Babies less than 6 months old should not be fed home-cooked beets, carrots, collard greens, spinach, or turnips, as this may cause methemoglobinemia, a blood disorder in which an abnormal amount of methemoglobin, a type of hemoglobin, is produced. Methemoglobin cannot release oxygen. While most cases of methemoglobinemia are genetic, some drugs can cause the condition, including benzocaine, certain antibiotics, nitrites (used as food additives), and nitrates (from foods). These vegetables, particularly beets, are high in nitrates.
The nitrates in foods may be converted to nitrites in young babies. It's difficult not to notice methemoglobinemia, as the baby's skin turns blue. In the US, nitrates are removed during commercial manufacturing, so these vegetables when store-bought should be safe, says the article, "Caution with High-Nitrate Foods," in the larger article, "Introducing Baby to Solid Foods," by Kimberly M. Sanders, ND, and Jacob Schor, ND, FABNO. The article appears on page 75 of the April 2014 issue of the Townsend Letter. Check it out in your library or magazine store or subscribe to the publication, if you like. The point is certain home-made vegetable purees should not be given to babies under 6 months of age.
The article also explains that breast-feeding may prevent the babies from developing this condition, even if they are exposed to high levels of nitrate. The studies that the article reference are, "Infant methemoglobinemia: the role of dietary nitrate in food and water." It's published in the journal Pediatrics. See, "The Role of Dietary Nitrate in Food and Water," American Academy of Pediatrics Committee on Nutrition; American Academy of Pediatrics Committee on Environmental Health. September 1, 2005. Authors are Greer FR, and Shannon M. The other referenced study in the Townsend Letter article is "Feeding solid foods," Chapter 7, in Feeding Infants: A Guide for Use in the Child Nutrition Programs. USDA Food and Nutrition Service.
The USDA guide presents information on infant development, nutrition for infants, breastfeeding and formula feeding, preventing tooth decay, feeding solid foods, drinking from a cup, choking prevention, sanitary food preparation and safe food handling, commercially prepared and home-prepared baby food, and some of the Infant Meal Pattern requirements. On another note you may wish to check out the news articles trending on another study, "Children with strict parents tend to be obese ."
For grown-ups, nitrates in vegetables protect against gastric ulcers, says another study
According to a May 7, 2008 news release, "Nitrates in vegetables protect against gastric ulcers." Fruits and vegetables that are rich in nitrates protect the stomach from damage. This takes place through conversion of nitrates into nitrites by the bacteria in the oral cavity and subsequent transformation into biologically active nitric oxide in the stomach. The Swedish researcher Joel Petersson has described the process, which also means that antibacterial mouthwashes can be harmful for the stomach.
"Nitrates in food have long been erroneously linked to an increased risk of cancer," says Joel Petersson of Uppsala University's Department of Medical Cell Biology, according to a May 7, 2008 news release, "Nitrates in vegetables protect against gastric ulcers." He instead thinks that nitrate-rich vegetables such as spinach, lettuce, radishes and beetroot have a positive affect on the stomach by activating the mucous membranes' own protective mechanisms, thus reducing the risk of problems such as gastric ulcers. Just don't feed home-made vegetables high in nitrates to babies.
In the body the blood circulation transports nitrates to the salivary glands, where they are concentrated
When we have eaten nitrate-rich food our saliva thus contains large amounts of nitrates, which the bacteria of the oral cavity partially convert into nitrites. When we swallow the nitrites they come into contact with acid gastric juice, and are then converted into the biologically active substance nitric oxide. This results in our developing high levels of nitric oxide in the stomach after eating vegetables.
It has long been known that nitric oxide is produced by various enzymes in the human body, but the fact that nitric oxide can also be formed in the stomach from nitrites in the saliva, entirely without the involvement of enzymes, is a relatively new discovery. Researchers still have very little idea of how the stomach is affected by these high levels of nitric oxide. Joel Petersson's thesis shows that the nitric oxide that is formed in the stomach stimulates the protective mechanisms of the mucous membrane – because the stomach constantly has to protect itself so as not to be broken down together with the food ingested.
Two such important defense mechanisms are the stomach's constant renewal of the mucous layer that covers the mucous membrane and its maintenance of a stable blood flow in the mucous membrane. The nitric oxide widens the blood vessels in the mucous membrane, thus increasing the blood flow and regulating elimination of the important mucus. Together, these factors lead to a more resistant mucous membrane.
Using animal models Joel Petersson and his colleagues have shown that nitrate additives in food protect against both gastric ulcers and the minor damage that often occurs in the gastrointestinal tract as a result of ingestion of anti-inflammatory drugs.
