Sunday, 12 July 2015

Diabetes in Australia and Vitamin D deficiency. Is there a link?

Diabetes in Australia and Vitamin D deficiency. Is there a link?

Literature review
Russell Setright

CVD and Diabetes
Recent research has found significant association between low serum levels of 25(OH)vit D and an increase in the incidence of diabetes, CVD and metabolic syndrome. This research examined 28 studies that included 99,745 men and women across a variety of ethnic groups. The studies revealed a significant association between high levels of vitamin D (25(OH)VitD) and a decreased risk of developing cardiovascular disease (33% compared to low levels of vitamin D), type 2 diabetes (55% reduction) and metabolic syndrome (51% reduction)  ( Levels of vitamin D and cardiometabolic disorders: Systematic review and meta-analysis J.Maturitas Volume 65, Issue 3, 225-236, March 2010).

Further evidence relating to the befits of adequate vitamin D levels was presented at the American College of Cardiology’s annual scientific session in Atlanta March 2010. Researchers from the Intermountain Medical Center Heart Institute in Murray, Utah, reviewed 31,000 of their patients aged 50 or older found that those with the lowest levels of serum 25(OH)vitD had a 170-per-cent greater risk of heart attacks than those with the highest serum levels.
Also, according to the authors of this study, the benefits of having more vitamin D were not limited to a cut in heart-attack risk. Those with the lowest readings also had an 80-per-cent greater risk of death, a 54-per-cent higher risk of diabetes, a 40-per-cent higher risk of coronary artery disease, a 72-per-cent higher risk of kidney failure and a 26-per-cent higher risk of depression.

Diabetes
The incidence of diabetes in Australia is increasing and, at the same time we are seeing a corresponding deficiency in vitamin D levels. As the above studies show there is a strong link between the development of diabetes type-2 and vitamin D deficiency. The following study examines the link in childhood type-1 diabetes and vitamin D supplementation.
A review and meta-analysis of the data from five trials that included 6455 infants, of which 1429 were cases and 5026 controls was published in the Archives of Disease in Childhood. The data from the five observational studies, found that infants who received vitamin D supplements were 29 per cent less likely to develop type-1 diabetes than non-supplemented infants (Zipitis C et al. "Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis" Archives of Disease in Childhood (British Medical Journal) .2007).

Also, a study, published in the Journal of the American Medical Association, September 2007 looked at 1770 children at high risk of developing type-1 diabetes.
Their study reported that an increased intake of omega-3 fatty acids from marine sources may reduce a child's risk of developing type-1 diabetes by 55 per cent.Vitamin D found in cod liver oil, a popular marine supplement, may have been a contributing factor.

Cardio Vascular Disease
Results of a large case-control study (Health Professionals Follow-up Study) was conducted in 18, 225 men. During the proceeding 10 years of follow-up, 454 men developed nonfatal myocardial infarction or fatal coronary heart disease. After adjustment for matched variables, men deficient in 25(OH)D less than 37.4nmol/Lt were at increased risk for MI (heart attack) compared with those considered to be sufficient in 25(OH)D 74nmol/mL.  And, after additional adjustment for family history of myocardial infarction, body mass index, physical activity, alcohol consumption, history of diabetes mellitus and hypertension, ethnicity, region, marine n-3 intake, low- and high-density lipoprotein cholesterol levels, and triglyceride levels, this relationship remained significant.
Even men with intermediate 25(OH)D levels were at elevated risk relative to those with sufficient 25(OH)D levels .

The authors concluded that Low levels of 25(OH)D are associated with higher risk of myocardial infarction, even after controlling for factors known to be associated with coronary artery disease (Giovannucci, E. et al. 25-Hydroxyvitamin D and Risk of Myocardial Infarction in Men, Arch Intern Med. 2008;168(11):1174-1180).

These benefits in part may be explained by maintaining optimal vitamin D can slow the turnover of leukocytes by inhibiting pro-inflammatory overreaction resulting in a reduction of leukocyte telomere shortening. Shortening of leukocyte telomeres is a marker of aging and a predictor of aging-related disease. Length of these telomeres decreases with each cell division and with increased inflammation.

A  study that examined whether vitamin D levels would attenuate the rate of telomere attrition in leukocytes, such that higher vitamin D concentrations would be associated with longer LTL. The results of this study suggested that higher vitamin D (25(OH)VitD) concentrations, which can be modified through vitamin D  supplementation, are associated with longer LTL, would explain the potentially beneficial effects of vitamin D on aging and age-related diseases.

(Richards J, et al.  Higher serum vitamin D concentrations are associated with longer leukocyte telomere length in women, American Journal of Clinical Nutrition, Vol. 86, No. 5, 1420-1425, November 2007)


Discussion
Although I have only included a few of the many studies that were evaluated, the message is consistent and clear in all of the studies.  Vitamin D deficiency is a major health issue and must be addressed.
Excessive sun exposure causes skin damage and in an endeavour to curb the incidence of skin cancer, the advice to cover up, apply sun screen and keep out of the sun is widely being practised. OH&S legislation has made this policy mandatory for workplace and schools. 
However, this practise has in part contributed to the vitamin D dilemma in Australia and diseases associated with this deficiency, including melanoma are on the increase and of major concern.

Governments and Health Care Professionals urgently need to examine the role that vitamin D deficiency plays in their disease treatment and prevention plans and consider supplementation and dietary changes as an effective alternative to dangerous sun exposure practises.
Also, periodic 25(OH)VitD blood tests would be advisable.

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