Vitamins and minerals sit atop the nutraceutical food chain when it comes to mitigating the risk factors of diabetes and metabolic syndrome. Although vitamins play a role in blood-glucose control, minerals dominate the category with significant volumes of research on zinc, vanadium and chromium, to name a few. In 2010, researchers are focusing on a couple of other nutritional ingredients for their role in the management of hyperglycaemia and related cell damage.
Vitamin D: Vitamin D deficiency has been associated with numerous non-skeletal diseases, including type 2 diabetes mellitus (T2DM). Circulating 25- hydroxyvitamin D (25(OH)D) concentrations are considered an indicator of vitamin D status. Compared to healthy controls, subjects with T2DM have been observed to have significantly lower circulating 25(OH)D concentrations.1,2,3 Seasonal variations in glucose and insulin concentrations have been reported,4 which may correlate with seasonal variations in 25(OH)D concentrations.5 However, many studies have been short in duration or have not taken into account confounding variables.
In April 2010, researchers from Tufts University of Boston released the results of a seven-year study examining the relationship between vitamin D status and the incidence of T2D. Using a subsample from the 1972 Framingham Offspring Study, researchers discovered that those with the highest 25(OH)D status had a 40 per cent lower incidence of T2D after adjustments made for various risk factors compared to those with the lowest levels.
These findings suggest that maintaining optimal 25(OH)D levels may help prevent T2D. Increasing evidence also shows vitamin D could have therapeutic benefits for those with pre-diabetes. Thus the role of vitamin D continues to expand beyond its traditional role as a bone-health ingredient.
Selenium: In 2009, research conducted by the National Health and Nutrition Examination Survey (NHANES) suggested a detrimental health link between high plasma selenium levels and diabetes.7 However, some limitations in relation to single point sampling and specifying diabetes type (type 1 Vs.2) may have biased the trial's conclusions.
A 2010 study from the Université Montpellier in France examined the risk of developing type 2 diabetes based on selenium levels in an elderly French population over a nine-year period.8 The study found men with higher plasma selenium levels had a significantly lower risk of elevated blood glucose, a relationship that was not observed in women. This study suggests a gender-specific protective effect of higher selenium status at baseline on later occurrences of diabetes.
The rationale behind the benefits of higher selenium intake is important to address given the recent cohort of negative selenium trials. One of the primary differences in the Montpellier trial is that selenium intakes in France, and more generally in Europe, are considerably lower than in the United States.9,10 Additionally, differences in supplemental intake of selenium may have also been a factor leading to a much greater intake of selenium over time as in the NHANES trial compared to this study.
In order to further clarify these differences between these trials is important to assess the dose and time response while controlling dietary intake before any consumer recommendations can be made.
Salvia hispanica: Salba seed is known as an excellent source of omega-3 fatty acids, fibre, protein and antioxidants, and because of this profile it has been researched for its therapeutic role in diabetes care. A Canadian trial assessed whether Salba whole seed reduces postprandial blood glucose in healthy subjects, as a possible explanation for its cardioprotective effects observed in individuals with diabetes.11
The randomised, double-blind trial gave 11 healthy men and women 0, 7, 15 or 24g Salba baked into white bread. Blood samples were collected over two hours after consumption. A significant dose-response reduction in postprandial blood glucose was observed with all three doses of Salba.
The decrease in postprandial blood glucose observed in this trial provides a potential explanation for improvements in blood pressure, coagulation and inflammatory markers previously observed after 12-week Salba supplementation in type II diabetes.12
Integrating functional foods
Although much of this article has been devoted to ingredients, the functional food market has always been a melting pot of innovation for foods that have minimal impact on blood glucose. One of the most popular marketing concepts for diabetic-type foods has been the glycemic index (GI), which represents how different foods influence blood-glucose levels — the higher the GI (Scale 1-100), the higher the rise in blood glucose.
According to a European Food Safety Authority (EFSA) opinion released in February, low-GI carbohydrates were "not sufficiently characterised" and the health benefits of consuming them have not been established. The fall-out of this may mean in the short term all label and marketing reference to GI and implications of a health benefit via diabetic-type foods would have to be removed in all 27 EU member states.
This could actually work to the benefit of some suppliers who offer well characterised and researched ingredients (such as fibres) could now find a new opportunity. To date, the category for foods that can help manage blood glucose and offer health benefits to pre-diabtics and diabetics have been a second cousin to pharma in the eyes of government. However, recent surveys show that the impact of dietary supplements could save the health-care system $24 billion or more.13
The future for the diabetic food and ingredients market in the US is very strong with increasing volumes of research emerging on well-established and more novel food ingredients. However, Europe is set to face more challenging times under the gaze of the current NHCR, although this may stimulate more robust research benefiting the functional-foods market and consumer alike.
Mark J Tallon, PhD, is founder of NutriSciences Ltd, a consultancy firm specialising in health-claim substantiation, product development and technical writing. www.NutriSciences.com
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11. Vuksan V, et al. Reduction in postprandial glucose excursion and prolongation of satiety: possible explanation of the long-term effects of whole grain Salba (Salvia Hispanica L.). Eur J Clin Nutr. 2010, 64(4):436-8.
12. Vuksan V, et al. Supplementation of conventional therapy with the novel grain Salba (Salvia hispanica L.) improves major and emerging cardiovascular risk factors in type 2 diabetes: results of a randomized controlled trial. Diabetes Care 2007; 30(11):2804-10.
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