Newsletter #200

We all like to hear good things about our favorite foods, right? However, the findings in this area are actually fairly impressive, even setting aside hedonic biases.

To summarize, cocoa flavanols seem to improve cognition in two major ways:

First of all, flavanols acutely improve vascular function and blood flow to the brain. This, in turn, results in short-term improvements in learning, memory, and other domains of cognition, which usually peak around two hours after consumption (this boost closely corresponds with increases in cerebral blood flow).

But consuming cocoa flavanols chronically - like over the course of weeks or months - also leads to longer-term changes in brain function. This is because flavanols have been shown to increase levels of brain-derived neurotrophic factor (BDNF), a protein that helps brain cells grow and connect to one another, and is essential for learning and long-term memory. And all of this, together, may also help preserve brain function over the aging process, which is pretty awesome. Worth noting, you probably need to use highly concentrated sources of cocoa in order to reliably reap these benefits, although some observational research suggests that smaller doses, like one or two servings of chocolate per week, are linked to improvements as well.

To learn more about the short- and long-term effects of cocoa flavanols on your brain, scroll on down 👇🏼

Researchers recruited 18 healthy adults and tested them in two different conditions: one in which they received flavanol-rich cocoa, and another in which they consumed a processed form of cocoa with negligible amounts of flavanols. Two hours after consuming the cocoa, the participants breathed air with 5% carbon dioxide - around 100 times as much as we normally experience. This is a standard procedure to challenge brain vasculature, and normally elicits an increase in blood flow to the brain to help clear the CO2. The researchers tracked changes in brain oxygenation levels, and had the participants complete a series of cognitive tests. The scientists found that when the participants were consuming the flavanols, they showed more efficient tissue oxygenation in the frontal cortex, a part of the brain that is important in planning and decision-making. Levels of maximal oxygenation were more than three times higher when the subjects consumed the flavanol-enriched beverage, and the oxygenation response was about a minute faster. This resulted in better performance on the most challenging cognitive tests, correctly solving these problems 11% faster than at baseline or while drinking the flavanol-depleted cocoa.

Thirty-two healthy participants visited the lab on four occasions, during which they underwent testing on various cardiovascular parameters and cognitive skills. On two of these sessions, they had a full night of sleep, and on the other two they came in after a night of total sleep deprivation. Two hours before each session, they were randomly assigned to consume a chocolate bar that was devised to be either high or low in cocoa flavanols. Sleep deprivation generally resulted in higher blood pressure, poorer flow-mediated dilation, and poorer performance on memory tests. However, compared to the low-flavanol group, subjects who ate the high-flavanol chocolate showed lower blood pressure (116.9 vs. 120.8 mmHg SBP), and prevented the impairment in flow-mediated dilation. Finally, flavanol-rich chocolate preserved working memory accuracy. Flow-mediated dilation was associated with memory performance, suggesting that blood flow to the brain may have mediated the cognitive improvements linked to the flavanols.

Researchers recruited 40 healthy older adults and had them consumed either a high a high-flavanol cocoa drink (494 mg total flavanols) or a low-flavanol cocoa drink (23 mg total flavanols) for 12 weeks. In comparison to the low-flavanol group, the participants who drank the high-flavanol cocoa beverage showed significant improvements in global cognition scores, as well as higher levels of BDNF. Notably, increases in serum BDNF were also correlated with improvements in cognitive performance, suggesting that changes in levels of BDNF likely underpin the observed benefits of chronic chocolate consumption on memory and other aspects of cognition.

Researchers at Columbia University Medical Center recruited 37 healthy older adults and randomly assigned them to consume either a high cocoa flavanol drink, or an otherwise similar drink that was engineered to be extremely low in flavanols. Subjects consumed the beverages for three months, and brain imaging and memory tests were performed both before and after the study. Individuals consuming the high cocoa flavanol drink showed improvements in the function of a part of the brain called the dentate gyrus. The dentate gyrus is a region of the hippocampus that tends to decline with age, and this is thought to be a source of age-related memory deterioration. Remarkably, the high-flavanol group also showed an improvement on the memory test equivalent to turning back the clock three decades. In other words, "If a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old," according to senior author Scott Small. Caveat: This study was partly funded by Mars. Doesn't necessarily invalidate the findings but always worth noting.

This is due to an inherited reflex condition that causes sneezing in response to certain intense stimuli, including chocolate but also bright lights.

It has been dubbed, aptly, the ‘ACHOO syndrome’ - Autosomal Dominant Compelling Helio-Ophthalmic Outburst .

This week, we’d like to highlight one of the courses from the Ideal Weight Program - developed by our good friend Stephan Guyenet. Adiposity (from Latin adeps, meaning fat) is simply a scientific term for body fatness. According to the CDC, around 40% of Americans are classified as obese, and the situation isn’t rosy around the rest of the world either. The causes of obesity are pretty readily identified. And we are actually able to reliably reduce body fat - in the short term. But long term fat loss is extremely elusive. Why is that?

In this course, Stephan describes the various ways that adiposity is measured, and how we know that excess fatness contributes to poorer health. He also discusses different approaches to reducing body fat, and why the most common (and intuitive) way that people are apt to go about it is effective, but largely unsustainable. Finally, Stephan lays out a six-pronged plan for fat loss, so that your natural impulses are aligned with your goals, and you don’t have to rely upon willpower to achieve (and more importantly maintain) your ideal body mass. Check it out!

And as always, thanks for reading! I kind of can't believe that we've churned out 200 of these newsletters (although to be fair I'm not totally sure if I've got the numbering totally right 😆).

If you're looking for more juicy health research (and occasionally random science or memes), be sure to visit with us on Twitter on @humanOS_me.

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