As a person living in Seattle (rains a lot!) who is of a darker skin color because of my race, I get told every now and then that I must be very lucky because I'm never going to be Vit D deficient.
I'm surprised that people think having darker skin color means I already have oodles of Vit D, when it's quite the opposite - people with dark skin color synthesize less Vitamin D on exposure to sunlight. I probably need lot more of that big ass star :)
I take 4,000 UI of Vitamin D each day in gelcap form (Vitamin D is fat-soluble, so much better absorbed that way than with dry tablets -- this information is based on blood tests that the cardiologist at the Heart Scan Blog did http://heartscanblog.blogspot.com/ ). Living in Canada and working inside most of the day, that seems to be a minimum for me. I could probably up the dose to 6,000 UI this winter...
As far as I understand it, higher levels of vitamin D3 greatly increases absorption of calcium from the gut, and the K2 is necessary to ensure that the calcium gets deposited in the right places.
Sorry, I don't have an existing set of references for this, but here are a couple things I found:
"Increased levels of vitamin D require increased levels of vitamin K, especially of vitamin K2 (menaquinone). Without enough vitamin K2 there is an increased risk of hardening of the arteries and other soft tissues."
Here is the summary: "The remarkable discovery that blood vessel cells can transform into bone-forming cells confirmed the little-known link between atherosclerosis and osteoporosis. At the core of this connection is insufficient D and K intake. These vital nutrients operate in synergy to optimize bone mineralization and prevent calcium deposits in vascular tissue. Low vitamin D is linked with arterial disease and bone loss, while vitamin K stimulates bone formation and modifies specific proteins (Gla) that help protect against arterial calcification.
Vitamin D taken in higher doses (5,000-10,000 IU/day) has become popular over the last two years based on findings showing that this potency is required to achieve optimal blood levels (over 50 ng/mL of 25-hydroxyvitamin D). Relatively few supplement takers, however, understand the critical need for aging humans to also take a daily vitamin K supplement. Fortunately, Life Extension members were informed in 1999 about the critical need of including vitamin K in their supplement regimen."
It looks like my multivitamin has 25 mcg of K1, but no K2. I'll look into it. From what I've read so far, it seems like deficiency is rare, but it might still be worth taking some extra.
Man, this is a terrible infographic imo, though this sort of thing gets linkshared around the internet like wildfire, so I must be in the minority on that. Some parts of it are fine, like the map, but some parts would be a lot more straightforward as a few sentences or some normal bullet points, instead of that confusing mess of flow-chart-esque lines in the "Vitamin D - ESSENTIAL FOR / INFLUENCES / SUSPECTED EFFECT" section. And the graphics in the "D-Day" section aren't really telling me much at all.
Also, why does the whole thing have to be one giant image?
Both the Mayo Clinic and WebMD are wrong. To put 2,000 IU into perspective, when you go out and expose most of your body to the sun for 30 minutes your skin produces anywhere from 10,000 IU to 50,000 IU. The body evolved this process for a reason, and anything less than 4,000 IU per day is probably not enough.
The average man uses 5,000 IU every day and this increases when fighting illness or chronic disease.[1] There are zero reported cases of vitamin D toxicity on doses less than 40,000 IU per day [2]. I'm not saying go out and take 40,000 IU every day, but 5,000 - 10,000 IU per day is right in the range (you should be on the high end of this if your at high-risk for deficiency i.e. if you are black, obese, work indoors everyday and don't see the noon-sun much, always wear sunscreen when going outside, or live far from the equator)
This is from memory, I don't have my sources right now, but most of what I've read is that the body can deal very well with too much Vitamin D. What it doesn't do well is a deficiency.
A few of my pharmacist friends told me about how some people are being prescribed doses of 50,000 UI, and I've read somewhere that below 14,000 UI a day over extended periods, no toxicity was found. So I kind of doubt that 2,000 UI is an upper bound, unless you have a very specific condition. Just spending a day on the beach probably gives you a MUCH higher dose than this.
But as I said, this is from memory. Take this with a grain of salt and do your own research. Personally, I'll keep taking my 4,000 UI/day, something that I've been doing for about 4-5 years (and while this is anecdotal, I've seen improvements in seasonal mood changes and the number of times I'm sick per year).
The 50,000 IU dose is a single dose, not a daily dose to be taken over some period of time. The half-life of vitamin D in the body is a few months, so a large single dose is effective for some time.
I'm not sure if I wrote it like that because I used to writing the acronym for "user interface" or because in French, my native language, they write it as "UI" (unités internationales). But thanks for the correction.
