Higher levels of folate (vitamin B9) have been found to be linked to less wheezing and a reduced likelihood of developing asthma.

People with the lowest folate levels had a 40 percent increased risk of wheezing, and a 16 percent higher risk of asthma compared with those who had the highest levels of folate.

http://www.medicalnewstoday.com/articles/150466.php

Hi there Franky -
This is another of your posts that got me all excited - until I realised that I hadn't a clue as to how much folate was too little, enough or too much.... I am sure that 'less than eight nanograms per milliliter of blood' says something to a researcher - but it doesn't help me.... Can you throw any light?

Without access to blood tests, one can only follow oral dosage recommendations.

Adults need at least 400 micrograms of folic acid daily, and pregnant women are advised to take 600 mcg. However, up to 2,000 mcg daily can be given as a 'therapeutic' dose, so perhaps one could start with 400 mcg and see how that goes, before gradually increasing the dose, if needed.

Some nutritionists recommend combining folic acid with vitamin B12.

Folic acid and indeed any B vitamin should always be taken in conjunction with the other B vitamins either in a B complex or a multivitamin product; they work in synergy and it always worries me when people take a shed-load more of one than the others, like doctors used to advise women to take extra B6 all the time for PMS. Drove me mad!