Folic acid deficiency is a leading cause of neural tube defects, which can cause a large number of serious and debilitating conditions to babies in the womb, including spina bifida.  

Flour is already fortified with calcium, niacin, thiamine and iron to improve public health. The government says the move to include folic acid will reduce neural tube defects by 20% in the UK and improve the health of pregnant women. It will also deliver savings of around £20m to the NHS over 10 years and boost the economy by more than £90m over 10 years.

Professor Chris Whitty, England's chief medical officer, said: 'The fortification of flour is a simple and effective way to help to reduce cases of neural tube defects, although it is important that women who are pregnant or intending to become pregnant continue to take folic acid supplements before and during the first 12 weeks of pregnancy.'

The changes will apply to the whole of the UK. Wales, Scotland and Northern Ireland will introduce their own regulations in due course.

Minister for food security, Daniel Zeichner, added: ‘Fortified flour has been providing our country with a public health boost for 80 years and this latest collaboration across government will help give the nation's children a strong start in life.

‘We are grateful to industry for their efforts to support a smooth transition, with manufacturers having a 24-month transition period to adjust their processes.'