The Claim
Casein in dairy milk binds to coffee polyphenols, resulting in a reduction of their bioavailability by 30–60%.
What the research says
Roughly balanced
Support and challenge are close. The picture may shift as more studies come in.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
When you add milk to your coffee, the protein in the milk (casein) latches onto the healthy compounds in coffee, making it harder for your body to absorb them—so you get 30% to 60% less of their benefit.
See the scientific wording
Casein in dairy milk binds to coffee polyphenols, reducing their bioavailability by 30–60%.
What the research says
1 studyThis study shows that the main protein in milk (casein) sticks to plant compounds called polyphenols, which are also in coffee. That means those healthy compounds might not be absorbed as well by your body—exactly what the claim says.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.