Nutritionism in practice involves singling out one or a few important nutrients in certain whole foods as the cause of benefits from those foods.  The person practicing nutritionism is implying that the singled-out nutrients provide the benefits shown in studies conducted using a whole food.  This approach grossly oversimplifies how the body metabolizes complete foods, with hundreds or even thousands of nutrients that interact.  It leads to adding individual nutrient supplements to foods. More broadly, it is an ideology that pervasively surrounds us. In his book In Defense of Food Michael Pollan says that nutritionism is an ideology – a way of organizing "large swaths of life and experience under a set of shared but unexamined assumptions."