Tomato is a natural source of oxalic acid.

Explanation:
Tomato is a natural source of an acid called oxalic acid. Tomatoes have around 50mg of oxalic acid and as it ripes, the content keeps increasing.

Oxalic acids act as anti-nutrients in the human body. Anti-nutrients are those substances which block the absorption of nutrients in our body.

Oxalic acids can bind with various minerals like magnesium, iron and mainly calcium. Oxalic acid binds with calcium forming calcium oxalate which can lead to several issues like hypocalcemia, kidney stones etc.