Foods contain nutrients but in turn contain other anti-nutritional substances that impair their absorption by the body . The spooning in legumes, tannins in tea, oxalic acid of some vegetables or avid in, the egg are essential in the food that contains them are beneficial but not when they are ingested. The good news is that cooking these foods can be eliminated or cancel this anti-nutritional effects and use their nutrients without problems, especially calcium, iron, protein and vitamin B1. On the other hand must take into account the combination of foods eg vegetables like spinach or chard should be eating away from milk because, as are vegetables rich in oxalates, when mixed with milk calcium salts

form insoluble calcium oxalate that hinder the absorption of the mineral. It's the same combining milk or yogurt with strawberries, but if you follow a varied and balanced diet ant nutritional this combination does not affect the body as long as in daily meals are rare these mixtures.