Reheating spinach and other greens – A discussion

What will you find in this post?

1. What happens when we reheat dishes made with greens like spinach, kale, malangai leaves/murungai keerai?
2. How you can store them in fridge and use it the following day?
3. Recipe for a gluten free baby food (9 months old+) with spinach, flattened rice (poha/aval) and ghee

One of the member from a facebook mommy group posted the below statement:

“Hey guys I read somewhere that mushroom and spinach should never ever be reheated and eaten cus it’s toxic !! Plz eat it and finish as soon as u cook or on the same day ….”

I saw that statement and was curious to know more about spinach (any greens like kale, mustard greens etc) first. Regular readers of my blog know that I currently work in clinical operations and I love to understand the science behind food. With my previous experience to use pubmed during my master’s (Molecular Medicine) thesis, I decided to read couple of articles on reheating greens along with some google search. Gladly I have access to read full text for certain journals.

Today I want to share details about one topic which we discussed in a facebook group. I went to PubMed, (PubMed comprises more than 23 million citations for biomedical literature from MEDLINE, life science journals, and online books) and did some reading.

In a nut shell, let me explain what actually happens. Spinach and other leafy vegetables contain high concentrations of nitrate.

Where does nitrate come from?

It comes from the soil where it was grown, weather condition based on the season of the year and water conditions (pH).

Nitrate itself is totally harmless. They are natural constituents of plants. They are present in large quantities in vegetables and in minor quantity in fruits.

The problem comes when Nitrate –> Nitrites —> Nitrosamines that is carcinogenic (cancer causing agent). Enzymes present in bacteria convert nitrate to nitrite.

If body lacks sufficient antioxidants, nitrites gets converted into nitrosamines. So this is where the discussion begins. All of us eat cooked spinach or other greens in some way. I eat spinach cooked in dahl, methi murgh (chicken cooked with fenugreek leaves, you can check the recipe here) or quiche, if I don’t finish it the same meal I store it in fridge and use it the following day. If you forget to put it back in the fridge after the meal and the outside temperature is high, then please THROW IT AWAY. If it is not properly stored, the bacteria present in the food converts the nitrates to nitrites.

Why I prefer to store them in fridge and use it the following day?

My understanding from the above mentioned paper is that if you can’t finish your spinach and want to save it for the next day, be sure to cool it quickly and keep it below 5 degrees Celsius to prevent nitrite production and buy organic one as there will be less uptake of pesticides in it. One should also eat foods like berries, beans, artichoke which are rich in antioxidants. In a nutshell, it is always better to eat organic/ pesticide free food, local food and store them well to avoid contamination. I totally agree to what my mom, your mom and elders say about not reheating left over spinach but the point is here is that these things come out of a health scare. They should be taken seriously and I want to share the science behind it with all.

This article is applicable to young adults/grown ups who eat greens on a regular basis and not for kids less than 2 years old. Please prepare fresh greens for them.

I prefer to use this over Gerber rice cereal for the following reasons:

1. No added preservative
2. I have eaten poha since my baby years
3. It is a known ingredients for me to work with
4. They are less expensive than store bought rice cereal.