The last paragraph of the article sums it all...

B vitamins are vital to our well-being. However, the best way to get them is through a well-balanced and healthy diet. Eggs, dairy, fish and meat are good sources of B12. Many products, like breakfast cereals and soy or rice milk, are fortified with the vitamin. If you do need a supplement, read the label carefully and choose a product that doesn’t provide more than the recommended daily allowance.

There is a publication that shows that the use of synthetic vitamins has been linked to the development of harmful conditions in the body.

Drugs should be used rationally. Taking above the daily recommended dose may be harmful.