From Fox News:
One of the most nutrient-dense foods people can eat is also one of the cheapest, yet most Americans turn up their noses at it. Organ meats — including kidneys, liver and heart — are also known as offal. They’re packed with protein while often containing more vitamins and minerals than premium muscle cuts, according to the Cleveland Clinic.
A 3-ounce serving of beef liver, sometimes called “nature’s multivitamin,” contains an average of 70.7 micrograms of vitamin B12, according to the National Institutes of Health. The same amount of top sirloin steak, meanwhile, typically contains 2.41 micrograms of B12, per the U.S. Department of Agriculture (USDA).