It's a question more people are starting to ask and for good reason
Int J Med Sci 17(3):310 Karussis D (2014) The diagnosis of multiple sclerosis and the various related demyelinating syndromes: a critical review
However, you can adjust the frequency based on your individual needs and preferences
On a voluntary basis, foods such as breakfast cereals, cereal bars, cereal snacks, crisp bread, pasta, baby foods, biscuits, buns, cakes, pastries, milk, milk powder, dairy products, sweets, fruit juices, coffee, cocoa, soft-drinks, soy products, dried soups, margarine, fat spreads, and table salt, are fortified with folic acid 98,122,174,224,300,458,559,614,642,643,654,660,666,671,688,692,694,695,696,697,698,701,725,726,727,728,729,730,731,732,733,734,735,736