HumanOS.me, Mill Valley, CA (2025)

04/22/2023

Hey friends, this week I came across a couple of new studies examining the effects of salt substitutes, which I was anxious to dive into since there hasn’t been a ton of research looking into these products.

Limiting salt intake seems like a generally smart move. It also happens to align with the pattern we tend to observe in hunter-gatherer populations, who consume far less sodium than industrialized people, and also have relatively low blood pressure even as they get older.

But omitting salt is hard, which is what makes salt substitutes an attractive option. They not only contain lower amounts of sodium, but they also partly replace that sodium with potassium, which may offer additional benefits.

Check out the newsletter to learn more: https://mailchi.mp/humanos.me/newsletter-259

04/15/2023

Depression is one of the most costly health conditions in the United States, and the situation does not seem to be getting a whole lot better.

The economic burden of major depressive disorder among U.S. adults was an estimated $236 billion in 2018, an increase of more than 35% since 2010. Much of this burden is not due to direct expenses of treatment, but the indirect toll that the disease takes on productivity (not to mention su***de).

Part of the problem, of course, is that treatments for depression just aren’t very good.

US clinical guidelines promote pharmacotherapy as the initial treatment approach. But as University of Michigan’s Elissa H. Patterson and Jay Kayser have discussed extensively, nearly 3 out of 4 people who use antidepressant medications fail to achieve remission from depression. Consequently, these individuals are deemed as having "treatment-resistant depression," which is pretty discouraging.

Meanwhile, lifestyle interventions, like physical activity, are characterized as "complementary alternative treatments." But a huge new review of more than a thousand studies suggests that exercise may actually elicit improvements in symptoms comparable to or even surpassing current available medications (plus added physical benefits). Which raises this question: should activity interventions actually be part of the first-line treatment for depression?

https://mailchi.mp/humanos.me/newsletter-258

04/08/2023

Does swimming increase appetite (and food intake)?

So, a little while ago, I was talking to an acquaintance who was trying to lose weight and had just joined my gym. The gym has an Olympic-sized pool, and he indicated that a major component of his fat loss plan involved swimming. I asked him how it was going, and he admitted that he was struggling, despite being committed to his pool sessions.

Actually, it might have been, in part, BECAUSE of them.

He said that he was absolutely ravenous as soon as he got home from the gym.

And he's far from the only person who has reported this. I've heard a number of people say that they're starving after going swimming.

But is this a real phenomenon? And does this mean that swimming is a worse choice for supporting fat loss?

I decided to dig through the literature and figure out what's going on. To find out what the research says, check out the newsletter!

NEWSLETTER: https://mailchi.mp/humanos.me/newsletter-257

04/01/2023

Videogames have been, in my view, unfairly maligned for decades, and recent neuroscience is slowly exonerating them.

For instance, a large study of more than 2200 children found that kids who reported playing videogames for more than 3 hours per day performed better on cognitive skill tests involving impulse control and working memory, compared to non-gamers. But even more impressively, playing videogames has been shown to have a lasting beneficial impact on cognition. Adults who were avid gamers in childhood were found to perform better in cognitive tests, despite not having played the games in years.

Now, there are a few reasons why this might be the case. Videogames involve problem-solving, working memory, motor skills, and (in some cases) teamwork. Interestingly, some researchers have suggested that videogames may also be functioning as a form of environmental enrichment for humans.

We've known for a long time that enriching the environment of laboratory animals with novel sights, sounds, smells, etc, to provoke sensory stimulation, engages their brain. This has been shown to enhance memory and neuroplasticity as well as shield the brain from age-related cognitive decline. (This is why zoos frequently introduce strange objects to their animals' otherwise static habitats.)

But of course, videogames vary tremendously in their capacity to stimulate our senses. If you've played games that were released within the past few years, you've probably noticed that the graphics are a major upgrade from games that you might have played when you were little. Modern 3-dimensional videogames are able to immerse players in a rich world, full of cool things to explore, and unique sights and sounds that are both highly realistic and hard to find in normal daily life. Think about, say, Tetris versus Call of Duty. Totally different experience, right?

So this raises a couple of questions. Can virtual environmental enrichment, through videogames, trigger improvements in cognition similar to what is seen in the animal literature? And accordingly, do more visually stimulating games, presenting the user with complex environments, have a greater impact on brainpower?

Check out the newsletter to learn more: https://mailchi.mp/humanos.me/newsletter-256

03/25/2023

The performance-enhancing effects of caffeine for a broad range of physical activities have been well-established in numerous meta-analyses.

An intriguing new review from Japan sheds a little more light on how exactly caffeine has this ergogenic impact.

Importantly, this may also mean that caffeine could augment some of the health-promoting effects associated with physical activity as well.

But one dilemma associated with caffeine, that many people wonder about, is the potential for tolerance. Does using caffeine regularly make you habituated to its effects? Do you need to "save" it for the times when you really need it? A new meta-analysis might provide the answer. 👀

Check out the newsletter to learn more!

https://mailchi.mp/humanos.me/newsletter-255

03/18/2023

Hey friends, in honor of Sleep Awareness Week, I thought we would take a look at how sleep affects aspects of immunity.

The connection between sleep and illness has been intuitively obvious to humans for a very long time.

“Sleep and watchfulness, both of them, when immoderate, constitute disease,” said the ancient Greek physician Hippocrates more than 2400 years ago. However, it's only quite recently, with the advent of technology to objectively measure sleep and the rise of scientific microbiology in the twentieth century, that we've been able to conduct experiments to rigorously test how sleep affects our ability to resist infections.

