It is now well recognized that with the use of so much sunscreen our vitamin D levels are reduced.  This is of concern when vitamin D is such a necessity for optimal functioning of our immune systems.  Vitamin D is a fat stored vitamin, thus during summer it would usually be synthesized in greater amounts to be stored for the onset of the winter colds and flu’s.  Not to mention the fact that it is required for other immune responses such as fighting cancer.

Vitamin D’s chemical structure is almost identical to cholesterol.  The conversion of vitamin D in the skin with further metabolism by liver enzymes produces the ‘active or hormonal’ form of vitamin D .  Parathyroid hormone is also required for the conversion and a deficiency of either calcium or phosphorus may impair the active form from being fully synthesised.

Vitamin D is stored in both muscle and fat tissue, with vitamin D3 levels in the serum correlated to the amount of D3 in fat tissue.  Radioactive studies on D3 found the whole body half-life of D3 molecules to be about 62 days.  Vitamin D status for beneficial health effects may need to be around 30 ng/ml (75 nmol/L)  although there is debate that it should in fact be higher.

A deficiency of vitamin D has been reported by researchers as a worldwide epidemic.  Of 28 studies assessing worldwide vitamin D status, Thailand was the only country that demonstrated a study population with mean serum values of above 33ng/ml.  As an important hormone in the body with receptors in a multitude of tissues, a deficiency of vitamin D can lead to and exacerbate a number of health disorders.  Symptoms such as inflammatory diseases, bone metabolism disorders, infectious diseases and immunological imbalances.  Dietary sources of vitamin D are inadequate to meet daily requirements.  Therefore, the majority of the world’s population relies on unimpeded skin exposure to UVB rays to allow for the endogenous production of vitamin D, or supplementation is required.

Vitamin D from food sources is absorbed primarily in the duodenum, thus those with malabsorptive disorders of the small intestine, such as Crohn’s disease, coeliac or gluten intolerance, leaky gut syndrome and ulcerative colitis have an increased risk of a deficiency.  Obesity is also a risk factor for deficiency due to the inability of fat tissue to sequester vitamin D.  The liver and kidney’s play a direct and indirect role in the physiology of vitamin D and therefore diseases of either organ could adversely effect the status of vitamin D.

More than 200 human genes that contain a vitamin D response element have been identified.  It is known that vitamin D regulates gene expression in many cell processes including apoptosis, proliferation, differentiation among other immune-modulating effects that may be associated with cancer.

As early as 1940 observation was made between the prevalence of skin cancer and a decrease in other cancers.  A cancer research article states “It is suggested that we may be able to reduce our cancer deaths by inducing a partial or complete immunity by exposure of suitable skin areas to sunlight or the proper artificial light rays of intensity and duration insufficient to produce an actual skin cancer.  A closer study of the action of solar radiation on the body might well reveal the nature of cancer immunity”.

Published in Breast Journal March 2008 it confirmed the 1940 hypothesis by demonstrating a decrease in breast cancer risk in 107 countries with increased UVB rays.  Other studies highlight an inverse association between serum levels and the risk of breast and colorectal cancers.  It was concluded that a 50 percent decreased incidence of colorectal and breast cancer occurred with a maintenance of serum vitamin D levels of greater than 34 ng/ml (colorectal cancer) and greater than 52 ng/ml (breast cancer).

Many other cancers have also been associated with decreased UVB exposure and/or deficient vitamin D serum levels, such as Hodgkinslymphoma, lung and prostate cancers.

Unimpeded mid-day sun exposure of  the whole may lead to endogenous synthesis equivalent to ingesting10,000 IU of vitamin D.  With six percent of skin exposed leadingto a slight pinking may provide around 600 IU.  When this is unable to be done then supplementation of 1000 IU per day is required to bring the serum levels to 30 ng/ml in around 50 percent of the general population.  If a deficiency is suspected a blood test can determine the levels and in severe cases a dose of 2000-5000 IU per day may be required for three months before retesting.

Numerous safety trials have recommended the experts lift the upper limit for vitamin D to 10,000 IU.  Vitamin D toxicity occurs typically when much larger doses are taken per day for months on end.  These levels were 50,000 IU and above.  A toxicity may show as hypercalcemiaor symptoms of anorexia, weight loss, weakness, fatigue, fever, chills, disorientation, vomiting, dehydration,  polyuria,  constipation, abdominal pain and renal dysfunction.

Article written by Carolyn McSweeney, Clinical Medical Herbalist, Clinical Nutritionist, NLP Master Practitioner and HNLP Coach
Text based on Alternative Medicine Review Vol 13, 2, 2008
Cancer, Lowered Immunity and Vitamin D Deficiency