Eggs are an inexpensive, protein-rich — and supposedly health — breakfast staple across the world, including in Asia. But new research published in the British Journal of Nutrition shows a link between consuming one or more eggs daily and an increased risk of type 2 diabetes.

It’s a link that has long been debated and is still inconclusive. Previous, related studies conducted in the U.S., Japan, Nordic and Mediterranean countries have arrived at contradictory conclusions. However, the researchers of the new study say that dietary context influences how much regular egg consumption increases the risk of diabetes and explains discrepancies between previous studies.

“Diet is a known and modifiable factor that contributes to the onset of type 2 diabetes, so understanding the range of dietary factors that might impact the growing prevalence of the disease is important,” Dr. Ming Li, epidemiologist, and public health expert, said in a statement.

Organizations like the American Diabetes Association recommend eggs as a decent nutritional choice for individuals with diabetes because of eggs’ high protein and low carbohydrate content. However, other medical professionals have pointed out that it is necessary to note what eggs are consumed with — for example, butter, cheese, bacon, muffins, bread, and more contain saturated fats, which are linked to the development of type 2 diabetes.

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“The per capita fat intake and egg consumption in the Mediterranean and Nordic countries are not low, but the diet is dominated with whole grains, vegetables, fruits, legumes, fish, dairy and unsaturated fat, these foods and their metabolites are beneficial for diabetes, similar to the Japanese diet,” the researchers write. In comparison, countries like China and India are moving away from grains and vegetables towards energy-dense food like meat, oil, and processed snacks — which, combined with daily egg consumption does more harm than good.

The recent longitudinal study was conducted over almost two decades (1991-2009) among more than 8,500 adults in China. It shows that higher long-term egg consumption (38gm or more than half an egg a day) increased diabetes risk in adults by almost 25%. Further, eating one or more eggs daily (that is, more than 50gms daily) increased diabetes risk by 60%. Researchers also noted this effect was more marked in women than men.

The researchers say their findings should inform dietary guidance within unique contexts. Dr. Li advocates for more research to explore the causal relationship between eggs and diabetes. She adds, “To beat diabetes, a multi-faceted approach is needed that not only encompasses research, but also a clear set of guidelines to help inform and guide the public. This study is one step towards that long-term goal.”