The Study
Molecular mechanism of the interactions between coffee polyphenols and milk proteins
This study is like looking at how two Lego pieces fit together in a picture — it shows how coffee stuff and milk stuff might stick to each other, but it doesn’t show if it actually happens in your coffee cup or if it helps your body.
Analysis score
Maximum 0 for a computational/algorithm study.
Where the score came from
When you add milk to coffee, the proteins in milk grab onto the healthy compounds in coffee and help them last longer without breaking down.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 50 / 100
Quality score
Based on clinical experience or non-systematic literature reviews. The lowest level of evidence as they are most susceptible to bias and personal perspective.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this suggests milk may help coffee antioxidants stay active longer in your drink, but it doesn't say if this changes health benefits.
- 2Coffee antioxidants are twice as soluble in proline as in water; binding strength matches how much proline is in the milk protein.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Food Research International
Year
2025
Authors
Kazuki Horita, Tomoshi Kameda, Hiroshi Suga, Atsushi Hirano
Related Content
Claims (5)
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.
Coffee compounds called polyphenols dissolve better in environments full of a substance called proline than in plain water, which suggests they like to stick together with proline.
A natural compound in coffee and fruits called caffeic acid sticks to a specific part of milk proteins because they both like to avoid water — kind of like oil clinging to oil.
When you add milk to coffee, the proteins in the milk might help keep the healthy compounds in coffee from breaking down too quickly — but scientists weren’t sure exactly how this works.
When coffee compounds meet milk proteins, the glow they produce gets stronger if the milk proteins have more of a specific building block called proline — so proline seems to help them stick together better.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.