The researchers from the University Medical Center in Nijmegen and the Erasmus University Medical Center in Rotterdam say that the preventive effects of nutrients other than folate on the occurrence of spina bifida is scarce.
Each year about 3 per cent of all new births around the world are affected with major structural birth defects, according to recent research, or more than 4 million each year. The primary cause of infant mortality and disabilities among children in industrialized countries, up to 70 per cent are thought to be preventable if a mother has adequate intake of folic acid around the time of conception.
But risk of spina bifida may also be three times higher for mothers with a low iron intake, suggests the new study, published in this month's Journal of Nutrition (134:1516-1522).
The researchers compared data on nutrient intakes from 106 mothers with spina bifida babies with 181 controls, using a food frequency questionnaire around two years after conception.
Case mothers had significantly lower intakes of plant proteins (7 per cent), polysaccharides (4 per cent), fibre (7 per cent), iron (6 per cent), magnesium (6 per cent), and niacin (4 per cent) than control mothers.
Mono- and disaccharide intakes were also 6 per cent higher in the case mothers than in control mothers.
Risk of spina bifida was 2.5 times higher for mothers in the lowest quartile of niacin intake and 5.4 times higher for plant proteins.
Those with the lowest iron intake appeared treble the risk, as did low fibre intake.
The researchers concluded that "low preconceptional intakes of plant proteins, iron, magnesium, and niacin are associated with a two- to five-fold increased risk of spina bifida".