By Ingvild Eide Graff
Although most of us are starting to feel that winter is letting go and spring is awakening, our vitamin D level is actually at its lowest right now. People can produce vitamin D in the skin from sunlight, but it is a long time since September 2014, when the sunlight was strong enough for us to produce the vitamin in our skin. Since early autumn, our bodies have depended on vitamin D from food, and not many types of food contain vitamin D. For most of us, our vitamin D status therefore steadily decreases until it reaches its annual low in April. That’s right – now. And it will take some time to reverse the level: The April sun is not nearly as effective as the May and June sun when it comes to producing vitamin D. We actually have to wait until late summer before our vitamin D status is back on top.
We can do something about this if we think a bit about what we eat. The health authorities recommend an intake of 10 micrograms of vitamin D every day. In 100 grams of herring, there are 25 micrograms of vitamin D. This means that two toppings of herring on your bread at lunchtime will give you enough vitamin D that day. Mackerel, halibut and salmon also contribute, but these species contain a little less vitamin D per portion. There is also some vitamin D in eggs, and certain dairy products such as butter, milk and cheese have been enriched with vitamin D. In Norway, cod liver oil is recommended for all children from around the age of four weeks, and this is an important contribution to ensuring sufficient vitamin D and marine omega-3 fatty acid levels.
Vitamin D deficiency in children can lead to the bone disease rickets. Vitamin D deficiency in adults can lead to a bone disease called osteomalacia. In Norway, few people’s vitamin D intake is so low that it has such serious consequences. Nevertheless, many Norwegians have a lower intake of vitamin D than recommended, especially in winter, and we know too little at present about what consequences such suboptimal vitamin D levels can have on our health. Among other things, it has been speculated that it may be important in relation to both obesity and mental disorders.
Some population groups are more at risk of vitamin D deficiency than others, especially people who eat little fatty fish and other types of seafood. Food consumption surveys in Norway have found that children and young women have a lower seafood intake than others, and they should therefore take special care to ensure that they get enough vitamin D, either by increasing their seafood intake or from other sources. Since dark skin produces less vitamin D than light skin, certain groups of immigrants in Norway are also at particular risk of deficiency.
The following is not an April Fool’s joke in FiskeribladetFiskaren: Your vitamin D status is now at its lowest, and if you want to do something about it, you should increase your intake of fat fish, semi-skimmed milk enriched with vitamin D, or cod liver oil. And if you want to stick to food that has a natural high ‘sun vitamin’ content: Herring is king of vitamin D!
Printed in the newspaper FiskeribladetFiskaren, 1 April 2015.