Tuesday 20 October 2009

The 'danger' of not supplementing for vitamin D

DISCLAIMER: Not a doctor, not a dietician. Etc.

Now the days are getting shorter, and greyer, do you in the UK and similar climates feel scared? Do you feel scared when you hear supplement manufacturers tell you it's essential to supplement for vitamin D in the UK, at least in the winter, else your health will suffer?

Dr Doug Graham ('80/10/10 Diet'): 'Whenever somebody's trying to scare us, the question is, 'Are they benefiting from it, and in what way? If they're selling us a product...we should ask how big is the danger, really?'

In the UK, the supplement sellers' trump card is that, no matter how much we good little health seekers get out in the sun in the summertime, we're stuffed in the winter because we have...the wrong kind of sun.

In this article I'm going to try to assess how big (or small) the danger is for vegans in the UK (from this point on please read for UK, 'UK and similar climates!') if they don't supplement for vitamin D in the winter.


As usual, sources vary, and figures are usually ranges, but a ballpark figure is around 400 IU a day (on average) for an adult.


People on all types of diet, that is, including cooked omnivorous, get the vast majority of their vitamin D from sunlight on the skin, not food. To give you an idea... John Cannell, Vitamin D Council: '10-15 minutes in noontime summer sun is enough and leads to the production of 10,000 IU of vitamin D'. (This compares with 300 IU from a portion of oily fish, 98 IU from a cup of (vitamin D-fortified) milk, and 20IU from an egg.)

To all intents and purposes, there's little difference between the vegetarian and vegan diet when it comes to vitamin D. Unless a vegetarian glugs down vast quantities of fortified milk (very little D in raw milk), which would bring its own attendant health problems, D food sources for the vegetarian are insignificant.

What did vegetarians/vegans in the UK do in the past, before supplements (or indeed fortified milk and other veg foods) were invented? We don't have much information on vegans (as we're a rare sort!), but I haven't found anything that suggests that UK vegetarians in history have, as a group, suffered from health problems - in fact, the reverse has tended to be the case. I wonder how they managed.

Some basics:


Vitamin D is a fat-soluble vitamin which acts like a hormone, regulating the formation of bone and the absorption of calcium and phosphorus from the intestine. It's created during a chemical reaction that starts when the skin is exposed to the sun's 'ultraviolet B' (UVB) rays. Substances within sebum (a fatty substance on the skin's surface) then work with the sun exposure to synthesise vitamin D, or, to be more precise, D3. The D3 is then absorbed (we hope, see later) from the surface of the skin into the bloodstream.

Vitamin D3 (cholecalciferol) is the D made by mammals, ie including humans, via the process described above.
(Vitamin D2 (ergocalciferol) is the D derived from fungal and plant sources.)

And note that UVB rays enable us to make vitamin D, but UVA rays destroy vitamin D.


It's most important role is in increasing absorption of calcium, and reducing urinary calcium loss. However, as it's also a regulator, in certain circumstances, D will take calcium from the bones if it's needed in the blood.

If there's not enough vitamin D, calcium deficiency will lead to bone softening, and fractures may result. Bones may form abnormally ('rickets'). Also, current research suggests D is involved in growth of lymphocytes, part of the body's defence system.


From the sun of course, and there's a lot of it about, even in the UK (some experts say that even on a cloudy summer day some vitamin D will form.)

Taking the summer sunshine, as no controversy there, most of us could get far more of it than we do.

Indoor living

It's my guess that many of those tapping away at their keyboards worrying about vitamin D and/or warning others to supplement for D have done so indoors with the sun shining outside. Although most of us enjoy being out in the sun once we're there, it can take self-discipline and effort to drag ourselves away from the computer. But so much better than popping a pill.

Remembering the massive amount of vitamin D that can be made by just 10-15 minutes in the sun, those working in offices, shops etc can get out at lunchtime, and spend any weekend time they do have working, or just lying in, the garden (or park if there's no garden.)

