Why do top nutritionists and food scientists avoid grain-fed beef and warn others to do the same?  Why do we hear about hamburger meat being recalled due to E. coli scares more and more frequently?

In the past, all beef was grass-fed beef, since cattle have evolved for millions of years to eat grass, but in the United States today what is commercially available is almost all grain-fed feedlot beef.The reason? It’s faster, and so more profitable. Seventy-five years ago, beef cattle were 4 or 5 years old at slaughter. Today, they grow to slaughter size in less than two years – an efficient, industrialized process that has transformed beef into a cheap fast food.

Switching a cow from grass to grain is so disturbing to the animal’s digestive system that it can kill the animal if not done gradually and if the animal is not continually fed antibiotics. These animals have evolved to forage and re-chew food that has been stored in the rumen (a fermenting chamber in the stomach).  However on feedlots, they are made to eat grain, primarily corn, in order to make them as fat as possible in a short amount of time.

Work conducted at Cornell University by Russell and Diez-Gonzalez in the late 1990s showed that cattle that were fed hay had far fewer E. coli than when they were fed a standard feedlot diet based on grain. (Microbes Infect 2, No. 1 (2000): 45-53.).  The reason for the greater occurrence of E. coli from grain-fed cattle, the researchers speculated, is that feeding grain to cattle makes their digestive tracts abnormally acidic. Over time, the E. coli in their systems become acclimated to this acid environment. When we ingest them, a high percentage will survive the acid shock of our digestive juices. By contrast, few E. coli from grass-fed cattle will survive because they have not become acid-resistant.

Animals raised in factory farms are given diets designed to boost their productivity and lower costs. The main ingredients are genetically modified grain and soy that are kept at artificially low prices by government subsidies. When animals are 100% grass-fed, their meat is not only lower in saturated fats but also slightly higher in omega-3 fatty acids,  which studies indicate may help prevent heart disease and bolster the immune system.

Upscale groceries like Whole Foods and Trader Joe’s are ramping up grass-fed offerings, including imports from Australia and Uruguay. Internet companies such as La Cense also sells high-quality Grass-Fed Beef.