Celery
One of the vegetables highest in nitrate, and the base under nearly every soup that tastes of anything.
How to use it
Raw as a stick, or as the base of a soup or stew with onion and carrot. The leaves are not waste and carry the most flavour.
The best version
Firm, smooth stalks that snap rather than bend, with the leaves still on. Celery and leaf celery are two different things: you eat the first and season with the second.
How to prepare it
Pull the strings off the outer stalks with a peeler. For soup, do not: those strings cook out and give up flavour.
What it does
Celery is among the vegetables highest in nitrate, and nitrate becomes nitric oxide in your body, which relaxes your blood vessels. That mechanism was measured with beetroot juice: seven trials, 218 people with high blood pressure, systolic pressure down by 4.95 mmHg.
Watch out
Celery juice as a cure is a sales story rather than research. What was measured is the nitrate, in a different vegetable, in a different drink.
Celery is one of the fourteen allergens that have to be declared by law, and reactions to it can be serious. If it is in a soup, it belongs on the label.