Vitamin B12 is a necessary nutrient in humans, and the only sources are dairy, meat derived from land animals, fortified nutritional yeast, seafood, fortified food products and vitamin B12 supplements. Without sufficient intake of Vitamin B12 we will become deficient of it and develop pernicious anemia, which is a condition where our blood cells become oddly shaped, and they fail to do its job of supplying oxygen to our body.
I mention this vitamin because if a person were to omit dairy and land animal sources of foods and do not use vitamin B12 supplement or eat seafood in regular intervals, there is a large chance that you can become deficient in vitamin B12. I cannot suggest a vegan or seafood diet to anybody without mentioning the importance of maintaining constant intakes of vitamin B12.
It does not matter how much whole foods or nutritious foods a person eats, if she does not eat specific foods that contain vitamin B12 she may suffer the effects of deficiency. So what can a person do to make sure his intake of vitamin B12 is sufficient? He can eat seafood on a weekly basis. Because seafood contain vitamin B12, eating it on a weekly basis can ensure adequate intake of vitamin B12. If you decide to be vegan by eating plant-based foods exclusively, then you would either need to incorporate fortified nutritional yeast, take vitamin B12 supplements, or eat foods that are fortified with vitamin B12.
You can buy fortified nutritional yeast online or at Whole Foods grocery store, and it is not that expensive. It also tastes pretty good, but I can imagine that some people may not like the taste of it. You may incorporate it into your cooking. For instance, you can sprinkle it on a salad or sprinkle some into a bowl of noodles. You may also mix some into spaghetti sauce or in to bread dough. The options are limitless.
For people that would like to use supplements, there are tablets, capsules, skin patches, nasal sprays, lozenges and injections. It is important to know that vitamin B12 is a water soluble vitamin, so any excess amount tends to be excreted into the urine. So there is no dangers in overdosing as long as one does not consume it in extreme excess. When people take vitamin B12 in large quantities, like in the case with taking supplements, its stores in the body will accumulate in the liver, enabling the body to go without vitamin B12 for a couple of years. So, as long as your intake of vitamin B12 is fairly consistent, you do not risk deficiency.
So, eating seafood and plant-based foods exclusively is healthy and nutritious as long as we keep in mind of intakes of vitamin B12. I want you to be able to be drug and alcohol free, and I believe you will be able to do it. Nutrition is very important for anybody, so I would like you to pay close attention to the quality of food that you eat. And always be mindful about vitamin B12 intake.