Eating left overs and processed foods with nitrites can increase triglycerides.
Manufacturers add nitrates and nitrites to foods such as cured sandwich meats, bacon, salami or sausages to give them color and to prolong their shelf life.
Connie , answering at Quora.com
A Swedish study found that children with type 1 diabetes had eaten more food containing nitrosamines, nitrite, and nitrate than those without diabetes (Dahlquist et al. 1990). A large study in Finland found that children with type 1 diabetes and their mothers ate more nitrite than children (and their mothers) who did not have diabetes. There was no difference for nitrate/nitrite in drinking water (Virtanen et al. 1994).
Links Between Nitrate/Nitrite and Diabetes/Obesity
A few dozen peer-reviewed studies published in scientific journals have examined the relationship between nitrate and/or nitrite and diabetes or obesity, beginning with a study on type 1 diabetes from Iceland in 1981. Those studies conclude that, “These findings suggest that an environmental factor in the etiology [causation] of human diabetes mellitus has been identified” (>Helgason et al. 1982). That environmental factor is Icelandic smoked mutton, which is high in nitrite. While this smoked mutton is not likely to be an important factor outside of Iceland, other sources of nitrate/nitrite may be.
For most of us, eating leftover vegetables will not cause problems as long as they’re not spoiled and are reheated properly, which doesn’t have anything to do with the nitrates.
There are two times when people should be cautious about nitrates. One of those times is during the first four months of life—but it’s not likely that babies that young are going eat leftover anything. If infants are exposed to excessive amounts of nitrates, it will be from well water that might be used to make their formula.
The second time to think about nitrates is during the last 8 to 10 weeks of pregnancy. But again, this refers to drinking water contaminated with really high levels of nitrates—not the amount typically found in vegetables.
You Didn’t Know Vegetables Have Nitrates, Did You?
Yes, they do. Some more than others. According to the U.S. Centers for Disease Control and Prevention, cauliflower, spinach, collard greens, broccoli, beets, and root vegetables contain more nitrates than other vegetables.