Newsletter #199

Hello Friends!

Welcome to the latest edition of the humanOS newsletter! Below, as usual, is a roundup of the various studies and other media that we came across. 🤓

This week, we learned that people who exercise regularly (just a little bit more than standard physical activity guidelines) are less likely to become depressed; getting 10000 steps per day can improve blood pressure and blood sugar at a level comparable to pharmaceutical drugs; eating a cup of blueberries with breakfast can make you smarter; selenium deficiency is connected to COVID-19 severity and mortality; and air pollution is correlated with body mass. Scroll down to learn more, and stay safe everyone. 👇

Researchers recruited 937 individuals in Brazil who were self-isolating during the COVID-19 pandemic. Participants were asked questions about how much time they spent on various intensities of physical activity, as well as sedentary behavior, and symptoms of depression and anxiety were assessed using validated inventories. They found that subjects who reported ≥30 minutes in moderate activity per day were ~30% less likely to present symptoms of depression/anxiety. Those reporting ≥15 minutes of vigorous activity were ~40% less likely to present such symptoms. Furthermore, individuals who spent ≥10 hours/day sedentary were more likely to have depressive symptoms.

Thirty-five healthy overweight participants who were sedentary at baseline (average ~4500 steps per day) were given pedometers and instructed to achieve at least 10000 steps per day. At the end of the intervention (twelve weeks), the subjects showed an average reduction in systolic blood pressure of 13.74 mmHG (going from pre-hypertensive to within the normal range) and an average drop in fasting blood glucose of 14.89 mg/dL.

In a randomized, double-blind, crossover design, thirty-five middle-aged participants consumed a meal with either a drink made with 35 grams of freeze-dried blueberries (equivalent to a cup of fresh fruit) or a matched placebo beverage on two different occasions. Participants completed cognitive tasks and had blood drawn before and at regular intervals for 8 hours after each meal/treatment. Subjects consuming the blueberry beverage showed improved cognitive performance, compared to placebo, particularly in tasks that were cognitively demanding and that were likely to induce mental fatigue. Additionally, subjects had lower postprandial blood sugar and insulin levels, compared to when consuming the placebo drink.

Researchers conducted a systematic review and meta-analysis to evaluate the effect of long-term exposure to ambient air pollutants on body weight status in adults. Three databases were searched for articles investigating the association of gaseous and particulate air pollutants with body weight status. They found that elevations in NO2, SO2, and O3 were found to increase risk of overweight/obesity by 13%, 4%, and 7% respectively per 10 μg/m3 increment.

Researchers analyzed 166 serum samples from 33 COVID-19 patients for total selenium, and compared them to reference data from a large European cross-sectional analysis of healthy individuals. As expected, they found that these patients showed a pronounced deficit in total serum selenium in comparison to healthy controls. Selenium status below the 2.5th percentile of the reference population was present in around 40% of COVID samples. Selenium status was also significantly higher in samples from surviving COVID patients, compared to non-survivors.

As we described above, observational evidence has linked selenium deficiency to COVID-19 morbidity and mortality. This does not mean, of course, that they are causally related, but I think it makes sense to ensure that you are getting enough of the mineral just to be safe. Eating just one Brazil nut per day is probably the most efficient way to meet your selenium requirements, and it’s actually pretty cheap over the long haul if you buy a big bag. And they may have other benefits as well. This study, for instance, found that consuming just a single dose of 20 or 50 grams of Brazil nuts substantially improved the lipid profile (LDL-C dropped by around 20 mg/dL, which is insane). It is worth noting that the safe upper limit for selenium is 400 mcg daily, which you can exceed with just a few kernels of Brazil nuts, so you probably don’t really want to eat more than a couple per day.

https://mailchi.mp/humanos.me/newsletter-199