Good old reliable milk. New research found that when it's combined with particular oral drugs, milk significantly improves their absorption by the body. It’s the latest in a series of studies showing that milk is a highly effective drug-delivery vehicle.

For something that many of us take for granted, milk has turned out to be incredibly valuable in the world of health and medicine. Over the years, New Atlas has reported on cows that produce human breast milk, HIV-inhibiting milk, or milk containing human insulin. But what’s become increasingly clear to scientists is that milk’s composition makes it an effective drug delivery system.

A new Monash University-led study found that adding both human and cow’s milk significantly improved the effectiveness of certain oral drugs. It’s the latest in a series of studies in which the researchers have investigated milk as a vehicle for improving drug delivery.

“Through our research over the years, we’ve consistently been able to demonstrate the way in which certain medicines are able to ‘piggyback’ with the milk, which our body treats like food and digests,” said Ben Boyd, a professor in the Monash Institute of Pharmaceutical Sciences (MIPS) and the study’s corresponding author. “Through this process, the milk and drug are absorbed, thereby enhancing the effectiveness of the drug.”

The term ‘bioavailability’ refers to how much of a drug actually reaches the bloodstream. Oral bioavailability, the bioavailability of drugs that are swallowed or otherwise delivered into the stomach, is affected by several factors, including the pH of the stomach and small intestine and enzymes and metabolism in the gastrointestinal (GI) tract. Therefore, the key to maximizing bioavailability is a drug’s formulation, which affects how well it is absorbed, distributed, and utilized by the body.

Many drugs are poorly water-soluble and lipophilic (fat-loving), and both pose challenges to bioavailability. As you’re probably aware, the human body, including the GI tract, is mostly water, so if a drug doesn’t dissolve well in water, its absorption into the bloodstream will be incomplete. Lipophilic drugs need fat for proper dissolution and absorption (which is why your pharmacist might tell you to take a particular medication with food).