Milk Products and Type 2 Diabetes
The relationship between milk product consumption and type 2 diabetes has been examined in a number of studies including several meta-analyses. The totality of the evidence to date indicates that milk products, including higher-fat milk products, as well as yogurt and cheese specifically, are 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 associated with a reduced risk of type 2 diabetes;
- Yogurt and cheese are associated with a reduced risk of type 2 diabetes;
- High-fat dairy/dairy fat is either neutral or associated with a decreased risk of developing type 2 diabetes;
- Recent evidence suggests that higher-fat milk products, including cheese, may be especially protective in those who have pre-diabetes.
Synopsis
A number of meta-analyses of prospective cohort studies have concluded that higher milk product consumption is associated with a reduced risk of type 2 diabetes. Yogurt and cheese appear to be particularly beneficial. The evidence also suggests that higher-fat dairy foods, including cheese, may decrease the risk of developing type 2 diabetes. Potential mechanisms may involve multiple dairy food components including calcium, vitamin D, dairy-derived fatty acids and amino acids, as well as probiotic and prebiotic effects on the gut microbiome.1,2,3,4
The evidence
A large meta-analysis published in 2018 by Imamura et al. analyzed associations between fatty acid biomarkers of dairy consumption and the risk of developing diabetes. The pooled findings from 16 prospective cohort studies with up to 20 years of follow-up (N=63,682), showed that:1
- Higher circulating and tissue concentrations of dairy biomarker fatty acids (15:0 and 17:0, and t16:1n-7) were associated with a lower risk of type 2 diabetes;
- Higher levels of the sum of these dairy biomarker fatty acids were associated with a 29% lower risk of type 2 diabetes (hazard ratio 0.71, 95% CI: 0.63-0.79; comparing the 10th to 90th percentile range in each cohort).
A meta-analysis published by Tian et al. in 2017 helps to clarify the relationships between different types of protein-rich foods and the development of type 2 diabetes. Findings from the 11 prospective cohort studies included in this meta-analysis indicate that higher intakes of dairy foods, including yogurt and whole milk in particular, are associated with a lower risk of type 2 diabetes (N=483,174).5
- Total dairy product consumption was associated with an 11% lower risk of type 2 diabetes, comparing high to low intakes (relative risk of 0.89, 95% CI: 0.84–0.94).
- Yogurt consumption was associated with a 17% reduced risk of type 2 diabetes, comparing high to low yogurt intakes (relative risk of 0.83, 95% CI: 0.70–0.98).
- Whole milk consumption was associated with a 13% decreased risk of type 2 diabetes, compared to low dairy fat intake (relative risk of 0.87, 95% CI: 0.78–0.96).
A dose-response meta-analysis published by Gijsbers et al. in 2016 examined the associations between dairy foods and the development of type 2 diabetes. This comprehensive analysis included data from 22 prospective cohort studies involving adults who were healthy at baseline (N=579,832).6
- Each added 200 g/day serving of total dairy foods was associated with a 3% reduced risk of type 2 diabetes (relative risk of 0.97, 95% CI: 0.95-1.0).
- Yogurt consumption of 80 g/day was associated with a 14% decreased risk of type 2 diabetes, compared to 0 g/day (relative risk of 0.86, 95% CI: 0.83-0.90).
A systematic review of 21 meta-analyses of prospective cohort studies published by Drouin-Chartier et al. in 2016 examined the relationship between dairy product consumption and cardiovascular health outcomes, including type 2 diabetes. This extensive, in-depth systematic review, which included quality assessment and grading of the evidence, concluded that:7
- Low-fat dairy and yogurt are associated with a decreased risk of type 2 diabetes (based on high-quality evidence);
- Total dairy and cheese are also associated with a decreased risk of type 2 diabetes (based on moderate-quality evidence);
- There is no evidence that the consumption of dairy fat or regular and high-fat dairy is detrimental to any cardiovascular health outcomes, including type 2 diabetes;
- The recommendation to focus on low-fat dairy instead of regular- and high-fat dairy is currently not evidence-based.
