameters that can predict why it's ultimately easier or harder for people to lose weight, and the hope is that our results we'll be able to offer personalized nutritional recommendations on how to lose weight, or maintain weight. To determine that, the participants' saliva, urine, microbiome and blood are being examined. The research team is paying special attention to the genetic blueprint; DNA.

The decoding of the human genome in the early 2000s has paved the way for nutrigenetics. This new approach to research makes the complex relationship between genetics and nutrition its central focus. Initial findings have already shed light on the digestibility of certain foods.

If we start with coffee, for instance: There are people who can drink multiple cups a day, and others where their heart will be racing after just one cup. Here, it's the CYP1A2 gene that's responsible. It regulates the production of a liver enzyme.

If a person produces less of the enzyme, their body breaks caffeine down less efficiently. Others may suffer from fructose intolerance. In some such cases, a mutation in the aldolase B gene is to blame.

From early childhood, those affected can experience vomiting, diarrhoea, or cramps. Alcohol is poisonous for living cells, and thus harmful to the body it must be broken down as quickly as possible. Variants in two genes slow this process down.

In Asia, a large section of the population has at least one of these variants. There were initially great hopes that nutrigenetics would provide an explanation for obesity, too, and a few genes that effect body weight have indeed been identified. However, the crucial variants within those genes have yet to be thoroughly explored.

Each person's DNA contains some three billion base pairs. A pair consists of either the base adenine and thymine, or guanine and cytosine. In at least one out of 1,000 pairs, one of those bases will be swapped in technical terms a 'SNiP'.

Most SNiPs have no impact on body function or health. Some of them, however, increase the risk of certain illnesses. SNiPs in the FTO gene influence body weight.

The gene regulates whether fat is stored, or burned. People with this risk variant are on average three kilos heavier. It does, though, have to be said that three kilograms are simply not that much, and as such the FTO gene though being the strongest gene in relation to body weight does not get us far in explaining the higher body weights that many people are living with.

People who bear variants of the FTO gene can help reduce their risk of obesity with sport and exercise. This has been confirmed many times, including by a Cambridge study of over 200,000 people a sobering result for nutrigenetics. Nevertheless, numerous companies offer diets based on genetic analysis.

To find out what' s behind those diets, Joachim is performing just such a DNA test for us. We choose the provider at random. Joachim receives the test kit in the mail.

According to the manufacturer, the test was developed by experts in medicine, biochemistry, and nutritional science. The promise: Using DNA - as I've understood it it's possible to determine what kind of metabolism I have, and whether I can then likely tolerate certain foods more or less, and then I can adjust my diet The most important: The saliva sample. The manufacturer promises to handle the sample discretely and comply with data protection guidelines.

A test like this one can be obtained for 189 euros. According to the manufacturer, {\an8}analysis by a certified laboratory will take two to three weeks. Fourteen days later, the results are available: A 65-page evaluation, along with nutritional tips, and recipes.

Christina Holzapfel takes a look at the result for us. According to the analysis, Joachim is a carbohydrate-protein type. He's been recommended a low-fat, high-carbohydrate diet.

This, based on an examination of his SNiPs: A total of 23. When you consider that we have 30,000 genes and many more SNiPs than that, this is only a small fraction. For example: We know there are several hundred SNiPs that are associated with body weight, and there are of course also SNiPs that are associated with nutrition so this is really a very small selection that has made its way into this report.

As we see, the wording is quite careful throughout. The word 'may' is used often because there isn't definitive scientific evidence for some of these things. In the end, it's a nutritional recommendation for which I don't need to have the genetic information to be able to provide.

The significance of 23 SNiPs out of several thousand can only be limited, then. Angela Clausen of Germany's North Rhine-Westphalian consumer advice organization has examined such products on the market, and urges caution. A decisive factor for me is that I have to inform myself in advance about what happens with my data if I actually go on such a diet, or agree to a genetic test like this.

I want to know in advance what happens with my data afterwards. Where will that data be stored? Will everything be deleted?

And I simply don’t want be left alone with my results. It's all well and good to get a 60-page printout, but much more important is that I also get a personal consultation by a doctor. Joachim would also have been able to book a nutritional consultation on top of his test - for an additional 200 euros.

