Although milk is known for its calcium, it also has other electrolytes such as potassium and magnesium to regulate blood pressure (via the University of Utah). One cup of low-fat milk has 391 milligrams of potassium and 30 milligrams of magnesium.
Milk might have other ingredients that can lower your blood pressure, per a 2016 article in the British Journal of Clinical Pharmacology. Your body has ACE enzymes that can raise blood pressure by narrowing your blood vessels. Doctors often prescribe ACE inhibitors to help manage high blood pressure. Milk has proteins that work like ACE inhibitors that can help people with high blood pressure, but they don’t cause low blood pressure in people whose blood pressure is normal.
It’s not that drinking milk every day can make huge changes in your blood pressure in less than a year, according to a 2017 review in BMJ. Drinking milk can cause slight changes in blood pressure, but it alone can’t prevent high blood pressure.