Newsletter #127: The Impact of the Mind on Glycemic Response 🧃🧠
Welcome to the latest edition of the humanOS newsletter!
This week, we learned that a supplement made from a by-product of olive oil production can significantly improve cardiovascular risk factors; people who report insomnia and get less than six hours of sleep per night may be at greater risk of cognitive impairment compared to good sleepers; surgical masks are effective at reducing aerosol generation but may not work as well when performing very intense exercise indoors.
Finally, here is a weird one: the glycemic response of people with type 2 diabetes is influenced by how much sugar they think that they are consuming. This reminds me of a study from a few years ago which showed that subjects who thought that they were drinking a high-calorie milkshake showed differences in levels of ghrelin (a gut peptide linked to satiety) compared to counterparts who thought that they were given a low-calorie milkshake - despite the fact that both milkshakes were exactly the same. The impact of psychological factors on physiological responses to food is pretty intriguing, and something that we probably need to explore further.
Scroll down for more info, and please stay safe everyone. 👇
This Week’s Research Highlights
🥤 Glucose metabolism appears to respond to perceived sugar intake more than actual sugar intake in type 2 diabetics.
Researchers recruited 30 subjects with type 2 diabetes. They presented the study as a “Beverage Tasting Study for Diabetes,” stating that the authors were interested in “the effects of specially designed beverages on the body's reaction and cognitive functioning among people with type 2 diabetes.”
Subjects visited the lab on two separate occasions, with a three-day interval between visits. At each session, participants were randomized to consume one of two beverages. One was labelled as “Low Sugar,” and one as “High Sugar,” as shown below. However, in actuality, both drinks were exactly the same (15 grams of sugar per container).
After participants finished the beverages, the researchers measured blood glucose levels three times at 20-min intervals. Remarkably, blood sugar levels were significantly higher after drinking the “High Sugar” beverage than the “Low Sugar” counterpart - despite actually containing the exact same amount of sugar! Blood glucose values aligned more with the subjective expectations of the participants than with actual sugar intake.
💊 An olive by-product improves cardiovascular risk factors.
Researchers obtained a by-product of olive oil production, generated during the milling process, known as olive pâté. Nineteen participants took four tablets per day of either pâté (containing 30 mg total of hydroxytyrosol), or a placebo for two months. This was followed by a two-month washout period, then another two months of crossed-over treatment (in other words, all participants experienced both placebo and intervention over the course of the study). After consuming the pâté for two months, participants showed a significant reduction in plasma levels of LDL cholesterol (–10.8 mg/dL) and urea (–4.1 mg/dL). Leukocyte response to exogenous oxidative stress was reduced (–12.8%) and levels of the antioxidant transcription factor Nrf-2 increased by 88.9%. Plasma levels of the pro-inflammatory protein MCP-1 were significantly reduced (–9.0 pg/mL).
🧠 Insomnia combined with inadequate sleep is associated with a significantly greater risk of cognitive impairment.
Researchers analyzed data from the Penn State Adult Cohort, a population-based sample of 1741 adults who had one night of sleep measured in a laboratory. Additionally, the subjects completed a clinical history and physical exam and were evaluated for cognitive function with a battery of tests to assess attention, memory, language, etc. The researchers found that adults who reported insomnia and who slept less than six hours in the lab were two times more likely to have cognitive impairment. This association was particularly strong for those with co-existing cardiometabolic conditions. Importantly, people who experienced insomnia but who still managed to get six or more hours of sleep did not appear to show a greater risk of cognitive deficits compared to good sleepers.
😷 Intense exercise increases generation of aerosols - even when wearing a mask.
Researchers recruited four healthy adult volunteers and had them perform exercise at various intensities in a cardiopulmonary gym. They used a light scattering particle counter to measure particle counts and size distribution (0.3, 0.5, 1, 2, 5, 10 micrometers) at different locations in the gym before, during, and after staged incremental-intensity exercise. The subjects were assigned to train on either treadmill or recumbent cross-trainer for 30 minutes while wearing surgical masks. The exercise consisted of 3×10 minute stages: 1) light (heart rate increased to 113±18 bpm), 2) hard (heart rate increased to 144±15 bpm), and 3) very hard (heart rate increased to 168±15 bpm). The researchers determined that light exercise while wearing the mask did not result in an increase in particulate generation above baseline. There was a trend toward increasing particles with hard exercise. However, very hard exercise, akin to what many of us perform when we train at the gym, significantly increased levels of potentially infectious particles in sampled air around the athlete. If you are trying to avoid catching or transmitting COVID-19, training indoors with other people may not be a great idea, even when adhering to standard public health mitigation measures.
Podcasts We Loved This Week
- Sarah Zhang: The Race For A COVID-19 Vaccine Heats Up. Via Science Friday.
- Stephen W. Porges: The Neurophysiology of Safety and How to Feel Safe. Via Nourish Balance Thrive.
- Alan Flanagan: Problems with the Meta-analysis in Nutrition. Via Sigma Nutrition Radio.
Products We Are Enjoying
Celestial Seasonings White Chocolate White Tea
I stumbled upon this tea at the grocery store last week and was pleasantly surprised by it. It’s a blend of peppermint, chocolate flavor, and white tea. White tea is made from Camellia sinensis (same as green and black tea), but it has a more mild flavor because the leaves are picked before they are fully open and developed. It doesn’t appear to have been studied as extensively as the more common varieties, but it is high in catechins like green tea, and consequently is likely to confer similar health benefits. This particular blend is very tasty - would make a good healthy treat on a cold day. I would suggest letting it steep for a couple of minutes, then adding a little bit of cashew or oat milk (or whatever creamy beverage you like).
