Where’s the beef? Clearly it’s here in the U.S., where beef dominates the retail meat department in volume of sales and total dollar amount. A three-ounce serving of lean beef is a great source of protein, zinc, vitamin B12, selenium, and phosphorus and also provides niacin, vitamin B6, iron, and riboflavin. The best beef will be aged 18 to 24 months when you buy it. Ground beef is by far the most popular cut available; other tender cuts can be grilled, broiled, roasted, or stir-fried.