Tag: sun

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.

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!