We should not wear sunscreen, as that blocks UVB rays. Caveat - if the sun is so strong that we feel uncomfortable in it we should, as an animal would do, seek a shady spot.


Wear fewer. From March at least, whenever it's sunny, we should push up our sleeves, get the shorts out!


It doesn't seem to me that this is much of a concern (re vitamin D at least!) in the UK, but...it's a good opportunity to discuss 'rickets'. Rickets in children was common in the Victorian era and the first half of the 20th century, when industrialisation led to smog (eg from burning coal), which blocked out much of the sun's UVB rays. My parents have often told of the 'peasoupers' of the Fifties. Also, certainly earlier in the 20th century, children were often working in factories in daylight hours anyway (before the start of compulsory schooling) so what little UVB rays were around they weren't getting. As the deprivation of sunlight = less vitamin D = less calcium absorption, then drinking gallons of milk would of course increase calcium and 'cure' rickets (as it did) but the cause of the rickets was lack of sunshine.

Prior to Victorian times, my googling finds no evidence to suggest that rickets was widespread. The rickets came with unnatural lifestyle.

In modern times, studies carried out in Delhi have linked atmospheric pollution with the development of vitamin D deficiency.

But even the London air is relatively clean compared with that of the Fifties, and London isn't amongst the most polluted cities in the world (16 out of 20 of them are in China, and in some the air is dark with coal dust!).


This is where the supplement sellers say 'nerr -gotcha!' to those of us who have the misfortune not to live in California.

As, a scientific study has shown that, in countries above 42 degrees north latitude, the sunlight November through February is insufficient for vitamin D synthesis, and that, in far northern latitudes, it's insufficient for up to six months. Hard luck us. UK is at 54 north - not exactly 'far northern', but, yes, perhaps our 'insufficient' period might extend a little way either side of November through February.

One reader became annoyed with me when I called this a 'theory' and said it was a 'scientifically proven fact'. I wish I had a penny (OK - a pound) for every scientific study that claimed such-and-such, only to be contradicted by a study a year or so later, where things had been done in a slightly different way, and different conclusions drawn. And haven't we been told all sorts of things about nutrition about scientists over the last 50 years, many of which have turned out to be...wrong?

(EDIT Nov 09 - It's mid-November and, amidst some cold blustery days, we have had a fair bit of sunshine, and this morning's been glorious! I've been in the garden, happily weeding, dead-heading...bulbs are coming up already, some are even budding! But, according to the scientists, this sunshine won't nourish me. You know what? I Don't Believe It. )

But, OK, for now, as I know many of you do believe it, let's go with the 'wrong kind of sun' for, say, late October to early March?


Yes, we can store the D. Sources conflict as to where. I've seen 'the liver' and 'in body fat'. Perhaps both are correct. Either way, the D can be stored and released into the bloodstream as needed.

However, supplement manufacturers tell us that the D we make in the summer will simply not last us the whole of the winter, and that at some point in the winter we are likely to be significantly 'deficient'.

But not everyone agrees.

Dr Colin Paterson (consultant physician, NHS health site): 'Most people in the UK get most of their vitamin D from exposure of the skin to sunlight. The average person has enough vitamin D stored in their body to last for two or three years.'

Oliver Gillie, former Sunday Times medical correspodnent, reviewing the literature on vitamin D: 'Active exposure of the skin to the sun by removing clothes and sunbathing is necessary to provide healthy levels of vitamin D that will provide a reserve for the autumn, winter and early spring (October to March or later) when the sun is not strong enough to induce synthesis of vitamin D. Vitamin D has a half-life in the body of about six weeks and so high levels must be achieved in summer to provide levels in the body which remain sufficient at the end of winter.'

