New roles for dairy proteins

Dairy proteins can potentially reduce blood glucose levels, according to Food for Health Ireland

Often seen as ‘traditional’, the dairy industry is now adapting, embracing and integrating a wide range of cutting edge technologies. These offer more efficient methods to discover new ingredients and alternative food matrices, as well as providing insights into ingredients’ specific mechanisms of action and helping to improve health and wellness.

Milk is an excellent source of nutrients and also exhibits a range of biological activities that influence digestion, growth and development, and resistance to disease. These biological activities are mainly due to the peptides and proteins present in milk. However, some of the biological activity of milk proteins is latent, and bioactivity is only released upon proteolytic action. Dairy ingredient manufactures can produce bioactive peptides by bacterial fermentation and/ or enzymatic hydrolysis.

Food for Health Ireland (FHI) researchers at University College Dublin (UCD) are currently testing milk-derived bioactives for their capability to improve blood glucose control, and therefore decrease the risk of type 2 diabetes mellitus (T2DM) and its comorbidities, if incorporated into a functional food.

T2DM is a key focus area for FHI as the incidence of type 2 diabetes mellitus (T2DM) has increased rapidly on a global scale. Approximately 366 million people worldwide had diabetes in 2011, with this figure expected to rise to 552 million by 2030 (1). T2DM accounts for 90 per cent of people with diabetes worldwide.

Dairy and glycemic control

An emerging body of evidence in academic literature suggests that intake of dairy products is associated with a lower risk of T2DM. A recent meta-analysis concluded that a high intake of dairy products was associated with a significantly lower risk of T2DM (2). Taking into account results from 17 studies the authors found a significant inverse association between intakes of dairy products, low-fat dairy products and cheese, and the risk of T2DM. Furthermore a meta-analysis performed by Tong and colleagues demonstrated a significant inverse association between low fat dairy and yogurt, and T2DM. Increased consumption of total and low-fat dairy products were seen to decrease the risk of T2DM by five per cent and 10 per cent respectively (3).

In addition, a number of prospective cohort studies have investigated the relationship between dairy products and glycemic management (4,5,6,7,8). Overall, results appear promising for an inverse association between dairy products and risk of T2DM. One of the key studies in this area is The Australian Obesity and Lifestyle Study (8), which showed a significant inverse association between high dairy intake and risk of T2DM in men (odds ratio 0.53). Similar results have emerged in other cohorts around the world.

Evidence from acute

interventions

While strong evidence exists from cohort studies, there is a lack of randomised controlled trials (RCTs) examining dairy consumption and the risk of T2DM. A recent RCT examined the effects of long term (six month) dairy consumption

on metabolic health in 23 healthy

volunteers (9). High dairy consumption (four servings per day) was associated with significantly improved plasma insulin and insulin resistance in comparison with the low dairy (maximum two servings per day) group. A limited number of acute intervention studies have been performed examining the link between milk proteins and glycemic management. Overall, the results seem positive with dairy proteins and peptides showing a positive effect on glucose levels (10,11). From these studies evidence is mounting for the positive health benefits of milk proteins and peptides in acute studies.

Further research is needed to validate the role of dairy in reducing and managing blood glucose. However, a multidisciplinary and integrated approach, such as that adopted by FHI, should lead to promising new dairy-based products, which have the potential to improve glycemic management.

Note: Food for Health Ireland (www.fhi.ie) is an innovation centre for the development of nutritional functional ingredients to improve health, wellness and quality of life. It links the scientific capabilities of Irish Academic partners (UCD, UCC, UL, DCU, NUIG, NUIM, Teagasc) with the Irish Food Industry

References

(1) Whiting, D R, Guariguata L et al (2011) IDF diabetes atlas: global estimates of the prevalence of diabetes for 2011 and 2030. Diabetes Res Clin Pract 94(3): 311-321

(2) Aune, D, Norat T, et al (2013). Dairy products and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies. Am J Clin Nutr 98(4): 1066-1083

(3) Tong, X, Dong J Y, et al (2011). Dairy consumption and risk of type 2 diabetes mellitus: a meta-analysis of cohort studies. Eur J Clin Nutr 65(9): 1027-1031

(4) Choi, H K, Willett, W C, et al (2005). Dairy consumption and risk of type 2 diabetes mellitus in men: a prospective study. Arch Intern Med 165(9): 997-1003

(5) Fumeron, F, Lamri, A et al (2011). Dairy products and the metabolic syndrome in a prospective study, DESIR. J Am Coll Nutr 30(5 Suppl 1): 454S-463S

(6) Sluijs, I, Forouhim, N G et al (2012). The amount and type of dairy product intake and incident type 2 diabetes: results from the EPIC-InterAct Study. Am J Clin Nutr 96(2): 382-390

(7) Soedamah-Muthu, S S, Verberne, L D et al (2012). Dairy consumption and incidence of hypertension: a dose-response meta-analysis of prospective cohort studies. Hypertension 60(5): 1131-1137

(8) Grantham, N M, Magliano, D J et al. (2013). The association between dairy food intake and the incidence of diabetes in Australia: the Australian Diabetes Obesity and Lifestyle Study (AusDiab). Public Health Nutr 16(2): 339-345

(9) Rideout, T C, Marinangeli, C P et al (2013). Consumption of low-fat dairy foods for 6 months improves insulin resistance without adversely affecting lipids or bodyweight in healthy adults: a randomized free-living cross-over study. Nutr J 12: 56

(10) Frid, A H, Nilsson, M et al. (2005). Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects. Am J Clin Nutr 82(1): 69-75

(11) Jonker, J T, Wijngaarden, M A et al (2011). Effects of low doses of casein hydrolysate on post-challenge glucose and insulin levels. Eur J Intern Med 22(3): 245-248