Drinking one glass of beetroot juice won’t help older adults with a certain type of heart failure exercise better, even though it raises a chemical in their blood — they might need to drink it every day for a while before they see any benefit.

Drinking beetroot juice every day for a week can help older adults with a certain type of heart condition ride a stationary bike longer before getting tired, which might make everyday activities easier for them.

Drinking beetroot juice with a specific amount of nitrate doesn’t make the body use less oxygen when older adults with a certain type of heart failure exercise lightly — so if they feel less tired, it’s probably because their blood flows better or their heart doesn’t have to work as hard, not because their muscles are using energy more efficiently.

If older adults with a specific type of heart condition drink beetroot juice every day for a week, their resting blood pressure may drop by about 14 points — which could be a meaningful improvement for their health.

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.

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.