In 2017, Hruby et al. published findings from their investigation of the associations between dairy food intakes and the development of prediabetes and type 2 diabetes. This study included 2,809 adults from the Framingham Heart Study Offspring Cohort who were followed for 12 years.8
Among those with normal glucose status at baseline:
- Total, low-fat, and high-fat dairy were associated with a 39%, 32%, and 25% lower risk of developing prediabetes, respectively, (comparing ≥14 compared with <4 servings/week).
Among those with prediabetes at baseline:
- High-fat dairy was associated with a 70% reduced risk of developing diabetes (≥14 compared with <1 serving/week for high-fat dairy);
- Cheese was associated with a 63% lower risk of developing type 2 diabetes (≥4 compared with <1 serving/week for cheese).
Potential mechanisms
There are several plausible biological mechanisms through which milk products may play a role in reducing the risk of developing type 2 diabetes: 2,3,4
Risk factors
Milk products help in weight management and reduce the risk of developing hypertension and metabolic syndrome, which are major risk factors for type 2 diabetes.
Glucose homeostasis
In a systematic review, results from longer intervention studies indicate that higher dairy intake may help improve insulin sensitivity.9
Calcium, vitamin D and magnesium
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.4,10,11 Evidence from cell culture and animal models also suggests calcium may reduce fat cell lipid accumulation and adiposity.4
Milk proteins
- Whey protein may promote insulin sensitivity, improve glucose tolerance and lipid profile, and help in weight control.3,9,12
- The essential amino acid leucine may counter mitochondrial dysfunction and increase thermogenesis.4
- Bioactive peptides may also help to control blood pressure.2
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.13,14,15
- Pentadecanoic acid (15:0) has been inversely associated with fasting plasma glucose and incident type 2 diabetes.15,16,17
- 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.3,18
- Milk products, particularly cheese, contain menaquinones (vitamin K2), which have been associated with reduced risk of developing type 2 diabetes.2,10,16
- A higher-fat dairy-based diet has been shown to significantly alter the gut microbiome and reduce liver fat (compared to a soy and sucrose-based diet) in animal studies.
Conclusion
Current evidence indicates that higher consumption of milk products is associated with a reduced risk of developing type 2 diabetes. Both lower-fat and higher-fat milk products may play a beneficial role in preventing type 2 diabetes; and emerging evidence suggests that higher-fat milk products may be especially protective in those who have prediabetes. Yogurt and cheese in particular, appear to be protective against type 2 diabetes.
References
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Imamura F et al. Fatty acid biomarkers of dairy fat consumption and incidence of type 2 diabetes: A pooled analysis of prospective cohort studies. PLoS Med 2018. doi: 10.1371/journal.pmed.1002670.
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Mozaffarian D and Wu JHY. Flavonoids, dairy foods, and cardiovascular and metabolic health: A review of emerging biologic pathways. Circ Res 2018;122:369-384.
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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.
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Hirahatake KM et al. Associations between dairy foods, diabetes, and metabolic health: potential mechanisms and future directions. Metabolism 2014;63:618-627.
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Tian et al. Dietary protein consumption and the risk of type 2 diabetes: A systematic review and meta-analysis of cohort studies. Nutrients 2017;9:982.
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Gijsbers L et al. Consumption of dairy foods and diabetes incidence: a dose-response meta-analysis of observational studies. Am J Clin Nutr 2016;103:1111-1124.
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Drouin-Chartier JP et al. Systematic review of the association between dairy product consumption and risk of cardiovascular-related clinical outcomes. Adv Nutr 2016;7:1026-1040.
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Hruby A et al. Associations of dairy intake with incident prediabetes or diabetes in middle-aged adults vary by both dairy type and glycemic status. J Nutr 2017;147:1764-1775.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 Nutr2014;100:1532-1540.
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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.
