Optimal Vitamin D Levels

Here’s a report on a study which measured vitamin D levels of Hadzabe and Maasai individuals living traditional hunter-gatherer or pastoral lifestyles, the data having been collected with an eye toward learning something about what would have been typical during our evolution as a species.

For the Hadzabe the mean was 109 nmol/l and for the Massai 119 nmol/l. These levels are not outside the reference range, but are way above the minimums.

[T]he mean vitamin D concentration of traditional Africans is indicative of the level that would have been typical throughout much of our evolution, and hence, the level that the human physiology would have grown accustomed to over millions of years. Hence, it’s not unreasonable to speculate that such a level may indeed represent optimality…

Source: The Vitamin D Levels of the Hadzabe and the Maasai: An Important Study That Flew Under the Radar

People not living traditional lifestyles can get enough sun to see similar levels, but probably not if they work in an office, and probably not at all in the winter (unless they live in the tropics).

I had my own vitamin D level measured once. It was 38.5 ng/mL (equivalent to 96 nmol/l) versus a reference range of

As I was observing just a few days ago, when exposed to sunlight, your skin does a lot more than just make vitamin D. I’m pretty sure that high vitamin D levels are just a marker for adequate sun exposure. Taking vitamin D supplements in sufficient quantity to raise your blood levels high enough to mimic those of people who get enough sun will produce no more benefit than gaming any metric does.

I’d be interested to know what my vitamin D levels are right now, after a long summer of getting plenty of sun. But not interested enough to go to the effort of convincing my doctor that it’s worth testing again, nor interested enough to pay for the test.

Turns out ALL the rays are actinic!

I observed years ago that the more sunlight I got the better I felt. Although “it’s the vitamin D” seemed like a reasonable hypothesis, I’ve been pretty careful not to just assume that—whenever I’ve written about this I’ve gone ahead and listed some of the other “active ingredients” that tend to come along with sun exposure—exercise, time in nature, etc. As I look into the matter more, I find there’s a growing body of evidence that sunlight itself does provide benefits, but it’s not just the UV light—the other frequencies of light are also actinic in all kinds of ways.

UV light

The UV light doesn’t just make vitamin D. It also has all sorts of other effects. In particular, it modulates your immune system in ways that reduce the risk of multiple sclerosis, and probably other autoimmune disorders and some cancers. It also reduces blood pressure. In mice it has been shown to limit diet-induced weight gain.

Blue light

We’ve long known that blue light (especially, but not exclusively, a specific frequency of blue-green light absorbed by a pigment in the eye called melanopsin) was critical for establishing and maintaining an appropriate circadian rhythm. Very recently we’ve discovered that adipose tissue expresses the genes that produce the same pigment and use it to vary how the cell acts. In particular, after exposure to an amount of blue-green light that might shine through skin exposed to full sun, fat cells reduce the amount of fat they store, and also produce less leptin (a hormone that affects feelings of satiety).

Red light

As I discussed a few weeks ago, there’s been a lot of research on the effects of red and near-infrared light exposure. Here’s a page with links to a bunch of studies that suggest that red and near-infrared light boosts collagen synthesis, speeds healing of burns, incisions and broken bones, reduces inflammation, and generally reduces the effects of aging on your skin.

I guess that leaves us with orange and yellow light unaccounted for, but I don’t doubt that they’ll turn out to be actinic as well.

Non-SAD

I am a little too prone to use black humor to distance myself from the depressing effects of the long, cold darkness of winter, which sometimes leaves people worrying about me unnecessarily. So I thought I’d mention that despite a bit of anxiety over the inevitable turn of the seasons, my mood is currently pretty great.

Beyond just feeling good right now, I’m hopeful. Over the past decade I’ve been handling winters better and better.

The biggest factor, I think, is that I no longer have a job to lose, so I no longer get into the spiral where seasonal depression makes me less productive, making me anxious about losing my job, making me more depressed, making me even less productivity. Sadly, advising others to take advantage of this strategy is not very useful (although I do and will continue to support and advocate for either a citizen wage or a guaranteed job).

