Kurt G. Harris MD

The PāNu approach to nutrition is grounded on clinical medicine and basic sciences disciplined by knowledge of evolutionary biology and paleoanthropology. The best evidence from multiple disciplines supports eating an animal-based diet high in fat, low in cereal grains and relatively low in carbohydrate.

Support PāNu

PāNu is ad-free, completely independent and has no outside sponsorship. If you value PāNu, now you can support it. Read this for more information.

In addition to buying from the book list, you can also support PāNu by making all of your Amazon purchases for any item through the Amazon Portal below

Amazon Portal

« Vitamin D Test Accuracy and Variation | Main | Check out Nephropal »

Vitamin D via Insolation – the natural route in the North

My recent serum vitamin D (25 (OH) D3) level is back, measuring 65 ng/ml. I had been relying solely on sunlight since early June 2009 and got very little sun in the month leading up to the test. Using a half-life for 25 (OH) D3 of 2 months, I would estimate I achieved a peak of approximately 90 ng/dl by the early part of September. My weekly dose of UVB I would estimate at 5 hours between the hours of 11 am and 2 pm central time, achieved by eating lunch sitting outside most days with my shirt off. Occasional days missed were balanced by many days with several hours of sun washing cars, working outside, etc. I live at 44.83 degrees north latitude, so this proves that I can get more than adequate levels of serum 25 D3 with natural UVB alone at my latitude. By “more than adequate”, I mean supra-classical levels of 25 D3, high enough to optimize innate and adaptive immunity and high enough to optimize the paracrine and autocrine effects of D at the tissue levels to control cell differentiation and interaction (read: discourage cancer). Read more about the non-classical benefits of D here.

Notice I didn’t say this proves you can achieve this, it only proves that I can. It’s a true n=1 experiment. I am, to use the colloquial, "white" and equal parts English, German, Norwegian, and Swedish by ancestry – northern european. My skin type would probably be classified straddling Fitzgerald Types II and III. A more useful scale of skin tone, which is less race- oriented and more linear, is the Von Luschan chromatic scale on which I am about 10 on a scale of 1 to 36 (Nicole Kidman to Seal). You can look at the shirtless photo and see how white I am just above the belt and how dark my arms are. My upper chest shows a touch of pink  color – this is a good illustration of the effect of a “minimal erythemal dose” or MED. As I have discussed previously, sunning up to but not beyond the MED optimizes your daily D manufacture. I never got (or get) more burned than this. The photo was taken July 2, 2009, only 4 weeks into my insolation regime. By the end of July, I was darker and would not burn even with several hours of exposure. I would also sit out longer before putting a shirt on as I got darker. The blog headshot is a good representation of my tan level at the end of July. I hope the shirtless photo helps give you an idea of how much sun I was getting as well as just how obese one can get eating 70% of calories as fat.


Reader Comments (27)

Interesting post, Kurt.

Also interesting how people differ. Last March or so I did the grassrootshealth test and it cam back 124. I'd been supping 6k per day, but also spent a week in Mexico in Feb and was in the sun 4 hours per day minimum (got pretty dark). Only a couple of weeks later I had some blood work done and got tested by Kaiser (an HMO) at like 85. Weird, that much difference in such short time.

Last month I again got my grassrootshealth test in the mail, took it, and it cam back around 100. Of course, I spent lots of time in the sun over the summer, in addition to taking my 6k most days.

Any idea on the upper level of D a person might want, i.e., optimal? I know that epidemiolody wise, 65 is a good number, but do you have any reason to suspect that there may be a point of diminishing (or negative) returns?

October 28, 2009 | Unregistered CommenterRichard Nikoley

Hey Richard -

More coming later on this evening!

From my reading so far, I think that the nonclassical effects are probably as high as you can get once you are above 50 or 60, but since the likelihood of harm is negligible below 200, and labs often are miscalibrated to read high, it may be prudent to shoot for at least 60. I have found no evidence for harm at the 60 to 150 level but doubt if there is extra benefit. I am going to increase my supplementation if I fall below 60.

October 28, 2009 | Registered CommenterKurt G. Harris MD

Have you any info re: the time for absorbtion of Vitamin D? I think I read on Dr. Mercola that vitamin D is absorbed through the skin, and that it takes some time for that to occur.

October 28, 2009 | Unregistered CommenterAnna Aadamson

Great post Dr. Harris, Looking great!

October 29, 2009 | Unregistered CommenterDanny Roddy


D is produced instantaneously within the skin with UVB absorption. It is then hydroxylated in the liver.

