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Back to Roles on Certain Health Conditions

Milk Products and Type 2 Diabetes: An Update

The relationship between milk product consumption and type 2 diabetes has been examined in several meta-analyses. Evidence to date suggests that milk product consumption is associated with a reduced risk of developing type 2 diabetes.

Highlights

  • Milk product consumption is associated with a decreased risk of developing type 2 diabetes;
  • Total dairy and low-fat milk products are largely associated with a reduced risk of type 2 diabetes;
  • High-fat dairy/dairy fat is either not associated or inversely associated with the risk of type 2 diabetes;
  • Fermented dairy, including cheese and yogurt, is either not associated or inversely associated with the risk of type 2 diabetes;
  • There appears to be an inverse dose-response relationship between yogurt and cheese and the risk of type 2 diabetes.

Synopsis

Several meta-analyses of numerous prospective cohort studies have examined the role of milk products in the development of type 2 diabetes. The totality of the evidence to date suggests that there is an inverse association between milk product consumption, including specific milk products such as yogurt and cheese, and the risk of developing type 2 diabetes.

The Evidence

A meta-analysis published in 2014 investigated the association between the consumption of different types of dairy products and the risk of type 2 diabetes. The analysis consisted of data from 14 prospective cohort studies (N = 459,790), including the Health Professionals Follow-Up Study, the Nurses’ Health Study and the Nurses’ Health Study II.1

  • Total, high-fat and low-fat dairy intake were not associated with the risk of type 2 diabetes;
  • Yogurt consumption (both plain and flavoured) was associated with an 18% decreased risk of type 2 diabetes (pooled relative risk of 0.82 per one serving of yogurt/day, 95% CI: 0.70-0.96).

Gao et al. conducted a meta-analysis to examine the dose-response relationship between dairy products and the risk of type 2 diabetes. The study included a total of 15 prospective cohort studies and 1 case-cohort study (N = 526,998).2

  • An inverse association was found between total dairy intake and the risk of type 2 diabetes, with a pooled relative risk of 0.94 per 200 g/day (95% CI: 0.91-0.97);
  • High-fat dairy was not associated with the risk of developing type 2 diabetes;
  • Low-fat dairy was associated with a 12% reduced risk of type 2 diabetes per 200 g/day;
  • Cheese consumption was associated with a 20% reduced risk of type 2 diabetes per 30 g/day;
  • Yogurt consumption was associated with a 9% decreased risk of type 2 diabetes per 50 g/day.

Another dose-response meta-analysis of 17 prospective cohort studies evaluated the association between dairy consumption and the risk of type 2 diabetes (N = 526,482).3

  • Total dairy consumption was associated with a 7% reduced risk of type 2 diabetes per 400 g/day;
  • High-fat dairy product intake was not associated with type 2 diabetes;
  • The consumption of low-fat dairy products was associated with a reduced risk of type 2 diabetes, with a relative risk of 0.91 per 200 g/day (95% CI: 0.86-0.96);
  • A higher consumption of fermented dairy was associated with a reduced risk of type 2 diabetes;
  • Cheese consumption was associated with a risk reduction of 8% for type 2 diabetes per 50 g/day (95% CI: 0.86-0.99);
  • A non-significant inverse association was observed between yogurt consumption and type 2 diabetes, with a relative risk of 0.78 (95% CI: 0.60-1.02).

A nested case-cohort within the European Prospective Investigation of Cancer (EPIC)-Norfolk Study assessed the association between dairy consumption and type 2 diabetes. The subcohort consisted of 4,127 adults aged 40 to 79 years, who were followed for 11 years. Dietary data were measured using a 7-day food diary.4

  • Total dairy intake was not associated with the risk of developing type 2 diabetes;
  • High-fat dairy (≥3.9% fat), low-fat dairy, milk (whole or reduced-fat), cheese and high-fat fermented dairy were not associated with the risk of type 2 diabetes;
  • An inverse association was observed between low-fat fermented dairy and the risk of type 2 diabetes;
  • Higher consumption of yogurt was associated with a 28% decreased risk of type 2 diabetes, with a hazard ratio of 0.72 for 22 g/day yogurt as compared to 0 g/day (95% CI: 0.55-0.95, ptrend = 0.017).

In a prospective cohort study, the association between dairy fatty acids and incident type 2 diabetes was investigated. A triethnic cohort of 1,625 Hispanic, African American and non-Hispanic white adults aged 40 to 60 years who were followed for 5 years was included in the study.5

  • Serum pentadecanoic acid (15:0) was found to be an independent biomarker for total dairy intake;
  • Serum pentadecanoic acid was associated with a 27% decreased risk for incident type 2 diabetes;
  • The highest tertile of serum pentadecanoic acid was associated with a significantly lower risk of type 2 diabetes after 5 years, with an odds ratio of 0.47 (95% CI: 0.26-0.86).

