Ruminant production systems are under pressure for their inefficient use of land, a recurring idea assuming they consume far more plant proteins than they produce in the form of animal protein and for their methane emission. However feed-food competition does in fact concern those proteins of plant origin that are consumable by human but are actually consumed by animals and this affirmation ignores that ruminants are able to produce products of high nutritive value from grassland and marginal area that cannot be used for crop production. In addition grassland provides many environmental services. In the last decades the intensification of ruminant production system, and particularly those of dairy systems, have increased protein production per ha of land use in Europe but this occurs thanks to an increased use of concentrate which contains edible protein and at the expense of grassland acreage. Therefore the interest of this evolution for the contribution of ruminants to food security may be questioned. Feeding animals mainly from non-edible resources can be seen as a conceptually interesting issue from a global food security point of view. After showing that the decrease in European grassland acreage was closely linked to the intensification of dairy systems and the associated reduction of the number of cows, the paper describes protein production for various ruminant production systems and demonstrates that grassland based ruminant production systems are most often much more efficient than concentrate based systems for procuring proteins. The development of grassland based systems seems very desirable to increase ruminant production systems to protein security. In addition an increased use of grassland for ruminant production could also bring positive responses to societal demand for more natural practices and could contribute to maintaining farmer incomes in a context of price volatility and the provision of various ecosystem services. The challenge might be to increase productivity of grassland based system using sustainable intensification of forage production, well suited animals and grazing management.