These objectives will be tested by growing lettuce with different fertiliser compositions resulting in high and low nitrate content and then investigating the bioavailability and short-term effect on BP in healthy young volunteers in a double-blind cross-over design. Eligible subjects will consume one meal each of either low or high nitrate lettuce. Urine, blood and saliva samples will be collected at baseline, for 6 hours after the ingestion and then again after 24hr. Blood Pressure BP will be measured continuously for 24 hours starting at baseline. The volunteers will repeat the intervention with the second treatment.