produce vitamin B12 the animal must consume sufficient amounts of cobalt. Soil that is deficient in cobalt may result in B12 deficiency, and B12 injections or cobalt supplementation may be required for livestock. Animal-derived foods Animals store vitamin B12 from their diets in their livers and muscles and some pass the vitamin into their eggs and milk. Meat, liver, eggs and milk are therefore sources of the vitamin for other animals, including humans. For humans, the bioavailability from eggs is less than 9%, compared to 40% to 60% from fish, fowl and meat. Insects are a source of B12 for animals (including other insects and humans). Animal-derived food sources with a high concentration of vitamin B12 include liver and other organ meats from lamb, veal, beef, and turkey; also shellfish and crab meat. Plants and algae Natural plant and algae sources of vitamin B12 include fermented plant foods such as tempeh and seaweed-derived foods such as nori and laver. Other types of algae are rich in B12, with some species, such as Porphyra yezoensis, containing as much cobalamin as liver. Methylcobalamin has been identified in Chlorella vulgaris. Since only bacteria and some archea possess the genes and enzymes necessary to synthesize vitamin B12, plant and algae sources all obtain the vitamin secondarily from symbiosis with various species of bacteria, or in the case of fermented plant foods, from bacterial fermentation. The Academy of Nutrition and Dietetics considers plant and algae sources "unreliable", stating that vegans should turn to fortified foods and supplements instead. Fortified foods Foods for which vitamin B12-fortified versions are available include breakfast cereals, plant-derived milk substitutes such as soy milk and oat milk, energy bars, and nutritional yeast. The fortification ingredient is cyanocobalamin. Microbial fermentation yields adenosylcobalamin, which is then converted to cyanocobalamin by addition of potassium cyanide or thiocyanate in the presence of sodium nitrite and heat. As of 2019, nineteen countries require food fortification of wheat flour, maize flour or rice with vitamin B12. Most of these are in southeast Africa or Central America. Vegan advocacy organizations, among others, recommend that every vegan consume B12 from either fortified foods or supplements. Supplements Vitamin B12 is included in multivitamin pills; in some countries grain-based foods such as bread and pasta are fortified with B12. In the US, non-prescription products can be purchased providing up to 5,000µg each, and it is a common ingredient in energy drinks