So Gillie is saying that provided we get enough in the summer, it will last the winter. A 'half-life' is the time taken for something to fall to half its initial value. We could only establish how much D was left after, eg, twelve weeks if we knew the rate of decline after the six-week point, and, of course, exactly how much D we might be using from our stores in that period! Suffice to say that, sure, stores must be getting low by late winter.

But, just because stores are low at one time of the year, does that necessarily mean our bodies are going to have problems? Can a healthy body not 'make it through' until levels are topped up again in the spring? How necessary is it for us to have 'high' stores every single month of the year? At worst, perhaps our bones are a little lower in mineral density towards the end of the winter, but I don't notice them crumbling en masse around February.

Pale skin absorbs more vitamin D

Now here's some good news for the pasty-faced!

Dark skin absorbs less sunlight than pale skin. Although science says we all came out of Africa originally, scientists at the Oslo University say that the skin of those who moved to colder countries lightened over thousands of years to give an evolutionary advantage. In other words, the skin lightened as a response to the different climate. Meaning that...for those who get less sunlight, nature compensates by ensuring that they absorb more. Neat, that!

So, our bodies are so clever that the skins of those who have migrated to cooler climates lighten specifically so they can make that much more vitamin D from the little sunlight they do get in the summer. Who knows, perhaps that's to help them through the winter! But then, that would be suggesting that our bodies know what they're doing, and are perfectly capable of making necessary adjustments for different climates...


Most people who take D supplements take it not because they have noticed any particular symptoms but because they have been persuaded by others that it's a good idea to take them.

But some raw vegans take supplements because they have had health issues and attribute these to D deficiency.

Now, it could be that symptoms are due to D deficiency, and the obvious answer is to get more sunshine. But some maintain that, despite getting lots more sunshine than the average, they are still experiencing symptoms of 'deficiency'

But it is possible that these symptoms could be down to something else entirely. Illness can be caused by a thousand lifestyle factors, including many unconnected with food or sunshine. Bone/teeth problems could be due to acid-forming elements in the diet (some on high-raw diets have alcohol, coffee etc), resulting in the body leeching calcium from the bones to maintain optimal pH, or...could be due to eating too much dried fruit combined with poor dental care.

But what if our raw vegan has a blood test and vitamin D is undeniably 'low'? Well, firstly of course it could well be 'low' if it's taken in late winter. But then surely the D of the population as a whole might be lower then than in mid-summer anyway, and, as explained earlier, I question whether this is necessarily a concern.

Secondly, it could be that the illness itself has depleted the vitamin D. I'm on shaky ground here, as I don't have a source, but have seen this suggested in the past. I've googled pretty exhaustively to find anything more than anecdotal corroboration, but if any of you can supply anything more on this let me know. It makes sense if we consider that the body, when healing itself, might draw on stores of various nutrients, and if D is one of those (as research indicates it has a role to play in the defence system), then it would not be surprising if a person who is ill finds, on testing, that they are indeed 'low' on D, but as a result rather than a cause of the illness. Bear with me on my musings?

But it could also be the case that, although his/her body has been doing its darndest to make plenty of vitamin D in the summer, various lifestyle practices could be combining to...destroy it!


Wash it off!

Thanks to Joseph Mercola MD for reporting results of research that shows that it takes up to 48 hours before the majority of the D formed on our skin when exposed to sunlight is absorbed, and that, according to Mercola, if in that 48 hours we shower or bathe with soap (or, we might presume, any sort of 'bodywash' that contains detergent), we'll wash away much of the D! As, the soap washes off the sebum, which is critical in vitamin D formation. It could be the modern preoccupation with daily showering that is responsible for low D levels. So, I'd suggest showering with water only, or just using soap/detergent on the bits of the body that, er, don't normally see sunlight anyway?

Get our sunshine through glass...

Whereas the UVB rays enable our bodies to make vitamin D, UVA rays break down the D we've just formed. Glass blocks UVB, so if we come out of the summer sun, then spend time in a room (or in a car) where the sun's shining through a window rather than directly on us, we're getting lots of UVA, but not UVB. Net effect - reduction of vitamin D. So best to make sure windows are all open wide, to get the sunlight directly onto our skin, or better still - get out there!