Putting early retirement aside as impractical for most people, I thought I’d briefly summarize my other current practices—mostly ordinary coping strategies—both as a reference for myself any time I start to feel my brain chemicals coming on, and perhaps as a resource for other people. Here’s what’s working for me:

  • Taking delight in things. In particular, I take delight in the opportunity to wear seasonally appropriate woollies. I also like to spend time in the Conservatory, go to art galleries or museums, listen to live music, and generally go on artist’s dates.
  • Getting plenty of exercise. Last winter I managed to get out for a run almost every week. As fall approaches I’m getting back to my lifting. (Here’s a great resource on the current science on using exercise to treat and prevent depression.)
  • Spending time in nature. I do that all summer, and it may be part of the reason that my mood is generally great in the summer. But I can do it in the winter too. (I don’t seem to have a post on this topic. I’ll be sure to write one this winter. In the meantime you can find various mentions by clicking on the vitamin N tag over on the sidebar.)
  • Light therapy. I’ve used my HappyLight™ for years, and it does seem to help. Getting outdoors anytime in the first couple of hours after dawn is probably even better—another thing I find easy to do in the summer that would probably help just as much in the winter.
  • Taking Vitamin D through the winter. The evidence for any benefit is scant, but even if it only helps through the placebo effect, it is at least a safe, cheap placebo. (There’s good evidence that people with high levels of vitamin D are healthier, but very little evidence that supplementing vitamin D makes people healthier. It could easily be purely associational—maybe more time spent outdoors both boosts vitamin D levels and makes people healthier and happier.)
  • Anything that boosts neurogenesis. That’s most of the things listed above, but lots of other things too, such as engaging in creative work. Also on the list are calorie restriction and adequate consumption of omega-3 fatty acids.

I have a few new possibilities up my sleeve:

  • There’s recent evidence that sauna bathing is dramatically effective at treating depression, probably through many mechanisms including the activation of heat-shock proteins. (One thing on my to-do list is finding a local fitness center or spa with a sauna and investigating the cost of a three or four month membership.)
  • Related to heat exposure is cold exposure, which activates many of the same protective proteins that heat exposure does. Cold exposure, of course, is trivially easy to achieve in the winter—just wear a coat or jacket one notch less warm than would be most comfortable.
  • Obviously sleep is very important, and with my Oura ring I’m tracking my own sleep carefully. This has already been helpful, and I’m hoping to be able to do more to improve my sleep (and thereby my mood) in the winter as well.

That’s what I’ve got at the moment, but I’m always on the lookout for things to alleviate seasonal depression.

Optimizing sun exposure

For most of my adult life I carefully limited my sun exposure. More recently—after discovering that the more sun exposure I got the better I felt—I’ve been trying to get as much as I could without getting burned. Just lately I’ve been groping towards something more nuanced.

Back in maybe the 1980s I briefly tried to follow the advice of dermatologists to never go out without sunblock. That didn’t work well—inevitably there would come the day when I was out in the sun longer than anticipated, and (not having built up a protective tan) I’d end up burned.

After that, for a decade or two, I came up with some simple rules: Unlimited sun before 8:00 AM and after 5:00 PM, but I’d aim to get 20 minutes of mid-day sun. If I was going to get more than that, I’d wear sunblock, but I tried to get that much sun every sunny day. That worked pretty well—I’d get enough of a tan to provide some protection on those days that I was unexpectedly out in the sun.

That schedule, of course, fell out pretty much automatically from working at a regular job. I stuck with it even after I wasn’t working at a regular job because it worked pretty well.

For various reasons, such as needing to take very long walks to train for our big Kal-Haven trail walk, I started spending more time out in the sun, and began to observe that the more time I spent in the sun the better I felt, leading me to get what was probably more sun than is really wise.

Since recently running into the idea that certain frequencies of red and near-infrared light are good for your skin and deeper tissues, I’ve been prompted to think about all this in a more systematic way, and have been trying to come up with a plan that maximizes the benefits while reducing the harm caused by sun exposure.

