The Sugar High Might Be a Myth

That afternoon treat might not improve your mood, and could make you more tired within the first hour of eating it.
Woman with red finger nails biting into a sugar donut

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The sugar rush is probably a myth

Sometimes during an afternoon slump, it’s tempting to reach for something sweet as a pick-me-up, in an attempt to get a sugar rush.

A sugar rush is the popular trope that eating sugar can lead to feeling less tired, and almost buzzed, from the sugar high, Konstantinos Mantantzis, a biological psychologist at Humboldt University of Berlin, says. “This notion can be traced back to studies suggesting that consumption of carbohydrates can make children hyperactive, an association that has been debunked in the past.” Mantantzis says that our idea of the sugar rush still persists, even though its legitimacy is questionable.


In a new meta-analysis in Neuroscience & Biobehavioral Reviews, Mantantzis and his colleagues looked at the effects of carbohydrate, or sugar, consumption on mood and combined the results together. They found that sugar consumption doesn’t improve any aspect of mood, and further, that sugar might make people less alert and more tired within the first hour after consuming it—the crash but without the rush.

“We are hoping that our results will go a long way to dispel the 'sugar rush' myth, a myth that has been very resistant to scientific evidence speaking against it,” Mantantzis tells me. “We already know that high sugar consumption can be detrimental to health, and now it seems that these negative effects might also spread to mood. Reducing sugar consumption might be an important step towards improved mood and overall well-being.”

I ask if it is possible that when people eat sugar, there are other factors that lead to the sugar rush—when I eat sweets, I’m often with friends, at the end of a meal with family, or celebrating something.

“It is possible that sugar consumption might often coincide with people spending time with friends and performing fun activities,” Mantantzis says. “The mood improvement in that case might be associated with the social or fun aspect of the activity rather than the consumption of sugar itself. This is something that future studies should investigate. Nevertheless, when it comes to sugar consumption in controlled laboratory settings, it looks like it might even lead to negative mood outcomes. “


Can a keto diet help people with schizophrenia?

A compelling new paper in the journal Schizophrenia Research reported two cases in which patients with schizophrenia who were able to go off of their antipsychotic medications after being treated with a keto diet. A strict keto diet results in the body using ketones, and not glucose, as a fuel source, and could be influencing a number of factors in the brain, like neurotransmitters, possible leading to the alleviation of symptoms, the paper says.

The keto diet has previously shown to reduce how often people with epilepsy have seizures— a Cochrane review found that the diet showed “promising results” for epilepsy, but also that there were a limited number of studies, small sample sizes, and that there could be adverse effects from having a keto diet as well, from “gastrointestinal‐related disturbances, to longer‐term cardiovascular complications.”

The new research recounted the cases of two women. Patient A is an 82-year-old woman who was diagnosed with schizophrenia at age 17. “Her symptoms included chronic paranoia, disorganized speech, and both visual and auditory hallucinations—seeing skeletons and hearing voices on a daily basis,” the study says.

She had tried many antipsychotic and mood stabilizing medications, and was still taking six drugs when, at age 70, she began a keto diet to lose weight. Within two weeks, the study reports, her psychotic symptoms reduced and over the next several months, she stopped taking all of her medications. “Her mood improved dramatically, and she no longer had suicidal thoughts,” the paper says. “Her hallucinations and paranoia remitted completely. She remains on the ketogenic diet today and has lost a total of 150 lb.” She is still not taking medications, and no longer needs a guardian.


Patient B in the study is 39, and was diagnosed with schizophrenia in 2003. She started a keto diet in 2013, stopped taking all of her many medications, and had to be hospitalized for psychosis, but continued the diet in the hospital. “Within one month, she reported complete resolution of her psychotic symptoms for the first time since 1993,” the paper says.

There are many theories as to how a keto diet might help psychiatric disorders like schizophrenia, first author and assistant professor in psychiatry at Harvard Medical School, Chris Palmer explains. Some people with schizophrenia have insulin resistance, which takes place in the brain as well, “making it likely that the brain cells aren’t getting enough energy/fuel from glucose, because it can’t get into the cells,” he says. Switching the energy source to ketones could re-provide the brain the energy it was lacking. Additionally, the keto diet has been shown to change neurotransmitter levels, which could play a role in psychiatric disorders.

“It also decreases inflammation, which has also been found to be elevated in psychiatric disorders,” Palmer says. He also mentions the microbiome. There is increasing evidence that the microbiome might be involved in many psychiatric disorders, including schizophrenia, but also depression and anxiety. The keto diet could be making changes to the microbiome that positively impact psychiatric or neurological symptoms.


