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IMPORTANT NEWSGovernment recommendations for Vitamin D intake prove inadequateIn a study performed at Osteoporosis Research Center, Creighton University, Omaha, published in June 2007, researchers found that adults will use 3,000 to 5,000 units of vitamin D per day, if it is available. This is between 7 and 12 times the recommended daily intake. A study published in March, 2007 had already shown that 60% of British adults suffer from hypovitaminosis D, and 90% have below optimal levels in Winter and Spring. The British Government finally admitted that supplementation "may be necessary" to combat rising levels of rickets (caused by Vitamin D deficiency) in the general population. |
Vitamin D has long been known to be essential for the maintenance of healthy bones and teeth - a lack of vitamin D causes rickets in children and osteoporosis or osteomalacia in adults.
Vitamin D may be called cholecalciferol or D3, which is found in foods of animal origin. Ergocalciferol (D2) is produced by the action of light on yeast. You may also find calcitriol (1-25 dihydroxy vitamin D, or 'activated' vitamin D). This form is made in the body from standard vitamin D by the liver and kidneys, so people with liver or kidney problems are not able to use vitamin D in the standard form, and would need to take this type instead (although it is likely that it will be prescribed by their doctors).
The body makes vitamin D when exposed to sunlight, so until recently the medical profession has been of the opinion that it is not necessary to supplement in most cases. Unfortunately, in areas where the weather is cool, many people do not get sufficient sunlight on the skin to provide a decent level of vitamin D in the system, at least for the most part.
"It's not possible to make up for 50 weeks without vitamin D by taking two weeks holiday in the sun," a nutritionist told me. "And even if it was possible, vitamin D is only stored for 60 days, meaning almost 300 days without sufficient vitamin D available."
The problem is made worse because most city dwellers rarely see the sun during the winter months at all, while people in areas where outdoor life is the norm have taken to covering up to avoid skin cancer.
Apart from sunlight, which produces 10 micrograms (400IU) in 3 hours shining on the face during the summer (only a tenth as much in winter), other sources of vitamin D include cod liver oil, kippers, mackerel, tinned salmon, sardines, tuna, eggs and milk.
What does it do?Vitamin D is also needed to make calcium and phosphates from food available to the body. The calcium is used for:
Professor Michael Holick of Boston University School of Medicine believes that the skin's ability to make vitamin D from sunlight was evolution's response to the move from the calcium-rich environment of the sea onto the land, because so many systems in the body use it.
The RDA for vitamin D in Europe is 5 mcg, in the US it is 400IU, and in the UK, there is no RDA at all. 1 mcg is equal to 40IU, so the European RDA is half that of the US. However, neither comes close to the recommendations by Professor Cedric Garland and his team after their exhaustive review into studies of vitamin D between 1966 and 2004.
"We now have proof that the incidence of colon, breast and ovarian cancer can be reduced dramatically by increasing the public's intake of vitamin D," Professor Garland said. He recommends a daily dose of 25mcg (1000IU). "A glass of milk, for example, has only 100IU. Other foods, such as orange juice, yoghurt and cheese are now beginning to be fortified, but you have to work fairly hard to reach 1000IU a day," he added. "The easiest and most reliable way of getting the appropriate amount is from food and a daily supplement." |
I will refer to the study mentioned above as "the Garland study". It was published in the December 2005 Journal of Steroid Biochemistry and Molecular Biology. The authors are well respected: Cedric F. Garland, Edward D. Gorham, Sharif B. Mohr and Frank C. Garland, affiliated with the Moores Cancer Center and the Department of Family and Preventive Medicine at UCSD School of Medicine; Martin Lipkin of Strang Cancer Prevention Center, New York; Harold L. Newmark, Rutgers, State University of New Jersey and the Cancer Institute of New Jersey; and Michael F. Holick, Department of Medicine, Boston University School of Medicine.
It seems that clinicians have been underestimating the body's true requirement for vitamin D to an enormous extent, and that many disorders, including cancers, are in fact deficiency diseases. They may take a lot longer to manifest than the 'classic' deficiency disorders discovered around the 1900s, but this only highlights the importance of good nutrient levels throughout life, even when there are no obvious immediate benefits.
As if all this weren't enough, there's more:
Absolutely incredible stuff, which has led many scientists to state that vitamin D is more than just a vitamin, it's a hormone. Thankfully, you can still get it without prescription.
These people are most likely to be vitamin D deficient (though it isn't an exhaustive list):
| Who | Why |
|---|---|
| vegetarians, especially vegans | almost all good dietary sources are animal products |
| the elderly | the body's ability to metabolise vitamin D is much reduced |
| people with kidney or liver problems | both organs are needed to make the form used by the body, calcitriol |
| obese patients | vitamin D may be trapped (because it is fat-soluble), rather than being available for use |
| anyone who doesn't spend much time in the sun, or who wears sunscreen or covers up whenever they're outdoors | screening the skin from UV light prevents vitamin D production by the body |
| dark-skinned people | the skin pigment reduces vitamin D production in a similar way to sunscreen |
| anyone taking steroids on a regular basis | steroids inhibit the calcium metabolism |
| anybody who lives in countries North of latitude 35ºN or South of latitude 35ºS - and during the Winter months, anybody who lives in countries North of latitude 50ºN (this includes the whole of the UK) or South of latitude 50ºS | sunlight levels are too weak |
Although the dose recommended in the Garland study (25mcg or 1000IU) may seem high, the UK Food Standards Agency has said that taking a vitamin D supplement of 1,000IU a day is "unlikely to cause harm".
Clinicians recommend that the daily dose should not exceed 5,000IU (125 mcg). That's five times the quantity recommended here. Even so, you should know that exceeding this dosage for an extended length of time can lead to thirst, loss of appetite, nausea and vomiting, drowsiness and abdominal pain.
I've spent quite a bit of time trying to find this out. Due to the UK's dictatorial laws, you can't get a 1000IU tablet of vitamin D. However, Healthy Direct have a 400IU tablet at a good price, in packs of 60 or 360 (search for vitamin D in the search box at the top. It's about the fourth one down in the list). I aim to take one morning and evening, as I also take multivitamins and cod liver oil. So far, I haven't been able to find any other supplier.
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