Nitrates in vegetables and well water

The short version

Nitrates are a natural part of many vegetables, and of soil and water. For a baby who starts solids at around 6 months, the vegetables themselves are not a reason to worry. The risk the AAP and CDC describe is mostly for babies under 3 to 4 months, and the main source is water from a private well used to make formula, not a bowl of puréed carrots.

Don’t skip vegetables because of nitrates. Spinach, beets, carrots and green beans give your baby new tastes and nutrients, and the NHS suggests both sweet vegetables like carrot and bitter ones like spinach from the start of weaning.

What nitrates do in a young baby

In the body, nitrate can turn into nitrite. Nitrite changes hemoglobin, the part of the blood that carries oxygen, into a form called methemoglobin that can’t carry oxygen well. A high level causes methemoglobinemia, sometimes called “blue baby syndrome” (EPA).

Young babies are more vulnerable than older children because (ATSDR, AAP):

• their stomach is less acidic, so gut bacteria can turn more nitrate into nitrite
• much of their hemoglobin is the newborn (fetal) type, which changes into methemoglobin more easily
• the enzyme that reverses the change works at only about half the adult level, and doesn’t reach adult levels until at least 4 months

Diarrhea and vomiting can raise the risk in young babies, even without extra nitrate (ATSDR).

Who is at risk

The AAP’s advice here comes from a 2005 clinical report, reaffirmed in 2010.

• Babies under about 4 months fed formula made with contaminated well water are the group most at risk (ATSDR, AAP). The EPA says babies under 6 months who drink water with nitrate above the legal limit could become seriously ill.
• Breastfed babies are not at risk from the water their mother drinks. The AAP says nitrate levels in breast milk don’t rise significantly, even when the mother drinks water with very high nitrate levels.
• Babies eating vegetables. The AAP says there seems to be little or no risk from commercially prepared baby foods in the US. Cases linked to home-prepared vegetable foods do still occur, which is why it advises avoiding homemade spinach, beets, green beans, squash and carrots before 3 months. Solid food isn’t recommended that early anyway: the NHS says to start at around 6 months, and the AAP report notes there’s no nutritional reason to start before 4 to 6 months.

Vegetables from 6 months

From around 6 months, offer these vegetables cooked soft, as you would any other first food. Variety helps: rotate them with other vegetables rather than serving one every day. See:

• Spinach, Swiss chard, kale and collard greens
• Beet, carrot and green beans
• Butternut squash and pumpkin

For more on first vegetables, see vegetables for babies and making purées.

Storing homemade purées of beets, spinach and carrots

The AAP report’s only storage line is for shop-bought baby food: once a jar or container is opened, keep it in the fridge and throw it away within 24 hours. It gives no fridge time for homemade purées. Homemade beet, spinach, carrot, green bean and squash purées follow the same storage rules as any other cooked baby food on this site:

• Cool quickly and chill. Cool cooked food within 1 to 2 hours, then refrigerate or freeze it (NHS). Throw away any food left out at room temperature for more than 2 hours (1 hour if it’s hotter than 90°F / 32°C).
• Fridge: in a covered container, use within 3 to 4 days (USDA FSIS), as on the spinach, beet and carrot pages. The NHS is stricter: it says to use batch-cooked baby food kept in the fridge within 2 days.
• Freezer: freeze in small portions soon after cooking if you won’t use them within that time. Use frozen vegetable purées within 3 months (this site’s rule for vegetable purées). Thaw them in the fridge and use them within 24 hours of thawing (NHS).
• Serve from a bowl, not the container, and throw away whatever is left in the bowl (NHS).

See batch cooking and freezing for the general method.

If you use a private well

The AAP says families with a private well should have the water tested for nitrate, ideally before the baby arrives. Nitrate gets into wells from fertilizer, septic systems, sewage and animal waste, moving through groundwater and run-off (EPA).

• The safe level. The US legal limit for public drinking water is 10 mg/L of nitrate measured as nitrogen (EPA). The AAP says water for babies should be below 10 ppm (the same as 10 mg/L).
• Testing. The AAP says any reference or public health laboratory can test for nitrate, and most state health departments list certified labs.
• If the level is high, don’t use that water for your baby’s formula or food. The AAP suggests another source, such as a public supply, a deeper well or bottled water free of nitrate.
• Boiling doesn’t remove nitrate. Water loses some volume as it boils, so the nitrate left behind becomes more concentrated. The AAP says boiling water with nitrate below 10 ppm for 1 minute kills germs without over-concentrating the nitrate.
• Filters. Ion-exchange and reverse osmosis systems remove nitrate; ordinary water softeners don’t (AAP).

For safe water for formula in general, see choosing and preparing formula and water for babies.

Signs to watch for

Nitrate poisoning from vegetables is uncommon: the AAP report describes only occasional cases worldwide. The main sign of methemoglobinemia is a blue, gray or brownish color to the skin, lips or inside of the mouth. Babies may also be irritable, breathe fast, be short of breath or seem less alert than usual (AAP, EPA).

Call 911 or go to the emergency room if your baby:Call 999 or go to A&E if your baby:Call your local emergency number (such as 112 in Europe or 000 in Australia) or go to the emergency department if your baby:

• has blue, gray, brownish, pale or blotchy skin, lips or tongue, or a brownish color inside the mouth (on brown or black skin, this may be easier to see on the palms or soles) (NHS, AAP)
• is breathing very fast or having difficulty breathing (NHS)
• is very sleepy, difficult to wake or can’t be woken (NHS)

Tell the doctors if you use well water.

Where US and UK advice differs

• The 3-month line. The AAP advises no homemade spinach, beets, green beans, squash or carrots before 3 months. The NHS doesn’t give a nitrate rule for vegetables, and suggests carrot and spinach among first foods from around 6 months. Both start solids well after 3 months, so in practice the advice is the same.
• Water for formula. The NHS says to make up formula with freshly boiled tap water and doesn’t usually recommend bottled water. US advice adds well testing, because many US families use private wells: if yours is high in nitrate, the AAP suggests a nitrate-free bottled water or another safe source.
• Storage. USDA FSIS gives 3 to 4 days in the fridge for cooked leftovers, which this site’s food pages use. The NHS says batch-cooked baby food kept in the fridge should be used within 2 days. The AAP’s 24-hour line is for an opened jar of shop-bought baby food, not for homemade purées.