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July's edition of Osteoporosis International included essential updates aboutVitamin D, fracture risk, and health:
Increasing evidence shows that the current mainstream guidelines for vitamin D intake are inadequate.
If you have had a bone density test with us, before July 2010, it is very important that you familiarize yourself with these updated guidelines. In fact, we recommend ALL women (and men!) living in the UK do so... and also be aware that we STRONGLY suspect over the next few years these guidelines will be revised - in an upward direction! This is certainly NOT a situation where the recommendations are set in stone!
Let's get started. The link below is particularly important for the over 60s; it is the International Osteoporosis Foundations' (known as the IOF) position statement for Vitamin D requirements for older adults:
Dawson-Hughes, B., Mithal., A., Bonjour, J.-P., Boonen, S., Burckhardt, P., Fuleihan, G.E.-H., Josse, R.G., Lips, P., Morales-Torres, J., & Yoshimura, N. (2010). IOF position statement: vitamin D recommendations for older adults. Osteoporosis International, 21: pp.1151-1154.
Link to news release here:
http://www.iofbonehealth.org/news/news-detail.html?newsID=327
Next: This large, heavyweight, review article, put forward a strong case for much higher intakes of vitamin D - even compared to the new IOF guidelines:
Bischoff-Ferrari, H.A., Shao, A., Dawson-Hughes, B., Hathcock, J., Giovannucci, E., Willet, W.C. (2010). Benefit-risk assessment of vitamin D supplementation . Osteoporosis International, 21: 1121-1132
Link to the article here: http://www.ncbi.nlm.nih.gov/pubmed/19957164
Here are a few key points from the benefit-risk assessment article:
- Our analysis suggests that mean serum 25(OH)D levels of about 75 to 110nmol/l (30 - 44ng/ml) provide optimal benefits for all investigated endpoints without increasing health risks. These levels can be best obtained with oral doses in the range of 1,800 to 4,000 IU of Vitamin D per day (45 - 100µg per day); further work is needed, including subject and environment factors, to better define the doses that will achieve optimal blood levels in the large majority of the population.
- The reliable evidence that excess vitamin D can cause hypercalcemia [excessive calcium in the bloodstream, sometimes seen as a sign of Vitamin D toxicity or overdose] comes from daily intakes of Vitamin D greater than 100,000 IU [!] which are far higher than those necessary to achieve benefits.
Another heavyweight study here:
Leidig-Bruckner, G., Roth, H.J., Bruckner, T., Lorenz, A., Raue, F., Frank Raue, K. (2010) Are commonly recommended dosages for vitamin D supplementation too low? Vitamin D status and effects of supplementation on serum 25-hydroxyvitamin D levels-an observational study during clinical practice conditions.Osteoporosis International, June 17th - Epub ahead of print.
Even if you simply read the last few sentences of the abstract, you get the idea - again, 2,000 - 3,000IU of Vitamin D per day are necessary to obtain a meaningful benefit:
Linkto abstract here: http://www.ncbi.nlm.nih.gov/pubmed/20556359
We say:
There are 5 different D vitamins: Vitamin D3 is synthesized endogenously (i.e., it is the one you make in your body). The other name for Vitamin D3 is cholecalciferol. Some supplements contain Vitamin D2, also known as ergocalciferol. There is some debate as to whether Vitamin D3 is ‘better' or more effective in supplement form - at the moment it would appear that both D3 and D2 can be beneficial in improving your Vitamin D status.
It is a BIG shame that ‘Vitamin' D is so called; it makes it very hard to stop thinking of it as something you obtain in sufficient quantities in your diet. Better to give it its other name, cholecalciferol.
Let's think of cholecalciferol as a chemical, or more accurately, a hormone, that your body produces when it is exposed to sunlight (rather like plants photosynthesize in sunlight). Diet is NOT a sufficient source of cholecalciferol.
