Harvey is vegetarian, but he has no allergies, so we can follow a dairy diet. The main concerns are iron and B vitamins. We try to add iron to Harveys diet using fortified cereals & vegetables, the same for B vitamins (which is not such a big concern for us as he has dairy). Eventually we may have to move to supplements as he gets older.
Still it's not as simple as that, the human body doesn't absorb non-haem iron (found in plants, fortified cereals & pulses) as easily as it can absorb haem iron (only found in animal food sources), so you have to be careful to get the balance of a meal correct, as some foods will inhibit iron absorption (spinach, chard, beet greens, rhubarb, sweet potato, whole grains, coffee, tea, bran & Soy products), and some can help the absorption (Orange, Orange Juice, Cantaloupe, strawberries, grapefruit etc Broccoli, brussels sprouts, tomato, tomato juice, potato, green & red peppers).
For B vitamins it can help if your lo is a Marmite fan.
We provide Harveys omega 3 + 6 using flaxseed(golden linseed) and Pure vegetable spread (which is vegan btw).
As with most things that are diet related, what's essential is a healthy balanced meal, and then nearly everything else falls into place.
I'm not sure how much research you've done, but the Vegan society will no doubt have reference for vegan infants that should be able to help you.
HTH
