by Dr.Harald Wiesendanger– Klartext updatet
What the leading media are hiding
The average German consumes five times more sugar today than at the beginning of the 20th century. Ever since trash TV and TikTok, coronoia, climate hysteria, and genderitis took hold, it’s been hard to shake the nasty suspicion that they have become just as stupid. The connection is by no means coincidental. Because sugar really does make you stupid – and how.
Sugar is seductive. It is universally regarded as a mood enhancer, a comforter, an energy booster that sweetens life. In all cultures, at all ages. As soon as a baby can smile, it does so involuntarily when a few drops of sugar solution are dripped onto its tongue.
And sugar is addictive. In the brain, it activates the dopaminergic reward system – similar to drugs – and provides a quick boost of happiness and energy. Over time, the dopamine receptors become dull. The result: you need more and more sugar to feel the same effect. More sugar, less euphoria, more cravings, even less control – a vicious circle. This interplay of reward, tolerance, withdrawal symptoms, and cravings makes sugar a biochemical addiction trap.
This addiction ensures booming business for the food industry. To get us to buy their products, they add plenty of sugar. This gives us a rush of happiness as soon as we consume them and makes us more willing to put more of them in our shopping carts. 80% of all industrially produced foods contain hidden sugar, sometimes in huge quantities, even if they don’t taste sweet at all. This is because sugar is an ideal additive for manufacturers: it is dirt cheap and improves taste and shelf life.
Sugar hides in the list of ingredients under names such as glucose, fructose, sucrose, maltodextrin, syrup, sweet whey powder, fruit sweetener, and invert sugar syrup. Per 100 grams, its content can be 4 g in sliced sausage, 6 g in white bread and mustard, in marinated meat 8 g, and in iced tea 9 g. Chicken wings or a serving of ready-made tomato soup contain up to 10 g of sugar, a jar of gherkins around 15 to 20 g, and a cup of fruit yogurt 12 to 16 g. Some crunchy cereals consist of a quarter sugar, ketchup a fifth. Supposedly healthy “children’s teas” contain almost nothing but sugar with flavorings – up to 94%.
As a result, the average German consumes 95 grams of sugar per day – almost four times more than the WHO recommends. That is equivalent to 32 standard sugar cubes. “It can’t be that bad,” says the average person. “Otherwise, it would be banned.”
The price of addiction
Addiction has its price. It is now widely known that industrial sugar is responsible for serious diseases such as obesity, high blood pressure, fatty liver, and diabetes. It makes us fat, sluggish, and morbid. But what the white poison does to our brains is still largely unknown. What massive damage can it cause there? How does it do it? What are the health consequences for us, both physically and mentally? What conclusions should we draw from this with regard to our diet?
One thing is certain: people who eat too much sugar over a long period of time have difficulty thinking clearly.
This has long been confirmed in animal experiments.
The hippocampus – the center of learning and memory – proved to be particularly susceptible to sugar cravings. In a 2012 study by the University of California in Los Angeles, rats were given a 15% fructose solution mixed with sugar from soft drinks, cereal bars, and fruit yogurts to drink for six weeks. The result: the animals showed a significant decline in learning ability and spatial orientation; they were no longer able to find their way out of a maze they had previously known. Synaptic activity in the brain was significantly reduced. (2) “Sugar affects the brain’s ability to process and store information,” says study leader Dr. Fernando Gomez-Pinilla.
Significantly, the negative effects could not be attributed to obesity or diabetes, but were caused directly by the sugar, even in rats of normal weight. Younger animals were particularly susceptible to cognitive impairment.
Calorie-free sweeteners proved to be no less problematic. In a study conducted by the University of Southern California in 2022, adolescent rats were fed saccharin, ACE-K, or stevia. They also showed long-term memory impairment and altered glucose metabolism.
Neuroscientists at Princeton University were able to demonstrate similar brain changes in sugar-addicted rats as in morphine addicts: a reduction in dopamine receptors, withdrawal symptoms, and loss of control.
IQ destroyer: Sugar doesn’t just dumb down lab mice
But can the results of animal experiments be readily transferred to humans?
Dozens of human studies now confirm that excessive sugar consumption also leads to neuroinflammation, oxidative stress, and increased susceptibility to cognitive and mental disorders in humans. (2)
As a meta-analysis of 77 human studies with a total of over 17,000 participants found in 2023, without exception, all of them found a clear link between the consumption of added sugar and an increased risk of cognitive impairment: Short- and long-term memory, attention, mental flexibility, concentration, spatial navigation, and so-called “executive functions” were all affected: planning, organizing, and following processes and instructions. High sugar consumption during pregnancy proved to be particularly harmful in the long term—even more so for the child than for the mother. The brain’s “neural plasticity” was reduced: its ability to adapt structurally and functionally. This disrupts learning processes and development in particular.
