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Vitamin D - how much do I need?

As our knowledge has grown, it has become evident that vitamin D is essential for the optimum functioning of most of the body’s systems. Originally it was thought that the kidneys provided the body’s needs. Now we know that many individual organs produce their own supplies (perhaps these are ‘back-up supplies’) as well. The body needs adequate levels of vitamin D in order to absorb calcium from food. The growing list of illnesses linked to inadequate blood levels of vitamin D now includes osteomalacia (rickets), periodontal (gum) disease, osteoporosis, rheumatoid arthritis, high blood pressure, colon, breast, prostate and ovarian cancers, heart disease, multiple sclerosis, atherosclerosis, tuberculosis, seasonal affective disorder, depression, obesity and type 1 diabetes.

View Vitamin Research Products' vitamin D3 1,000iu supplement

How much vitamin D3 do I need?
This is controversial. Taking all of the latest research into account ...

for good health ...

  • Dr. John Cannell of The Vitamin D Council, recommends a daily supplement of 2,000 international units (iu)
  • top vitamin D researcher Dr. Robert Heaney of Creighton University in Omaha (US) warns that around a fifth of the population (see below) may need more

The US Government ruled that [1] 2,000iu a day is safe for all adults (children - 1,000iu) in normal health to take without a doctor’s supervision.

to prevent ill health ...

even conservative bodies like the Canadian Cancer Society (CCS) and the Canadian Dermatology Association (CDA) now recommend taking 1,000iu a day from October to April, and taking 1,000iu a day all year round for adults susceptible to vitamin D3 deficiency, e.g.:

  • people who are older
  • people with dark skin
  • people who don’t go outside often, and
  • people who habitually wear clothing that covers most of their skin

Cautionary notes
Although, given enough direct exposure to sunshine, the body produces 20,000iu a day (see below), and one study suggested that a healthy adult man used 3,000 - 5,000iu a day, [2] until more research has been carried out on the safety of taking in vitamin D3 via the mouth, the Vitamin D Council cautions that:

  • people taking more than 2,000iu a day should work with a doctor or nutritional therapist and should check their blood serum vitamin D3 levels several times a year
  • vitamin D3 supplements should not be taken at the same time as preformed retinol vitamin A supplements. They interfere with vitamin D3's functions. (Taking vitamin D3 at the same time as beta-carotene supplements should be fine, but you should check with your GP or nutritional therapist

View Vitamin Research Products' vitamin D3 1,000iu supplement

The body is much more D3 hungry
The body appears to think that it needs significantly more than either Governments or researchers recommend. Given enough direct sunlight on the skin and eyes, it will actually produce 20,000iu a day for itself. Even more amazingly, it limits the amount of new vitamin D3 produced to 20,000iu a day. After that, if any more is produced, the same direct sunshine works to destroy it! No-one knows why yet, but zoologists do know that Nature never designs systems as complex as the vitamin D3 system for no good reason. The massive amount made so quickly underlines the importance of vitamin D3 to good health.

Official recommended daily allowances
The US Department of Health, on the other hand, still only recommends a daily intake of ...

  • Birth to 50 years: 200IU
  • Breastfeeding mothers: 200IU
  • 51 to 70 years: 400IU
  • 70+ years: 600IU

So why are there such big differences between Government RDAs for D3, the advice from medical experts (see above) and specialist medical associations and what the body does?

  • RDAs were first set during World War II by the US National Academy of Sciences as guidelines for keeping soldiers alive, rather than for the best possible health.
  • RDAs are usually way behind the latest research findings as to what is needed to reduce the risks of developing a particular disease

View Vitamin Research Products' vitamin D3 1,000iu supplement

[1] US Institute of Medicine Food and Nutrition Board 1997
[2] Heaney,R et al. Am. Jnl. Clin. Nutr. 2003;77:204-10

(12278) Nick Anderson. Green Health Watch 13.2.06