The truth about the odd-tasting oils we were told were healthy

When many people struggled to eat a healthy diet, odd-tasting oils were touted as a fix-all. It turns out one of them did indeed pack a vitamin punch.

These days, the words “cod liver oil” are vaguely sepia-tinged. They conjure up an image of a murky spoonful of something, brandished by a school nurse or a Dickensian headmaster.

But cod liver oil is one of those rare remedies from the age of snake oil and patent medicine that actually had something to it. Made from heating the livers of codfish and catching the oil that leaks out, the stuff is fantastically rich in vitamin D and vitamin A. Before the discovery of vitamins – that would have to wait a few more years – people had noticed that children dosed with cod liver oil were less likely to develop rickets, the childhood bone disease from which the term “rickety” is derived and which can cause seizures and heart attacks.

So, decades ago, many governments turned to fortifying foods. In 1940, the UK began mandatory fortification of margarine with vitamin D. Bread, milk, and breakfast cereal manufacturers joined in. In the USA, fluid milk has been fortified with vitamin D by law since 1933, and breakfast cereals, bread and flour are all routinely, if voluntary, fortified. Even in the 21st Century, governments have changed policy to try to raise levels of vitamin D: Finland introduced its own voluntary fortification plan in 2003, with near-universal participation from food manufacturers.

There are likely a number of factors behind the rise of rickets in the UK. But it does suggest that something like the spoonful of cod liver oil might make a return.  

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