I’m still in the research stage, but here are the early changes that I’m making:

First, I’m reducing the amount of mid-day sun I’m getting. I’ve been going for around 40 minutes (as much as I can get without risk of burning), but I’m bringing that back to around 20 minutes. Still enough time to make plenty of vitamin D.

Having gotten the amount of mid-day (2:27 PM) sun exposure I wanted, I moved the rest of my walk into the woods.

Second, I’m replacing that 20 minutes of mid-day sun with 20 (or more) minutes of sunlight during the period that the UV index is between 1 and 3. (This time of year, where I live, that’s maybe 7:30 AM until 9:00 AM.) My hope is that part of the reason more sun makes me feel better is the red light (rather than the UV), and that morning and evening sun can provide those frequencies.

Taken during at 8:59 AM during a walk in the prairie.

Third, I’m trying to get some very early (dawn) sun exposure. This is specifically for the effect early morning light has on the circadian rhythm.

Early morning (6:53 AM) sun over the Lake Park/Winfield Village prairie.

Only in the middle of writing this did I realize the extent to which I’ve come back to what I did for most of my working years—except that instead of having to squeeze my morning sun exposure into the time I spent crossing the parking lot, now I can extend it to 20 minutes or longer, and combine it with a proper walk in nature for some sweet, sweet vitamin N.

Non-deadly, yet perhaps actinic rays

Sun shining through a lily flower.

I went for a long-for-me, 7.22-mile run this morning, and listened to a podcast about light therapy.

(I go back and forth on listening to podcasts during runs. When I listen I feel like I miss out on being fully embodied in my physical activity. When I don’t listen I fall behind on stuff I really want to listen to. Today I listened.)

The podcast had Paleo Magazineʼs Ashleigh Van Houten interviewing Scott Nelson, the founder of Joovv, talking about the health benefits of exposing your skin to red and near-infrared light. I’d heard about this, but had assumed it was some woo-woo new-agey thing. Turns out it’s probably not. There’s been a huge amount of research on the benefits of exposing your skin to red light in the 660-nanometer and near-infrared light in 850-nanometer range.

(There was apparently a lot of research funded by NASA back in the 1990s when they had to use lasers to get light of just the right frequency. Nowadays LEDs make it easy to get the intensity and frequency of light that you want.)

So, I’m out on my run, listening to Ashleigh and Scott talk about all the health benefits to your skin (of the red light) and to deeper connective tissues (of the near-infrared) and thinking that it all sounds really cool, but knowing that I’m probably never going to want to spend even hundreds, let alone thousands, of dollars to buy a device that will shine bright red light on my skin.

At around the mid-point, maybe 4 miles into my run, I paused for a drink of water out of the fountain in Morrissey Park, thinking it was pretty hot for just 8:40 AM . Which made me think of this giant glowing orb in the sky, which was shining down on me with pretty intense light at a wide range of frequencies, most definitely including red and near-infrared.

Turns out, sure enough—the energy in the red and near-infrared frequencies of sunlight is right in the range of therapeutic doses shown to have health benefits.

Of course, full sunlight is full of other frequencies of light, including blue (prone to mess up your circadian rhythm if you’re exposed too close to bedtime, but just what you want to get your circadian rhythm set correctly if you get your exposure in the early morning like I was doing), and ultraviolet (dangerous in excess, but the UV index was zero when I started my run at 7:40 AM and probably didn’t reach 5 before I was safely back indoors). So you need to treat sunlight with respect. But I already knew that.

I have mentioned before that I feel better when I spend a lot of time outdoors, and have speculated that sun exposure is part of the reason. (Along with time in nature, moving more, appropriate quantities of community and solitude, etc.) The information about red and near-infrared light exposure seems to lean a bit in the sunlight direction—but with the welcome news that it’s not just the vitamin D that helps make me feel better, which means maybe I can feel great without having to expose myself so much to the deadly actinic rays of the sun.

Maybe there are non-deadly actinic rays!