Still, despite the success in these two case studies, a lot more work will have to be done to see if a keto diet’s benefits extend to more people, and to fully elucidate the mechanisms by which the keto diet could help alleviate schizophrenia symptoms. Palmer says that at this point it’s not clear if all schizophrenia patients would benefit from the diet, or if it’s just a subset of patients that do.

“At this point, no one knows for sure what causes schizophrenia, and some researchers think that there are probably many causes of this disorder,” he tells me. “Given this uncertainty, I think it is unlikely that one single treatment such as the [keto diet] will help everyone with the disorder. Some people may respond to the diet, and others might not, just like with every other treatment we have in psychiatry…this new line of research will hopefully lead to novel and unique ways to treat these serious disorders, because sadly for so many people, our current treatments don’t work well for them.”

People associate certain colors to vowels

People with synesthesia get their wires crossed when it comes to the senses: colors can have smells, or numbers can have colors, sounds can have visuals attached to them. But previous research has shown that all people, not just synesthetes, make associations across sensory domains, meaning we all ascribe certain sounds to objects, or colors to letters or numbers, even if we don’t see or hear them literally—and that we often have the same associations as one another.


In a new study in Behavior Research Methods, researchers wanted to see if that held true in a larger sample size of people, and asked more than a thousand people to take an online test where they chose colors for 16 spoken vowels.

They found that on the whole, people were more likely to find vowel sounds to be of a certain color. “People are more likely to find the vowel sound in b ee t to be yellower, while the vowel in b oo t is darker and bluer,” Christine Cuskley, Lecturer in Language and Cognition at Newcastle University, and study first author tells me.

Color and vowel associations for people with and without synesthesia

Vowel-color associations in two non-synesthete subjects (left) and in two synesthetes (right). Credit: Mark Dingemanse / Radboud University

A majority also felt that “aa” as in baa was more red than green, and that “ee” as in beet was more light than dark. “There seems to be a logic to how we link sound and color, and the structure of language has an important role in this process,” says co-author Mark Dingemanse in a statement.

Even when people weren’t making the same exact color choices, almost 70 percent of people made associations that were ‘structured,” meaning “they are mapping colour space and vowel space together, even if they're doing it in slightly different ways,” Cuskley says.

(You can see and interact with each person’s color, vowel associations here.)

So why do people think of vowels as being similar colors? Some experimental work suggests that these associating colors and words helps us to learn language, and other work has also suggested that these associations might have been important in language evolution, Cuskley says.


And in earlier work, study co-author Tessa van Leeuwen examined the brain areas involved in letter-colour synaesthesia, including the area processing visual letter shape and the area that processes colour. For synaesthetes, during the process of learning letters, the colour becomes associated with the letter and the letter area and the colour area in the brain show extra connections to each other, which doesn’t take place for non-synaesthetes.

“It is now interesting to see that the structure of underlying associations of color to spoken vowels is very similar across synesthetes and non-synesthetes, suggesting that exactly which color gets associated to which letter in synesthetes may be driven by principles shared by all of us,” Cuskley says.

Your weekly science and health reads

Black hole image revealed for first time ever. By Dennis Overbye in The New York Times. In case you missed this, we finally got to see what a black hole looks like! Even if you already saw the image, don’t miss veteran space writer, Dennis Overbye’s, descriptions: “It is a smoke ring framing a one-way portal to eternity.”

What Remains: For the past 148 years, Yosemite’s Lyell Glacier has taught us about the Earth — how it was created, where it was going, and now, how it might end. By Daniel Duane in The California Sunday Magazine.
The last days of a glacier, and what it means about our planet.

Tiny bees are not the worst creature to get stuck in your eye. By Haley Weiss in The Atlantic.
“Last week, Taiwan’s CTS news channel reported that a 29-year-old woman had gone out for a walk in the mountains and returned home with eye pain that wouldn’t go away. The next day, an ophthalmologist pulled four bees—all still alive—from under her right eyelid.”

A mysterious infection, spanning the globe in a climate of secrecy. By Matt Richtel and Andrew Jacobs in The New York Times.
A terrifying story about a drug-resistant fungus: “The man at Mount Sinai died after 90 days in the hospital, but C. auris did not. Tests showed it was everywhere in his room, so invasive that the hospital needed special cleaning equipment and had to rip out some of the ceiling and floor tiles to eradicate it.”

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