Diabetes and the vitamin d connection

The global diabetes epidemic as a consequence of lifestyle-induced low-grade inflammation

The recent major increase in the global incidence of type 2 diabetes suggests that most cases of this disease are caused by changes in environment and lifestyle. All major risk factors for type 2 diabetes (overnutrition, low dietary fibre, sedentary lifestyle, sleep deprivation and depression) have been found to induce local or systemic low-grade inflammation that is usually transient or milder in individuals not at risk for type 2 diabetes. By contrast, inflammatory responses to lifestyle factors are more pronounced and prolonged in individuals at risk of type 2 diabetes and appear to occur also in the pancreatic islets. Chronic low-grade inflammation will eventually lead to overt diabetes if counter-regulatory circuits to inflammation and metabolic stress are compromised because of a genetic and/or epigenetic predisposition. Hence, it is not the lifestyle change per se but a deficient counter-regulatory response in predisposed individuals which is crucial to disease pathogenesis. Novel approaches of intervention may target these deficient defence mechanisms.

Vitamin D levels in subjects with and without type 1 diabetes residing in a solar rich environment

OBJECTIVE

Previous studies, largely in northern Europe, have suggested an association between type 1 diabetes and reduced serum 25-hydroxy(OH) vitamin D levels, a concept we tested in individuals residing in a solar-rich region (Florida).

RESEARCH DESIGN AND METHODS

Serum samples from 415 individuals residing in Florida were cross-sectionally analyzed: 153 control subjects, 46 new-onset type 1 diabetic patients, 110 established type 1 diabetic patients (samples >or=5 months from diagnosis), and 106 first-degree relatives of the diabetic patients.

RESULTS

In this study, 25-OH vitamin D levels (median, range, interquartile range [IQR]) were similar among control subjects (20.1, below detection [bd]-163.5, 13.0-37.4 ng/ml), new-onset type 1 diabetic patients (21.2, bd-48.6, 12.2-30.2 ng/ml), established type 1 diabetic patients (23.2, bd-263.8, 13.8-33.9 ng/ml), and first-degree relatives (22.2, bd-59.9, 12.7-33.1 ng/ml) (P = 0.87). Mean 25-OH vitamin D levels were less than the optimal World Health Organization level of 30 ng/ml in all study groups.

CONCLUSIONS

Reduced serum 25-OH vitamin D levels were not specifically associated with type 1 diabetes. The uniform suboptimal 225-OH vitamin D levels, despite residence in a zone with abundant sunshine, support additional dietary vitamin D fortification practices.

Seasonal variation of maternal serum vitamin D in Newfoundland and Labrador

BACKGROUND

Research has suggested that vitamin D insufficiency and deficiency is common at northern latitudes, and that vitamin D insufficiency and deficiency may be common during pregnancy. We measured the serum 25-hydroxyvitamin D (25-[OH]D) status of pregnant women across the province of Newfoundland and Labrador in both summer and winter to investigate seasonal differences, age associations, and differences in geospatial distribution across the province.

METHODS

We uniformly and randomly sampled blood from pregnant women in each of 79 census consolidated subdivisions across Newfoundland and Labrador from January to March 2007 and from July to September 2007.

RESULTS

We obtained 304 samples from the end of winter (March) and 289 samples from the end of summer (September). Mean serum 25-(OH)D concentration was 52.1 nmol/L in winter and 68.6 nmol/L in summer (P < 0.001); 89% were vitamin D insufficient in the winter and 64% in the summer (P < 0.001); 6.6% were vitamin D deficient in winter and 1.7% in summer (P = 0.003), and younger women tended to be more vitamin D insufficient in the winter than older women. The geospatial distribution of vitamin D insufficiency tends to follow a north-south distribution in the winter.

CONCLUSIONS

A significant proportion of pregnant women in Newfoundland and Labrador are vitamin D insufficient. Vitamin D insufficiency may have important adverse health consequences for both the mother and the fetus. Further study is necessary to address health outcomes and effects of vitamin D supplementation and lifestyle changes in this population.

A strategy for analyzing gene-nutrient interactions in type 2 diabetes

Type 2 diabetes mellitus (T2DM), like all chronic diseases, results from interactions between multiple genes and multiple environmental factors. Nevertheless, many research studies focus on either nutrition or genetic factors independently of each other. The challenges of analyzing gene-nutrient interactions in T2DM are the (i) genetic heterogeneity in humans, (ii) complexity of environmental factors, particularly dietary chemicals, and (iii) diverse physiologies that produce the same apparent disease. Many of these variables are not accounted for in the design or study of T2DM or, indeed, most chronic diseases, although exceptions are noteworthy. Establishing experimental paradigms to analyze the complexity of these interactions and physiologies is challenging, but possible. This article provides a strategy to extend nutrigenomic experimental strategies to include early environmental influences that may promote adult-onset disease.