. A week has now passed in our experiment. Weighing food, taking notes, and measuring blood sugar have become part of the participants' daily routine.

Along with their usual diet, they've had certain dietary tasks to perform which are taking some getting used to. Today was especially interesting: This morning there was dry white bread, then two hours later there was a Fanta, and at midday plain rice again. Today's my third day with this white bread challenge.

. . and now I have to eat all this just like that.

So, bon appetit! Our test subjects are supposed to eat carbohydrate-rich foods on their own, but also in combination with other nutrients such as fats and proteins. It's the only way to identify what really drives blood sugar up.

Fats and proteins also influence blood glucose levels. Proteins contain glucogenic amino acids. When our bodies are not supplied with carbohydrates, the liver can also convert these nutrients into vital glucose.

This takes much longer than the direct breakdown of carbohydrates, and it takes hours for blood glucose levels to rise. Fats and proteins can also additionally delay the stomach from emptying. Carbohydrates ingested at the same time thus enter the intestine more slowly, releasing their glucose later.

Blood glucose levels rise more moderately. Essentially, the blood sugar response to certain foods can be altered by combining that food with something else, as some are more likely to have a weakened blood sugar response when paired with fat. Others are more likely to have this if the food is combined with protein.

Knowing this means I can choose to put butter on bread, or instead a protein spread like cottage cheese, for example. As the researchers in Israel see it, personalized nutrition ought to make general recommendations more precise. So in general, these one-size-fits-all-recommendations still hold.

Don't smoke. Exercise more. Don't overeat.

Those are perfectly fine. But if you want to go to a more granular level of greater improvement in your own personal health, {then going personal and measuring yourselves and going through a scientific process would give you a much higher chance of achieving long and meaningful results. Eran Elinav's research findings have also been incorporated into an app.

It's available in Israel and the U. S. , and some 70,000 people are already using it like Eliahu and Evelyn Rosenberg.

Eliahu is diabetic, and as such he's had to pay attention to his sugar levels for a long time now. The app is designed to help him keep his blood sugar as unfluctuating and as low as possible. It was trial and error at the beginning.

It was difficult because I didn’t know what I was doing obviously. But you learn it very quickly. Probably after about a month or two, I didn’t need to weigh things.

I knew more or less. And now I just check myself occasionally. Previously, Eliahu had being trying to lower his sugar levels without lasting success - for 25 years.

Then, four years ago, with the help of the app he changed his diet. He saw improvements within just two months. The dietitian would tell you: you can’t eat that, you can’t eat that.

Here, whatever I want to eat, I can test immediately, and know immediately if it is good for me or not. And that basically is the biggest advantage. The app's recommendations are based on Eliahu's microbiome analysis.

He strictly adheres to the guidelines. He should avoid pasta and rice he's only allowed the occasional exception when pairing them with fatty goulash. Even eating salat slows his blood sugar response thanks to the oily sesame paste.

It gave me a tool to work with. Something which made my life much easier to live with. And once you see good results, that’s the biggest achievement.

Eliahu's success is no isolated case: In a Weizmann Institute study of 200 people with pre-diabetic conditions, personalized dietary recommendations achieved better results than a set Mediterranean diet. Heilbronn, Germany. At the Baden-Württemberg Cooperative State University, Katja Lotz is leading a research project on personalized nutrition.

Today, the students are to come up with a menu for a rehabilitation facility. Right now, the clinics have meal plans, and they're adapting those to different disease patterns - however, the menus are still highly standardized and cost-driven. We have a number of projects underway here with our students that address this: How can menus be personalized?

Simply taking into account, for instance, 'Is this for a woman or a man? ' as there are differences in energy intake there too. Here we see the portion size for the man: He's 25, average height and weight, a competitive athlete; and here by comparison: a woman of the same age, with average height and weight and here are their metabolic rates.

The basal metabolic rate is the energy our body needs for its vital functions: For our hearts to beat, for us to think, breathe, and digest our food. It varies depending on weight, age, and height. On average, the basal metabolic rate is five to 7% higher for men than it is for women: That can be up to 300 kilocalories per day.