The memory area of the brain – the hippocampus – is also particularly affected in humans, as is the ability to process stimuli and adapt in the prefrontal cortex, not least in seniors, but also in all previous age groups. In a highly regarded long-term study, researchers analyzed the eating habits of more than 1,000 children. Children with high sugar consumption – especially in the form of soft drinks – performed significantly worse in intelligence tests.
The famous “Whitehall II Study,” which involved over 10,000 British civil servants, showed that people with the highest sugar consumption had up to a 23 percent higher risk of dementia, regardless of their body weight.
Even slightly elevated blood sugar levels reduce memory performance and disrupt glucose utilization in brain cells; the hippocampus shrinks.
A Harvard study found that people with consistently high blood sugar had measurably poorer memory performance — long before they developed symptoms of diabetes. MRI scans showed reduced blood flow and structural changes in the brain.
A study published in China in 2023 demonstrated a direct link between sugar consumption, insulin resistance in the brain, and the loss of gray matter.
Several studies have consistently shown that high sugar consumption reduces cognitive performance and causes the notorious brain fog – with concentration and memory problems and a feeling of being dazed or “foggy” in the head.
What a “diet tip” from the 1960s: “Eat lots of sugar – it helps you lose weight because it curbs your appetite.” Whose brain is more damaged by sugar: that of the advertising copywriter or that of the consumer who falls for it?
The sugar-sweet path to Alzheimer’s
It is not only ridiculous but downright despicable to tell residents of nursing homes that they can and should prevent dementia by staying “mentally active” (3), for example, by playing board games (4), solving crossword puzzles (5), and engaging in other mental exercises. At the same time, their food trays are filled with hidden sugar, from white flour bread and cold cuts to colored fruit-flavored drinks, cookies, fruit yogurts, and puddings. With all due respect, such cost-optimized food amounts to culinary stupefaction and euthanasia—and that for a monthly personal contribution of over $3,000 per nursing home place.
Those responsible for this are ultimately contributing to the destruction of mental health. (Psychotropic drugs and other medications administered – an average of 9.3 per nursing home resident – do the rest.) Every nursing home management team should know that high sugar consumption can promote processes that increase the risk of Alzheimer’s and other forms of dementia in several ways. (6) This is not just a matter of “empty calories,” but of profound effects on blood sugar, insulin, blood vessels, inflammation, and nerve cells (7):
1. Insulin resistance (“type 3 diabetes”) develops in the brain. Long-term high sugar consumption causes the pancreas to produce more insulin, to which the brain cells respond less and less effectively. Insulin is not only responsible for sugar metabolism, but is also important for signal transmission between neurons and memory formation. If the brain becomes insulin-resistant, nerve cells are less able to use energy – they “starve” even though there is enough sugar available.
2. Free radicals form in greater quantities in brain membranes: these are highly reactive molecules that cause oxidative stress. They attack fats, which are also found in the membranes of nerve cells. This slows down communication between cells and can even block it completely.
3. Too much sugar contributes to the formation and accumulation of beta-amyloid and tau proteins, both of which are typical signs of Alzheimer’s disease. Animal studies show that rats on a high-sugar diet had more amyloid plaques and memory problems.
4. A diet high in sugar promotes arteriosclerosis and microangiopathy: damage to small blood vessels. The brain is less well supplied with blood, and nerve cells receive less oxygen and nutrients. Vascular damage exacerbates Alzheimer’s symptoms and accelerates its progression.
5. More AGEs (advanced glycation end products) are formed: harmful substances that arise when sugar molecules permanently bind to proteins, fats, or genetic material. AGEs accumulate in tissues, making them inelastic, activating the immune system, and causing low-grade chronic inflammation, which promotes the breakdown of nerve cells in the brain.
6. Excess sugar can damage the “powerhouses” of cells: the mitochondria. Nerve cells are particularly dependent on a stable energy supply – mitochondrial stress accelerates functional decline.
