When people drink beetroot juice every day for 12 weeks, some see a big jump in nitrite levels in their blood after drinking it, others barely see any change—even the same person might respond differently each time. A few people just don’t respond at all.

Even if healthy middle-aged and older adults take the same amount of beetroot juice every day, some people still get more nitrite in their blood than others—so something else, like their mouth bacteria or genes, must be why they respond differently.

Drinking beetroot juice with 380 mg of nitrate every day for 12 weeks doesn’t make your body respond any stronger to it over time—even though nitrate levels in your blood go up, your body doesn’t get better at using it or start reacting less.

If you drink a small glass of beetroot juice every day for three months, your body’s nitrate and nitrite levels go up a lot—this means your body might be making more of a helpful molecule that supports blood flow.

If older adults with high blood pressure drink beetroot juice every day for a month, their body shows more of certain chemicals in their blood and saliva that help relax blood vessels — which means their body is using a natural pathway to make nitric oxide.

Drinking beetroot juice once can temporarily make blood flow better in the arms of older people with high blood pressure, but if they drink it every day, that boost goes away after a while.