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- Reporter, Veronique Greenwood
- Reporter, BBC News
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7 hours ago
At a time when many people were concerned about eating healthy, an oil with a strange taste was advertised as a panacea. However, it turned out that one of the oils actually contained a lot of vitamins.
When you hear the word ‘cod liver oil,’ a faint brown liquid comes to mind. It reminds me of the cloudy liquid that a school nurse or a principal in a Charles Dickens novel would pour out by the spoonful for a sick student.
Many treatments popular in the 18th and 19th centuries have not stood the test of time. For example, we no longer give opiates to crying babies. Fig syrup and castor oil may be somewhat effective for constipation, but they are no longer considered panaceas. It’s hard to tell when people stopped buying sulfur and molasses at pharmacies.
Among the treatments available in an era when fake and patented medicines were mixed, cod liver oil is a rare example of actually having health-related benefits. Liver oil is made from the oil produced by heating cod liver, and is rich in vitamin D and vitamin A. Even before academics discovered the nutrient called vitamins, people knew from experience that children who consumed cod liver oil were less likely to develop rickets, a childhood bone disease that can cause seizures and heart attacks.
Photo caption: In the past, children suffered from the fishy taste of cod liver oil, but its health benefits may not be exaggerated.
The amazing efficacy of cod liver oil received attention again in 1919 when it was discovered that calcium deficiency and vitamin D deficiency were the causes of rickets. So during World War II, the British government gave cod liver oil free to children under 5 years old. A poster was created that said, “Don’t forget the orange juice and cod liver oil!”
Whatever its other properties, cod liver oil is often not easy to swallow. Like other oils, when it comes into contact with oxygen, it becomes rancid and produces a fishy smell. But the less unpleasant alternative of obtaining vitamin D – exposure to sunlight and letting enzymes produce vitamin D under the skin’s surface – is as difficult to achieve for British children as it was 100 years ago. (And with the Korea Meteorological Administration predicting that winter rain will increase 30% by 2070 compared to 1990, the situation is likely to get worse.) So several decades ago, governments turned to foods fortified with vitamin D. Britain also mandated fortification of margarine with vitamin D starting in 1940. And bread, milk, and cereal manufacturers also joined this trend. The United States has been enforcing a law to fortify vitamin D in powdered milk since 1933. Even in the 21st century, there are countries that have increased the vitamin D content in food through policy. A representative example is Finland, which introduced its own voluntary reinforcement plan in 2003 with the full participation of food manufacturers.
However, in the UK, plans to fortify foods with vitamin D encountered obstacles from the start. A disease called ‘hypercalcemia’ was discovered where excess calcium in the blood causes kidney stones and various other problems. Experts at the time assumed that children were overdosing on vitamin D, and accordingly, in the 1950s, the British government banned the use of vitamin D fortifiers except margarine and infant formula.
Photo captionFortifying certain foods, such as milk, with vitamin D reduces the need to consume vitamin D-rich oils
However, this does not mean that the era of Ganyu has returned immediately. The UK stopped fortifying margarine with vitamin D in 2013 in the name of encouraging supplement consumption (few people will listen to or even know about this suggestion). However, as testing methods for vitamin D levels have improved in recent years, a surprising fact has been revealed.
Between January and March, when sunlight is at its lowest point of the year, a significant proportion of British children (nearly 40% in some age groups) are deficient in vitamin D. About 30% of adults also show similar patterns. The situation was especially serious for people with darker skin.
Judith Buttress, a public health nutritionist at the British Academy of Nutritional Sciences, wrote in an editorial in the Journal of Nutrition, “Vitamin D deficiency among South Asians in the UK is an almost universal phenomenon.”
Rickets also returned. Hospitalizations for rickets in the UK have declined steadily over the decades, following a decline in the 60s and 70s. Looking at statistics from 1991 alone, there were 0.34 cases of rickets per 100,000 people under the age of 15 in the UK. However, in the 2000s, the incidence of rickets began to rise and showed a sharp increase. In 2011, an academic report was published saying, “The hospitalization rate for rickets in the UK has reached the highest level in 50 years.”
So, are foods fortified with vitamin D needed again? The UK’s Nutrition Science Advisory Committee is said to be considering this option. Cases of hypercalcemia that occurred in the UK after eating vitamin D-fortified foods are believed to have occurred due to a genetic disease that interferes with vitamin absorption. This means that eating a lot of fortified foods does not necessarily cause problems. Because of this, things may change in the future.
Of course, there may be several factors contributing to the increase in rickets in the UK. However, there is also the prospect that the era of people taking a spoonful of cod liver oil may come again in this situation.
