2. Natto is actually a soybean product with rich nutrition, including protein, fat, various amino acids, unsaturated fatty acids, lecithin, folic acid, dietary fiber, soap, isoflavones, multivitamins, calcium, iron, potassium and other minerals. However, if you eat too much, it will easily burden your kidneys. It is generally recommended to eat about 50g of natto a a every day to meet your physical needs, without causing physical discomfort due to excessive consumption.