Dead Monky - 30 November 2010 11:37 AM

Hmm.  You know, maybe we should consider fortifying something with it like we do with bread and folate.

Well, I think there are other things like cereals that are fortified with Vit. D. Problem is that the amounts are small. Perhaps now they might up the amounts enough that they could make a difference.

But it’s a blunt instrument, especially when some people may need significantly more than others ...

Well, sometimes the blunt instrument works best.  Worked with folate and iodine.

But yeah, quite a few cereals are fortified with vitamin D.  Especially kids’ cereals.

The Count is back

I thought I’d revisit this topic, as I’ve come to some new insights on vitamin D. As a result, I have increased my daily intake to a total of 10,000 IU per day. I estimate how much I’m getting from Sun exposure and take supplements so that I get the 10,000 IU per day on average. I believe that this is the right thing to do for a number of reasons:

1) 10,000 IU/day is what you would naturally get from sun exposure if you lived as our recent ancestors. Dynamical equilbrium is reached between vitamin D production and destruction within half an hour or so, if you are in the tropics at this level. So, if you are outside for some hours every day, then you are guaranteed to get this dose on the long term. Your calcidiol levels will be approximately 220 nmol/l. To get significantly lower calcidiol levels, you woud have to get significantly less vitamin D over a prolonged period of time, which is unnatural if you live in the tropics as our recent ancestors

However, if you lived in Ice age Europe, you would not get the 10,000 IU per day after the start of Fall. Your vitamin D levels would slowly go down. How fast depends on how much vitamin D you have stored in your fat reserves. It would be natural to assume that your fat reserves would be saturated with vitamin D, so this actually only depends on the total amount of fat reserves you have. This then points to a very clever mechanism:

2) Vitamin D’s real role in the body is to act as a signal. Calcidiol levels lower than the maximum attainable via solar exposure is a signal that the prospects for getting enough food from Nature in the near future is below optimal. Clearly when the Sun no longer rises high in the sky in the afternoon in Fall, this is a signal that hard times are coming and the smart thing to do is to save mor energy from each meal. This is better than waiting until food shortages arise before taking any measures. And the less fat reserves you have, the earlier in Fall you want to start. So, what would you cut back your energy spending on? It seems sensible to start with things that do not pose any risk to your health. So, you can imagine that as calcidiol levels drop from 220 nmol/l to 180 nmol/l, all that happens is that the body does not invest as much in maintaining optimal fitness levels. If you run a marathon, you will not recuperate as fast as you are used you. Thing is that even if you do not run a marathon, keeping your body in shape so that you could recuperate fast, costs energy.

Then as your calcidiol levels go down further, more energy saving measures are taken. But these now have increasing risks for your health. The lower your calcidiol levels become the more serious the prospect of severe food shortages is estimated to be, hence it pays to take more risky energy saving measures. When calcidiol levels sink below 150 nmol/l, less energy will be made available to your immune system. You’ll lose some very expensive layers of defense that you can do without in almost all circumstances anyway. The risk of certain diseases may then increase, but you save a lot more energy, making it more likely that you will survive the Winter.

Then when Winter arrives and your calcidiol levels go below 80 nmol/l, you will cut back on other expensive processes in your body. E.g. getting calcium from food is not free of charge. There are enzymes that have to be produced that do this. By cutting back on this, you may get a bit less calcium from food, but you then save energy.  You will still get enough calcium from food if you get 1 gram per day, but if you get 400 mg or less per day, the body will get some of it from the bones. Because the calcium in the bones is very concentrated, it costs less energy to get it from there than from the food we eat. When calcidiol lelvels get below 20 nmol/l, you will struggle to get enough calcium from food, even if it is rich in calcium. You can imagine that such low levels point to it being late in Winter and you having lost quite a lot of your fat reserves, so you want to extract as much energy as possible out of every meal that you eat.

Of course, this is just my speculative theory, but it is the only thing I can think of that makes sense. Why else would animals have evolved to make maintaining their bones artificially dependent on a chemical that is not going to be produced when the Sun is not high in the sky? Note that vitamin D itself does not get the calcium out of food, it merely switches on genes that code for the proteines that do this.

Other arguments:

3) It is now recommended that babies get 400 IU per day from supplements. This has been shown to be necessary and siufficient. However, one can ask why Nature hasn’t taken care of this. Why is there not enough vitamin D in breat milk? It turns out that if lactating women have calcidiol levels of about 150 nmol/l or more, their breat milk actually does provide for the 400 IU per day for their babies. It is just that almost no women living in the West have such high calcidiol levels. Women need to use at least 6700 IU per day to get such high calcidiol levels. This fits in with my theory that the RDA should be 10,000 IU per day leading to calcidiol levels of around 220 nmol/l, because 150 nmol/l is a threshold value where the body is on the verge of cutting back on providing the best care for its baby.

