Lettuce has no nutritional value for hamsters and contains about 90% water, a hamster’s digestive system cannot cope with large amounts of water and may cause diarrhea, or loose stools, depending how much is eaten.
Sodium nitrate occurs naturally in foods such as carrots etc: But green leafy vegetables like spinach and lettuce etc: contain much higher levels of nitrate than most other foods. Some plants, depending on where and how they are grown, such as lettuce and spinach are very high in nitrates relative to the nutritional contribution they make, and it may be reasonable to use other types of vegetables in their place wherever possible.
Sodium Nitrate is converted into Sodium Nitrite by the digestive process once it has been eaten. Studies of nitrate in food have demonstrated that there can be both beneficial and potentially detrimental health effects. The consumption of green leafy vegetables may lead to an increased nitrate intake. Prolonged use of vegetables containing higher levels of nitrate may cause liver damage. Nitrite binds to haemoglobin and can result in less oxygen being carried around in the blood. No carcinogenicity evidence is attached to sodium nitrate intake but studies have reported other effects such as frequent urination, abdominal pain, muscle weakness, blood in stools and urine.
Parsley is toxic; as it is high in oxalic acid. Oxalic acid combines with metals such as calcium, iron, sodium, magnesium, and potassium in the body to form oxalate crystals which precipitate and irritate the gut and kidneys.