A meta-analysis, presented at the annual meeting of the European Association for the Study of Diabetes (EASD) conference, links low-fat dairy products to a reduced risk of developing type 2 diabetes, (T2D) while finding that red and processed meats increase the risk.
The US Centers for Disease Control and Prevention (CDC), estimates that 1 in 10 people (37m Americans) live with diabetes, and that more than one in three people have prediabetes.
The disease can increase health complication risks, including cardiovascular disease, kidney failure, stroke, blindness, and circulatory issues, which could necessitate the amputation of toes, feet, or a part of the leg.
Now researchers from University of Naples Federico II in Naples, Italy, have gathered evidence showing that certain foods can cut the risk of T2D onset.
Annalisa Giosuè, PhD., of the institution’s Department of Clinical Medicine, spearheaded an extensive investigation to explore the relationship between different animal-based foods and the condition, and presented her team’s findings at the annual meeting of the European Association for the Study of Diabetes (EASD) conference earlier this month.
High-level ‘review of review’
Current dietary guidelines for T2D prevention recommend limited intake of most animal products. However, research suggests that certain animal products might offer health benefits for lowering T2D risk.
Type 2 diabetes is one of the major causes of diet-related death worldwide.
“Learning more about how different dietary components increase or decrease the risk of type 2 diabetes is key to its prevention,” Giosuè told MedicalNewsToday.
To that end, she and colleagues examined 13 existing meta-analyses that studied which foods were linked to increased risk of T2D.
This type of “review of reviews” pulls together one of the most comprehensive levels of evidence possible in medical research, they said.
Which meats promote T2D?
The 13 meta-analyses provided estimates of how 12 different animal-based foods may elevate or lower the risk of developing T2D. Categories included: total meat, red, white and processed meat; total, full-fat and low-fat dairy; fish, milk, cheese, yogurt and eggs.
Daily consumption of 100g of total meat was associated with a 20% higher risk. The same amount of red meat was associated with a 22% increase in risk.
Half that amount of processed meats, such as deli meat, bacon, and sausages, may have contributed to a 30% increase in T2D risk.
“Meat, particularly red and processed meats, is a relevant source of saturated fatty acids, cholesterol, advanced [glycation end] products, and heme [animal-derived] iron, known to promote chronic subclinical inflammation and impair insulin sensitivity — the capacity of the cells to properly respond to insulin stimulation by absorbing glucose from the blood, thus lowering glycemic levels,” said Giosuè.
She added that sodium, nitrates, and nitrites in processed meats might “not only damage insulin-producing pancreatic cells but also induce oxidative stress and vascular dysfunction, which, in turn, [reduce] the sensitivity of the cells to insulin”.
On the other hand, 50g (of white meat, which includes chicken and turkey, corresponded with only a 4% higher T2D risk.
She believes this is because this meat has less fat, a healthier fatty acid profile, and less animal-derived iron.
Dairy’s protective potential
The team found that dairy foods might offer protection against T2D or have no effect on its onset. Consumption of 200g (almost one cup) of milk was associated with a 10% lower risk of T2D, and 100g of yogurt correlated with a 6% risk reduction. A cup of total dairy and low fat dairy were each associated with a 5% and 3% reduced T2D risk, respectively.
However, the meta-analyses showed that cheese and full-fat dairy had no effect on T2D risk. The quality of the evidence was low to moderate, though.
Giosuè told MNT ofd several benefits of regularly eating dairy products:
“Nutritionally speaking, dairy products are a source of nutrients, vitamins, and other components (namely calcium, proteins, peptides, etc.) with potential beneficial effects on glucose metabolism. For instance, whey protein has a well-known effect on the modulation of the rise of glucose blood levels after meals, and also on the control of appetite and body weight.
“Protective effects in relation to body weight gain and obesity – drivers of type 2 diabetes development – have [also] been reported for probiotics, which can be found in yogurt, the other dairy item whose consumption is associated with a reduced risk of type 2 diabetes,” she said.
Other low quality evidence suggested that neither daily 100g servings of fish nor one egg per day affect T2D risk significantly.
Eating to curb diabetes
The study adds credence to the belief that limiting or avoiding the consumption of animal-based foods, namely red and processed meat, can help prevent T2D.
“Our findings on the most suitable intake of animal foods to prevent type 2 diabetes incidence are highly concordant with the features of the Mediterranean diet, which is the plant-based dietary pattern that has more consistently shown over time the potential to reduce the risk of type 2 diabetes and cardiovascular diseases,” she added.
