Nitrates in vegetables: what health professionals should know.
When infants start solids, vegetables like carrots, sweet potatoes, and beetroot are often among the first foods introduced. These colourful vegetables are nutrient-rich and excellent first foods. Occasionally, parents may ask about nitrates in vegetables and whether they are safe for babies. Here’s a summary of the evidence and Australian guidance for health professionals.
What are nitrates?
Nitrates are natural compounds found in soil and water. Vegetables absorb them as they grow, especially those that grow close to the soil. Nitrates can also enter food or water from fertilisers and agricultural runoff.1
In the body, nitrates can convert to nitrites. In very high amounts, nitrites can interfere with the way blood carries oxygen, leading to a condition called methemoglobinemia or “blue baby syndrome”. This is extremely rare in Australia and generally linked to contaminated drinking water, not normal vegetable consumption.1,2,3
Why infants are more sensitive to nitrates
Infants, especially those under three months (who are not yet ready for solids), process nitrates differently than older children and adults due to several physiological factors.
Blood chemistry differences
- Newborns have more fetal haemoglobin (responsible for carrying oxygen around the body), which is more easily affected by nitrites.
Digestive system factors
- Babies’ stomach acid is less acidic, allowing gut bacteria to convert nitrates into nitrites more easily. As babies grow, stomach acidity increases, reducing this conversion.2,4,5
Immature enzyme systems
- In infants, a key enzyme involved in processing nitrates is less active, which means their bodies take longer to neutralise nitrate effects compared to older children and adults.4,5
Why this matters most for very young infants
- The greatest risk is in babies under three months, especially those formula-fed with water high in nitrates (e.g. untreated bore, well or tank water).
- By about six months, when most babies start solids, digestive and enzyme systems have matured enough to process nitrates safely.
- Danger arises only when high nitrate levels combine with an infant’s immature digestive and blood systems.3,5,6
Australian guidance on nitrates
1. Drinking water standards
Australian drinking water is subject to strict guidelines and treatment to ensure safety. However, bore, well and tank water are not subject to these guidelines or treatment. If bore, well or tank water is in use, especially in rural or farming areas, testing should be encouraged to ensure the water is safe for use when preparing food of formula. Boiling water does not remove nitrates.3
2. Food and infant feeding guidance
The NHMRC Infant Feeding Guidelines recommend starting solid foods at around six months of age, when babies are developmentally ready.7
The Food Standards Australia New Zealand (FSANZ) agency has reviewed nitrate levels in Australian foods and concluded that current exposure from vegetables poses no appreciable health risk for the general population, including infants starting solids.8
Practical tips for preparing root vegetables safely
Even though the risk from nitrates in Australian vegetables is low, you can support parents with these practical tips:
- Wash vegetables thoroughly to remove soil and surface residues.
- Use safe water for cooking and preparing purees.
- Avoid long storage at room temperature. Cool or freeze purees promptly after cooking.
- Vary the vegetables offered. Balance root vegetables with greens, legumes, and fruits.3,9,10,11,12
Extra caution
- Private water sources for formula or cooking.
- Infants with gut illness or infection, which may alter nitrate processing.3,4, 9,12
Key points
- In Australia, vegetables, including root vegetables are safe and recommended as first foods from around six months.
- Ensuring safe water and following basic food hygiene are the most important safety steps.
- Nitrates are naturally present in vegetables, and with safe preparation and variety, root vegetables remain a nutritious part of an infant’s diet.
References
- Department of Climate Change, Energy, the Environment and Water. Total nitrogen fact sheet. Available from: https://www.dcceew.gov.au/environment/protection/npi/substances/fact-sheets/total-nitrogen
- World Health Organization. Chemical fact sheets: Nitrate & Nitrite. Available from: https://www.who.int/publications/m/item/chemical-fact-sheets–nitrate-nitrite
- National Health and Medical Research Council. Australian Drinking Water Guidelines: Nitrate and Nitrite. Available from: https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/physical-chemical-characteristics/nitrate-and-nitrite
- National Center for Biotechnology Information. Nitrate and Nitrite. Available from: https://www.ncbi.nlm.nih.gov/books/NBK592486/
- National Research Council (US) Committee on Diet and Health. Dietary Reference Intakes. Available from: https://nap.nationalacademies.org/read/9038/chapter/5
- World Health Organization. Nitrate and Nitrite: Chemical fact sheet [PDF]. Available from: https://www.who.int/docs/default-source/wash-documents/wash-chemicals/nitrate-nitrite-chemical-fact-sheet.pdf
- NHMRC & Department of Health. Infant Feeding Guidelines. 2012.
- Food Standards Australia New Zealand (FSANZ). Nitrates and Nitrites in Food. 2023.
- National Health and Medical Research Council. Australian Drinking Water Guidelines. Available from: https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines
- NSW Food Authority. Food Safety Fact Sheet [PDF]. Available from: https://www.foodauthority.nsw.gov.au/media/1361
- Food Standards Australia New Zealand. Prevention of foodborne illness. Available from: https://www.foodstandards.gov.au/consumer/prevention-of-foodborne-illness
- National Health and Medical Research Council. Infant Feeding Guidelines [PDF]. Available from: https://www.eatforhealth.gov.au/sites/default/files/files/the_guidelines/170131_n56_infant_feeding_guidelines.pdf