Pregnant women pass vitamin D on to their babies at a much higher extent than previously thought, scientists have discovered.

Vitamin D is essential for healthy bones, but is present in very few foods. It is also known as the sunshine vitamin, because it is made in the body when ultraviolet rays from sunlight strike the skin. However, Ireland's northerly latitude and lack of winter sunlight means that we cannot make enough vitamin D in this way. As a result, some people choose to take supplements.

According to UK and Greek scientists, current research indicates that around 19% of a newborn baby's supply, or deficiency of vitamin D, comes from its mother. However, they have discovered that the true figure is around 56%.

The team came up with this figure after using a new measuring technique, which they developed. This technique is able to examine eight different types of the vitamin in more detail for the first time.

The scientists examined 120 samples taken from 60 mothers and their babies. All were from Greece. The study found that even though Greek people see more sunshine than people in the UK and Ireland, many of those examined still had low levels of vitamin D, indicating that diet is still an important source.

According to Prof Declan Naughton of London's Kingston University, the results emphasised the importance of pregnant women obtaining enough vitamin D via their diet, as well as through sunshine exposure. Good dietary sources include oily fish, such as salmon, egg yolks and fortified foods, such as milk and breakfast cereals.

"The impact that mothers deficient in vitamin D have on their babies' levels is a much bigger problem than we thought. Maintaining good supplies during pregnancy is clearly of vital importance for both mothers' and babies' long-term health," Prof Naughton said.

He noted that a lack of vitamin D during pregnancy has been linked to a range of health issues, such as an increased risk of a caesarean section and smaller than average babies. In children, it can cause rickets, which causes a bending or distortion of the bones.

A recent report on Irishhealth.com revealed that this condition is ‘re-emerging' in Ireland. For more, see here.

Details of these findings are published in Nutrition Journal.