Hello!
I am really upset that a Whole Foods employee would give you that kind of advice. The CEO of Whole Foods is actually basically a vegan (he eats eggs from his own hens), and Whole Foods has launched the huge Health Starts Here program based off of the Engine 2 Diet by the son of one of the doctors who wrote the China Study. Health Starts Here is a no oil, completely vegan diet. So even though that employee scared you with his opinion wearing the Whole Foods apron - Whole Foods as a company believes that veganism is a healthy way to live.
It's true that there are many different factors that go into vitamins. My sister eats chicken, fish, and dairy in her diet and has a B12 deficiency! She does not absorb B12 through the vitamin form and has to inject herself with a B12 shot once a month. On the contrary, my friend has been vegan for 5 years. She started experiencing fatigue from her busy schedule at school and went to a new doctor who was convinced she was lacking B12 along with several other vitamins. They tested her only to find that her B12 levels was better than the average person - and she doesn't even take vitamins but instead gets b12 through supplemented vegan foods.
My personal understanding of B12 is that it comes from bacteria, not animals. The animals consume the bacteria from eating in from the ground, and we are consuming the vitamins that they have consumed from plants in many cases. Vitamins are tricky business - but a simple test at the doctor's office every couple of years can keep track of your vitamin levels as well as your kids. I would suggest buying the highest quality of vitamins available to you. I purchase The raw Code vitamins, which come from food. I also drink and eat tons of vegetarian foods supplemented with B12. Also, remember all of the people who have been vegan for decades and are still shining examples of health. A vegan diet can be one of the healthiest diets in the world. Focus on eating whole foods more than processed foods and get a check-up every once in a while, and I bet you'll do great :)