October 29, 2009 | Registered CommenterKurt G. Harris MD

Looking good.

October 29, 2009 | Unregistered CommenterChris

You have a fantastic blog here!

Please tell us what is your shoulders exercise routine !

Keep up the good job

October 29, 2009 | Unregistered CommenterG

Hey Danny

Thank you


I had no problem loading the image denovo, but I have resized it again just for you!


Chinups 15-20, then 12, then 10, bench press 185# x10 then then 185# x 8-9, clean and jerk or snatch with 90 -95 lbs 10 reps, then 8 or so. Sometimes air squats, sometimes with 150 lbs weight. Lifting sessions average about once a week. I also shoot a 52 lb longbow (not that accurately) during bow season. I run 5 K about 2x per week cross-country (trails only). I usually do the run, then segue into the lifting routine (if it's my day to do it) and do it pretty fast. I do sprints one in a while instead of the 5K run, usually 150 yards all out with 20 sec in between and do that 6 or 7 times. I do that on grass or dirt also. When it's really cold out(below freezing) I run indoors on a very boring rubber track. Maximum workout time per week is about 2 hours.

Sometimes I do 150 yd sprints alternating with sets of 25 pushups - maybe 5 times total as fast as I can.

October 29, 2009 | Registered CommenterKurt G. Harris MD

Thanks Kurt- this is why I was asking- quote from Dr. Mercola site

"It is important to remember, if you are using the sun or a safe tanning bed to obtain your vitamin D, that the vitamin D takes about 48 hours to be completely absorbed into your blood stream, and you can easily wash it off with soap and water.

So you might want to consider only using soap in your armpits and groin for at least 48 hours to allow all the vitamin D to be absorbed. Personally I never use soap on my body other than these places (and my hands of course). Seems a waste to remove the sebum which is a collection of fatty acids on the skin. Over-washing can impair one of primary methods of staying healthy."

October 29, 2009 | Unregistered CommenterAnna Aadamson


Are you pulling my leg? Unless you are showering and using a belt sander on your skin, you cannot possibly "wash off" the vitamin D.

See this wikipedia page http://en.wikipedia.org/wiki/Vitamin_D

The bottom two layers of the epidermis are where the D is made in hairless mammals like homo sapiens.

Only animals covered with feathers or fur make D on the surface.

Does "Doctor" Mercola wear a red nose and have big floppy feet?

A cursory review of his website shows he sells lots of nutrional supplements and promotes the totally bullshit idea of "nutritional typing" - some of us are designed to eat carbs! I guess I have my answer.

Sorry to be so harsh. I hate scam artists like that.

October 29, 2009 | Unregistered CommenterKurt G Harris MD

Great post doc!

I'm seeing an endocrinologist for my high blood pressure and he actually wants me to get my Vitamin D level up to 150 - 200 ng/ml. I have been unable to find any research that discusses levels this high but am glad to see that you think such a level is not toxic.

October 29, 2009 | Unregistered CommenterJohn Espetus


Are you sure that is ng/dl and not nm/l ? 200 nm/L is 40 ng/dl.

October 29, 2009 | Registered CommenterKurt G. Harris MD


Can you tell me what a diet of 70% fat looks like? What does your daily diet consist of. Any advice would be appreciated? Thanks for the great blog!

October 29, 2009 | Unregistered Commentermarc

Well heck Dr. Kurt- I feel better already! Now I can wash in Mexico instead of turn into a dreadlock hippy! Thanks for the info source.

October 29, 2009 | Unregistered CommenterAnna Adamson


You will need to find other reasons to be a dreadlocked hippie!

I have noticed substantially less absolute need for personal hygeine with paleo or at least VLC eating. I have stopped using deodorant completely. My shirts could easily be worn several days in a row before washing. On VLC the glucose in your sweat, sebum, etc must be much lower. Less sugar - less bacteria.

I still brush and floss in the evenings, but without carbs and esp. sugar the "hair on the teeth" sensation does not occur.

Nothing looks dumber than white people with dreads. Fine for Bob Marley.

October 29, 2009 | Registered CommenterKurt G. Harris MD

And they'd look even worse on a Grannie! Interesting about hygiene requirments changing.

I am starting to change my diet again- was low carb for awhile, stopped, gained some (not all) weight back, got two new knees, and now want to give them an easier load to haul. Had more energy when low carbing, heartburn disappeared etc. but I got a craving for things like oatmeal for some reason.

