Vitamin D Health Benefits: The Sunshine Vitamin

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Sunbathing is a well known way of "taking" vitamin D - don't overdo it, though!

Sunbathing is a well known way of “taking” vitamin D – don’t overdo it, though!

Recent studies have found that vitamin D is an important aid in the prevention of colon cancer, breast cancer and ovarian cancer.

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.


UK Government admits supplementation with vitamin D may be necessary

In 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.


Cochrane Research has found that taking 35-50mcg (1400-2000 IU) vitamin D a day reduced the risk of severe asthma attacks requiring a hospital admission or a visit to A&E from 6% to 3%. The number of asthma attacks requiring steroid also dropped.

Another study by the Journal of Clinical Oncology found that low levels of vitamin D are associated with an increased risk of aggressive prostate cancer.

In 2017 the TEDDY: The Environmental Determinants of Diabetes in the Young study found that low levels of vitamin D in childhood is associated with the development of Type I diabetes. The authors believe that supplementation from an early age may help to prevent Type I diabetes developing altogether.


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).

Recent research shows improved outcomes in patients taking vitamin D3. The same research showed that patients taking vitamin D2 (sourced from vegetables) actually had worse outcomes than patients who took no vitamin D supplement at all.

Sources of vitamin D

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?

  • lowers blood pressure
  • controls levels of calcium and phosphorus in the body
  • regulates the immune system
  • maintains healthy lung tissue
  • also used in the breasts, sex organs, the stomach, pancreas, skin, hair follicles, brain and prostate gland (each of these organs has a vitamin D receptor).

Vitamin D is also needed to make calcium and phosphates from food available to the body. The calcium is used for:

  • formation and maintenance of bones and teeth
  • regulating heart rhythm
  • strengthening muscles
  • lowering insulin resistance (one of the major factors leading to heart disease)
  • regulating cell production (and protecting against uncontrolled growth, ie. cancer)
  • by the parathyroids to regulate blood pressure by controlling calcium levels

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.

How much do you need? More than you might think

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.

Reclassifying cancer, schizophrenia and multiple sclerosis as deficiency diseases?

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.

More than just your bones and teeth


  • The Garland study showed a massive reduction in the incidence of breast, ovarian and colon cancer in test participants who took 1000IU (25mcg) of vitamin D daily.
  • Professor Johan Moan of the Institute for Cancer Research, Oslo found that diagnoses of cancer made in the summer (when blood levels of vitamin D are highest) have a 50% higher survival rate when compared with winter diagnoses.
  • In a 2005 report by Oliver Gillie of Britain’s Health Research Forum (“the Gillie report”), a lack of vitamin D was linked with sixteen different cancers,
  • Studies published in the Journal of Molecular Biology in January-March 2001 and in the Journal of Andrology in January-February 2002 show a strong link between vitamin D deficiency and prostate cancer.
  • Two studies in 2000 and two in 2001 showed a link between vitamin D deficiency and colorectal cancer.

Other disorders:

  • High rates of heart disease in Scotland may be caused as much by the weak sunlight and short summers in the north, which lead to low levels of vitamin D, as by diet.
  • Peter N. Black and Robert Scragg of the University of Auckland have published a report stating that getting ample vitamin D helps people to breathe easier and more deeply. The study, published in December 2005 shows that high levels of vitamin D help to prevent COPD, emphysema and chronic bronchitis. “We were taken aback at how large the effect was,” Professor Black said.
  • Research by Professor Michael Holick of Boston shows that topical vitamin D in the form of calcitriol can be used to treat psoriasis.
  • Studies in 2000 and 2001 show a link between vitamin D deficiency and obesity. Another, in August 2001 showed that vitamin D lowers leptin production (which is a hormone produced by fat deposits in the body).
  • Disorders which involve the immune system, including type 1 diabetes, multiple sclerosis, rheumatoid arthritis, Sjogren’s Syndrome, thyroiditis, Crohn’s disease and probably others are improved by supplements of vitamin D (but not so much by eating food containing vitamin D, surprisingly). This study was carried out at the University of Alabama, Birmingham USA and published in late 2003.
  • The Gillie report found links between vitamin D deficiency and diabetes, polycystic ovary disease and dental decay.

As if all this weren’t enough, there’s more:

Nervous system:

  • The Gillie report also showed deficiency may be a contributory factor in several diseases of the nervous system including schizophrenia, as well as multiple sclerosis and high blood pressure.
  • Professor Rebecca Mason of Sydney University has discovered that vitamin D deficiency can lead to a lack of co-ordination and balance – so that an elderly person deficient in vitamin D is more likely to fall over, and as their bones will also be brittle (because vitamin D deficiency causes bone loss), they are also more likely to suffer a broken bone as a result.
  • In 2002, the New Scientist published research which suggests that lack of sunlight (and hence vitamin D) during pregnancy greatly increases the child’s risk of developing schizophrenia in later life. This research was endorsed by the Queensland Centre of Schizophrenia Research, Brisbane, Australia.
  • A 1999 study by Alam W. Hollis showed that vitamin D supplementation was a better treatment for Seasonal Affective Disorder than light boxes.
  • The November 2000 edition of the Proceeds of the Nutrition Society contains a study by CE Hayes showing that Vitamin D is a natural inhibitor of multiple sclerosis. Another study, published by Kassandra Munger of the Harvard School of Public Health in Boston in 2004, confirms this link.

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.

Who needs it?

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

It’s important to prevent deficiency in pregnant and nursing mothers

  • As mentioned above, low levels of vitamin D during pregnancy are linked with a much increased risk of schizophrenia in the child.
  • Breast milk often contains less vitamin D than bottle feeding milk (perhaps the only nutritional advantage of bottle feeding).

“1000IU dose is safe,” says UK Food Standards Agency

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.

Where can I get it?

I offer vitamin D3 1,000iu (this is the type of vitamin D which is most easily absorbed by the body) in my online shop.

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