There have been numerous media reports and noise from organisations that claim dairy has an adverse effect on your health. According to these reports, the health consequences include increased risk of chronic diseases such as obesity, osteoporosis, cancer, cardiovascular disease and type 2 diabetes1. This stream of inconsistent (and often misleading) information has led the consumer to question dairy and health1. This is evident in the increased consumption of plant-based drinks, including soy, rice, almond and oats1. Those living with Type 2 Diabetes Mellitus (T2DM) are at increased risk of other chronic illnesses1. Identifying the modifiable risk factors that help to prevent T2DM is therefore of considerable public health importance. 

WHAT DOES THE RESEARCH ON DAIRY INTAKE SAY?

Over the years research has yielded mixed results, with some showing a decreased risk while others suggesting an increased risk2. It has been hypothesized that dairy has a protective effect against type 2 diabetes due to the content of calcium, magnesium, vitamin D and whey proteins2. These are said to reduce body fat and insulin resistance as well as improving insulin secretion2,3. However, this protective effect may be offset in the higher fat dairy products such as cheese and cream2.

A big factor in the increased prevalence of type 2 diabetes is driven by the obesity epidemic. Research shows that in children, those in the highest dairy intake group were 38% less likely to be overweight or obese compared to those in the lowest dairy intake group. An increase in dairy intake of one serving per day was associated with a 0.65% lower body fat and 13% lower risk of overweight or obesity4. Childhood overweight and obesity is becoming more prevalent and another major contributor to the current obesity epidemic as childhood obesity frequently tracks into adulthood. In adults, five out of nine studies showed a protective association of dairy consumption against inappropriate weight gain5,6. Dairy products and their proteins are important during weight loss and weight maintenance1,6. This is due to their high satiating effect, which helps to prevent over-consumption of energy and improves body composition by reducing body fat mass and preserving lean body mass1,6. 

Over the years various systematic reviews and meta-analyses have been published that show beneficial effects of dairy in T2DM prevention. According to a 2018 review, literature suggests that the appropriate consumption of milk and its derivatives (according to available nutritional guidelines) may be beneficial across all age groups, especially in infancy and childhood where bone mass growth is in a critical phase7. The exception however is in specific medical conditions such as lactose intolerance or milk protein allergy7. They further suggested that consumption of milk has protective effects against overweight, obesity, diabetes and cardiovascular disease7. 

This result was also seen in two large meta-analyses2,7. The first found that there was a 7% risk reduction (RR) per 400g of total dairy products consumed per day, however no further reduction in risk was found above an intake of 400g/d2. There was 9 % RR per 200g low-fat dairy products/d, 13% per 200g milk/d, 8% per 50g cheese/d, 22% per 200g yogurt/d and only a 2% RR per 200g for high-fat dairy2. In the 2016 meta-analysis, there was a 3% lower T2DM RR per 200g total dairy intake/d, 4% RR per 200g/d of low-fat dairy, with yoghurt showing the greatest benefit at 14% per 80g/d8 and with no benefit seen for milk. Interestingly, fermented dairy products especially yoghurt, had the greatest protective effect against T2DM7,8. This could be due to the gut microbiota or whey protein (primarily in milk and yoghurt) as an agent that reduces postprandial plasma glucose concentration in type 2 diabetic subjects1.

HOW MUCH AND WHAT TYPE OF DAIRY SHOULD WE HAVE? 

The Society for Endocrinology, Metabolism and Diabetes of South Africa (SEMSDA) and American Diabetes Association (ADA) suggest that including sources of dairy in your meal plan is a great way to get high-quality protein and calcium9,10. They suggest that the healthiest choices of dairy products are: 

• Fat-free (skim) or low-fat (1% milk)9, 10, 11
• Yogurt (low fat plain9, regular or Greek yogurt10)
• Some reduced fat cheeses10

They also go on to say that for good health, carbohydrate intake from vegetables, fruits, whole grains, legumes, and dairy products should be advised over intake from other carbohydrate sources, especially those that contain added fats, sugars, or sodium12. If you drink milk be sure to count it in your meal plan as dairy contains carbohydrates and monitoring carbohydrate intake remains a key strategy for glycaemic control9,12. The amount you should consume is individualised, but general recommendations include 2 portions of dairy per day. 

