By drinking milk and eating bread fortified with vitamin D, it is possible to avoid vitamin D deficiency during the winter months, according to a PhD project from the National Food Institute, Technical University of Denmark.
Vitamin D is important for bone health and a lack of the vitamin can among other things cause osteoporosis. During the summer months we get the recommended intake of vitamin D through the sun producing the vitamin in our skin. However, during the winter months the recommended intake has to be met through our diet and possible dietary supplements.
Danes’ intake of vitamin D is clearly below the recommended level, especially in winter when many of us have a definite lack of the essential vitamin. Katja Howarth Madsen’s PhD project from the National Food Institute shows that our Vitamin D intake can be increased through food fortification
Fortification works
Almost 800 children and adults from about 200 families participated in Katja Howarth Madsen’s study. Half of the participants had their normal intake of milk and bread exchanged with vitamin D fortified products, while the other half drank normal milk and ate normal bread. The study took place over six months during the winter so that the participants were not affected by vitamin D from the sun.
Blood tests taken throughout the study showed that vitamin D status fell only slightly among the participants who were given fortified products. By the end of the study only 1% had a vitamin D status that would be described as deficient. However, among the participants who were not given fortified products 25% were vitamin D deficient when the study was over.
Fortification affects people differently
The study shows that intake of the vitamin does not have the same effect on everyone. For example vitamin D status was more similar in children from the same family than in their parents. This suggests that genes most probably play a role in relation to vitamin D status.
The study also shows that people with the highest vitamin D status in the autumn required a lower intake of the vitamin throughout the winter to maintain an adequate status than people who started the study with a low vitamin D status
Read more
Read the Danish summary of Katja Howarth Madsen’s PhD thesis: Vitamin D status and effects of food fortification in families (pdf).
A copy of the PhD thesis is accessible at the National Food Institute. When the articles in the thesis have been published the thesis will be made available at www.food.dtu.dk. Send an email to food@food.dtu.dk if you want to be notified when this happens.
Katja Howarth Madsen’s PhD project has also been described in the newsletter Food Culture: D-vitamin: Berigelse virker, viser forskning (available in Danish only).
Please also read the National Food Institute’s press release from June 2010: Begrænset viden om D-vitamin og sygdomme (available in Danish only).