4) 10,000 IU per day is guaranteed to be safe. Obviously a dose that you would naturally get from Nature is unlikely to be unsafe. But direct tests also point this out. It is estimated to be at least a factor 4 below the minumum value at which you can expect that some people could get hypercalcemia. A test in which 50,000 IU per day was given to people for 8 weeks showed no evidence of elevated calcium levels. The calcidiol level of some of these people was higher than 600 nmol/l. While it cannot be ruled out that in some people you could see hypercalemia at these levels, it should still be rare. The safe limit for calcidiol is set at 500 nmol/l and 220 nmol/l is so far below this value that one shouldn’t worry about it.

5) Last but not least: I’ve improved my fitness by quite a bit since starting to take vitamin D supplements

To answer a few of your points in no particular order.

African-American young children who lived in northern latitudes did show lower levels of vitamin D than did Caucasian kids and suffered more illness (however possibly also caused by other dietary deficiencies).  So, I’ll postulate that part of the dark pigmentation function was to block excess UV.  As humans migrated north, those with lighter skin were able to get more D from the winter sun so those with more pigmentation weren’t able to reproduce as effectively there causing the shift to low melanin skin.

Some animals can produce vitamins and amino acids that others can’t so possibly those animals with thick fur do that.  Of course, many fish have high levels of D (cod liver oil) so possibly animals like polar bears get plenty from their diet.

As I understand it, researchers have found the functions of D are much more widespread than just maintaining calcium levels.  It seems to also inhibit cancer cells, and increase neural efficiency along with other values.

Occam

Well, FWIW the Institute of Medicine’s recent report on Vit. D that I referenced above (you can see the webpage HERE; the report itself is HERE) is the most thorough study to date. It discounts all other effects from Vit. D than bone health, and suggests a safe upper bound of 4,000 IU/day for adults. (Report p. 441ff). The report (p. 430, p. 444) suggests risks rise at over 10,000 IU/day, and serum levels are optimal around 40-50 nmol/L (p. 433), or perhaps 50-75 for older people (p. 434).

I still take 1-2,000 IU/day, getting no sun. My serum levels are at 51, so there’s no reason for me to take more. Not with the evidence in the IoM’s report.

... also serum levels seem to max out around 2,000 IU/day (pp. 382, 384).

NB: if you’re interested in Vitamin D’s role in areas other than bone health, the IoM deals with those issues from pp. 125-344. Basically they discount them all as unproven, at least pending further study. (Concluding statement on cancer p. 139. Breast cancer in particular p. 142. Colorectal cancer p. 145. Prostate cancer p. 147. Cardiovascular disease p. 152. Etc.)

I cannot order Vit D pills in the US.

“Order not allowed in your country”. 

GdB - 13 April 2011 05:54 AM

I cannot order Vit D pills in the US.

“Order not allowed in your country”. 

The local grocery store here in Buffalo will sell you all the vit D you want. (Or did you mean “from” the US?? I see you are in Switz.)

GdB - 13 April 2011 05:54 AM

I cannot order Vit D pills in the US.

“Order not allowed in your country”. 

Huh? You can order Vitamin D anywhere in the US. As traveler notes, perhaps there’s a problem with importation from the US into your country, but you should be able to buy it locally at any pharmacy, and it shouldn’t be expensive.

I think it is not plausible that you will find strong links between vitamin D levels and cancer, even if vitamin D does have a positive role here. Obviously, any influence that vitamin D has on cancer must be an indirect effect, as people typically did not die from cancer in prehistoric times. The role it plays in the immune system is, however, well established. Trying the compute the RDA for vitamin D by looking at serious disease is thus a seriously flawed stategy. See here for other criticisms of the way the IOM argued:

When evaluating the evidence on vitamin D, the IOM gave randomized clinical trials the most weight, since, in theory, such trials are the most rigorous: Researchers that randomly assign study participants to receive a treatment, such as a vitamin supplement, or a sugar pill (placebo), can be more certain that the treatment itself is responsible for any results.

But in reality, randomized clinical trials do not always offer the best evidence on vitamin supplements and health: They are expensive to conduct, so often they last only a few years, and they tend to enroll people who are already at a high risk of disease—for example, people who are older or who are not in the best health. As a result, these trials may be too short or too late in life to show the benefit of a vitamin supplement, if one exists.