I like the idea of a full fat diet since it is more satisfying- hey, even our Mexican ldog oves whipped cream and lost 9 pounds last year!

October 30, 2009 | Unregistered CommenterAnna Adamson

Hi Kurt,

One of the above posters mentioned asked about what your diet looks like. I too would appreciate seeing what an average day for you looks like as sometimes I feel like I am eating too much protein or too many carbs on certain days, even when I keep it "natural."

October 30, 2009 | Unregistered CommenterGordon Loving

Looking really good, Kurt!

And thanks for dispelling the "48 hour wait to shower or wash off your vitamin D" business.

October 30, 2009 | Unregistered CommenterSatya

Dr. Kurt,
You asked: "Are you sure that is ng/dl and not nm/l ? 200 nm/L is 40 ng/dl."

I did a double-take when he said I should get my Vitamin D levels up that high since I had already done a lot of research on Vitamin D so I immediately asked him which he meant. He was very clear that he wanted me to get up to 150 -200 ng/dl.

I went to this doctor specifically because I knew he does not statinate and uses things like Vitamin D and arginine and would not be opposed to my high-fat, VLC diet. I have what most doctors would say is very high cholesterol but he ordered the VAP test and is thrilled with my pattern A results (along with low triglycerides and low blood glucose). He mentioned he is associated with the Buck Institute (research on anti-aging) and the Vitamin D Council but I still haven't turned up any research that uses amounts that high.


October 30, 2009 | Unregistered CommenterJohn Espetus


Sounds like he thinks the anti-metabolic syndrome non-classical effects of 25-D may enhanced at high levels and help with the hypertension. If he has a reference for those levels I'd like to see it. Not saying it can't help, just haven't seen evidence yet. Low insuliin levels help through the renin-angiotensin system of course.

Any doc who doesn't statinate and who can interpret your VAP sounds like a keeper.

Might be prudent to get an ionized calcium once in while if shooting for those levels, though.

October 30, 2009 | Registered CommenterKurt G. Harris MD

Dr. Kurt,
Thanks very much for your reply. Yes, he did mention treating metabolic syndrome with the Vitamin D. I didn't ask him for research on those high levels at the time since he had just handed me a bunch of articles on Vitamin D to take home and I thought I would find the info there. But none of the research he gave me mentioned levels that high. I have my next appointment with him in December and will ask him then and post back for you. I will also ask him for an ionized calcium test, although he did reassure me that as long as I didn't take any calcium supplements, I would be fine with the high dose of Vitamin D.

He is definitely a keeper. He believes in empowering his patients - he sent me my lab test results without my having to ask and then went over them in detail at my next appointment. He has spent at least an hour with me at each appointment answering questions and is not threatened at all that I might be doing some "internet research" on my own, something other doctors I've seen do not appreciate. Heck, without the internet, I never would have found him!


October 31, 2009 | Unregistered CommenterJohn Espetus

Great post. I have a question for John - can you give the name of the doctor associated with the Buck Institute? I'm curious, because my husband has a former colleague in aging research who moved to the Buck some years ago.

Back to the topic of sun-induced Vit D production. I'm 47 yo. I've been unable to raise my Vit D levels to where I want them 70-85 ng/mL) with sun exposure alone. I can easily achieve and maintain that level with 5000iU D3 daily supplementation though. I had a 25 (OH)D test result of 44 ng/mL in December 07, after supplementing with 2-3,000 iU daily for much of 2007, which I continued until April 2008, when I stopped supplementing and tried to use regular midday sun exposure instead (though I didn't make total time calculations like you did). I live in So Cal and have a flexible daytime schedule so it isn't difficult to be in the sun, though most people I know avoid it (Vit D deficiency seems as much a problem here as in northern areas). And we had a two week trip to Italy in July 2008 including one week at a farmhouse, so I was out in the sun even more than usual during that summer of no Vit D3 supplementation (I rarely use sunscreen anymore except on my nose; instead I cover up with a lightweight SPF long-sleeved shirt and hat). In late August 2008 my 25 (OH)D test result went down to 40 ng/mL. I can only assume that for many years when I wasn't supplementing Vit D3 and was actively avoiding all midday sun exposure, I was quite deficient. I should note that I had a basal cell carcinoma removed from my nose about 10 years ago (when I was still consuming a fairly SAD diet that was quite high in carbs) so I am still a bit cautious about sun over-exposure, though I don't seem to burn as easily as I used to. But my upper chest skin is really reddened with photo-damaged capillaries, so I tend to stick to high neckline clothing in midday sun. That area and my nose are probably quite damaged so I think they will need perpetual protection to minimize further photo-damage.

