Folate is a water-soluble B vitamin that is found naturally in a variety of foods. Excellent food sources of folate include asparagus, bran flakes, broccoli, Brussels sprouts, chickpeas, dried beans, lentils and spinach.
Folic acid is the synthetic form of folate that can be found in most supplements and is added to fortified foods (such as bread and breakfast cereals).
As well as a healthy diet (with at least 600 mcg of folate), it is recommended that women planning a pregnancy take an additional 400 mcg of folic acid each day for at least one month before and three months after conception.
Pregnancy supplements typically have 400 mcg or more of folic acid and I find most women planning pregnancy are taking a pregnancy supplement before becoming pregnant
Folic acid is more easily absorbed than naturally occurring folate, but this is not a major issue in deciding which to take. Indeed the answer to which is best is that ‘both’ are important.