BBC NEWS | Health | Folic acid ‘reduces stroke risks’:

“olate is a water-soluble B vitamin that occurs naturally in food. Folic acid is the synthetic form of folate that is found in supplements and added to fortified foods

Both folic acid and vitamin B12 are essential for good health and good levels can be achieved by eating a healthy, balanced diet.

Green vegetables are rich in folic acid or folate, while B12 is found in foods such as eggs and meat.

Yet 13 million people do not consume enough folate, according to the Food Standards Agency.

How much?

The current advice is that all adults consume 200 micrograms of folate per day, and that women who are pregnant or thinking of having a baby should take a daily 400 microgram supplement from the time they start trying for a baby until the 12th week of pregnancy.”