But cutting out beef isn't a decision that makes sense nutritionally, said Julie Garden-Robinson, professor and food and nutrition specialist at North Dakota State University. "Beef is an excellent source of many nutrients, including zinc, iron and protein. We sometimes call that the 'zip factor' in nutrition, because these nutrients help build and maintain lean muscles, maintain the health of our blood and help regulate several body processes. Beef also provides minerals such as selenium, phosphorus and magnesium, along with several B vitamins. In particular, only animal products contain vitamin B-12," she said. "Therefore, completely excluding all animal-based products from your diet could result in a type of anemia, fatigue and long-term issues."