Nitrites in luncheon meat becomes nitrosamines in the stomach, a carcinogen.
When you do eat luncheon meat, eat it with tomatoes and Vitamin C rich foods and high fiber greens.
For most people, eating leftover vegetables would not significantly increase the risk of cancer. Yet, caution should be taken when feeding infants with vegetables. Vegetables naturally contain nitrate and nitrite. Some processed foods such as cured meats also contain nitrate and nitrite as food additives.
Some vegetables are a rich source of nitrates, but vegetables also contain ascorbic acid ( Vitamin C ), which is an inhibitor of nitrosamine formation. No one knows whether the vegetables’ ascorbic acid completely counteracts the nitrosamine formation.