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Vitamin D reduces mortality risk

The medical importance of vitamin D (calciferol) is most likely even higher than suggested by recently published studies. A study, which also involves the endocrinologist Bernhard Böhm from Ulm, has attracted enormous attention as it suggests that vitamin D deficiency increases mortality.

Böhm is still careful with his statements but is sure that the data from the researchers clearly affirm that vitamin D deficiency increases the risk of mortality. A clinical trial would substantiate the researchers’ findings, but Böhm assumes that it will be difficult to get financial support for such investigations, despite the medical importance of the findings. Vitamin D does not generate enough profits, is not a medicine and patent protection has already expired. Böhm and his colleagues are now hoping for support through the EU.

Clear association between mortality and vitamin D

Prof. Dr. Bernhard Böhm (Photo: Pytlik)

The new data are so important because it is the first time that researchers have identified a direct association between vitamin D deficiency and an elevated risk of cardiovascular diseases and mortality in general. The study found that low levels of the major forms of vitamin D (25-hydroxyvitamin D) and the biologically active 1,25-dihydroxyvitamin D seem to be linked to an increased risk of mortality.

The findings are based on a large patient sample and hence statistically reliable. The data were acquired from the blood samples of 3,200 men and women of the LURIC study collective and have been monitored over the last eight years. The average age of the study participants was 62. They were recruited between 1997 and 2000; 737 participants have died in the meantime.

Seasonal fluctuations of the vitamin D level

The study was conducted to find an answer to the old, but still unanswered question on the association between the vitamin D level and cardiovascular diseases. More people seem to contract cardiovascular diseases during the winter months. The researchers also predicted that the vitamin D level rose during the summer months and hence reduced the risk of contracting such diseases.

The LURIC data showed that a low vitamin D level is associated with an increased risk of mortality. Death rates were higher among those individuals that had the lowest serum vitamin D levels.

Studies: vitamin is of growing importance for human health

Recently, many studies have given weight to the significance of vitamin D for human health. Vitamin is a steroid hormone. It is clear that vitamin D performs many regulatory functions in the body: It regulates the absorption of calcium in the intestines, which leads to improved calcium availability and hence stronger bones. The researchers were able to show in animal experiments that vitamin D also reduces inflammation. Although inflammations are closely associated with heart disease (and also numerous other illnesses such as hypertension and diabetes), previous investigations did not focus on the role vitamin D might have here.

The mechanism of action is now known

Böhm was surprised to find that the non-active ‘storage’ form of vitamin D (25-hydroxyvitamin D) plays the decisive role and 1,25 dihydroxyvitamin D (which is known to have a high metabolic effect in a Petri dish) a less important role. Since many somatic cells are able to store vitamin D, Böhm assumed that the transformation takes place according to local needs within the body. However, the researchers did not examine how vitamin D targets inflammatory centres. Böhm has plans to publish a study on the mechanism of action of vitamin D in the near future. The study was rated positive by all reviewers that assessed the study; something Böhm states has never happened before.

An expected surprise

Why were such important results not found earlier? Böhm assumes that this has something to do with the patients that participated in the study. In 2007, Böhm published a paper with some colleagues on natriuretic peptides, which are involved in the homeostatic control of sodium in the body and ensure that the body releases or retains sodium. These peptides, which also serve as markers for cardiac insufficiency, apparently also play a role in cardiovascular dysfunctions. The surprising findings of Böhm and his colleagues now reveal that vitamin D directly influences the system of natriuretic peptides.

Vitamin D decreases risk of kidney problems

Only a clinical trial can answer the question of the effectiveness of vitamin D: Will the administration of vitamin D pills reduce fatalities? Böhm’s confidence is the result of an additional observation in kidney patients who received vitamin D pills. The patients’, whose vitamin metabolism was greatly disturbed, had very low levels of metabolically effective vitamin D.