Physical activity increases the energy required. As such, individual energy consumption has to be added to the basal metabolic rate. It accounts for roughly one third of the body's total requirements.

If you don't know exactly what your energy requirements are, you can eat too much - or too little. So if you want to lose weight, for example, it can be helpful to determine your own energy needs and adjust your diet accordingly. A male competitive athlete requires a portion roughly twice the size of one for a woman of the same age with a sedentary job.

Currently we give generalized, evidence-based recommendations on nutrition, ordered into groups. For example; One group would be infants, one toddlers, one group would be adolescents, and then comes adults which are very broadly defined. So here as well, we need to break the groups down much further, and individualize much more strongly.

We can see this in the example of salt. To prevent high blood pressure, the German Nutrition Society recommends reducing use of common salt in food; but in a third of people, {\an8}salt has no effect on blood pressure, and in a small group it even has the effect of lowering blood pressure. Salt is a wonderful flavor enhancer.

If we take salt off people's plates, especially from people suffering from high blood pressure in old age, when they can already taste even less, then an aspect of pleasure has also been taken away and for me the enjoyment aspect is crucial when it comes to personalized nutrition. If someone likes to eat a piece of chocolate, for example, then that should be incorporated into their life plan. We are living ever longer, which raises the question: How can we remain active and mobile for as long as possible?

The German Institute of Human Nutrition in Potsdam-Rehbrücke is focused on the 50 plus age group. There has been minimal research, because people say 'Oh, they're old anyway', but of course it makes a difference how I live out the three decades after I've turned 60. That's a third of my life.

Information on nutritional status can now be determined easily and objectively. Now I'm measuring your skin's carotenoid content, and this will tell us how much fruit and vegetables you have eaten. Carotenoids contributes to cardiovascular health, and help prevent inflammation.

How much is present in the body can be determined by skin color. Toxicologist Tilman Grune heads an interdisciplinary competence cluster in the Berlin-Brandenburg area. His goal is to optimize nutrition in old age.

A look through the microscope shows the long-term effect of unhealthy eating: Tissue samples from mice show how cells change as they age. In the pancreas, alpha and beta cells form island-like structures, which regulate blood sugar levels. The beta cells - colored green - produce the hormone insulin.

Poor nutrition causes these cells to break down, and the islands lose their structure. In older animals with type two diabetes, the beta cells are especially degraded, preventing insulin production. So the diet is what’s leading to disease here, because of the high calorie, and in the form of high fat and high carbohydrate high sugar diet.

Are general recommendations enough to prevent this? In an intervention study, 1500 test subjects aged between 50 and 70 changed their diets for three years. Half of them followed the general recommendations of the German Nutrition Society, while the other half followed a diet with more vegetable proteins, fiber, and unsaturated fatty acids.

The result: later in life, it still pays to examine things closely. In the second group, metabolism improved - and liver fat decreased. The more you have, the more likely you are to develop type two diabetes and if you lower it back to normal levels, then there's a lower chance of developing metabolic diseases.

Often, the consequences of poor nutrition don't show up for decades but that's not the case with migraines. As early as a hundred years ago, researchers already spotted a connection between migraines and blood sugar levels. Christian Sina's attention was drawn to that again in the course of his research.

His theory is that the onset of a migraine attack is a protective reaction to looming drop in energy. In order to conserve energy, the body tries to restrict all sensory input the pain is intended to make the sufferer retreat. When we arrive at this rapid drop in blood glucose levels as a result of insulin release, sometimes the blood glucose level will dip below the actual baseline, and in effect we have an energy deficiency at least it's perceived that way in the brain.

We see that as a major triggering component of migraine attacks, and that's what we're addressing now a lower, stable blood glucose response from a personalized diet. Manuela Fastje suffered her first migraine at age 20. After that, the painful attacks came three to four times a month bringing severe limitations into her life.

It's like a thunderstorm in your head. You actually just want to be left in peace; even the ticking of a clock makes your head hurt, and you're no longer able to function at all. In the fall of 2021, she had Christian Sina and his team monitor her blood sugar for two weeks, just as they're doing with our test subjects.

