No, it’s a myth that started a long time ago. The texture of milk can make some people feel their saliva is thicker, but there’s no evidence that it creates phlegm. The myth may have hung around because milk is an emulsion, meaning it has droplets of one liquid suspended in another liquid.
When a person drinks milk, it mixes with their saliva and this can make it feel more viscous. This can make people feel like there’s more mucus, but it’s just aggregates of milk emulsion lingering in their throat. Milk is an important source of nutrition, and should not be avoided because of this myth.
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Asked by: Hannah Wilkinson, Somerset
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