Sugar: The insidious psychological terrorist
Sugar not only manipulates thought processes – it also influences our emotions. Studies show that excessive sugar consumption leads to a worse mood in the long term, makes us irritable, and is associated with an increased risk of depression, anxiety, and aggression. (8)
A large-scale longitudinal study, the EU-funded MOODFOOD project, involving over 10,000 people found that men who consumed more than 67 g of sugar per day — the equivalent of two cans of cola — had a 23% higher risk of developing a mental illness such as depression within five years. The study ruled out that existing depression led to more sugar consumption.
It gets on our nerves
Sugar is not a harmless treat, but a creeping saboteur of our mental health. While it pleases our taste buds, it ruins our brains. Pediatrician and neuroendocrinologist Robert Lustig, professor at the University of California in San Francisco and one of the world’s most prominent critics of sugar, sums it up: “Sugar is not just a calorie source – it is an endocrine disruptor, a neurotoxin, and an addictive substance.”
Most consumers seem to be well aware of how unhealthy this sweet poison is. Only 4.7% consider table sugar to be healthy. 86% of those surveyed believe that sugar consumption in today’s diet is too high. The gap between knowledge and action is alarming. Changing behavior requires more than just information – especially when it comes to junkies. A veritable mafia of incompetent politicians, unscrupulous industry bosses, their lobbyists and PR professionals, corrupt scientists, doctors and media professionals ensures that the necessary education is largely absent. Because only sick people benefit the healthcare industry; they alone secure growth markets. (9)
Can the damage done be repaired?
Some of the damage that sugar causes to the brain can be partially reversed, especially if consumption is reduced in time and healthy lifestyle habits are maintained. The amazing “neural plasticity” of the brain allows synapses to adapt and even damaged brain cells in certain regions, especially in the hippocampus, to regenerate once the harmful influence disappears. (10) Even an eight-week change in diet can alter neural circuits and normalize the reward centers in the brain. (11)
It becomes more difficult if the risk of diabetes is already significantly increased or functional losses such as dementia are already pronounced: in these cases, some damage — vascular deposits, advanced neurodegeneration — is no longer fully reversible. Nevertheless, reducing sugar can slow down the progression and stabilize individual brain functions. (12)
“Reduce to zero”?
One thing is certain: if you want to do something good for your brain, you need to use willpower to leave sugar where it tempts you – in the bakery window, on the supermarket shelf. Not in your breakfast, not in your yogurt, not in your liver, not in your blood – and certainly not in your brain.
“How much should we reduce our sugar consumption?” neurologist Dale Bredesen, a world-renowned Alzheimer’s expert, was recently asked in an interview. “How much is still safe?” Bredesen’s answer was uncompromising: “Let’s reduce it to zero. Because we don’t need it.”
Robert Lustig doesn’t see it quite so strictly: “A little bit is no problem.” He himself snacks on dark chocolate “every now and then,” treats himself to “a dessert after dinner twice a year,” and sometimes a piece of cheesecake. But that’s it for him. Because “a lot of it kills – slowly.” (13)
He is referring to the pure white crystalline powder used in the food industry: pure sugar. Nature doesn’t know it. But what about the sugar that nature itself provides us with: in fruit, vegetables, milk, and dairy products? Per 100 grams, apples and pears contain 10 to 12 g, bananas 12 to 17 g, grapes 16 to 18 g, and fresh dates up to 35 g. Peas, carrots, beetroot, onions contain 3 to 7 g, natural yogurt, kefir,and cow’s milk still contain 3 to 4 g.
“Natural” does not mean “low in sugar” – but in nature, sugar always occurs in valuable combination with fiber, bitter substances, enzymes, vitamins, and polyphenols. And we should not do without it – but we should consume it in moderation.
This is because, in human studies, natural sources of fructose from fruit have even had a positive effect on cognition in some cases. The “matrix” of fiber and nutrients causes our body to metabolize fructose more slowly and not immediately process it in the liver, as is the case with isolated industrial sugar. This prevents negative effects on the brain and cognition. Epidemiological studies suggest that a high fruit and vegetable intake is even associated with a reduced incidence of Alzheimer’s disease and better cognitive health. (14)
Therefore, demonizing sugar across the board demonstrates a glaring lack of knowledge. Over the course of evolution, our brains were only able to develop to such a complex level because nature provided us with sugar, an extremely effective fuel. As the purest of all energy sources, sugar benefits our bodies in many metabolic processes.
And so this article ends with good news: not by completely abstaining from sugar, but by consuming the right sugars—directly from natural sources or broken down through cooking—we can stop cell aging, protect our blood vessels, activate fat burning, and keep our brains fit. (15)
A wise Chinese proverb says: “The best time to plant a tree was twenty years ago. The second best time is now.” It’s never too late to become what you could have been. Healthier, for example.