I was eating ice cream during the test phase but then I had to acknowledge that this was sending my blood sugar levels soaring and crashing and then I had to consider eating less ice cream after all. The evaluation revealed that protein weakens her blood sugar response. Today, she eats cheese curds and yogurt with her fruit.

Generalized dietary recommendations had never helped her. For example, they always say cheese isn't good. If you get migraines you should avoid eating too much cheese if possible, because it's suspected of triggering attacks.

{\an8}For me though, it's not like that at all. A current study with 300 participants is testing personalized nutrition in hopes of attaining approval as a migraine therapy. Manuela Fastje intends to stick to her eating recommendations.

Although nothing has changed in her stressful shift work as an anesthesiologist, her migraine symptoms have decreased significantly. }I'm now having maybe one migraine a month, but they're much easier to manage, and the overall intensity has also decreased, and paying a little attention to my diet is worth it. What has the two-week experimental phase revealed for the participants in our nutrition experiment?

They meet again. Toast and plain quark is pretty hardcore. But it's also great how you can see the spikes.

It's certainly. . .

Something's going on there in the body. Right now I am very curious about the results. The 14 test days weren't as bad as I expected.

My mood's good, I'm excited to know if I can keep eating like this now will it be good for my life in future, or do I need to somehow restrict myself? Hello and welcome. I'll do it this way.

I'm happy to see you all here. Let's analyze this data. At the experiment's outset, everyone received pure glucose.

I think it’s you’ve had different results after taking the same thing. So, while the curve here in orange Ute, that's you - you are at the top here at 140 and have a relatively flat curve, while with you, Matze, things are different. And what about our test subjects' eating preferences?

I remember you saying that you love chocolate. You tested milk chocolate once, and gummy bears once. And if you look here at the gummy bears, you can see that your glucose is having to be strongly regulated.

With the chocolate it’s different. Here you come up to 120, and then drop down, so we can give the all-clear on that. So, chocolate is better than gummy bears.

Perfect! It still shouldn't be too much chocolate, due to the calories. Another thing that stands out is that Ute's blood sugar always drops sharply overnight.

Christian Sina advises her to eat a snack before going to bed. Her blood sugar has a stable reaction to apples. Suddenly we see a curve here with Joachim.

Oh! You see it, right? You can clearly see the increase.

Apples and bananas aren't so good for Joachim, so Christian Sina advises him against snacking in the evening, because his blood sugar level doesn't regulate itself down sufficiently at night. I don't think it's going to be hard for me, because now I've seen these images and I feel motivated to do something. It's things you maybe know, but now that I've seen it so graphically laid out, I'll definitely follow through now.

Even a supposedly healthy spelt-and-caraway bread roll causes a major spike. Nevertheless, Joachim just has to eat them with butter. Here you've had it with butter, and you can see the lesser effect clearly.

Amazing! " For Matthias, there's no food that causes a particularly sharp rise in blood sugar. Surprisingly, he can tolerate white bread better than whole-grain.

I'm satisfied with that, yes. There's nothing I have to do without, and that's a good start. It means nothing's really been wrong in the past.

A difficult revelation for teacher Natalie: Her much-loved pizza leads to extreme spikes in blood sugar. Christian Sina advises her to switch to pasta, which her metabolism can tolerate better. I do also really like pasta.

It might maybe mean one or two fewer pizzas, and eating something else instead. What is healthy? What's unhealthy?

Scientific studies have been examining more and more people individually and it turns out the answer is different for everyone. Whether your average, healthy 18-year-old who's still metabolically flexible and who exercises a lot needs personalized nutrition? there's actually not enough data to say.

It may be different for someone with increased risk, who's perhaps already had pathological changes in their vascular system, who's overweight, or maybe even obese. Then it would make sense to consider the option of personalized nutrition. What can personalized nutrition do to combat lifestyle diseases, such as obesity and diabetes?

We've seen this in decades of unbelievable efforts in attempts and money spent in trying to find solutions to these very common diseases, which almost universally have failed. But with the advance of science and scientific research, and with the addition of the personalization aspect into this equation, I'm quite optimistic that in the next couple of decades we would be able to improve people's lives.