Modern humans do get up to all sorts of things that can deplete vitamin levels. We also have ways of preventing the D we have made from being absorbed. For example:

Obese people are less than half as able to utilise vitamin D made through the skin as lean persons. Consequently, the average raw vegan is much more able than the average to absorb vitamin D.

Alcohol - interferes with the conversion of vitamin D to its biologically active form.


Dissenting points of view, basically, but I'm happy to provide them here!

(BTW as a side issue, there's a bit of a 'tricky' here for vegans anyway, in that the most effective form of vitamin D is D3 - that produced by mammals, eg us - and the least effective form is D2, derived from plants exposed to UVB. And 'least effective' is being rather kind, when one considers what some say about D2, eg Dr John Cannell: 'a vitamin D-like patent drug whose patent has expired. It does not normally occur in the human body and is probably a weak antagonist at the receptor site, meaning it may actually partially block vitamin D actions.' So the raw vegan who wants to supplement has to choose between D2 as described above, or D3, which is made from animal products, eg from lanolin - a skin secretion of sheep extracted in the processing of wool - so not vegan.)

Possible health problems from supplemental vitamin D:

Nutritionist Katherine Zeratsky, RD, LD: 'Vitamin D toxicity usually results from taking an excessive amount of vitamin D supplements...you may be at greater risk if you have health problems, such as liver or kidney conditions...the main consequence of vitamin D toxicity is a build-up of calcium in your blood, causing symptoms such as: nausea, poor appetite, constipation, weakness, confusion, heart rhythm abnormalities, kidney stones...'

Charlette R Gallagher ('Taking the fear out of eating') explains that the effect of too much D on bones is similar to that of too little and that calcium may be removed from bone and too much deposited in soft tissue, resulting in arthritis-like pain and kidney damage. This is confirmed by the American Dietetic Association: 'excess amounts of vitamin D can cause...reduced bone density.' Some people have found, in taking supplemental vitamin D, that their problems have worsened rather than improved. I remember reading an account by a well-known raw fooder in the UK who noted that the condition of her children's teeth worsened while supplementing for Vitamin D rather than improving.

I'll bet some reading are thinking, 'maybe, but I don't have liver/kidney problems, and all that only applies to excessive doses!' You trust your supplement manufacturer, and are confident that the dose you are taking is not excessive. But who's deciding here how much you need? Your clever body? Does the supplement manufacturer by some magical process know exactly how much D your body made in the summer, how much it's using each day, and, therefore, the optimal dose (in supplement form) for you?

But, for those who are nevertheless convinced that the D they are taking is 'just right'...

J C Waterhouse, PhD, lead author of a study of vitamin D and chronic disease, says: 'We have found that vitamin D supplementation, even at levels many consider desirable, interferes with recovery...' [in patients].

Professor Trevor G Marshall (School of Biological Sciences and Biotechnology, Murdoch University, Western Australia, Jan 2008): 'What we've shown is that all forms of vitamin D from outside the body are counterproductive to the body's own ability to regulate its own internal production.' Marshall showed that quite nominal doses of ingested vitamin D can suppress the proper operation of the immune system. He sums up by saying that 'The comprehensive studies are just not showing that supplementary vitamin D makes people healthier.'


The animal world is full of clues as to how to live healthfully. So, as looking at domesticated mammals (ingesting various unnatural substances in their feeds) would complicate things, let's consider wild mammals such as squirrels, deer, rabbits. They don't supplement (and neither do they eat oily fish or vitamin D-fortified milk). Sure, they'll get lots more sunlight each summer than we will (which gives us a clue as to lifestyle adjustments to be made). However, the supplement manufacturers like to make us feel that no matter how much sunshine we get in the UK summer our health is going to be compromised if we don't take D supplements in the winter. Yet these animals are doing just fine! (but note they don't sit behind windows, soap themselves down daily, drink alcohol or overeat either...)


