The most nitrate-rich food is beetroot, he said.However, he also recommended the following foods:SpinachRhubarbCeleryLettuceWatercressRocketFennelLeekParsleyCeleriacChinese cabbage.He added: ‘Nitrates in plant foods are not to be confused with nitrates added to processed meats to preserve the meat, enhance its flavour, and impart the ‘desirable’ pink colour.”In processed meats, the nitrites react with the amines in the meat during processing, curing, storage, and cooking to form nitrosamines, which are known carcinogens – a mechanism thought to explain processed meat’s links with colorectal cancer.READ MORE: Vitamin D deficiency linked to risk of premature death in new study – 4 most common signs