I am still trying to get midday sun exposure by laying out in the sun in my garden while protecting my photo-damaged skin areas because I think it is good for "setting my internal clock" and other benefits. I set a timer to remind me when time's up. It's usually too bright to read, so I listen to UCTV and Grassroots Health lectures on YouTube and similar podcasts while I'm out there, often on the subject of the latest Vit D research. But taking 5000iU D3 daily really seems to be the trick to keep my 25 (OH)D level up where I want it. My husband and son also take a similar daily dose of 1000 iU per each 25 pounds of body weight to maintain a similar 25 (OH)D range. We all double the dose for a few days if we are exposed to ill people and that seems to minimize or even prevent colds, etc.

October 31, 2009 | Unregistered CommenterAnother Anna

Great post. For this winter, I've been giving my kids Vitamin D chewables every other day (about 400 IU) and Vitamin D gummy bears (about 400 IU, as well). The Vitamin D gummy bears are called vitamin candy in our house, and is the only type of candy besides an ice cream every now and then that makes it inside our house.

Getting the word out on vitamin D and getting outdoors and playing in the cold winter sun (with no burning) for kids this winter is important.

November 3, 2009 | Unregistered CommenterZach

You look so great!
Just wondering if you've sucked your belly in.
I'm kinda a lean guy, but i can't achieve such a flat stomach. It may be because of my hollow back.

I wouldn't even nearly look like you, even if i'm on fasting and drinking no water (filling up my belly).

I'm 21 and so jealous of your body. That's the dream body. I suppose i should give it some time.

Greets from Germany


This is not a "posed" photo - in the body building sense. Genetics determine lots of things both good and bad. My waist size was 34 on the SAD, now it is 30. I think it is valuable to show what you look like if you presume to tell people it's not dangerous to eat fat.

November 9, 2009 | Unregistered CommenterPaul

Thanks for confirming that the washing off vitamin D thing is bogus, Dr. Harris. There is something I'd like to ask you about. Assuming that one is an average caucasian and achieves and achieves a minimal erythemal dose (MED) in 30 minutes of sun exposure during the summer, are there any benefits to spending longer periods in the sun? Obviously one would want to avoid sunburn but once somebody has some protection from a tan, they are capable of spending more time in the sun than before. Would they still get all the vitamin D that they are going to get from the initial half hour or so of exposure and not gain anything from the additional time in the sun? Approaching it from another way, do I get the same amount of vitamin D from two 45-minute sunbathing sessions as I would from three 30 minute sessions? I suspect not but I know you have the authoritative answer.


My idea, which I perhaps did not express that well, is that as you get darker you will have to stay out longer to get your MED. I started at 30 minutes and ended at about 2 hours. The thing I don't know is if when you get to the point where you don't get red at all, how long should you stay out. At 1:30 of sun a day, you can see I got my levels up to 90, so my feeling is that you should start with MED and the first time you can't get a little red anymore, stop at that level of exposure. At that point, your skin tone should be stable, and logically your D production rate should be as well. Make sense?

November 11, 2009 | Unregistered CommenterJeff

Makes perfect sense. I guess the important thing that I was overlooking is that 1 MED is not a static thing. So it seems all those estimates of necessary sun exposure that one hears such as "ten - fifteen minutes a day" or "thirty minutes three times a week" or at best guesses of the amount of time it will take for the average untanned caucasian to reach somewhere around 3 MEDs a week (10,000 - 20,000 IU three times a week). Like with so many things, it seems "your mileage may vary". Thanks for the explanation.


No Problem. MED varies with your tan. absorption of UV changes as you tan.

November 11, 2009 | Unregistered CommenterJeff

I had my 25(OH)D result yesterday. 54.7 ng/ml. This is after supplementing with 6,000 iu D3 for 6 months. I am upping to 10,000 for the next month, prior to another blood draw.
I have suffered from mild alopecia areata over the past 8 years, normally occurring December-April. I think this may be due to vitamin D deficiency and auto-immune problems, so hopefully, this winter it won't occur.

I am also full paleo for 2 years now. Last winter only one 2cm bald patch, which grew back after 6 months.


I would speculate the alopecia is more likely due to gluten grains - the removal of which may require years for the adaptive immune response to cool down.

November 20, 2009 | Unregistered CommenterBill
Comments for this entry have been disabled. Additional comments may not be added to this entry at this time.