The concern over various toxins contaminating the vegetable produce and the water that we consume is growing day by day. Not only toxins but certain naturally occurring substances in plants when present in excess can also act like toxins and one of them is nitrates. Well water in certain areas can also contain high levels of nitrates. Nitrate containing plant foods (carrots, spinach, beets, green beans, courgette, collard greens etc) and food prepared with water containing high levels of nitrates are particularly be dangerous when given to infants below three months of age. It can lead to a condition called ‘the blue baby syndrome’ or Methemoglobinemia in which babies develop a blue-grey skin color and become irritable or lethargic.1
Nitrates and nitrites are hemoglobin oxidizing agents. Infants below three months of age have lower levels of an enzyme called NADH-cytochrome b5 reductase, which converts methemoglobin back to hemoglobin thus are at risk of developing methemoglobinemia.2
The high pH of infant stomachs also makes them more susceptible to methemoglobinemia. Higher pH provides a favorable environment to the growth of nitrate reducing intestinal bacteria which convert nitrate to nitrite.3
The risk of exposure to nitrates is more when infant food is prepared with well water containing nitrates. There is very little or no risk with the commercially prepared infant foods, as these companies voluntarily screen their products for levels of nitrates. Breastfed infants though have no risk of nitrate poisoning even if the mother consumes food with high levels of nitrates.4
Studies have shown that consumption of silver beets and storing homemade purees of mixed vegetables for over twelve hours in refrigerator could cause methemoglobinemia in infants over six months of age.5
Long term storage of vegetables can also lead to methemoglobinemia as natural degradation of food on storage increases the levels of nitrites.6
Protecting your child from methemoglobinemia:-
Do not introduce solids before three months of age. According to American academy of Pediatrics solids should not be given before 4-6 months of age.
If water from private wells is being used for preparation of baby food, it should be tested for nitrate levels. The levels of nitrate nitrogen should be less then 10 ppm.
When using commercially prepared baby food, refrigerate the containers after opening and discard them if stored over 24 hours.
Home prepared baby food should be prepared from fresh produce and should be used immediately. Storage over 12 hours should be avoided.
When making vegetable purees, discard the water used to boil the vegetables, as nitrates leach into the water.
1. Blue babies and nitrate-contaminated well water. Knobeloch L, Salna B, Hogan A, Postle J, Anderson H. Environ Health Perspect. 2000 Jul; 108(7):675-8. Comment in:
Environ Health Perspect. 2001 Jan;109(1):A12-4.
2. Methemoglobinemia caused by the ingestion of courgette soup given in order to resolve constipation in two formula-fed infants. Savino F, Maccario S, Guidi C, Castagno E, Farinasso D, Cresi F, Silvestro L, Mussa GC. Dipartimento di Scienze. Ann Nutr Metab. 2006; 50(4):368-71. Epub 2006 Jun 29.
4. Infant methemoglobinemia: the role of dietary nitrate in food and water.Greer FR, Shannon M; American Academy of Pediatrics Committee on Nutrition; American Academy of Pediatrics Committee on Environmental Health. Pediatrics. 2005 Sep; 116(3):784-6.