It is true that all the essential vitamins and minerals can be found in vegan products. The problem is that some nutrients, like iron or vitamin B12, are most abundant in animal products. For example, daily Nutrient Reference Value (NRV) of vitamin B12 can be obtained from 96g of beef (240kcal), or 119g of fortified cereals (427kcal). In addition, this amount of cereals (which are one of the most B12-rich vegan sources) will provide 14g of sugar (zero grams in beef), and less than half of the proteins contained in beef. This example illustrates why in practice assuring healthy and balanced diet rich in all of the essential nutrients may be tricky.