Dr Roy Taylor, a physician, author, professor, and director of Newcastle Magnetic Resonance Centre at Newcastle University in the UK and not involved in the study, argued that the wide availability of “cheaper” and more accessible processed foods is driving the spike in T2D cases.
He was especially concerned about the increase in cases among children.
T2D is considered a chronic condition, though there is evidence to suggest that it may be reversible through diet and lifestyle modifications, according to the American Diabetes Association.
Numerous studies have shown a link between consumption of ultra-processed foods and increased risk of T2D. Other research has shown that interventions like a low calorie diet, physical activity, or bariatric surgery, may be effective for reversing T2D.
While more research is needed to determine whether a mostly plant-based diet, such as the Mediterranean diet, could reverse T2D, a growing body of evidence shows that a Mediterranean-style diet may help prevent or delay the progression of the condition.
Call for stronger evidence
The Italian researchers acknowledged that the 13 meta-analyses included inferior data in some cases. Thus, they are hesitant to offer “solid recommendations” for T2D prevention based on their study at this time.
Nevertheless, Giosuè said: “Our study gives further support to the belief that a plant-based dietary pattern including limited intakes of meat, moderate intakes of fish, eggs and full-fat dairy and the habitual consumption of yogurt, milk or low fat dairy, might represent the most feasible, sustainable and definitely successful population strategy to optimise the prevention of type 2 diabetes.”
Study details
Appropriate consumption of different animal-based foods to reduce type 2 diabetes risk: an umbrella review of meta-analyses of prospective studies
Giosuè, I. Calabrese, G. Riccardi, O. Vaccaro, M. Vitale.
Background and aims
Dietary recommendations for the prevention of type 2 diabetes (T2D) clearly indicate the most appropriate choices for plant-based foods; as for foods of animal origin, a limited consumption of all items is generally recommended. However, not all animal protein sources are equal; moreover, they are largely used worldwide. Therefore, we have reviewed data on the relationship between the consumption of various foods of animal origin and the incidence of T2D to support dietary recommendations for T2D prevention with updated and reliable scientific evidence on the appropriate choices for animal-based foods. Materials and methods: The study is an umbrella review of dose-response meta-analyses of prospective cohort studies. A systematic search of the literature was conducted in PubMed, Web of Science, Scopus and Embase according to PRISMA guidelines. The methodological quality of each meta-analysis was evaluated trough AMSTAR (A Measurement Tool to Assess Systematic Reviews). For each food group, we meta-analyzed the risk ratios (RR) for T2D incidence reported in the primary studies included in the available meta-analyses. The quality of evidence was evaluated with a modified version of NutriGrade.
Results
13 meta-analyses met the criteria for inclusion in the review with 175 summary RR on consumption of total meat (n=13), red meat (n=21), white meat (n=8), processed meats (n=24), fish (n=12), total dairy (n=21), full-fat dairy (n=14), low-fat dairy (n=15), milk (n=11), cheese (n=10), yogurt (n=10) and eggs (n=16) in relation to T2D incidence. There was a substantial increase in T2D risk with the consumption of 100 g/day of total meat (RR 1.20, 95% CI 1.13-1.27) or red meat (RR 1.22, 95% CI 1.14-1.30) or 50/day of processed meats (RR 1.30, 95% CI 1.22-1.39), with a moderate quality of evidence; also 50 g/day of white meat showed a positive relationship with T2D risk (RR 1.04, 95% CI 1.00-1.08). As for dairy foods, we found an inverse association for T2D incidence with the intake of 200 g/day of total dairy (RR 0.95, 95% CI 0.92-0.98), low-fat dairy (RR 0.97, 95% CI 0.93-1.00) or milk (RR 0.90, 95% CI 0.83-0.98), as well as 100 g/day of yogurt (RR 0.94, 95% CI 0.90-0.98); conversely, a neutral relationship emerged for 200 g/day of full-fat dairy (RR 0.98, 95% CI 0.93-1.03) or 30 g/day of cheese (RR 0.97, 95% CI 0.91-1.04), with a quality of evidence scored between moderate and low. Finally, the consumption of 100 g/day of fish and 1 egg/day showed a neutral association with T2D risk (RR 1.04, 95% CI 0.99-1.09 and 1.07, 95% CI 0.99-1.15, respectively), with low quality of evidence.
Conclusion
The scientific evidence we have extensively reviewed shows that the habitual consumption of dairy foods in moderate amounts – especially low-fat types, milk and yogurt – could be appropriate for the optimisation of T2D prevention. Within this context, moderate amounts of fish and eggs could represent suitable substitutes for red and processed meats in most eating occasions.
Presentation at European Association for the Study of Diabetes (EASD) conference (Open access)
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