Dosing up the nation with folic acid is not the answer to cutting defects. A targeted campaign and more research is so much more practical

When is the government going to get the message that people don't want to be told what to eat? 

The latest 'we know what's best for you' prescription coming from the Food Standards Agency is that it wants to add folic acid to the nation's bread and flour to cut the incidence of neural tube defects.

But blanket medication of the population is a blunt weapon. Half a million Britons - men, women and children, including the aged and infertile - will have to consume this synthetic vitamin for every baby saved. 

Instead, the government should be running a focused campaign targeted specifically at schoolgirls and women of childbearing age.

This would stress the need for natural folate in the diet - in the form of foods such as cabbage, peanuts, lettuce and even pizza - and encourage young women to eat wholemeal bread, possibly by handing out free tokens.

Failing that, it could fall back on recommending that pregnant women take folic acid supplements - the synthetic equivalent of folate - with the option of injections for those who find pill-taking impractical.

But the government line is that a minority of pregnant girls are too hapless to keep taking the pills, and therefore the only alternative is dosing up the whole population.

It isn't just rampant libertarians who will object to this measure. Many people simply don't trust the government to get the science right.

It is true that mandatory folic acid fortification in the US has substantially reduced the incidence of defects such as spina bifida.

However, evidence is also emerging that by masking the symptoms of anaemia in older people it is contributing to a rise in dementia.

Some studies also suggest that folic acid speeds up the progress of certain cancers. And does folic acid affect the body in exactly the same way as natural folate? Nobody knows - so let's have some research before we pour sackloads of the stuff into the nation's staple food.

There is always going to be a tiny minority that never pays a blind bit of attention to public health campaigns. But surely we can't gear our entire public health policy around it ? 

Ultimately, we have to trust that most people, when given a proper explanation, advice and a clear summary of the advantages and disadvantages, will make a sensible choice about what they eat. n

Joanna Blythman is the author of Bad Food Britain