Could dairy products, fish and coffee play a role in preventing type 2 diabetes? Health24 takes a look at the latest research.
In a previous article, we looked at the effects of protein and fibre on the risk of type 2 diabetes. Research pooled from numerous large population studies showed that high protein intakes increase the risk of type 2 diabetes by up to 67%, while a high fibre intake of about 35g per day reduces the risk by 34%.
In this article, we take a closer look at some of the other dietary factors that may play a role in lowering your risk of developing this life-threatening condition. This valuable information was shared by Prof Renée Blaauw at the South African Sugar Association’s Nutrition in Non-Communicable Disease Prevention Roadshow earlier this year.
Milk and dairy products are often blamed for a myriad of ills, and many South Africans avoid these foods in an attempt to improve their health. This is unfortunate, as dairy products contain the highest quantity of easily absorbable and utilisable calcium in the diet.
A meta-analysis of seven studies that probed the effect of dairy products on the risk of developing type 2 diabetes indicated that people who had the highest intake of milk and dairy products were 14% less likely to develop type 2 diabetes compared to people who consumed very little dairy.
Researchers also identified a difference in effect depending on the fat content of the dairy products. The total positive effect of dairy products produced a reduction in risk of 14% as mentioned above, but low-fat dairy products (low-fat milk, yoghurt, cottage cheese) reduced the risk by up to 18%. In general, the risk for type 2 diabetes was lowered by 10% for every extra serving of low-fat dairy per day.
Gao and co-authors concluded that “a modest increase in daily intake of dairy products such as low fat dairy, cheese and yoghurt may contribute to the prevention of type 2 diabetes”. They caution that these results need to be confirmed with randomised controlled trials.
Other researchers suggested that calcium, vitamin D and whey proteins in dairy products may help to reduce the risk of type 2 diabetes. For example, there’s some evidence that whey proteins can increase insulin sensitivity.
Read: Dairy may lower diabetes risk
Omega-3 fatty acids
One would expect the protective omega-3 fatty acids to be useful in preventing type 2 diabetes, but a meta-analysis conducted by Wu and co-authors at the Harvard School of Public Health wasn’t able to identify either a negative or a positive effect of fish consumption on type 2 diabetes. Fish is a rich source of omega-3 fatty acids.
The basic results of the meta-analysis appeared to be neutral. However, the results did show that alpha-linolenic acid (ALA), an omega-3 fatty acid derived from plants, found in linseed and flax oils, may possibly slightly lower the risk of type 2 diabetes. Considering that type 2 diabetes is associated with chronic, low-grade inflammation, particularly in fat tissue, and that signals from the chronically inflamed tissue prevent insulin from working efficiently, it’s feasible to expect that anti-inflammatory compounds like omega-3 fatty acids would counteract inflammation and thus help to reduce the risk of type 2 diabetes. More in-depth research may help to clarify the role of omega-3 fatty acids, and fish, seafood and/or omega-3-rich plants in reducing the risk of type 2 diabetes.
Read: Coffee may cut diabetes risk
The coffee question
For many years, coffee has been blamed for a variety of health problems, including insulin-dependent diabetes and type 2 diabetes. More recently, however, research has begun to exonerate this maligned beverage. Much more positive findings have now emerged about coffee. This also applies to the role coffee may play in the development of type 2 diabetes.
Researchers at Harvard University combined the results of more than 1,1 million study participants, including 45,335 people with type 2 diabetes, to determine if caffeinated coffee or decaffeinated coffee increases or decreases the risk of this disease.
Coffee consumption was found to be inversely associated with the risk of type 2 diabetes, therefore, the more coffee the subjects consumed, the lower their risk of developing type 2 diabetes. This was true for both caffeinated and decaffeinated coffee. One cup of coffee a day reduced the risk of type 2 diabetes by 8%, and 6 cups of coffee per day reduced the risk by 23%.
It’s important to keep in mind that none of the studies determined what effect adding milk or sugar to coffee may have on coffee’s protective effect.
The authors suggested that compounds such as chlorogenic acid, a phenolic compound found in coffee, may be responsible for the positive effect – chlorogenic acid reduced blood glucose concentrations in studies using experimental animals. Other bioactive components of coffee such as lignans, quinides and trigonelline may also play a role.
This protective effect doesn’t seem to be linked to coffee’s caffeine content, which is why it’s still best not to consume more than six cups of caffeinated coffee a day. Increasing your caffeine intake may cause a variety of other negative physiological effects, including increased heart rate or palpitations, increased blood pressure, insomnia, tremors and jitteriness.
The recommendation is, therefore, to consume coffee in moderate quantities of not more than six cups a day. Both caffeinated and decaffeinated coffee may protect us from developing diabetes.
- (Dr Ingrid van Heerden, registered dietician, May 2015)
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Blaauw R (2015). Dietary Factors for the Prevention of Diabetes Mellitus. Lecture presented on 12 February 2015, at the SASA Nutrition in NCD Prevention Roadshow, Pretoria; Ding M et al (2014). Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a meta-analysis of cohort studies. Diabetes Care, 37(2):569-86; Gao D et al (2013). PloS One, 2013 Sep 27, 8(9): e73965; Tong X et al (2011). Dairy consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. European Journal of Clinical Nutrition, 65(9):1027-31; Wu JH et al (2012). Omega-3 fatty acids and incident type 2 diabetes: a systematic review and meta-analysis. British Journal of Nutrition, June, 107, Suppl. 2:S214-27.
Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.