Like many American kids I grew up eating turkey or ham and cheese sandwiches. And if I was lucky, mom occasionally bought me a Lunchables. Which is funny looking back; even in grade school I didn't think they tasted that good. It must have been the novelty of it...and their great marketing. In college I continued to make deli meat sandwiches, mostly out of convenience and cost. But over the past several years it dawned on me... I HATE deli meat (except for the occasional roast beef and very rarely salami). This is probably a good thing since most deli meats are preserved with sodium-nitrate. Nitrates are a naturally occurring nitrogen compound found in vegetables. Leafy greens and root vegetables are especially high in them: cauliflower, collards, broccoli, spinach, potatoes, beets, turnips... When plants die and decompose, they release these nitrates into the ground. This is a good thing and part of the reason why smart farmers rotate crops. Corn is notorious for depleting the nitrogen in soil, where as soy beans replenish it. Veggie nitrates are natural.
As I mentioned above, most processed meats (deli meat, bacon, sausage, ham) are preserved with sodium nitrate. Tap water is another sources of nitrates since farms often use nitrate containing fertilizers which run off and contaminate ground water aquifers. Consuming excess nitrates found in processed meats has been shown to increase a child's chances for leukemia if they consume 12+ hotdogs in 1 month; they have also been linked to colon cancer in adults. While most kids are not eating 12 hotdogs/month, they probably are eating hotdogs, deli meat, hamburgers, sausages, bacon and pepperoni pizza at least once per day at school. To avoid these nitrates opt for nitrate free products such as those from Applegate farms and specific products by Hormel. The American Meat Industry will tell you that nitrates are safe, however I'm not convinced. But to be fair, here is a link to what they have to say.
No studies have shown a link between the nitrates in water and cancer. However, there is a link between these nitrates and methemoglobinemia or "blue baby syndrome." The nitrate is converted into a nitrite in the colon and is absorbed into the blood stream reacting with iron and hemoglobin in the fetal blood causing it to become methemoglobin. Methemoglobin is unable to cary oxygen and this can result in breathing difficulties, low blood pressure, and developmental delays. This is easily avoidable by either breastfeeding or using only filtered water to mix formula.
You may be wondering how I got on this topic? Ryan and I made pasta bake the other night with Trader Joe's High Fiber pasta. I compromised since Ryan wasn't in the mood for whole wheat. The next day I looked at the ingredients and noticed that it contains Thiamine Mononitrate. AAAHHH not a nitrate!!! Being the inquisitive RD that I am, I did a little research. Thiamine Mononitrate (TM) is a synthetic form of the vitamin B1 or thiamine. Thiamine is important in many different bodily functions and plays a roll in vision, hair/skin integrity, and the nervous system. Processed grain products have been fortified with B vitamins for many years as a way to prevent dietary deficiency. However, studies now show that TM does not actually prevent or reverse Thiamine deficiency; only natural sources do. B vitamins are water soluble and when consumed in excess the body eliminates them in the urine. However, TM is fat soluble and the body has difficulty removing it. This can lead to accumulation in the liver and other fatty tissue. The nitrates in TM may also accumulate in the kidneys. This accumulation can cause problems such as kidney stones. For healthy individuals I would recommend they try and avoid foods with TM in it. People with liver or kidney disease should absolutely avoid this food additive. To ensure adequate intake of Thiamine focus on consuming these foods: Pork, Tree Nuts (peanuts don't count), Sunflower and Sesame Seeds, and fish.