According to Böhm, these patients have a disproportionately high risk of fatal cardiovascular diseases, even compared with cardiac patients. This risk of death can be reduced by the administration of vitamin D, even though other risk factors such as blood lipids or high blood pressure remain the same. According to Böhm, this fact alone, although it was observed in a far smaller group of patients, suggests the importance of vitamin D, and can also be generalised for larger groups, including cardiovascular patients without kidney dysfunction.

Vitamin D is a kind of central chemical switch

Böhm believes his results have even greater consequences. He refers to new insights into osteoporosis research, which indicate a striking link between high mortality resulting from fractures close to hip joints one year after surgery, and the original vitamin D level of a person.

The level of vitamin D also plays a role in sudden cardiac death, is significant for musculature (muscular strength) and an “important modulator” of cardiovascular diseases. There is yet more: according to Böhm, there are also indications that type 1 diabetes directly correlates with a reduced level of vitamin D. Animal tests have already shown that vitamin D improves the animals' immune response.

While the exact mechanism of action of vitamin D is yet to be clarified, the indirect influence of vitamin D on the mortality risk appears obvious and seems biologically plausible.

Vitamin D deficiency, a global phenomenon

80 to 90 per cent of the vitamin D requirements of humans are covered through sunlight and the chemical processes occurring in the deeper layers of skin. Only about 10 to 20 per cent of our daily vitamin D requirements are covered by foods (e.g., fatty fish or eggs). The main cause of vitamin D deficiency is a lack of exposure to sunlight: the lack of outdoor exercise, extensive stays in closed rooms as well as increased air pollution.

50% of senior citizens in the first world have too low vitamin D levels

Typical groups at risk among adults include: nursing home residents, individuals who predominantly work night shifts or during the day in closed rooms, as well as dark-skinned people. Current numbers show that 50 to 60 percent of the elderly population in North America and the rest of the world suffer from vitamin D deficiency. According to Böhm, these people are often unable to counteract inflammations. Due to progressive urbanisation and modern lifestyles, children are also increasingly affected by vitamin D deficiency.

The effects of vitamin D on human physiology cannot currently be reduced to one or two basic mechanisms. There is, however, growing evidence that the human body must be supplied with enough vitamin D to ensure a well-functioning metabolism. The German Nutrition Society recommends an average of five micrograms of vitamin D per day and twice this amount for infants, toddlers and senior citizens.

A half an hour stroll at lunchtime

What do medical doctors recommend health-conscious people that want to replenish their vitamin D stores? Böhm recommends a short, intense dose of sunshine at midday. This time of day has the best sun spectrum for vitamin D synthesis in the skin. And those who take commercial vitamin D supplements can basically do no wrong as, according to Böhm, the steroid hormone is not toxic. The expert assures that an overdose is nearly impossible. The ideal value of over 30 nanograms/ml can be detected by a simple, inexpensive routine test of calcium levels.

wp, 4 August 2008
© BIOPRO Baden-Württemberg GmbH

Dobnig, Harald et al.: Independant Association of Low Serum 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels With All-Cause and Cardiovascular Mortality, in. Archives of Internal Medicine Vol. 168(Nr. 12), S. 1340ff.

März, Winfried et al.: N-Terminal Pro-B-Type Natriuretic Peptide Predicts Total and Cardiovascular Mortality in Individuals with or without Stable Coronary Artery Disease: The Ludwigshafen Risk and Cardiovascular Health Study, in: Clinical Chemistry 53:6; 1075-1083, 2007.

Mayo Clinic (2008, July 15). Vitamin D: Builds Bones And Much More. Science Daily. Retrieved July 17, 2008, from: https://www.gesundheitsindustrie-bw.dewww.sciencedaily.com/releases/2008/07/080714162515.htm

Dalhousie University (2008, February 16). A Ray Of Sunshine In the fight Against Cancer: Vitamin D May Help. Science Daily. Retrieved July 17, 2008, from: https://www.gesundheitsindustrie-bw.dewww.sciencedaily.com/releases/2008/02/080206210402.htm

Vitamin D und Krebsvorbeugung: Experte empfiehlt 30 Minuten Sonne pro Tag, in: aid-infodienst, 21/08, 21 May 2008
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