Cohort studies can overcome some of the shortcomings of clinical trials, since they can follow large groups of initially-healthy people for long periods of time—long enough for links between vitamin levels and disease risks to emerge. Laboratory studies and animal studies also help fill in the research picture.
Most of the randomized trials of vitamin D have focused on bone health, and there’s been a lack of randomized trials on vitamin D and other chronic diseases. Unfortunately, the IOM committee interpreted this lack of trials as evidence of no benefit—in effect, ignoring the substantial evidence from cohort and other studies that vitamin D plays an important role in lowering the risk of several chronic diseases.

GdB - 13 April 2011 05:54 AM

I cannot order Vit D pills in the US.

“Order not allowed in your country”. 

Order it from another store that doesn’t check if it is allowed in your country. You can also order from Britain (try e.g. BigVits). Then, while the supplements are more expensive, the postal charge will be less if you live in Europe.

Count Iblis - 13 April 2011 07:37 AM

I think it is not plausible that you will find strong links between vitamin D levels and cancer, even if vitamin D does have a positive role here. Obviously, any influence that vitamin D has on cancer must be an indirect effect, as people typically did not die from cancer in prehistoric times. The role it plays in the immune system is, however, well established. Trying the compute the RDA for vitamin D by looking at serious disease is thus a seriously flawed stategy. See here for other criticisms of the way the IOM argued:

When evaluating the evidence on vitamin D, the IOM gave randomized clinical trials the most weight, since, in theory, such trials are the most rigorous: Researchers that randomly assign study participants to receive a treatment, such as a vitamin supplement, or a sugar pill (placebo), can be more certain that the treatment itself is responsible for any results.

But in reality, randomized clinical trials do not always offer the best evidence on vitamin supplements and health: They are expensive to conduct, so often they last only a few years, and they tend to enroll people who are already at a high risk of disease—for example, people who are older or who are not in the best health. As a result, these trials may be too short or too late in life to show the benefit of a vitamin supplement, if one exists.

Cohort studies can overcome some of the shortcomings of clinical trials, since they can follow large groups of initially-healthy people for long periods of time—long enough for links between vitamin levels and disease risks to emerge. Laboratory studies and animal studies also help fill in the research picture.
Most of the randomized trials of vitamin D have focused on bone health, and there’s been a lack of randomized trials on vitamin D and other chronic diseases. Unfortunately, the IOM committee interpreted this lack of trials as evidence of no benefit—in effect, ignoring the substantial evidence from cohort and other studies that vitamin D plays an important role in lowering the risk of several chronic diseases.

Thanks for that. One of my initial sources in this thread was Harvard, and clearly they take the evidence more seriously than the IoM did. I think though that the point is clear whatever we want to say about the quality of the limited evidence.

(1) More studies are needed.

(2) People should be taking supplements of 1,000-2,000 IU/day in most cases.

(3) Everyone should be talking to their doctor about Vitamin D levels and trying to get them somewhere around the optimum.

dougsmith - 13 April 2011 08:45 AM

...

(2) People should be taking supplements of 1,000-2,000 IU/day in most cases.

 

The “form” of that supplement may be the sunshine. No need for supplements if plentiful sun, no?

traveler - 13 April 2011 10:21 AM

dougsmith - 13 April 2011 08:45 AM

...

(2) People should be taking supplements of 1,000-2,000 IU/day in most cases.

 

The “form” of that supplement may be the sunshine. No need for supplements if plentiful sun, no?

Right, though there is no lower bound to the amount of sunshine that’s bad for you: UV light from the sun causes skin cancer, and any amount is bad. What is overall healthiest is to avoid direct sun (or use sunscreen, which amounts to the same thing) and take a supplement.

Do recall that the amount of solar energy you get—and therefore the amount of Vitamin D—depends on latitude. Someone in the tropics, or in the tropics at high altitude, will get much more solar energy per minute than someone around NY. And that goes doubly for NY in winter. And that goes triply if you are darker skinned, quadruply if you’re over 60 years old. (The elderly are much less efficient at creating Vit. D from the sun). It’s not clear that anyone can get enough sun in high altitude winter (e.g., NY) to give their RDA of Vitamin D. It seems that in the ‘olden days’ people got so much sun exposure in summer that the D was stored in the fat to last over the winter ...

That said, the IoM report says that most Americans get enough Vitamin D normally, through daily sun exposure and the limited amount added to milk. Given all I know now, I think that’s at least questionable, particularly for anyone who works indoors year round and tries to avoid regular sun exposure.

I wonder what effect avoiding exposure to sun and taking vitamin D supplements instead would have on mental health. Is it really the healthiest solution to avoid direst sun? According to some preliminary genetic research I have typical odds of developing Squamous Cell Carcinoma and slightly decreased risk of developing Melanoma, but I know that I’ll go insane if I don’t see the sun for a few days in a row. Perhaps I simply get vitamin D deficient, but I wonder if there could be “a little more” to the need of being exposed to direct sun than just the vitamin D.