Movement trumps exercise

Last Thursday Jackie and I (along with several other Urbana Parks Department volunteers) spent a couple of hours clearing invasive bush honeysuckle at the Perkins Road natural area. (The photo is from a year ago. Sadly, we did not have a fire this time. We just piled the honeysuckle up in great huge brush piles.)

Like last time the work consisted of cutting and then carrying or dragging honeysuckle trunks and branches across a forest floor made rough by many tangled roots and littered with small stumps where honeysuckle had been cleared in past.

The next day Jackie commented that her feet were tired, and suggested that the stewardship work was more to the point than the various foot exercises suggested by movement teachers such as Katy Bowman and our new local Restorative Exercise Specialist Ashley Price. (Exercises such as rolling your foot on a ball or standing in boot trays filled with river rocks.)

To which I said, “Yes! Exactly!”

Movement trumps exercise.

That’s not to say that exercises don’t have their place. Especially for people whose lifetime movement history has left them unready to safely perform certain movements, but also just for people whose schedule makes it hard to fit in as much movement as they’d like, exercises can be an excellent way to make yourself ready or keep yourself ready.

But to actually use your whole body capabilities to perform real work? To engage in bending, squatting, dragging, lifting, carrying—and do so while in nature, as part of a community effort, making the land better? So much better.

<whispering in Katy Bowman voice>Hashtag #VitaminN Hashtag #VitaminCommunity Hashtag #VitaminTexture</whispering> (This last will make no sense if you don’t listen to the Katy Says podcast.)

Nature pyramid!

Via The Art of Manliness I found this great graphic of a nature pyramid (à la the food pyramid) at the Nature Kids Institute. It’s aimed at kids, but really the prescription for adults should be exactly the same.

It’s tougher in the winter, of course—when the grass is snow-covered and the paths are icy, they simply aren’t so runable or walkable. But that’s okay. It’s still worth getting outside.

It’s also tougher in Illinois to find wilderness than in most other places I’ve lived. There was real wilderness in Michigan and Indiana and Florida (although when I lived in Florida I did a pretty poor job of spending time in it), and of course vast amounts of real wilderness in Utah and California. Still, there are places in Champaign county where I can at least get out of sight and out of earshot of roads, even if it isn’t really free of human influence.

Anyway, these quantities seem like good initial target minimums for time in nature. Maybe not optimal, but adequate, and probably a lot better than most people manage.

Gathering garlic mustard

I’ve been occasionally joining Jackie when she does stewardship workdays at natural areas around the county as part of her Master Naturalist work. They’re fun, and they fit in very well with my shift away from exercise and toward movement. Our work Sunday, clearing garlic mustard from the South Arboretum Woods, is a great example.

(Garlic mustard is a nasty invasive, largely because the first-year growth leafs out very early, and covers the ground almost completely. Native plants emerge a little later in the spring, by which time they can’t get enough light to get going. The upshot is that the understory loses most of its natural diversity, becoming just a vast carpet of garlic mustard.)

What we did Sunday was make our way through the woods, spotting and then pulling up all the second-year garlic mustard. (It’s a biennial. The first year is the low ground cover. The second year it puts up a flowering stalk and produces seeds. If you can get the flowering stalks before they set seed, you can make a dent in the local garlic mustard density.)

What struck me was how similar our activity was to “gathering” à la hunting and gathering. It was physically similar—walking through the woods, and then squatting, bending, reaching, and pulling. It was also mentally similar—doing exactly the same pattern-matching that someone seeking to gather edible or medicinal plants would do.

I suspect that both of these aspects of this activity enhance the well-known beneficial effects of “forest bathing” (aka spending time in the woods).

The area we were clearing has a lot of downed branches, big and small, some partially or completely hidden by the ground cover, making for a complex walking surface—more good stuff for both the body and the brain.

Of course, volunteering for and participating in a stewardship work day produces all sorts of additional benefits—in particular, doing something good for the local communities (both the human community that uses the space and the natural community that inhabits it) is rewarding, as is making social connections with the other volunteers and engaging together on a common effort.

Every time I do one, I am reinforced in my desire to do more stewardship workdays, despite my slothful nature.

