Vitamin D deficiency in the UK is “not acceptable” as it is revealed that 23% of adults are not hitting their recommended daily intake.

Five of Europe’s leading nutritional scientists have spoken out following the issue revealed in the National Diet & Nutrition Survey last week.

A deficiency in the vitamin can lead to brittle bones in the elderly and under-fours as well as spina bifida in foetuses, which affects around one in 1,000 pregnancies.

Adding the vitamin to food is one solution and bakeries could be part of it by adding extra nutrients to flour. The industry is awaiting a government decision on the mandatory addition of folic acid - a B vitamin - to flour, which has been delayed until 2015. Experts claim fortifying flour this way could prevent 300 babies a year from developing spina bifida and other birth defects.

However, conversely, experts have also called for more research to be done into the effects of high vitamin D intake.

The EU recommendation for children and adults is five micrograms or 200 IU per day while the UK recommends 10 micrograms for over-65s.

In 2009 yeast-maker GB Ingredients’ owner Lallemand pioneered a new yeast containing vitamin D brought about naturally from ultra-violet action on the yeast. Two slices or 100g of bread made with Vitamin D yeast provide 15% of the recommended intake.