Vitamin D supplements needed to prevent rickets
prevent a resurgence of rickets, say researchers in a seminar
published in tomorrow's issue of The Lancet. Experts have
been warning of rising cases of the bone disease in European and US
populations in recent years. The UK team goes further by
specifically recommending supplementary intakes.
Pregnant women and children should take vitamin D supplements to prevent a resurgence of rickets, say researchers in a seminar published in tomorrow's issue of The Lancet.
Rickets - a common disease in the last century - is still a global public health problem, warn Brian Wharton from the Institute of Child Health in London and Nick Bishop from the University of Sheffield. Several current lifestyle factors are making the resurgence of the disease a possibility.
These include the promotion of exclusive breastfeeding for long periods without vitamin D supplementation, particularly for babies whose mothers are vitamin D deficient. There are also reduced opportunities for production of the vitamin in the skin because of female modesty and fear of skin cancer.
The study also reveals a high prevalence of rickets in immigrant populations in more temperate regions.
Rickets is the failure to mineralise new bone tissue. A lack of vitamin D inhibits a key stage of the bone formation process. Calcium and phosphate are also involved in bone development and researchers in the US have connected a lower calcium intake to the increasing cases of rickets there.
Diet becomes an important source of vitamin D only when there is inadequate exposure to sunshine, the case in much of the northern hemisphere. Data included in the new report show the very low vitamin D intakes of UK children. Even though most of the intake is from fortified foods, such as cereals or yellow spreads, most children would need supplements to reach the recommended daily allowance, yet only half take dietary supplements, write the researchers.
"A safety net of extra dietary vitamin D should be re-emphasised, not only for children but also for pregnant women," write the researchers.
They failed to explain the prevalence among immigrant populations however. "The reason why many immigrant children in temperate zones have vitamin D deficiency is unclear. We speculate that in addition to differences in genetic factors, sun exposure, and skin pigmentation, iron deficiency may affect vitamin D handling in the skin or gut or its intermediary metabolism," they added.
The seminar urges all pregnant women living outside the tropics to receive a supplement of 10-25 ug of vitamin D daily during the second and third trimester of pregnancy. Children should also take supplements up to the age of puberty, especially those from communities with low consumption of milk.
Schemes promoting subsidised unfortified foods, such as milk, should also be reviewed, noted the researchers.
The EU Scientific Committee on Food recommends an upper safe limit of 50 ug vitamin D daily for adults, while a recent UK expert group advised 25 ug for daily supplementation.
European researchers are also investigating whether fortification of food with vitamin D is a feasible strategy to remedy the insufficient vitamin D status in European populations, and to determine at what level fortification should be pitched. The Optiford project is focusing on three groups - teenage girls, the elderly and Muslim families - to assess the dose levels that could benefit bone accretion in these groups.