For those who choose to avoid milk, be mindful of the plant milks and make sure you read and understand the labels. Out of the milk alternatives available, soy is the only plant-based milk substitute that has a similar protein content to cow’s milk, whereas oat, rice, and almond milk are extremely low1. These plant drinks are often considered “healthier” due to the fact they are plant based, however this might not always be the case. They may be lower in saturated fat and cholesterol, however some of these products have a higher energy content compared milk, due to a high content of oil and added sugar1. Many of their ingredients lists consist of multiple ingredients with names difficult to identify, whereas milk contains only one ingredient… milk!

CONCLUSION

The research on dairy shows a protective effect against development of T2DM and obesity. With low fat dairy being more beneficial compared to higher fat types and yoghurt showing the greatest benefit. Whether you choose milk, cheese, yoghurt or alternatives such as soy, almond, oat or rice, make sure that you consider the overall carbohydrate and fat content. Considering both the quality and quantity of carbohydrate containing foods and an individualised approach guided by the patient’s glycaemic control is recommended. Chat to your Registered Dietitian about an individualised plan for you. Visit www.adsa.org.za to find one in your area.

REFERENCES

1. PubMed (2016). Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence. Available at: https://www.ncbi.nlm.nih.gov/pubmed/27882862 (Accessed: September 2018)
2. Semantic scholar (2013). Dairy products and the risk of type 2 diabetes: a systematic review and

dose-response meta-analysis of cohort studies1–3. Available at: https://pdfs.semanticscholar.org/5e55/662c4642285e6ed15aa10cc39c66f872e7d5.pdf (Accessed: September 2018)

1. Oxford Academic (2015). Dairy Foods and Dairy Proteins in the Management of Type 2 Diabetes: A Systematic Review of the Clinical Evidence. Available at: https://academic.oup.com/advances/article/6/3/245/4568651 (Accessed: September 2018)
2. PubMed (2016). Long-term association between dairy consumption and risk of childhood obesity: a systematic review and meta-analysis of prospective cohort studies. Available at: https://www.ncbi.nlm.nih.gov/pubmed/26862005 (Accessed: September 2018)
3. Wiley Online Library (2011). Dairy consumption and overweight and obesity: a systematic review of prospective cohort studies. Available at: https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1467-789X.2011.00881.x (Accessed: September 2018)
4. The American Journal of Clinical Nutrition (2014). A changing view on saturated fatty acids and dairy: from

enemy to friend. Available at: http://www.ilfattoalimentare.it/wp-content/uploads/2015/06/A-changing-view-on-saturated-fatty-acids-and-dairy-from-enemy-to-friend.pdf (Accessed: September 2018)

1. PubMed (2018). Cow's Milk Consumption and Health: A Health Professional's Guide. Available at: https://www.ncbi.nlm.nih.gov/pubmed/30247998 (Accessed: September 2018)
2. Semantic scholar (2016). Consumption of dairy foods and diabetes incidence: a dose-response meta-analysis of observational studies. Available at: https://sciencing.com/non-linear-relationship-10003107.html (Accessed: September 2018)
3. Journal of Endocrinology, Metabolism and Diabetes of South Africa (2017). SEMDSA 2017 Guidelines for the

Management of Type 2 diabetes mellitus: Chapter 6. Available at: https://www.semdsa.org.za/images/647-4385-1-PB.pdf (Accessed: September 2018)

1. American Diabetes Association (2017). Dairy. Available at: http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/making-healthy-food-choices/dairy.html?loc=ff-slabnav (Accessed: September 2018)
2. American Diabetes Association (2017). What Can I Drink? Available at: http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/making-healthy-food-choices/what-can-i-drink.html (Accessed: September 2018)
3. ADA Diabetes Care (2014). Nutrition Therapy Recommendations for the Management of Adults with Diabetes. Available at: http://care.diabetesjournals.org/content/37/Supplement_1/S120 (Accessed: September 2018)