Folic acid should be routinely added to all white and brown wheat flour, the British Food Standards Agency (FSA) has recommended.
The aim of the move is to cut birth defects such as spina bifida.
If made compulsory, it would affect flours used to make bread and other products such as cakes and biscuits.
The food watchdog last month agreed to recommend that folic acid should be added to bread or flour.
However, the FSA’s Board members wanted more time to decide exactly which food would be fortified.
Papers for the next board meeting, released tonight, say mandatory fortification of all white and brown wheat flours should be recommended to UK health ministers.
The folic acid contained in these products should be labelled, the board papers say.
And the potential for a labelling threshold should be looked into for products where folic acid levels are not “nutritionally significant”.
Around 4.4 million tonnes of flour is produced in the UK at a value of just under £1bn (€1.47bn) per year.
The FSA’s Board will consider the issue at Thursday’s meeting and finalise its advice to health ministers.
Adding folic acid to all wheat flour rather than just bread has “significant practical advantages”, the board papers say.
Wholemeal flour – which has more natural folate than white or brown flour - could be exempt from fortification in order to give consumers more choice, they add.
However, organic flour may not be exempt, with the board papers saying: “… there is no evidence to suggest that organic white and brown flours contain more natural folate than non-organic flours.”
Folic acid is a synthetic form of the B vitamin folate.
It is found naturally in some foods including broccoli, Brussels sprouts, asparagus, peas, chickpeas and brown rice.
Women who plan to get pregnant are already advised to increase their folate intake because it prevents neural tube defects (NTDs) such as spina bifida in unborn babies.
However, this strategy is not effective because about half of pregnancies are unplanned.
Folate helps to form healthy red blood cells.
At last month’s meeting, the FSA board agreed that fortifying food with folic acid was the best way of reducing NTDs in the UK.
It said new controls on the voluntary addition of folic acid to food by manufacturers will be essential if the measure was made essential.
The FSA board rejected mandatory fortification five years ago due to lack of available evidence about possible risks and benefits.
A final decision on whether folic acid is compulsorily added to white and brown wheat flour will rest with Government.