Until recently, no one thought much about what cattle were given to eat and how their feed could affect the nutritional quality of beef. Food critics and others who enjoy fine steaks argue the merits of corn-fed versus grass-fed beef as far as flavor and tenderness are concerned, but they rarely discuss nutrition and food safety issues.
These issues now have come to the forefront of the discussion about beef. With the surge in popularity of the Atkins and other high-protein diets, we are learning that not all beef is created equal.
Traditionally, cattle lived on pastures and open range land, grazing on a diet of grass. As cud-chewing ruminants, their digestive systems are designed to break down grass and convert it to protein.
After World War II, surpluses of corn and other grains in the United States drove prices down. This low-cost grain was fed to cattle, and ranchers found that their animals gained weight more quickly on this diet, which meant they could be slaughtered at a younger age. Grain-fed animals became more profitable to their owners.
During the second half of the 20th century, the feedlot system developed. The use of antibiotics to prevent disease and hormones to encourage weight gain became standard in the cattle industry. Calves and cattle graze on grass for the first part of their lives, then are shipped to feedlots where they are switched to an all-grain diet to fatten them for slaughter. All cattle are grass-fed for their first year or more, but most are "grain-finished" in feedlots for the last three to six months of their lives.
The American public has grown used to the taste and appearance of grain-finished beef. It tends to be more tender because it is higher in fat. Also, the taste of grain-finished beef is consistent, whereas the flavor of grass-fed beef can vary depending on what type of grasses the cattle last ate.
Advocates of grass-finished beef point to research that shows beef from 100 percent grass-fed cattle is more nutritious and safer than grain-fed or grain-finished beef.
In general, the beef from 100 percent grass-fed cattle is nutritionally similar to wild venison and elk meat. One study found that it contains 2.5 grams of fat per 100 grams, as compared to 5.5 grams in grain-finished beef, which means it has fewer calories and less cholesterol.
Grass-fed beef has significantly higher amounts of vitamin E and beta-carotene per serving. These nutrients are antioxidants, which can reduce the risk of heart disease by preventing the oxidation of LDL ("bad") cholesterol that causes fat to build up in the arteries.
Grass-fed beef contains a higher ratio of omega-3 fatty acids than grain-fed beef. This substance protects against heart disease. Grass itself is full of omega-3 fatty acids, but corn and other grains are not. When cattle are changed from a diet of grass to grains, their meat loses most of the stored omega-3 fatty acids.
From a food safety perspective, cattle that graze on grass their whole lives are less likely to be infected with bovine sponigiform encephalopathy (BSE, or "mad cow disease") than cattle in feedlots that may be fed animal products.
Also, grass-fed cattle who are kept out of feedlots seem to be less likely to carry and transmit E. coli 0157:H7. This bacteria causes serious food-borne illness in humans if beef is not cooked thoroughly. There are more than 70,000 cases in the United States each year; a few lead to kidney failure and death.
Overall, it is natural that cattle raised on grass and allowed to roam will be healthier than grain-fed feedlot cattle and will pass on these health benefits to those who eat their meat.
Kathryn B. Brown is a family nurse practitioner with a master's degree in nursing from OHSU. Is there a health topic you would like to read about? Send ideas to firstname.lastname@example.org.