While many sites state soy sauce to be safe for consumption, it can also have negative effects on some women during pregnancy. Although soy sauce is a good source of Riboflavin, Vitamin B6, Magnesium and Copper, and a very good source of Protein, Niacin, Iron, Phosphorus and Manganese, it is more of a condiment than a proper nutritional food. Several times, it is prepared from genetically modified ingredients, and even if it isn’t, it is full of artificial perservatives and often contains pesticide residue. Soy sauce also contains glyphosate, a residue that can cause gestational diabetes and placental abnormalities in the pregnant mother, and birth defects in the baby. It is also high in phytic acid and trypsin - substances that inhibit the formation and absorption of essential minerals like calcium, magnesium, copper, iron and zinc. However, if you still want to add soy sauce to your diet, we recommend that you eat it in moderation and consult your doctor for further advice.