Spinach is able to restore energy to your body, improve the quality of your blood, increase your vitality and it has great nutritional qualities. Spinach is a good source of vitamin B3, magnesium, iron, and manganese, as well as an excellent source of vitamin C, vitamin A, and vitamin K. But, will all the benefits of this leafy green come one side effect. After eating it, it leaves a weird sensation in your mouth, more specifically, on your teeth. 

The chalky and gritty feeling on your teeth also known as ‘Spinach Teeth’ is a harmless side effect that many people experience after eating spinach. Compared to other crops, spinach has higher amounts of oxalic acid, which it most like uses to defend itself against insects and animals that try to eat it. Oxalic acid is an antinutrient because it blocks the body’s ability to absorb nutrients by bonding with minerals. When speaking of spinach, the nutrient that is blocked is calcium. 

The calcium in your saliva combined with the oxalic acid in the spinach creates calcium oxalate crystals that don’t dissolve in water thus giving a chalky feel to your teeth and sticking to them. The unusual texture and feeling you get are caused by the tiny crystals floating around in your mouth. These crystals are what some people describe as a bitter taste to spinach and give that tannic, gritty feeling in your mouth. Other foods that have high levels of oxalic acid include tea, chocolate, nuts, strawberries, rhubarb, wheat bran, beets, and all dry beans with the exception of green and lima beans. 

You shouldn’t be worried that this type of acid will erode your tooth enamel. The pH levels of spinach, especially when it is cooked don’t have much of an effect because they are so close to neutral. Actually, oxalic acid can actually help in reducing tooth sensitivity.

However, in case you have a high risk of kidney stones, you might want to be careful. Calcium oxalate stones can be formed as a result of consuming lots of foods with oxalic acids. The food you should be most concentered about is spinach by far because it has the most oxalic acid.

There are several theories on how to avoid spinach teeth, and some of them even contradict one another. Some people say to blanch or cook the spinach, while some say to just eat the spinach raw and not cook it at all. Others say to avoid combining spinach with milk because the milk has even more calcium that helps in forming the crystals. Another theory is to steam the spinach or to squeeze some lemon juice on top of the spinach because the vitamin C (ascorbic acid) in the lemon juice dissolves the oxalic acid.