I assume these are both result from the fact that "The U.S. Dietary Reference Intake Tolerable Upper Intake Level (upper limit) of vitamin D for children and adults is set at 50 micrograms/day (2,000 IU)," the U.S. Dietary Reference being a product of the USDA.
There's a long history of government medical pronouncements being mistaken or outdated (e.g. encouraging grains over fat consumption), perhaps due to the incentives under which regulatory bodies operate - there's little disincentive for being suboptimal or even mistaken, as in the case of fat.
The incidences I've found of Vitamin D toxicity have been found at far higher levels, 40-50,000 IU.
For reference a toxic aspirin dose is roughly 30x a standard dose.
Most guides to getting Vitamin D make blanket statements about how much ultraviolet light is available. The amount of sun varies throughout the winter and by time of day, as well as latitude. You can probably get more UVB at high noon in December than you can at 3pm in October.
I'd love to see a guide that shows you how long you need to be out at a specific time, date, latitude and skin color.
I found the wikipedia entry useful in citing specific interesting studies (e.g., suggesting >50,000 IUs/day (orally) may be needed for toxicity). Plus a clarification of the 'how' of sunlight-produced D self-limiting:
I feel like I should be offended about the Northern Hemisphere-centric nature of the plot. What about the lack of sunlight below 42 S from May to July?
(Admittedly that only includes half of New Zealand's South Island, the tip of Tasmania, and part of Patagonia. Plus all of Antarctica, but I assume if you're wintering in Antarctica you're probably well aware of Vitamin D deficiency.)
10 minutes outside in summer? Does that address our alledged reduced ability to make vitamin D with age? Does it address that vitamin D is made from cholesterol and lots of people are on an anti-cholesterol crusade? Does it address that UVA hinders the reaction which UVB encourages, and therefore sitting in the sun behind glass might undo some of the benefit? (hint: no).
Does the daily recommended amount for supplementation address which kinds of Vitamin D are useful and which aren't? Which kinds are more easily absorbed? That different people absorb different amounts? That it's possible to overdose? (hint: no).
These skirt around the real point which is to raise some particular blood level of a specific kind of Vitamin D. If you aren't getting that, specifically, measured then whatever else you do in terms of sunlight or supplementation is winging it and hoping for the best (and risking overdose) or merely assuaging some guilt that you should be healthier by doing "something".
I have a lot of physician friends who say that testing vitamin D levels is the latest "fad", so to speak.
I got tested out of curiosity and was in the intermediate range (30-40 ng/ml) (technically not "normal" (>40ng/ml), but not "low" (<30 ng/ml)).
Amazingly, I had higher levels than anyone else I talked to who had been tested. My friend said it was the highest level he could remember (of his patients). My doctor still suggested that I take 1 or 2 2000 IU D3 capsules per day.
If you're curious, get tested. I did have to convince my doctor that I wanted to know the number. He said, "trust me, it will be lower than it should be."
Fad or not, get tested for vit D and calcium absorption.
I was a rugby player at amateur level until 3 years ago, when I fractured twice my left wrist in 8 months. Seeing that the second fracture was due to a pretty light contact, I asked to get tested and I was diagnosed with osteoporosis. This is quite rare for a 36 years old male such as myself, I understand it may not be so rare in the next years.
I remember Dr. Weil saying that if you live north of, say, Atlanta, there isn't enough UV exposure for to get sufficient vitamin D from the sun during winter months. He recommended sardines as a natural source of vitamin D.
Quick note on the infographic. It is extremely important to not take cod liver oil as your vitamin D source. The problem with cod liver oil is that it contains toxic levels of vitamin A, which acts as an antagonist against vitamin D. They use the same receptor and so when there is too much vitamin A in the blood, even moderate toxicity, the good effects of vitamin D will be greatly diminished.
Also, if you are going to take a multivitamin, make sure it is 100% beta carotene, as other forms of vitamin A (eg. retinol, the kind of vitamin A that cod liver oil contains) cannot be flushed out of the system and will lead to toxicity -- therefore you cancel out any benefit you would have gotten from the D. Below is a more thorough commentary on the latest research:
Dr. John Cannell, MD.