Potential Mechanisms

The mechanisms underlying the inverse association between milk product intake and type 2 diabetes remain to be elucidated.

Milk products may help in weight management and have a protective effect against hypertension and metabolic syndrome, which are major risk factors for type 2 diabetes.

Glucose homeostasis

In a systematic review, results from longer intervention studies indicated that higher dairy intake may help improve insulin sensitivity.6 A 2015 randomized controlled crossover trial found that dairy products had a more favourable effect than sugar-sweetened products on glucose homeostasis among individuals at risk for type 2 diabetes.7

Calcium and vitamin D

Calcium and vitamin D, as well as magnesium, may reduce the risk of type 2 diabetes through their role in modulating insulin resistance, pancreatic beta-cell function, and inflammation.3,8

Milk proteins

  • Whey protein may promote insulin sensitivity, improve glucose tolerance and lipid profile, and help in weight control;1,6,9
  • Bioactive peptides may also help in improving blood pressure.

Dairy fatty acids

  • Trans-palmitoleic acid (trans-16:1n-7) has been associated with lower insulin resistance, lower blood pressure, a better lipid profile and a reduced risk of type 2 diabetes;10,11,12
  • Pentadecanoic acid (15:0) has been inversely associated with fasting plasma glucose and incident type 2 diabetes;5,12,13
  • Conjugated linoleic acid may play a role in the prevention of obesity, which is a risk factor for type 2 diabetes.

Other dairy components

  • Probiotic bacteria, found in fermented milk products such as yogurt, have been shown to improve blood lipid profile and antioxidant status of individuals with type 2 diabetes.1,4
  • Milk products, particularly fermented ones, contain menaquinones (vitamin K2), which have been associated with reduced type 2 diabetes risk.3,4

Conclusions

Evidence suggests that there is an inverse association between the consumption of milk products and the risk of developing type 2 diabetes.

High-fat milk products are not associated with type 2 diabetes. In fact, certain dairy fatty acids may have a beneficial role in the prevention of type 2 diabetes.

The association between different types of milk products and the risk of diabetes is less clear, but evidence suggests that yogurt and cheese may be protective against type 2 diabetes.

References

  1. Chen M et al. Dairy consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. BMC Med 2014;12:215.
  2. Gao D et al. Dairy products consumption and risk of type 2 diabetes: systematic review and dose-response meta-analysis. PLoS One 2013;8:e73965.
  3. Aune D et al. Dairy products and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies. Am J Clin Nutr 2013;98:1066-1083.
  4. O’Connor LM et al. Dietary dairy product intake and incident type 2 diabetes: a prospective study using dietary data from a 7-day food diary. Diabetologia 2014;57:909-917.
  5. Santaren ID et al. Serum pentadecanoic acid (15:0), a short-term marker of dairy food intake, is inversely associated with incident type 2 diabetes and its underlying disorders. Am J Clin Nutr 2014;100:1532-1540.
  6. Turner KM et al. Dairy consumption and insulin sensitivity: a systematic review of short- and long-term intervention studies. Nutr Metab Cardiovasc Dis 2015;25:3-8.
  7. Maki KC et al. Sugar-sweetened product consumption alters glucose homeostasis compared with dairy product consumption in men and women at risk of type 2 diabetes mellitus. J Nutr 2015.
  8. Pittas AG et al. The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. J Clin Endocrinol Metab 2007;92:2017-2029.
  9. Bjørnshave A and Hermansen K. Effects of dairy protein and fat on the metabolic syndrome and type 2 diabetes. Rev Diabet Stud 2014;11:153-166.
  10. Mozaffarian D et al. Trans-palmitoleic acid, metabolic risk factors, and new-onset diabetes in US adults: a cohort study. Ann Intern Med 2010;153:790-799.
  11. Mozaffarian D et al. Trans-palmitoleic acid, other dairy fat biomarkers, and incident diabetes: the Multi-Ethnic Study of Atherosclerosis (MESA). Am J Clin Nutr 2013;97:854-861.
  12. Kratz M et al. Dairy fat intake is associated with glucose tolerance, hepatic and systemic insulin sensitivity, and liver fat but not β-cell function in humans. Am J Clin Nutr 2014;99:1385-1396.
  13. Forouhi NG et al. Differences in the prospective association between individual plasma phospholipid saturated fatty acids and incident type 2 diabetes: the EPIC-InterAct case-cohort study. Lancet Diabetes Endocrinol 2014;2:810-818.

Keywords: type 2 diabetes , healthy weight , calcium , vitamin D


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