"These sorts of drugs are very common in the event of pain and inflammation. They have the major disadvantage of causing a large number of serious side effects in the form of bleeding and ulcers in the gastrointestinal tract. With the aid of a nitrate-rich diet you can thus avoid such damage," he explains in the news release.
The thesis also shows that the bacteria in the oral cavity are very important to the process of nitrates in food protecting the stomach's mucous membrane
This has been examined in that rats have been given nitrate-rich feed, whereby some of them have also simultaneously received an antibacterial oral spray. When these rats were then given anti inflammatory drugs, damage to the mucous membrane only occurred in the ones that had received the oral spray. In the latter the nitrates no longer had a protective effect on the mucous membrane, as the oral spray had killed the important bacteria that normally convert nitrates into nitrites.
In his opinion the research results also provide a new approach to the importance of fruit and vegetables in our diet. "This shows how important our oral flora is. The fact that these bacteria are not just involved in our oral hygiene but also play an important role in the normal functions of the gastrointestinal tract is not entirely new.
It is currently an important issue, as antibacterial mouthwashes have become more and more common. If a mouthwash eliminates the bacterial flora in the mouth this may be important to the normal functioning of the stomach, as the protective levels of nitric oxide greatly decrease," says Joel Petersson, according to the news release. "If we followed the National Swedish Food Administration's recommendation and ate 500 g of fruit and vegetables per person per day, it would definitely be better for our stomachs."
Research supports calls to study health benefits of nitrate, nitrite
A Michigan State University researcher is challenging health standards that consider nitrates and nitrites in food to be harmful, according to an August 20, 2009 news release, "Research supports calls to study health benefits of nitrate, nitrite." Norman Hord's research suggests that although there are negative health effects associated with the use of nitrogen-based fertilizers and excessive nitrates in groundwater, nitrates and nitrites -- as they occur in plants -- may actually provide health benefits.
Many food components are beneficial at low and harmful at high intakes, according to the study's abstract. Hord and his team claim that nitrate is beneficial at intakes now considered toxic. What do we know about the health effects of nitrate and nitrite?
Nitrate and nitrite are naturally occurring ions associated with the nitrogen cycle in soil and water
They are regulated in water and certain foods by the Environmental Protection Agency and the Food and Drug Administration because they have been associated with gastrointestinal cancer, blood disorders in infants and other health problems. The World Health Organization established a standard of 222 milligrams per day as an acceptable daily nitrate intake.
Most of the concern with these compounds relates to their presence in drinking water from shallow wells near farms and the consumption of processed meats. In most diets, however, between 70 percent and 80 percent of the nitrates comes from vegetables, government and research sources say, according to the news release.
"We and others have shown that components of vegetables and fruit that originate in the soil may function as nutrients by contributing to cardiovascular health," says Hord, according to the news release. Hord is an associate professor of food science and human nutrition. "Since these components of plant foods have important health implications, the regulatory limits on the consumption of plant foods that contain nitrates and nitrites need to be seriously reconsidered."
Infants can develop methemoglobinemia from eating foods with nitrates and nitrites
Hord is the primary author of the study, "Food sources of nitrates and nitrites: the physiologic context for potential health benefits," The abstract of that study mentions, "The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia."
Also, you may wish to see, "Nitrate in foods: harmful or healthy?" American Journal of Clinical Nutrition, July 2009. Published online since May 20, 2009. Hord collaborated with Nathan Bryan and Yaoping Tang at the University of Texas Health Science Center in Houston. Their thesis and supporting arguments were published in the July 2009 issue of the American Journal of Clinical Nutrition.
"We wanted to show the toxicity risk cited as the basis for federal regulatory levels for nitrate and nitrite are irrational because plant foods contain high concentrations of these food components," Hord says, according to the news release. "People consuming a variety of fruits and vegetables may be ingesting much more nitrate and nitrite than recommended -- more than 1,000 milligrams -- with no adverse health effects. We're calling for a systematic reevaluation of the literature to highlight the potential beneficial contributions that nitrates and nitrites from vegetables and fruits make to cardiovascular health."
In an accompanying editorial, "Nitrate in Foods: Harmful or Healthy?," Martjin Katan from the Institute of Health Sciences at VU University in Amsterdam said it is undisputed that nitrates benefit arteries, and he called for a trial to investigate whether consuming a food pattern rich in nitrate-containing vegetables is effective in lowering blood pressure.
For grown-ups, another study says the use of nitrates may increase bone strength. You also may wish to check out the news release about that other study, "Use of nitrates may increase bone strength." The funders for Hord's group's study are the Michigan Agricultural Experiment Station, MSU, and the American Heart Association.