For instance, Sheldon Cohen at Carnegie Mellon has conducted an array of trials in which brave volunteers are administered nasal drops containing either respiratory viruses or saline (placebo), and then keeping them in quarantine to see if they get sick. In one such study, subjects who were getting less than 7 hours of sleep per night were nearly three times more likely to go on to develop a cold, compared to those who averaged 8 hours.

Furthermore, sleep loss may interfere with the ability of the immune system to respond appropriately to vaccines. When flu vaccines were administered to subjects who were in a state of sleep debt their mean antibody titers 10 days later were less than half of those in control subjects.

More recently, several studies were published examining how sleep loss affects

1) odds of developing an infection;
2) antibody response to vaccination;
3) probability of experiencing "long COVID" symptoms.

Check out the newsletter to learn more:

03/11/2023

Hey friends, this week I'd like to talk about one of the most underappreciated sleep aids: masks. Like, the kind that you wear over your eyes.

First, let's talk about why they might be useful in the first place. Obviously, it's really tough to get deep restorative sleep when you're surrounded by a lot of external stimuli, like bright light or noise. If you stop and think about it from an evolutionary standpoint, that makes a ton of sense. In a natural environment, sounds or movement around us could signify potential danger. Consequently, most of us need the right conditions to fall asleep and stay asleep — quiet, comfortable, and free of stimulation.

That's where sleep masks enter the picture. They can help create those conditions by blocking out any light that might deliver an alerting signal to the brain. This is especially useful in the modern world, where light pollution can pervade at any time or place from artificial light sources.

Strangely enough, there have been very few studies that have actually examined the effects of sleep masks, and virtually none that look at masks in isolation. Most of this literature looks at the effects of eye masks (together with ear plugs) as a way to improve sleep in ICU patients.

But what about healthy folks? Well, a newly published trial suggests that wearing a sleep mask could not only improve the quality of your sleep, but also lead to a modest boost in performance the next day. Given that these masks are pretty much risk-free, and not terribly expensive, I was hyped to see this. It also caught my eye because of another recent study which suggested that we may be more sensitive to the brightness of ambient light than previously thought — even through closed eyelids. Check out the newsletter to learn more. 👀

https://mailchi.mp/humanos.me/newsletter-253

03/04/2023

We are about a week away from the start of Daylight Saving Time in the US. That time change, obviously, means that we "lose" an hour of sleep. Fortunately, this is mostly a transient issue, since our biological clocks eventually recalibrate to the new schedule.

However, many of us are stuck in a chronic state of social jet lag — meaning that our biological clocks are constantly misaligned with the time when we are required to be awake and alert. This leads to a pervasive reduction in overall sleep year-round, which is accompanied by a host of acute performance decrements and potentially some long-term health issues.

One group in whom this has been studied extensively is students. Students are an apt model because they generally have strict schedules forcing them to wake up earlier, and because adolescents tend to have a delayed circadian phase that drives them to fall asleep later. This is obviously a recipe for inadequate slumber, and it likely has grim implications for their grades, as you'll see in the two new studies described within. Check out the newsletter to learn more: https://mailchi.mp/humanos.me/newsletter-252

02/25/2023

One of the silver linings of the pandemic is that it has brought the issue of clean air to the forefront, and has elicited public discussion of possible long-term payoffs of improving ventilation in the buildings we spend most of our time in.

That dialogue, of course, is mostly oriented around reducing transmission of infectious diseases. But some preliminary evidence suggests that improving air quality by removing common indoor pollutants, like volatile organic compounds and fine particulate matter, could also improve our thinking and productivity.

For example, a study that looked at more than three hundred healthy office workers in 43 different commercial buildings found that higher concentrations of fine particulate matter in their workspaces were associated with slower response times and reduced accuracy in cognitive tests that were administered while they were at work. Importantly, these effects were evident at levels that are commonly observed in indoor environments.

The two studies that we will be digging into today examine effects of indoor air pollutants on expert chess players and on schoolchildren.

Head here to learn more: https://mailchi.mp/humanos.me/newsletter-251

02/18/2023

Depression is estimated to affect a staggering 300 million people around the world, costing the global economy as much as $1 trillion in lost productivity every year. Unfortunately, it is a difficult problem to solve. A tremendous portion of people battling depression are treatment-resistant, likely because it is a complex, multifactorial disease process.

Observational evidence, as well as some intervention studies, have suggested that a healthy diet, and particularly higher intake of foods rich in dietary fiber, may decrease risk of depression. However, there hasn't been very much research that directly examines how dietary fiber might interact with mental health outcomes…until quite recently. I stumbled upon a few new-ish studies that not only show a link between higher fiber intake and lower risk of depression, but also suggest that fiber (as well as some other health-promoting dietary components) may exert this effect by dampening inflammation, which I thought was worth diving into.

https://mailchi.mp/humanos.me/newsletter-250

02/11/2023

We recently came across a couple of intriguing new studies exploring benefits of zinc - both supplementally and from food - on biomarkers related to brainpower and lifespan.

To learn more, check out our newsletter 👀

https://mailchi.mp/humanos.me/newsletter-249

02/04/2023

Can Eating Collagen Build Stronger Tendons? - https://mailchi.mp/humanos.me/newsletter-248

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