How Does Consuming Glucose Affect Your Memory?
While many people believe sugar makes kids hyperactive, this theory has long been debunked by research. However researchers are only just beginning to understand the complex relationship between glucose and learning.
Earlier this year on this blog, we debunked the widely believed myth that sugar causes hyperactivity in children. But could it be possible that under certain specific circumstances, sugar actually helps with learning? In this blog post we'll attempt to tackle that question.
It makes logical sense that sugar could cause hyperactivity due to the fact that glucose is the brain's number one source of fuel. The reason sugar does not cause hyperactivity is that the human body is very good at regulating the amount of glucose in our blood. This fact has been confirmed by numerous double-blind, placebo controlled, randomized controlled trials. There is however a growing body of evidence to suggest the existence of a "glucose memory facilitation effect" in which consuming glucose may aid the formation of new memories.
A review of the literature published in 2011 concluded that there is robust evidence that glucose has an important effect on cognitive performance. In a recent article for The Psychologist, the co-author of the literature review, Michael Smith, looked at what this means in practical terms. Smith, inspired by the fact that among adolescents, only 40 percent of boys and 30 percent of girls eat breakfast decided to research the effects of glucose on learning in quite some depth. We've known for some time that in older people or individuals with impaired memories, consuming glucose can bring cognitive benefits — but the effects of glucose on young people have remained a controversial issue. The researchers found that compared to adolescents given a placebo, those given a glucose drink had improved memories for word lists after a period of 20 to 40 minutes, but the finding was only present in those adolescents whose bodies were efficient at processing the glucose. A later study by the same authors found that anxious adolescents' memories improved after consuming glucose, compared to a placebo.
Next the researchers looked at the glycaemia index (G.I.) of foods given to young people at breakfast. Previous research suggested that low G.I. foods (such as porridge) are linked to improved cognitive performance, but in these studies, the memory component required fairly low cognitive demand. When the researchers compared the effects of low G.I. foods (bran with milk) and high G.I. foods (cornflakes with milk) while testing the participants with harder memory problems, the young people performed better after the high G.I. meal.
These findings present a problem for anyone trying to send a straightforward public health message. While high G.I. foods contain high levels of sugar, which we all know is not good for anyone's health, high levels of glucose are clearly not a bad thing under all circumstances. It does seem that while low G.I. foods are key to the sustained attention necessary to get kids through the school day, when faced with a demanding task or high levels of anxiety, a well-timed dose of glucose can actually provide a boost to memory and cognitive performance for a short window of time.
Smith M.A., J. Anke M. van Eekelen & Jonathan K. Foster (2011). Glucose enhancement of human memory: A comprehensive research review of the glucose memory facilitation effect, Neuroscience , 35 (3) 770-783. DOI: http://dx.doi.org/10.1016/j.neubiorev.2010.09.008
Smith M.A. & Jonathan K. Foster (2008). Glucoregulatory and order effects on verbal episodic memory in healthy adolescents after oral glucose administration, Biological Psychology, 79 (2) 209-215. DOI: http://dx.doi.org/10.1016/j.biopsycho.2008.05.001
Smith M.A., H. L. Hii, J. K. Foster & J. van Eekelen (2009). Glucose enhancement of memory is modulated by trait anxiety in healthy adolescent males, Journal of Psychopharmacology, 25 (1) 60-70. DOI: http://dx.doi.org/10.1177/0269881109348164
Smith M.A. & Jonathan K. Foster (2008). The impact of a high versus a low glycaemic index breakfast cereal meal on verbal episodic memory in healthy adolescents, Nutritional Neuroscience, 11 (5) 219-227. DOI:http://dx.doi.org/10.1179/147683008x344110
Timlin M.T., M. A. Pereira, M. Story & D. Neumark-Sztainer (2008). Breakfast Eating and Weight Change in a 5-Year Prospective Analysis of Adolescents: Project EAT (Eating Among Teens), PEDIATRICS, 121 (3) e638-e645. DOI:http://dx.doi.org/10.1542/peds.2007-1035
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It's one of the most consistent patterns in the unviverse. What causes it?
- Spinning discs are everywhere – just look at our solar system, the rings of Saturn, and all the spiral galaxies in the universe.
- Spinning discs are the result of two things: The force of gravity and a phenomenon in physics called the conservation of angular momentum.
- Gravity brings matter together; the closer the matter gets, the more it accelerates – much like an ice skater who spins faster and faster the closer their arms get to their body. Then, this spinning cloud collapses due to up and down and diagonal collisions that cancel each other out until the only motion they have in common is the spin – and voila: A flat disc.
It turns out, that tattoo ink can travel throughout your body and settle in lymph nodes.
In the slightly macabre experiment to find out where tattoo ink travels to in the body, French and German researchers recently used synchrotron X-ray fluorescence in four "inked" human cadavers — as well as one without. The results of their 2017 study? Some of the tattoo ink apparently settled in lymph nodes.
Image from the study.
As the authors explain in the study — they hail from Ludwig Maximilian University of Munich, the European Synchrotron Radiation Facility, and the German Federal Institute for Risk Assessment — it would have been unethical to test this on live animals since those creatures would not be able to give permission to be tattooed.
Because of the prevalence of tattoos these days, the researchers wanted to find out if the ink could be harmful in some way.
"The increasing prevalence of tattoos provoked safety concerns with respect to particle distribution and effects inside the human body," they write.
It works like this: Since lymph nodes filter lymph, which is the fluid that carries white blood cells throughout the body in an effort to fight infections that are encountered, that is where some of the ink particles collect.
Image by authors of the study.
Titanium dioxide appears to be the thing that travels. It's a white tattoo ink pigment that's mixed with other colors all the time to control shades.
The study's authors will keep working on this in the meantime.
“In future experiments we will also look into the pigment and heavy metal burden of other, more distant internal organs and tissues in order to track any possible bio-distribution of tattoo ink ingredients throughout the body. The outcome of these investigations not only will be helpful in the assessment of the health risks associated with tattooing but also in the judgment of other exposures such as, e.g., the entrance of TiO2 nanoparticles present in cosmetics at the site of damaged skin."
Do you have a magnetic compass in your head?
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