As there is less sunlight in the winter (and, if the scientists are to be believed, in the UK and similar climates it's 'the wrong sort'), perhaps we should compensate by sleeping for far longer.

Essene Gospel of Peace: 'And God will send you each morning the angel of sunshine to wake you from your sleep...But when the sun is set and your Heavenly Father sends you his most precious angel, sleep, then take your rest, and be all the night with the angel of sleep...Wake not by night, neither sleep by day...'

Now, I've tended to disregard these instructions, as, after all, in the depths of the UK winter sunset is around 5 pm and sunrise around 7 am. Sleeping from 5 pm to 7 am would be a 'problem' for me, as firstly our modern lives are organised on the premise that it's 'normal' to be awake in the evenings and secondly I've persuaded myself that 14 hours sleep would be 'too much' for me (in fact many of you will have heard me show off about how few hours I do sleep).

But light finally started to dawn for me when I read that the Hunzas, one of the longest-living, healthiest cultures in the world, 'have no electric lighting, so in the long winters they sleep longer hours, thus conserving heir energy at a time when the sun's radiance is at its lowest ebb.' (John Robbins 'Healthy at 100').

Could it be that (as with so many things!) we have got it all wrong? With electric light keeping us awake when nature wants us to sleep? As there is less sunlight in the winter, and if even the amount we do get we can't make Vitamin D from, then the obvious thing would be to 'conserve energy', so that there are fewer demands on our bodies in the winter, meaning that we maximise energy stores to be able to eliminate any toxins that do come our way?

Yes, it certainly would be a tough call to go to our beds at sunset in winter, as we would no longer be able to take part in evening social engagements, and I certainly don't feel ready to 'go there' yet. But, this winter, on the nights I'm in, I'll be feeling less guilty at going to bed at 9, and, on waking in the morning (usually around 4.30 am!), will try closing my eyes again and getting a bit more sleep.


If you're dark-skinned, I can only suggest you research more thoroughly than I have, as there are indeed some question marks here for you.

However, as a paleface in the UK, I'm no longer scared by the supplement manufacturers. I've assessed the 'danger' for myself and certainly don't believe it's 'large', and feel that it probably doesn't exist at all.

I won't be taking a D supplement, but will do my best to protect my health by:

1. Spending more time in the garden - gardening, sunbathing, socialising, whatever.
2. Not wearing sunscreen. If the sun's that strong, I'll seek shade.
3. Endeavouring (this is a hard one for me!), when the sun's shining through the study window, to stop what I'm doing, and get out there! (Or at least open the window, very wide.)
4. Wearing fewer clothes in the summer. Jeans less, short skirts more.
5. Minimising the use of soap/detergent on my body.
6. Trying to sleep longer in the winter.

And you?

I'm sure it's not coincidence that at the time of writing this article I came across this quote from Buddha: 'Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense.'


Anonymous said...

Thanks for another very interesting article Debbie. It's well timed of course for autumn! My partner is a big sun block wearer so I'll see if this influences him in any way. I can't stand the feel of it on my skin. A colleague was just yesterday singing the praises of D supplements. Somehow I think I'll survive without ... for now at least. Best wishes, Antony :-)

Debbie Took said...

Hi Antony

I survived two weeks in Thailand recently without sunscreen. I did get a little burned on thighs and shoulders, but that was because I spent too much time on a moped, ie the breeze created while travelling tricked my body into thinking it could spend longer in very intense sunlight than it should have!

n/a said...

I agree; I've never thought vitamin D has needed to be supplemented. :) Thanks for posting, as always.

Tony Brick said...
This comment has been removed by a blog administrator.
Debbie Took said...

Sorry, Tony, your comment was useful, but I removed it because it published with links to Viagra, etc!