Soy milk is often an option for those avoiding dairy in their coffee, however many coffee shops now provide more plant-based choices such as almond, coconut and oat milks.

While non-dairy milks provide some advantages (they typically contain lower levels of sugar and more protein), they may alter both flavor and nutrition in your coffee cup. We’ve witnessed first-hand that adding non-dairy alternatives can cause curdling issues and create an unpleasant experience; here, we explore why and how this happens and offer tips to prevent future incidents.

Researchers discovered in the lab that mixing coffee with soy milk significantly decreased the amount of chlorogenic acids entering bloodstream, due to isoflavones present in soy milk binding to chemicals found in coffee to prevent it from being absorbed by our bodies.

Soy isoflavones are phytoestrogens – compounds with similar properties to female hormone oestrogen – and research suggests a link between higher intake of isoflavones and an increased risk of heart disease and cancer in women.

Research found that when both coffee and soymilk were combined together, their consumption led to a 42% reduction in urinary excretion of CGA and its metabolites as compared with when either were eaten separately, suggesting isoflavones present in soymilk may bind with CGA to inhibit its absorption, perhaps explaining why these two foods should not be eaten together.

Soy milk did not inhibit the absorption of chlorogenic acids as effectively when combined with black coffee, likely because its acidity promoted an enzymatic breakdown of CGA and its metabolites.

No matter your choice of beverage, it is crucial that the beans you use in both cases come from ethical sources. Soybean production is one of the leading causes of deforestation in Brazil where most soybeans are grown and processed – thus it is vital that we support non-GMO soy bean production.

Coffee is not only an enjoyable beverage; it is also a potent antioxidant that can protect against inflammation and reduce the risk of heart disease and depression. Coffee has also been proven to have positive impacts on blood pressure, lung function and insulin sensitivity; in fact, studies have demonstrated that people who regularly drink coffee live longer than those who don’t drink coffee! In addition, coffee offers polyphenol phytonutrients like flavonoids and chlorogenic acids for healthful living.