Diet and Nutrition Claims

As ruminants, cows are designed to live on grass. That's what they're fed early in life, but as they get older, they're usually sent to feedlots and put on a grain diet to fatten them up as quickly as possible. The result is that beef from grain-fed cattle is higher in fat overall--and, consequently, more tender (and some would say tastier)--than that from cattle eating only grass their entire lives.

Both grass- and grain-fed beef contain saturated fat, the type that's often associated with a greater risk of heart disease. But in grass-fed beef, a higher percentage of the saturated fat is a type known as stearic acid, which does not raise cholesterol levels.

In addition, grass-fed beef is richer in omega-3 fatty acids than conventional beef, and research shows that subjects who consume grass-fed beef have higher blood levels of this good fat than those who eat conventional beef. Still, the amount of omega-3s in beef pales in comparison to that in fish such as salmon. What's more, this fat comes in a form known as alpha-linolenic acid (ALA), whose benefits aren't as well documented as those of the omega-3s in fish.

Grass-fed beef also has an edge when it comes to a type of fat called conjugated linoleic acid (CLA), which is often claimed to prevent heart disease, cancer, diabetes, and obesity. However, most of the evidence comes from lab and animal studies, so it's hard to draw any firm conclusions about its effects on human health.

As for safety, we often hear that conventional beef is more likely than grass-fed beef to cause foodborne illness. That's because grain makes the stomachs of cattle more acidic, and the acidic environment is thought to lead to a higher prevalence of harmful E. coli bacteria. While some studies have found this to be true, others suggest that grass-fed beef is just as likely to be contaminated as the conventional kind.

One thing we know for certain is that cattle fed an all-grass diet rarely require antibiotics, while those raised on grain routinely get the drugs. Many scientists believe that the widespread use of antibiotics in animals is contributing to the rise of drug- resistant bacteria, so choosing grass-fed over grain-fed beef may be one small way of promoting better public health.

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