Your baby resembles a tadpole more than a human, but is growing fast. The circulatory system is beginning to form, and the tiny heart will start to beat this week. Your baby is the size of a sesame seed. Read about your pregnancy at 5 weeks.
Stores of B12 can last for up to a year. Foods high in Vitamin B12 include shellfish, liver, fish, crab, fortified soy products (tofu, soymilk), fortified cereals, red meat, low fat dairy, cheese, and eggs.
Which foods contain it: Vitamin B-12 is found primarily in meat and dairy products, so anyone on a strict vegan diet is at risk for deficiency. The only source of B-12 is through fortified foods. Some of the best sources of vitamin B-12 include: 1  eggs.  cheese (one serving is the size of a domino)