Notes
(1) https://www.uclahealth.org/news/release/high-fructose-diet-sabotages-learning-memory?utm_; https://www.livescience.com/20329-sugar-stupid.html?utm_
(2) https://pmc.ncbi.nlm.nih.gov/articles/PMC9323357/, https://www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626, https://pmc.ncbi.nlm.nih.gov/articles/PMC9471313/
(3) Weltgesundheitsorganisation (2019): “Risk reduction of cognitive decline and dementia: WHO guidelines”; G. Livingston u.a.: „Dementia prevention, intervention, and care: 2020 report of the Lancet Commission“, The Lancet 396/2020, S. 413-446; NHS: „How to reduce your risk of dementia“.
(4) National Institute on Aging: „Preventing Alzheimer’s Disease: What Do We Know?“
(5) https://www.medicalnewstoday.com/articles/do-reading-puzzles-and-similar-activities-really-stave-off-dementia; https://www.scinexx.de/news/biowissen/kreuzwortraetsel-verlangsamen-gedaechtnisverlust/
(6) S.M. de la Monte/J.R. Wands, J. R. (2008): „Alzheimer’s disease is type 3 diabetes–evidence reviewed“, Journal of Diabetes Science and Technology (6), 1101–1113; P.K. Crane u.a. (2013): „Glucose levels and risk of dementia“, New England Journal of Medicine, 369, 540–548; S.E.Arnold u.a. (2018): „Brain insulin resistance in type 2 diabetes and Alzheimer disease“, Alzheimer’s & Dementia, 14(7), 801–815, https://doi.org/10.1016/j.jalz.2018.01.011; https://menschen-mit-diabetes.de/ratgeber/diabetes-typ-3
(7) https://www.brain-effect.com/magazin/zucker-leistungsfaehigkeit; https://www.ukr.de/newsroom/detail/ist-weniger-zucker-besser-fuer-unser-gehirn; https://www.mpg.de/20023125/0320-neur-suessigkeiten-veraendern-unser-gehirn-153735-x; https://www.ndr.de/ratgeber/gesundheit/Studie-zeigt-Zucker-und-Fette-veraendern-das-Gehirn,zucker684.html; https://www.tagesschau.de/wissen/gesundheit/zucker-gehirn-100.html
(8) https://www.helmholtz.de/newsroom/artikel/loest-zucker-depressionen-aus/; https://www.zentrum-der-gesundheit.de/news/gesundheit/allgemein-gesundheit/zucker-depressionen
(9) Hans-Ulrich Grimm: Garantiert gesundheitsgefährdend – Wie uns die Zucker-Mafia krank macht, München 2013.
(10) https://www.ukr.de/newsroom/detail/ist-weniger-zucker-besser-fuer-unser-gehirn; https://hirnstiftung.org/2025/04/zu-viel-zucker-versalzt-die-hirngesundheit/; https://www.deutschlandfunk.de/zucker-adipositas-diabetes-zuckersteuer-100.html; https://www.sf.mpg.de/2078461/Wie-beeinflusst-Zucker-unser-Gehirn; https://www.ndr.de/ratgeber/gesundheit/Studie-zeigt-Zucker-und-Fette-veraendern-das-Gehirn,zucker684.html
(11) https://www.sf.mpg.de/2078461/Wie-beeinflusst-Zucker-unser-Gehirn, https://www.mpg.de/20023125/0320-neur-suessigkeiten-veraendern-unser-gehirn-153735-x
(12) https://www.dgn.org/artikel/world-brain-day-2024-zu-viel-zucker-versalzt-die-hirngesundheit; https://hirnstiftung.org/2025/04/zu-viel-zucker-versalzt-die-hirngesundheit/
(13) In Hans-Ulrich Grimm: Garantiert gesundheitsgefährdend, a.a.O., S. 11, 13.
(14) TF Hughes u.a.: „Midlife fruit and vegetable consumption and risk of dementia in later life in Swedish twins“, American Journal of Geriatric Psychiatry 18 (5) 2010, S. 413-420, doi:10.1097/JGP.0b013e3181c65250; Paul T. Williams: „Lower Risk of Alzheimer’s Disease Mortality with Exercise, Statin, and Fruit Intake“, Journal of Alzheimer’s Disease 44 (4) 2015, S. 1121 – 1129.
(15) See Johannes Coy: Fit mit Zucker (2019).