Having a sufficient intake of cholecalciferol (through sunlight or supplement), and optimal levels of vitamin D in your bloodstream (known as optimal serum 25(OH)D, or serum 25OHD, 25-hydroxyvitamin D), will provide other benefits, as well as reducing your risk of fracture. There are also strong associations with bowel cancer, other nasty, killer, cancers, multiple sclerosis, depression and other mental health problems - to name but a few.
As it is unadvisable to obtain the revised quantities of cholecalciferol from food (Well - at a stretch you could - but after all of the pints of milk and portions oily fish you had eaten, you would either be fat and/or deficient in other vitamins and minerals - you wouldn't be able to eat much else), you need to make the decision: Sunlight, or supplement? Or (probably best) both?
TAKE ACTION:
How much sun exposure?
When humans (and nearly all known life on this planet) evolved, they evolved in the sun. Outdoors. We spend an unprecedented amount of time indoors - and our vitamin D status is poor as a result.
Here is a useful calculator that you can use to help you decide how much sun exposure you should be aiming for (NB! Sunscreen dramatically reduces or even stops vitamin D production):
http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html
We think that these guidelines are pretty conservative - note that they say ‘minimum sun exposure'. Furthermore, you need to commit to doing this regularly, and for life. Pretty difficult in our climate, particularly if you work full time.
Conversely, avoid excessive sun exposure - this simply means: don't let yourself burn. That will increase your risk of skin cancer (There is evidence that excessive sun exposure increases your risk of the less deadly, nonmelanoma skin cancers (usually these are easily treatable) - but maybe not the deadly skin cancer, melanoma - interesting, eh). Be aware that it takes a few hours AFTER your sun exposure before you can tell how much you have 'caught' the sun, so don't wait until you burn before you get into the shade! Adequate cholecalciferol will reduce your risk of some of the nastiest cancers there are - for example, bowel cancer. We think it is worth the increased risk of non-melanoma skin cancer, in order to reduce your risk of the really dangerous cancers. There is more information about this in Holick's book 'The Vitamin D solution' - see below for more details.
Recommending what supplements to take, and how much, is out of our area of qualification; however, we can soon recommend some important and fascinating books by experts on the subject. In fact, until mainstream guidelines catch up, we consider it an essential requirement to read at least one of these books:
The Vitamin D Solution - Michael Holick PhD, MD. This book also has useful guidelines for sun exposure. A ‘bigger' read than ‘Power of Vitamin D' - lots of statistics, facts and figures. The Question and Answer section at the back of the book is very good, we think worth the price of the book itself! Michael Holick is Professor of Medicine, Physiology and Biophysics and director of the General Clinical Research Center at Boston University Medical Centre.
Note that Holick and Zaidi do not agree on calcium requirements. We concur with Zaidi - mainly because of concern that excessive calcium intake might increase heart disease risk ; we'll let you read the books though.
We have ordered a couple of other books on the subject - we'll post any that we feel are of value! If you have found anything informative, do let us know!
A question Tracey and I are often asked is: do we take any supplements?
The answer is - yes, for the past few months! We both take between 3,000 and 5,000 IU of Vitamin D per day - unless we are outside for a few hours in the day, or on holiday in a sunny climate (in other words, we're taking these supplements practically every day!)
We also take a multi vitamin and mineral tablet every day - A ‘complete' one - there are all sorts of brands on the market, e.g., Sanatogen ‘Gold', Centrum one a day. Isobel is currently taking one that Tesco manufacture - most main supermarkets have a cheaper ‘rival'!
We have yet to find a ‘complete' supplement that contains anything but a small fraction of the cholecalciferol required - so don't think you have adequate serum 25(OH)D status simply because you're taking a multivitamin! Further, there is no chance that the Vitamin D in the multivitamin will tip us into the ‘overdose' level. Also, check the label of any supplements you are taking to ensure that you DON'T overdose on Vitamin A - that IS toxic in excess (bone resorption, and therefore weakening, being one of the main problems!). When it comes to Vitamin A, don't go over 100% of the RDA when you supplement.