(The picture at the top is another view of the Cecropia moth that Jackie spotted while we were there.)

Theory and Practice of Neurogenesis

Even though I’m finding my self-care regimen for seasonal depression pretty adequate these days, I’m always interested in more tools. One thing that caught my attention recently was an interview with Brant Cortright in which he talked about his book The Neurogenesis Diet and Lifestyle.

Cortright has a bunch of interesting things to say, one of which I already knew: that depression is not a disorder of serotonin deficiency. According to him—and this I did not know—the way SSRIs work is by promoting neurogenesis. In the interview he said that depression turns out to be caused by a lack of neurogenesis, as are several other disorders (e.g. Alzheimer’s).

I checked the local libraries for copies of his book without success, but in my searches I happened upon this article: Successful brain aging: plasticity, environmental enrichment, and lifestyle by Francisco Mora, which seems to cover pretty much the same ground.

People are looking very hard at drugs besides SSRIs to promote brain plasticity, but the whole idea sounds problematic to me, so I’m interested in the various non-drug interventions suggested by Cortright and Mora. Fortunately, it seems that neurogenesis is easy to increase, by doing the obvious things we already know about:

  • Environmental enrichment
  • Calorie restriction
  • Aerobic exercise
  • Adequate levels of certain nutrients (omega-3s, vitamin E).

I think of my artist dates in particular as environmental enrichment, but of course time spent in nature counts as well. The parkour I do probably counts double, because there’s learning how to execute the moves, but there’s also learning to see the environment as a place where those moves are useful.

My weight loss practices have been substantially motivated by the science around calorie restriction as a way to improve health generally, with additional neurogenesis just one factor.

My experience over the previous 30 years convinced me that approaching calorie restriction in a numerical, analytical fashion—tracking what I ate, estimating the calorie content, aiming for some target X% below maintenance—would be unsuccessful. Instead, I came at it from the other direction: If I’m losing weight, I must be restricting my calories.

The caloric deficit implied by my weight loss over the past five years is just about 100 calories per day. Maintenance for me is probably around 1800 calories per day, so I’ve averaged about 5.5% below. It would probably be more accurate to say that I’ve averaged about 10% below maintenance for about half that time, as I’ve generally lost weight during the summers while maintaining a stable weight through the winters. Either number is well shy of the “20% to 40%” reduction that’s been shown to decrease the rate of aging of the brain, but I rather suspect that the benefit exists even at these lower levels—with the added bonus of being sustainable over a much longer period of time. (I mean, how long can you maintain a 40% deficit below maintenance before you simply waste away?)

According to Mora, aerobic exercise seems to increase neurogenesis by the same chemical pathways as calorie restriction. According to Cortright, it has to be aerobic activity of substantial duration—some twenty minutes or more. In particular, the sort of HIIT workouts so beloved of the paleo/primal folks don’t seem to produce the same effect. That’s fine with me: Humans are much too well-adapted for endurance running for me to buy into the idea that primitive humans didn’t do marathon-distance runs when they needed to. Besides, I enjoy long runs.

Of course, neurogenesis is reduced by the obvious things:

  • Neurotoxins (mercury, lead, pesticides, etc.)
  • Traumatic brain injuries (concussions, etc.)
  • High blood glucose levels
  • Stress.

My parents made a considerable effort to keep me and my brother free of neurotoxins, and I have managed to avoid concussions so far. I’m sure I subjected myself to excessive blood glucose levels for years, but I think I’ve got that under control now. I also subjected myself to excessive levels of stress for years, due to the vicious circle of my seasonal depression making me unproductive, my lack of productivity making me stress about losing my job, and the stress no doubt worsening my depression. I’ve got that under control now as well.

Really then, this whole neurogenesis thing doesn’t so much give me new strategies for staving off depression, as provide a conceptual framework for organizing the strategies I’m already using.

Even just that seems worthwhile.

(The image at the top is of these great doors at the Environmental Education Center at Kennekuk County Park. The branching trees reminded me of neurons, a little.)