via Vitamin D Council
"Although activated vitamin D and vitamin A signal through common cofactors, they compete for each others function. Retinoic acid antagonizes the action of vitamin D and its active metabolite. In humans, even the vitamin A in a single serving of liver impairs vitamin D's rapid intestinal calcium response. In a dietary intake study, Oh, et al, found that a high retinol intake completely thwarted vitamin D's otherwise protective effect on distal colorectal adenoma, and they found a clear relationship between vitamin D and vitamin A intakes, as the women in the highest quintile of vitamin D intake also ingested around 10,000 IU/d of retinol." [1a, 1b, 1c]
"Furthermore, the consumption of preformed retinol even in amounts consumed by many Americans in both multivitamins and cod liver oil may cause bone toxicity in individuals with inadequate vitamin D status. Women in the highest quintile of total vitamin A intake have a 1.5-times elevated risk of hip fracture." [2]
"Indeed, a recent Cochrane Review found that vitamin A supplements increased total mortality rate by 16%, perhaps through antagonism of vitamin D." [3]
"Another recent Cochrane meta-analysis concluded that although vitamin A significantly reduced the incidence of acute lower respiratory tract infections in children with low intake of retinol, as occurs in the Third World, it appears to increase the risk and/or worsen the clinical course in children in developed countries." [4]
"As early as 1933, Alfred Hess, who discovered that sunlight both prevented and cured rickets warned about vitamin A consumption, concluding, ...as to a requirement of thousands of units of vitamin A daily, the unquestionable answer is that this constitutes therapeutic absurdity, which, happily, will prove to be only a passing fad (p 662)."
"Unfortunately, Hess's prophecy of a passing fad proved premature and Americans continue consuming multivitamins and/or cod liver oil containing small amounts of vitamin D but undesirable quantities of vitamin A. For example, multivitamins, until recently, had small amounts of vitamin D (200 to 400 IU) but high amounts of preformed retinol (5,000 to 10,000 IU). This pales in comparison to a tablespoon of modern cod liver oil, most of which contains sub-physiological amounts of vitamin D (400 to 1200 IU) but supra-physiological amounts of completely preformed retinol (5,000 to 15,000 IU or, in some cases, 30,000 IU)." [5, 6]
"Clinical lore holds that Vitamin A is an anti-infective. We suggest that lore exists because of old cod liver oil studies. Semba reviewed early literature on vitamin A, usually given as cod or halibut liver oil, as a successful anti-infective. For reasons that are not entirely clear, fish liver oils of the time contained much higher amounts of vitamin D then does modern cod liver oil, perhaps because modern processing removes the vitamin D during distillation and then replace it at lower doses. Furthermore, a meta-analysis concluded that vitamin A, when given alone, increases the incidence of respiratory tract infections. If vitamin A increases the risk of respiratory infections, its high content in modern cod liver oils will only mask the full benefit of adequate vitamin D nutrition."
"As the prevalence of vitamin A deficiency in the United States is apparently much lower than the prevalence of subclinical vitamin A toxicity, we cannot recommend cod liver oil for either adults or children. (We exclude fish body oil from our warning, as it contains no vitamin A or vitamin D but is a very important source of omega-3 fatty acids.) For example, in a recent assessment of serum retinyl esters in a group of obese individuals, four percent had levels >10% of total retinol which usually indicates hypervitaminosis A. Instead, a diet rich in carrots, sweet potatoes, cantaloupe, and other orange fruits and vegetables will supply all the carotenoids the body needs to make retinol without the potential for hypervitaminosis A, especially when additional preformed retinol already exists in dairy products, eggs, and fortified cereal. We wish our diet were as rich in vitamin D. With the exception of infants on formula or toddlers drinking large amounts of milk or fortified juice, adequate amounts of vitamin D are virtually impossible to obtain from diet." [7,8,9]
[1b] All-trans retinoic acid antagonizes the action of calciferol and its active metabolite, 1,25-dihydroxycholecalciferol, in rats.
http://www.ncbi.nlm.nih.gov/pubmed/15987844
What a horribly unscientific infographic! UVA "ages" the skin and UVB burns your skin but also creates vitamin D? The truth is that UVA is a longer wavelength radiation that for the most part lacks the power to penetrate the skin, while UVB does do damage to the DNA. It's exactly that sort of genetic damage that "ages" the skin, in the terminology of the author. It can also lead to cancer.
Living in Seattle was brutal for me, it left me incredibly depressed and I ultimate fled back to San Francisco for my sanity. Even SF is pretty rough, so I only live in the corporate apartment complexes in SOMA where I can lay in the sun an hour a day after swimming, it keeps me quite happy (and tan!)
Probably not, because we've lived up here in this "gray and cloudy" environment for thousands of thousands of years, and we're doing just fine; we're adapted. But we are aware that living "up here" is a problem for people who comes from "down there".
I'm surprised that people think having darker skin color means I already have oodles of Vit D, when it's quite the opposite - people with dark skin color synthesize less Vitamin D on exposure to sunlight. I probably need lot more of that big ass star :)