In a paper assessing the likely impact on mortality rates of doubling serum vitamin D levels from 54 to 110 nmol/l in six regions of the world, Dr William B Grant estimates that this would increase life expectancy by two years across all six regions.
"The predicted reduction in all-cause mortality rates ranges from 7.6 percent for African females to 17.3 percent for European females", claimed Grant, who is a director at the San Franciso-based Sunlight, Nutrition and Health Research Center and the author of several papers on vitamin D.
His latest study, published in the European Journal of Clinical Nutrition, concludes: “Increasing serum 25(OH)D levels is the most cost-effective way to reduce global mortality rates, as the cost of vitamin D is very low and there are few adverse effects from oral intake and/or frequent moderate UVB irradiance with sufficient body surface area exposed.”
Epidemiological approaches are valid
While many policymakers might argue that the only reliable means of determining whether vitamin D reduced the risk of disease was via randomized controlled trials (RCTs), this was not the case, insisted Grant.
“I believe that this restriction is unnecessary and is generally used to delay acceptance of more favorable policies for vitamin D and UV irradiance. Vitamin D is not a drug, for which RCTs would be required, but is instead a natural compound essential for optimal health.
“Analysis of findings from traditional epidemiological approaches should supply enough information for informed decision making.”
Agreement on vitamin D policy 'sorely lacking’
In order to increase vitamin D intakes, policymakers would first have to agree that society would benefit from higher levels, observed Grant, who recently postulated that vitamin D deficiency may have contributed to Mozart's premature demise.
“Unfortunately, such agreement is sorely lacking to date. For example, the International Agency for Research on Cancer reviewed the evidence regarding vitamin D and cancer, finding a beneficial effect only for colorectal cancer.
“However, the members of the review committee were largely dermatologists and made many errors and omissions in their review.”
IOM report failed to consider relevant studies
Meanwhile, last year's controversial report by the Institute of Medicine (IOM), which said evidence linking vitamin D with a reduced risk of certain cancers, cardiovascular disease, diabetes and autoimmune disorders was “inconsistent and inconclusive”, was also flawed, he claimed.
"Unfortunately, federal sponsors directed the committee not to consider studies where vitamin D came from non-oral sources such as solar UVB irradiance and case control studies that measured serum 25(OH)D levels at the time of disease diagnosis. These two types of studies provide much of the stronger evidence for several diseases."
Michael Holick, professor of Medicine at Boston University Medical Center, is one of several high profile vitamin D researchers that has questioned the findings.
He told NutraIngredients-USA: "In my opinion and supported by the recent Endocrine Practice Guidelines For Vitamin D to prevent vitamin D deficiency children should receive 1,000 international units of vitamin D daily and adults 1,500-2,000 international units vitamin D daily.
"The Endocrine Practice Guidelines for Vitamin D recommended that vitamin D has the non-skeletal benefit of improving muscle function and reducing risk of falling. There are many association studies and a few randomized controlled trials that support the beneficial effect of vitamin D and reducing risk of some cancers."
Vitamin D and disease
While our bodies manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.
Vitamin D-sensitive diseases that account for more than half of global mortality rates are cardiovascular disease, cancer, respiratory infections, respiratory diseases, tuberculosis and diabetes mellitus, according to Grant.
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Source: European Journal of Clinical Nutrition
Published online ahead of print: doi: 10.1038/ejcn.2011.68
‘An estimate of the global reduction in mortality rates through doubling vitamin D levels’
Author: WB Grant