Hi N.,
Check out the books "Disease proof your child" and "Eat to Live". The author, Dr. Fuhrman, promotes an (almost) vegan diet as a means to achieving health. He provides scientific study after study (unlike Dr. Mercola - whose test groups are usually small and time periods short) to back up his recommendations. His book geared towards kids has recipes and nutritional guidelines to help you feed your child enough plant based fat and protein, while stocking them full of all of the other really good stuff. Good luck!
Oh, to specifically answer your question:
Pro: if approached properly your children will (statistically) be healthier
Con: a lot more work and research than just going along with the diet that is encouraging our nation's health crises. A child can be severely malnourished and overweight - by eating a diet that does not incorporate plant foods. Any diet takes consideration, effort, research and balance. My family is not vegan, because I am too lazy (honestly) to make it work and be healthy. But, I think it can not only be healthy but can be healthier than the average American Diet. Look at our national rates of heart disease, obesity and diabetes. It's not coming out of no where.
I want to add the following information, so that I'm not making strong statements without backing them up:
Comparison of Iron Sources
Food Iron (mg/100 calories)
Spinach, cooked 5.4
Collard greens, cooked 3.1
Lentils, cooked 2.7
Broccoli, cooked 2.1
Potato, baked 1.3
Blueberries 0.4
Sirloin steak, broiled 1.6
Hamburger, broiled 0.8
Chicken, no skin, 0.6
Turkey, breast, 0.4
Pork chop, pan fried, 0.2
Notice that, per calorie, vegetable sources are higher in Iron
Protein Sources
Keep in mind that a toddler needs around 16 grams of protein a day. Supplement with a b12 vitamin, which is missing in a Vegan diet.
Food Grams of protein
Almonds (3 oz) 10
Banana 1.2
Broccoli (2 cups) 10
Brown rice (1 cup) 5
Chickpea (1 cup) 15
Corn (1 cup) 4.2
Lentils (1 cup) 18
Peas - frozen (1 cup) 9
Spinach - frozen (1 cup) 7
Tofu (4 ounces) 11
Whole wheat bread (2 slices) 5
Calcium is a funny one, because while a food may be high in it, the human body is not actually able to absorb all of it. Here is a comparison of what is eaten vs. what is absorbed.
100 calories of - calcium - percentage and amount absorbed
Skim milk - 334 mg - 32% - 107 mg
Kale - 449 mg - 59 % - 435 mg
Bok choy - 787 mg - 54 % - 435 mg
Broccoli - 189 mg - 53 % - 100 mg
Calcium Content of Common Foods
Almonds, raw (1/2 cup) 180 mg
Orange, (2) 120 mg
broccoli (1 cup) 180 mg
Raisins (1/2 cup) 60 mg
Spinach (1 cup) 244 mg
Sesame seeds (1/4 cup) 350 mg
Tofu (1 cup) 300 mg
"When you eat less animal protein and less salt, you do not lose as much calcium in the urine and therefore need less calcium. Excess animal protein and sodium promote excessive calcium loss in the urine, increasing calcium requirements."